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Mediator kinases CDK19 and CDK8, pleiotropic regulators of transcriptional reprogramming, are differentially regulated by androgen signaling, but both kinases are upregulated in castration-resistant prostate cancer (CRPC). Genetic or pharmacological inhibition of CDK8 and CDK19 reverses the castration-resistant phenotype and restores the sensitivity of CRPC xenografts to androgen deprivation in vivo. Prolonged CDK8/19 inhibitor treatment combined with castration not only suppressed the growth of CRPC xenografts but also induced tumor regression and cures. Transcriptomic analysis revealed that Mediator kinase inhibition amplified and modulated the effects of castration on gene expression, disrupting CRPC adaptation to androgen deprivation. Mediator kinase inactivation in tumor cells also affected stromal gene expression, indicating that Mediator kinase activity in CRPC molded the tumor microenvironment. The combination of castration and Mediator kinase inhibition downregulated the MYC pathway, and Mediator kinase inhibition suppressed a MYC-driven CRPC tumor model even without castration. CDK8/19 inhibitors showed efficacy in patient-derived xenograft models of CRPC, and a gene signature of Mediator kinase activity correlated with tumor progression and overall survival in clinical samples of metastatic CRPC. These results indicate that Mediator kinases mediated androgen-independent in vivo growth of CRPC, supporting the development of CDK8/19 inhibitors for the treatment of this presently incurable disease.

The eukaryotic transcriptional Mediator comprises a large core (cMED) and a dissociable CDK8 kinase module (CKM). cMED recruits RNA polymerase II (RNA Pol II) and promotes pre-initiation complex formation in a manner repressed by the CKM through mechanisms presently unknown. Herein, we report cryoelectron microscopy structures of the complete human Mediator and its CKM. The CKM binds to multiple regions on cMED through both MED12 and MED13, including a large intrinsically disordered region (IDR) in the latter. MED12 and MED13 together anchor the CKM to the cMED hook, positioning CDK8 downstream and proximal to the transcription start site. Notably, the MED13 IDR obstructs the recruitment of RNA Pol II/MED26 onto cMED by direct occlusion of their respective binding sites, leading to functional repression of cMED-dependent transcription. Combined with biochemical and functional analyses, these structures provide a conserved mechanistic framework to explain the basis for CKM-mediated repression of cMED function. [Display omitted] • Structures of the complete human Mediator and its CDK8 kinase module (CKM) are presented • CKM binds cMED through MED12 and the intrinsically disordered region (IDR) of MED13 • MED13 IDR blocks RNA Pol II/MED26 from binding to cMED by occupying their binding sites • Human and yeast MED13 share a conserved mechanism for transcriptional repression Chao and Chen et al. present cryo-EM structures of the complete human Mediator and its CDK8 kinase module (CKM). The CKM uses its MED13 IDR to occupy RNA-polymerase-II- and MED26-binding sites, blocking their interactions with Mediator and repressing Mediator-dependent transcription—a mechanism conserved in humans and yeast. [ABSTRACT FROM AUTHOR]

Recent studies indicate that replication checkpoint modulators (RCMs) such as inhibitors of CHK1, ATR, and WEE1 have promising monotherapy activity in solid tumors, including platinum-resistant high grade serous ovarian cancer (HGSOC). However, clinical response rates are generally below 30%. While RCM-induced DNA damage has been extensively examined in preclinical and clinical studies, the link between replication checkpoint interruption and tumor shrinkage remains incompletely understood. Here we utilized HGSOC cell lines and patient-derived xenografts (PDXs) to study events leading from RCM treatment to ovarian cancer cell death. These studies show that RCMs increase CDC25A levels and CDK2 signaling in vitro, leading to dysregulated cell cycle progression and increased replication stress in HGSOC cell lines independent of homologous recombination status. These events lead to sequential activation of JNK and multiple BH3-only proteins, including BCL2L11/BIM, BBC3/PUMA and the BMF, all of which are required to fully initiate RCM-induced apoptosis. Activation of the same signaling pathway occurs in HGSOC PDXs that are resistant to poly(ADP-ribose) polymerase inhibitors but respond to RCMs ex vivo with a decrease in cell number in 3-dimensional culture and in vivo with xenograft shrinkage or a significantly diminished growth rate. These findings identify key cell death-initiating events that link replication checkpoint inhibition to antitumor response in ovarian cancer. [ABSTRACT FROM AUTHOR]

Mcm10 plays an essential role in the activation of replicative helicase CMG through the cell cycle-regulated interaction with the prototype MCM double hexamer in Saccharomyces cerevisiae. In this study, we reported that Mcm10 is phosphorylated by S-phase cyclin-dependent kinases (S-CDKs) at S66, which enhances Mcm10--MCM association during the S phase. S66A single mutation or even deletion of whole N-terminus (a.a. 1-128) only causes mild growth defects. Nevertheless, S66 becomes indispensable in the absence of the Mcm10 C-terminus ((a.a. 463-571), the major MCM-binding domain. Using a two-degron strategy to efficiently deplete Mcm10, we show that mcm10-S66AΔC has a severe defect in proceeding into the S phase. Notably, both lethality and S-phase deficiency can be rescued by artificially tethering mcm10-S66AΔC to MCM. These findings illustrate how the Mcm10-MCM association is regulated as a crucial event in DNA replication initiation. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) is a heterogeneous disease characterized by significant global mortality and incidence rates. Annually, approximately 1 million cases of BC are diagnosed worldwide, with over 170,000 classified as triple-negative. Triple-negative breast cancer (TNBC) is a particularly aggressive subtype lacking targeted therapeutic options, which contributes to poorer outcomes compared to other BC subtypes. The five-year survival rate for patients with TNBC is roughly 30% lower than that for patients with other subtypes. TNBC treatment options are limited to surgery, radiotherapy, and chemotherapy. There is a critical need for the development of targeted therapies. Enhancing early detection through effective diagnostic and prognostic biomarkers can significantly improve survival rates. This review explores recent advancements in clinically relevant proteomic, genetic, and metabolomic biomarkers for TNBC, highlighting their potential roles as prognostic, diagnostic, and predictive markers that could facilitate personalized treatment approaches. [ABSTRACT FROM AUTHOR]

Non-excitable cells express sodium voltage-gated channel alpha subunit 1 gene and protein (known as SCN1A and NaV 1.1, respectively); however, the functions of NaV 1.1 are unclear. In this study, we investigated the role of SCN1A and NaV 1.1 in human mesenchymal stem cells (MSCs). We found that SCN1A was expressed in MSCs, and abundant expression of NaV 1.1 was observed in the endoplasmic reticulum; however, this expression was not found to be related to Na+ currents. SCN1A-silencing reduced MSC proliferation and delayed the cell cycle in the S phase. SCN1A silencing also suppressed the protein levels of CDK2 and AKT (herein referring to total AKT), despite similar mRNA expression, and inhibited AKT phosphorylation in MSCs. A cycloheximide-chase assay showed that SCN1A-silencing induced CDK2 but not AKT protein degradation in MSCs. A proteolysis inhibition assay using epoxomicin, bafilomycin A1 and NH4 Cl revealed that both the ubiquitin–proteasome system and the autophagy and endo- lysosome system were irrelevant to CDK2 and AKT protein reduction in SCN1A-silenced MSCs. The AKT inhibitor LY294002 did not affect the degradation and nuclear localization of CDK2 in MSCs. Likewise, the AKT activator SC79 did not attenuate the SCN1A-silencing effects on CDK2 in MSCs. These results suggest that NaV 1.1 contributes to the cell cycle of MSCs by regulating the post-translational control of AKT and CDK2. [ABSTRACT FROM AUTHOR]

Osteosarcoma (OS) is a bone malignant tumor affecting children, adolescents, and young adults. Currently, osteosarcoma is treated with chemotherapy regimens established over 40 years ago. The investigation of novel therapeutic strategies for the treatment of osteosarcoma remains an important clinical need. Cyclin-dependent kinases (CDKs) have been considered promising molecular targets in cancer therapy. Among these, CDK12 has been shown to play a crucial role in the pathogenesis of malignancies, but its clinical significance and biological mechanisms in osteosarcoma remain unclear. In the present study, we aim to determine the expression and function of CDK12 and evaluate its prognostic and therapeutic value in metastatic osteosarcoma. We found that overexpression of CDK12 was associated with high tumor grade, tumor progression and reduced patient survival. The underlying mechanism revealed that knockdown of CDK12 expression with small interfering RNA or functional inhibition with the CDK12-targeting agent THZ531 effectively exhibited time- and dose-dependent cytotoxicity. Downregulation of CDK12 paused transcription by reducing RNAP II phosphorylation, interfered with DNA damage repair with increased γH2AX, and decreased cell proliferation through the PI3K-AKT pathway. This was accompanied by the promotion of apoptosis, as evidenced by enhanced Bax expression and reduced Bcl-xL expression. Furthermore, the CDK12 selective inhibitor THZ531 also hindered ex vivo 3D spheroid formation, growth of in vitro 2D cell colony, and prevented cell mobility. Our findings highlight the clinical importance of CDK12 as a potentially valuable prognostic biomarker and therapeutic target in metastatic osteosarcoma. [ABSTRACT FROM AUTHOR]

Protein kinases have essential responsibilities in controlling several cellular processes, and their abnormal regulation is strongly related to the development of cancer. The implementation of protein kinase inhibitors has significantly transformed cancer therapy by modifying treatment strategies. These inhibitors have received substantial FDA clearance in recent decades. Protein kinases have emerged as primary objectives for therapeutic interventions, particularly in the context of cancer treatment. At present, 69 therapeutics have been approved by the FDA that target approximately 24 protein kinases, which are specifically prescribed for the treatment of neoplastic illnesses. These novel agents specifically inhibit certain protein kinases, such as receptor protein-tyrosine kinases, protein-serine/threonine kinases, dual-specificity kinases, nonreceptor protein-tyrosine kinases, and receptor protein-tyrosine kinases. This review presents a comprehensive overview of novel targets of kinase inhibitors, with a specific focus on cyclin-dependent kinases (CDKs) and epidermal growth factor receptor (EGFR). The majority of the reviewed studies commenced with an assessment of cancer cell lines and concluded with a comprehensive biological evaluation of individual kinase targets. The reviewed articles provide detailed information on the structural features of potent anticancer agents and their specific activity, which refers to their ability to selectively inhibit cancer-promoting kinases including CDKs and EGFR. Additionally, the latest FDA-approved anticancer agents targeting these enzymes were highlighted accordingly. [ABSTRACT FROM AUTHOR]

Simple Summary: Improved outcomes have been reported with adjuvant treatment combining cyclin-dependent kinase 4/6 inhibitors with endocrine therapy, in high-risk patients with ER-positive and HER2-negative breast cancer, regardless of age. In this real-world data analysis, MonarchE and NataLEE high-risk patients accounted for 9.5% and 33% of patients undergoing upfront surgery, respectively. Significantly higher eligibility rates were observed in patients who underwent a mastectomy, >70 years and ≤40 years for adjuvant abemaciclib and ribociclib, and in patients >80 years for ribociclib. A higher discontinuation rate for abemaciclib was reported in patients ≥65 years and it can be assumed that discontinuation rates may increase with more older patients. If the results of the NataLEE trial translate into clinical practice, the number of patients potentially eligible for adjuvant CDK4/6 inhibitors may increase, especially in the elderly population. Background: Despite early diagnosis, approximately 20% of patients with ER-positive and HER2-negative breast cancer (BC) will experience disease recurrence. Improved survival has been reported with adjuvant treatment combining cyclin-dependent kinase 4/6 inhibitors with endocrine therapy, in high-risk patients with ER-positive and HER2-negative BC, regardless of age. Older patients have higher rates of ER-positive/HER2-negative BC than younger patients. Methods: In this real-world data analysis, MonarchE and NataLEE high-risk patients accounted for 9.5% and 33% of patients undergoing upfront surgery, respectively. Significantly higher eligibility rates were observed in patients who underwent a mastectomy, >70 years and ≤40 years for adjuvant abemaciclib and ribociclib, and in patients >80 years for ribociclib. Results: Eligibility rates in patients ≤40 years and >80 years who underwent mastectomy were 27.8% and 24.7% for abemaciclib, respectively, and 56.6% and 65.2% for ribociclib, respectively. A higher discontinuation rate for abemaciclib was reported in patients aged ≥65 years and it can be assumed that discontinuation rates may increase in even older patients. Conclusions: If the results of the NataLEE trial translate into clinical practice, the number of patients potentially eligible for adjuvant CDK4/6 inhibitors may increase, especially in the elderly population. [ABSTRACT FROM AUTHOR]

Simple Summary: Cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) loss is a key factor in diagnosing meningiomas as Central Nervous System (CNS) WHO grade 3 tumors. Typically, detecting this gene loss involves costly and complex techniques like sequencing or FISH. However, the MTAP gene, which is located near CDKN2A/B on the same chromosome, may provide a more accessible way to detect these losses through a simpler, more affordable test called immunohistochemistry (IHC). This study explored different concentrations and antibodies for MTAP and p16 across two institutions to evaluate their potential as surrogate markers for CDKN2A/B loss. The results showed that p16 expression varied and did not align with either MTAP expression or CDKN2A FISH results. This study suggests that IHC for MTAP is a promising, cost-effective method for identifying high-grade meningiomas, offering a quicker and less expensive alternative to existing techniques. Background: Homozygous cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) loss is one of the parameters that support the designation of meningiomas as Central Nervous System (CNS) WHO grade 3 tumors. Evaluation of CDKN2A/B by sequencing or Fluorescence in situ hybridization (FISH) is costly and not always readily accessible. An immunohistochemistry (IHC)-based marker for the evaluation of CDKN2A/B loss would provide faster results at a lower cost. Methods: This retrospective study included patients diagnosed with meningioma at our institution between 2016 and 2019. Archival tumor tissue was used for analysis. MTAP immunohistochemistry (IHC) was performed at various dilutions (1:1200, 1:400, 1:200, 1:100) using two different antibodies, and p16 IHC was conducted simultaneously. These analyses were carried out at two different institutions. To determine the sensitivity and specificity of MTAP and p16 as surrogate markers for CDKN2A/B loss, CDKN2A FISH was utilized as the gold standard. Results: Overall, 46/49 tumors showed strong MTAP staining (94%) at institution 1, and 44/49 (90%) showed either faint positive or positive results at institution 2. One grade 3 meningioma that demonstrated homozygous CDKN2A loss by FISH also showed loss of MTAP expression by IHC. One grade 2 meningioma showed regional CDKN2A loss by FISH and variable MTAP expression under different IHC conditions. MTAP expression evaluation was superior at a dilution of 1:100 with the Abnova Anti-MTAP Monoclonal antibody. Conclusions: P16 expression was variable and did not correlate with either MTAP expression or CDKN2A FISH results. MTAP IHC is a promising surrogate marker for the evaluation of CDKN2A status in meningiomas. [ABSTRACT FROM AUTHOR]

Simple Summary: Patients with hormone receptor-positive (HR+)/HER2-negative metastatic breast cancer who have PIK3CA mutations and have progressed on first-line therapies are considered for treatment with alpelisib alongside endocrine therapy (ET). Combination therapeutic strategies may extend the clinical benefit of alpelisib. This study investigated the potential of onvansertib, a highly specific inhibitor of polo-like kinase 1 (PLK1), to enhance the efficacy of alpelisib in preclinical models of HR+ breast cancer. Our findings demonstrated that onvansertib synergizes with alpelisib in PIK3CA-mutant HR+ breast cancer cell lines and patient-derived xenografts that are resistant to ET and cyclin-dependent kinase 4/6 inhibitors. The combination inhibited PLK1 and PI3K signaling, induced cell cycle arrest, and triggered apoptotic death in both cell lines and xenograft tumors. Overall, our preclinical data encourage the clinical exploration of this combination for PIK3CA-mutant HR+ metastatic breast cancer patients progressing on standard-of-care therapies. Background: Endocrine therapy (ET) combined with cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) is the preferred first-line treatment for hormone receptor-positive (HR+)/HER2- metastatic breast cancer. Although this is beneficial, acquired resistance leads to disease progression, and patients harboring PIK3CA mutations are treated with targeted therapies such as the PI3Kα inhibitor, alpelisib, alongside ET. Drug-associated resistance mechanisms limit the efficacy of alpelisib, highlighting the need for better combination therapies. This study aimed to evaluate the efficacy of combining alpelisib with a highly specific PLK1 inhibitor, onvansertib, in PIK3CA-mutant HR+ breast cancer preclinical models. Methods: We assessed the effect of the alpelisib and onvansertib combination on cell viability, PI3K signaling pathway, cell cycle phase distribution and apoptosis in PI3K-activated HR+ breast cancer cell lines. The antitumor activity of the combination was evaluated in three PIK3CA-mutant HR+ breast cancer patient-derived xenograft (PDX) models, resistant to ET and CDK4/6 inhibitor palbociclib. Pharmacodynamics studies were performed using immunohistochemistry and Simple Western analyses in tumor tissues. Results: The combination synergistically inhibited cell viability, suppressed PI3K signaling, induced G2/M arrest and apoptosis in PI3K-activated cell lines. In the three PDX models, the combination demonstrated superior anti-tumor activity compared to the single agents. Pharmacodynamic studies confirmed the inhibition of both PLK1 and PI3K activity and pronounced apoptosis in the combination-treated tumors. Conclusions: Our findings support that targeting PLK1 and PI3Kα with onvansertib and alpelisib, respectively, may be a promising strategy for patients with PIK3CA-mutant HR+ breast cancer failing ET + CDK4/6i therapies and warrant clinical evaluation. [ABSTRACT FROM AUTHOR]

Energy landscapes can provide intuitive depictions of population heterogeneity and dynamics. However, it is unclear whether individual cell behavior, hypothesized to be determined by initial position and noise, is faithfully recapitulated. Using the p21-/Cdk2-dependent quiescence-proliferation decision in breast cancer dormancy as a testbed, we examined single-cell dynamics on the landscape when perturbed by hypoxia, a dormancy-inducing stress. Combining trajectory-based energy landscape generation with single-cell time-lapse microscopy, we found that a combination of initial position and velocity on a p21/Cdk2 landscape, but not position alone, was required to explain the observed cell fate heterogeneity under hypoxia. This is likely due to additional cell state information such as epigenetic features and/or other species encoded in velocity but missing in instantaneous position determined by p21 and Cdk2 levels alone. Here, velocity dependence manifested as inertia: cells with higher cell cycle velocities prior to hypoxia continued progressing along the cell cycle under hypoxia, resisting the change in landscape towards cell cycle exit. Such inertial effects may markedly influence cell fate trajectories in tumors and other dynamically changing microenvironments where cell state transitions are governed by coordination across several biochemical species. [ABSTRACT FROM AUTHOR]

Context.--Eosinophilic solid and cystic renal cell carcinoma is now defined in the 5th edition of the 2022 World Health Organization classification of urogenital tumors. Objective.--To perform morphologic, immunohistochemical, and preliminary genetic studies about this new entity in China for the purpose of understanding it better. Design.--The study includes 18 patients from a regional tertiary oncology center in northern China (Tianjin, China). We investigated the clinical and immunohistochemical features of these cases. Results.--The mean age of patients was 49.6 years, and the male to female ratio was 11:7. Macroscopically, 1 case had the classic cystic and solid appearance, whereas the others appeared purely solid. Microscopically, all 18 tumors shared a similar solid and focal macrocystic or microcystic growth pattern, and the cells were characterized by voluminous and eosinophilic cytoplasm, along with coarse ampho-philic stippling. Immunohistochemically, most of the tumors had a predominant cytokeratin (CK) 20-positive feature, ranging from focal cytoplasmic staining to diffuse membranous accentuation. Initially, we separated these cases into different immunohistochemical phenotypes. Group 1 (7 of 18; 38.5%) was characterized by positive phospho-4EBP1 and phospho-S6, which can imply hyperactive mechanistic target of rapamycin complex 1 (mTORC1) signaling. Group 2 (4 of 18; 23%) was negative for NF2, probably implying a germ-line mutation of NF2. Group 3 (7 of 18; 38.5%) consisted of the remaining cases. One case had metastatic spread and exhibited an aggressive clinical course, and we detected cyclin-dependent kinase inhibitor 2A (CDKN2A) mutation in this case; other patients were alive and without disease progression. Conclusions.--Our research proposes that eosinophilic solid and cystic renal cell carcinoma exhibits prototypical pathologic features with CK20 positivity and has aggressive potential. [ABSTRACT FROM AUTHOR]

Although histological and molecular classifications have been extensively studied for gastric cancer (GC), targeted therapies for GC remain limited. CDH1 mutations (MT) are characteristic of genomically stable GC and are associated with poor prognosis, but lack effective or targeted therapies. Here, we showed the overall mutation frequency of CDH1 was 9.7% (155 of 1596). CDH1-MT GC showed significantly lower rates of PD-L1 positivity (CPS score ≥1) than CDH1-wildtype (WT) GC (56.7% vs. 73.3%, p < 0.05). Compared to CDH1-WT GC, mutations of ARID1A, WRN, POT1, CDK12, and FANCC were significantly higher, while TP53 and APC were significantly lower in CDH1-MT GC (p < 0.05); The rates of KRAS and HER2 amplifications were significantly lower, while CRKL and IGF1R amplifications were significantly higher in CDH1-MT GC, compared to CDH1-WT GC (p < 0.05). Frequently altered genes in CDH1-MT GC were especially enriched in DNA damage repair and cell cycle checkpoint pathways. Inhibition of E-cadherin sensitized GC cell lines to PARP and Wee1 inhibitors by disrupting DNA damage repair pathway and cell cycle checkpoint. This is the largest study to investigate the distinct genomic landscape of CDH1-MT GC. Our data indicated GC patients with CDH1 mutations could potentially benefit from agents targeting PARP and Wee1. [ABSTRACT FROM AUTHOR]

PURPOSE: The National Cancer Institute-Children's Oncology Group Pediatric Molecular Analysis for Therapy Choice trial assigned patients age 1-21 years with relapsed or refractory solid tumors, lymphomas, and histiocytic disorders to phase II treatment arms of molecularly targeted therapies on the basis of genetic alterations detected in their tumor. Patients with tumors that harbored prespecified genomic alterations in the cyclinD-CDK4/6-INK4a-Rb pathway with intact Rb expression were assigned and treated with the cdk4/6 inhibitor palbociclib. METHODS: Patients received palbociclib orally once daily for 21 days of 28-day cycles until disease progression, intolerable toxicity, or up to 2 years. The primary end point was objective response rate; secondary end points included safety/tolerability and progression-free survival. RESULTS: Twenty-three patients (median age, 15 years; range, 8-21) were enrolled; 20 received protocol therapy and were evaluable for toxicity and response. Of the evaluable patients, the most common diagnoses were osteosarcoma (n = 9) and rhabdomyosarcoma (n = 6). A single actionable gene amplification was found in 19 tumors (CDK4 , n = 11, CDK6 , n = 2, CCND3 , n = 6), with one tumor harboring two amplifications (CDK4 and CCND2). Hematologic toxicities were the most common treatment-related events. No objective responses were seen. Two patients with tumors harboring CDK4 amplifications (neuroblastoma and sarcoma) had best response of stable disease for six and three cycles. Six-month progression was 10% (95% CI, 1.7 to 27.2). CONCLUSION: The CDK4/6 inhibitor palbociclib at 75 mg/m2 orally daily was tolerable in this heavily pretreated cohort. No objective responses were observed in this histology-agnostic biomarker-selected population with treatment-refractory solid tumors, demonstrating that pathway alteration alone is insufficient in pediatric cancers to generate a response to palbociclib monotherapy. Study reports on the NCI-COG Pediatric MATCH trial arm I (palbociclib)—no objective responses observed. [ABSTRACT FROM AUTHOR]

AbstractBackgroundMethodsResultsConclusion\nPLAIN LANGUAGE SUMMARYCyclin-dependent kinase 4/6 (CDK 4/6) inhibitors have emerged as a significant advancement in the treatment of HR+/HER2− metastatic breast cancer (MBC). Despite the clinical efficacy of CDK 4/6 inhibitors in HR+/HER2− metastatic breast cancer, there remains a significant gap in understanding their cost-effectiveness, particularly regarding the long-term economic impact and the key drivers of costs, when used in combination with endocrine therapy. This study aims to systematically review and conduct a meta-analysis of cost-effectiveness studies evaluating CDK4/6 inhibitors in treatment of HR+/HER2− advanced breast cancer and identify key drivers of costs of CDK4/6 inhibitors in combination with endocrine therapy.A comprehensive search of PubMed and Embase was conducted to identify peer-reviewed studies from February 2015 to March 2022 reporting cost-effectiveness of CDK4/6 inhibitors in MBC treatment. Incremental net benefits (INBs) were estimated, and meta-analysis was conducted. This review adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.We identified 120 articles, of which 18 were eligible for systematic review and 16 for meta-analysis. None of the three CDK4/6 inhibitors had positive INB compared to endocrine/aromatase inhibitors therapy alone. The pooled INB was estimated at −$149,266.87 (95% Confidence Interval (CI) = −$196,961.54, −$101,572.20).The combination of CDK4/6 inhibitors and letrozole/endocrine therapy for the treatment of postmenopausal patients with advanced HR+/HER2 − MBC was not cost-effective.Breast cancer, a significant health concern worldwide, represents around 30% of new cancer diagnoses and 25% of cancer related fatalities. Among these cases, approximately two-thirds are characterized by hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2−) tumors. In the metastatic stage, up to half of patients exhibit inherent resistance to endocrine therapy, leading to poorer survival rates, while others, initially responsive, eventually develop resistance, leading to disease progression and eventual mortality. Nevertheless, recent advancements in CDK4/6 inhibitors have shown efficacy in overcoming both inherent and acquired endocrine resistance, representing a substantial breakthrough in HR+/HER2− metastatic breast cancer treatment. This study conducts a review of literature focusing on comparative cost-effectiveness and economic evaluations of the three CDK4/6 inhibitors, evaluating the pooled incremental net benefit (INB) reported in these studies. It marks the first attempt to compare all three CDK4/6 inhibitors and employs a meta-analysis approach to ascertain the option demonstrating the most positive INB. Our findings indicate that CDK4/6 inhibitors fail to provide an economic advantage over letrozole or endocrine therapy alone. The aim of this study is to offer insights for clinical and reimbursement decision-making in the treatment of postmenopausal patients with advanced HR+/HER2− breast cancer, providing valuable guidance for policymakers, payers, and clinicians. [ABSTRACT FROM AUTHOR]

Experiments are increasingly performed in vitro; therefore, cell culture technology is essential for scientific progress. Fetal bovine serum (FBS) is a key cell culture supplement providing growth factors, amino acids, and hormones. However, FBS is not readily available on the market, has contamination risks, and has ethical concerns. This study aimed to investigate Haematococcus pluvialis extracts (HE) as a potential substitute for FBS. Therefore, we assessed the effects of HE on cell maintenance, growth, and cycle progression in human lung fibroblasts (MRC-5). Cell progression and monosaccharide, fatty acid, and free amino acid compositions were analyzed using cell cycle analysis, bio-liquid chromatography, gas chromatography, and high-performance liquid chromatography, respectively. The results of nutritional profiles showed that the extracts contained essential amino acids required for synthesizing non-essential amino acids and other metabolic intermediates. Furthermore, most of the components present in HE were consistent with those found in FBS. HE enhanced cell viability and regulated cell cycle phases. Additionally, the interaction between growth factor cocktails and HE significantly improved cell viability, promoted cell cycle progression, and activated key cell cycle regulators, such as cyclin A and cyclin-dependent kinases 1 (CDK1). Our findings suggest that HE have considerable potential to substitute FBS in MRC-5 cell cultures and have functional and ethical advantages. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) has different molecular subgroups related to different risks and treatments. Tumor biopsies for BC detection are invasive and may not reflect tumor heterogeneity. Liquid biopsies have become relevant because they might overcome these limitations. We rationalize that liquid cfDNA biopsies through shallow whole genome sequencing (sWGS) could improve the detection of tumor alterations, complementing the genomic profiling. We evaluated the feasibility to detect somatic copy number alterations (SCNAs) in BC using shallow whole genome sequencing (sWGS) in cfDNA from archived samples from National Cancer Institute of Colombia patients. We sequenced tumor tissues from 38 BC patients with different molecular subtypes using a gene panel of 176 genes significantly mutated in cancer, and by liquid biopsies using sWGS on 20 paired samples to detect SCNAs and compare with the tumor samples. We identified an extensive intertumoral heterogeneity between the molecular subtypes of BC, with a mean tumor load of 602 mutations in the gene panel of tumor tissues. There was a 12.3% of concordance in deletions in the cfDNA-tumor pairs considering only the genes covered by the panel encompassing seven genes: BRCA1, CDK12, NF1, MAP2K4, NCOR1, TP53, and KEAP1 in three patients. This study shows the feasibility to complement the genomic analysis of tumor tissue biopsies to detect SCNA in BC using sWGS in cfDNA, providing a wider identification of potential therapeutic targets. [ABSTRACT FROM AUTHOR]

The centromere, a chromosome locus defined by the histone H3-like protein centromeric protein A (CENP-A), promotes assembly of the kinetochore to bind microtubules during cell division. Centromere maintenance requires CENP-A to be actively replenished by dedicated protein machinery in the early G1 phase of the cell cycle to compensate for its dilution after DNA replication. Cyclin-dependent kinases (CDKs) limit CENP-A deposition to once per cell cycle and function as negative regulators outside of early G1. Antithetically, Polo-like kinase 1 (PLK1) promotes CENP-A deposition in early G1, but the molecular details of this process are still unknown. We reveal here a phosphorylation network that recruits PLK1 to the deposition machinery to control a conformational switch required for licensing the CENP-A deposition reaction. Our findings clarify how PLK1 contributes to the epigenetic maintenance of centromeres. [ABSTRACT FROM AUTHOR]

Cyclin-dependent kinase 2 (CDK2) has been recognized as one of the crucial factors in cell cycle regulation and has been proposed as a potential target for cancer therapies, particularly for colorectal cancer (CRC). Due to the increased incidence rate of CRC and challenges associated with existing treatment options, there is a need for efficient and selective anti-cancer compounds. The current work aims to explore the ability of novel kaempferol derivatives as CDK2 inhibitors by performing conceptual pharmacophore modeling, molecular docking, and molecular dynamic analysis. Kaempferol and its derivatives were obtained from PubChem, and the optimized 3D structures of the compounds were generated using Maestro Ligprep. Subsequently, a pharmacophore model was developed to identify compounds with high fitness values, resulting in the selection of several kaempferol derivatives for further study. We evaluated the ADMET properties of these compounds to assess their therapeutic potential. Molecular docking was conducted using Maestro and BIOVIA Discovery Studio version 4.0 to predict the binding affinities of the compounds to CDK2. The top candidates were subjected to MM-GBSA analysis to predict their binding free energies. Molecular dynamics simulations using GROMACS were performed to assess the thermodynamic stability of the ligand-protein complexes. The results revealed several kaempferol derivatives with high predicted binding affinities to CDK2 and favorable ADMET properties. Specifically, compounds 5281642, 5318980, and 14427423 demonstrated binding free energies of-30.26, -38.66, and -34.2 kcal/mol, respectively. Molecular dynamics simulations indicated that these ligand-protein complexes remained stable throughout the simulation period, with RMSD values remaining below 2 Ä. In conclusion, the identified kaempferol derivatives show potential as CDK2 inhibitors based on computational predictions and demonstrate stability in molecular dynamics simulations, suggesting their future application in CRC treatment by targeting CDK2. These computational findings encourage further experimental validation and development of kaempferol derivatives as anti-cancer agents. [ABSTRACT FROM AUTHOR]

Background: There are limited real-world data (RWD) regarding the use of cyclin-dependent kinase (CDK) 4/6 inhibitors in western Balkan. The aim of our study was thus to analyze factors influencing progression-free survival (PFS) and overall survival (OS), along with the differences in adverse effects of CDK 4/6 therapy in a tertiary healthcare center in Croatia. Methods: We evaluated medical and demographic data for 163 consecutive patients with metastatic breast cancer treated with CDK4/6 inhibitors for at least one month, from October 2018, after the drug became available in Croatia. Eligible patients in our study were those patients who were treated with palbociclib, ribociclib, or abemaciclib. Results: The median PFS of CDK4/6 inhibitors treatment was 2.2 years (95% CI 1.8–3.3), with the longest ongoing treatment for 5.4 years. Treatment with CDK4/6 inhibitors in the first line was associated with a longer PFS compared to the second line or beyond (HR 0.50, 95% CI 0.3–0.9), and patients without liver metastasis exhibited longer survival compared to patients with liver metastasis (HR 0.46, 95% CI 0.2–0.8) (both p < 0.05). Regarding the choice of CDK4/6 inhibitors, ribociclib exhibited longer PFS compared to palbociclib (HR 0.49, 95% CI 0.29–0.82) (p = 0.0032), although the effect was not statistically significant when separating patients who were treated with CDK4/6 inhibitors in the first-line (HR 0.59, 95% CI 0.29–1.2), or second- or later-line therapy (0.49, 95% CI 0.15–1.55); the trend was present in both lines, however. The presence of liver metastasis (p = 0.04), initial luminal A grade (p = 0.039), and time to metastasis up to 5 years from the initial cancer (p = 0.002) were the only factors that remained statistically significant for PFS in multivariate analysis. Median OS since the diagnosis of metastatic disease was 4.5 years (95% CI 3.9–6.3), median OS since the start of CDK4/6 inhibitors treatment was 3.7 years (95% CI 3.4–4.4), while median OS from initial cancer diagnosis was 15.8 years (95% CI 13.8–18.3). There was no difference in OS based on the choice of CDK4/6 inhibitor (p = 0.44) or the adjuvant hormonal therapy (p = 0.12), although a nonsignificant trend for better OS with ribociclib was present for both regardless of whether it was in first- or second/later-line therapies (p > 0.05). In a multivariate analysis, only the presence of liver metastasis (p = 0.0003) and time to metastasis under 5 years from primary breast cancer (p = 0.03) were associated with a worse OS. Conclusions: Our study provides the RWD with the use of CDK4/6 inhibitors in the treatment of metastatic HR+/HER2− breast cancer. To our best knowledge, there are limited RWD regarding CDK 4/6 inhibitors use in western Balkan; thus, our study provides valuable data from everyday clinical practice for this region of Europe, bridging the gap between randomized clinical trials and clinical reality in western Balkan. [ABSTRACT FROM AUTHOR]

Background. Cyclin-dependent kinase 8 (CDK8) is a multifaceted regulator and represents a catalytic component of the transcriptional Mediator complex. CDK8 activity, on the one hand, increases transcriptional elongation by the recruitment of Mediator/super elongation complexes, but, on the other hand, negatively regulates CDK7-controlled transcriptional initiation through inactivating cyclin H phosphorylation. Recently, these combined properties of CDK8 have also suggested its rate-limiting importance for herpesviral replication. Objectives. In this paper, we focused on human cytomegalovirus (HCMV) and addressed the question of whether the pharmacological inhibition or knock-down of CDK8 may affect viral replication efficiency in cell culture models. Methods. A number of human and animal herpesviruses, as well as non-herpesviruses, were used to analyze the importance of CDK8 for viral replication in cell culture models, and to assess the antiviral efficacy of CDK8 inhibitors. Results. Using clinically relevant CDK8 inhibitors (CCT-251921, MSC-2530818, and BI-1347), HCMV replication was found strongly reduced even at nanomolar drug concentrations. The EC50 values were consistent for three different HCMV strains (i.e., AD169, TB40, and Merlin) analyzed in two human cell types (i.e., primary fibroblasts and astrocytoma cells), and the drugs comprised a low level of cytotoxicity. The findings highlighted the following: (i) the pronounced in vitro SI values of anti-HCMV activity obtained with CDK8 inhibitors; (ii) a confirmation of the anti-HCMV efficacy by CDK8–siRNA knock-down; (iii) a CDK8-dependent reduction in viral immediate early, early, and late protein levels; (iv) a main importance of CDK8 for viral late-stage replication; (v) several mechanistic aspects, which point to a strong impact on viral progeny production and release, but a lack of CDK8 relevance for viral entry or nuclear egress; (vi) a significant anti-HCMV drug synergy for combinations of inhibitors against host CDK8 and the viral kinase vCDK/pUL97 (maribavir); (vii) finally, a broad-spectrum antiviral activity, as seen for the comparison of selected α-, β-, γ-, and non-herpesviruses. Conclusions. In summary, these novel data provide evidence for the importance of CDK8 as a positive regulator of herpesviral replication efficiency, and moreover, suggest its exploitability as an antiviral target for novel strategies of host-directed drug development. [ABSTRACT FROM AUTHOR]

The MDCK cell line is perceived as better than the embryos of hen eggs for the production of influenza vaccines, but the tumorigenicity of these cells is concerning. Epidermal growth factor receptor (EGFR) is likely to be a crucial target that contributes to the tumorigenicity of MDCK cells. In this study, EGFR-knockdown and EGFR-overexpression cell lines were established. EGFR's influence on cell growth, migration, clonogenic ability, and flu virus susceptibility was evaluated in vitro, and its role in cell tumorigenicity was examined in nude mice. GST pull-down coupled with mass spectrometry (MS) and bioinformatics analysis identified EGFR-interacting proteins. The expression levels of these proteins, as well as those of PI3K–AKT- and MAPK–ERK-signaling-pathway-related molecules, were confirmed at both gene and protein levels. The result indicates that EGFR overexpression can enhance cell proliferation, migration, and clonal formation; EGFR knockdown could effectively curtail tumorigenesis and amplify the titers of influenza viruses in MDCK cells. An analysis of the underlying mechanism identified a total of 21 interacting proteins implicated in tumor formation, and among these, AKT1, CDK4, GNB2, and MAPK8 were confirmed at both gene and protein levels. EGFR can activate key factors of the PI3K–AKT signaling pathway, AKT and PI3K, and promote their phosphorylation levels. Consequently, we concluded that EGFR interacts with GNB2, facilitating transmembrane signal transduction, activating the PI3K–AKT signaling cascade, controlling cell cycle alterations, stimulating cell proliferation, and promoting tumorigenesis. [ABSTRACT FROM AUTHOR]

Objective: This study aims to clarify the mechanical action of cyclin-dependent protein kinase 1 (CDK1) in the development of endometrial carcinoma (EMCA), which may be associated with the phosphorylation of kinesin family member C1 (KIFC1) and further activate the PI3K/AKT pathway. Methods: The protein and gene expression of CDK1 in EMCA tissues and tumor cell lines were evaluated by western blot, quantitative polymerase chain reaction, and immunohistochemistry staining. Next, Cell Counting Kit-8 and colony formation assay detected cell survival and proliferation. Cell migration and invasion were measured by Transwell assay. Cell apoptosis and cell cycle were tested by flow cytometry. Immunofluorescence staining of γH2AX was used to evaluate DNA damage, respectively. Subsequently, a co-immunoprecipitation assay was used to detect the interaction between CDK1 and KIFC1. The phosphorylated protein of KIFC1 and PI3K/AKT was detected by western blot. Finally, the effect of CDK1 on the tumor formation of EMCA was evaluated in a nude mouse xenograft model. Results: CDK1 was highly expressed in EMCA tumor cell lines and tissues, which contributed to cell survival, proliferation, invasion, and migration, inhibited cell apoptosis, and induced DNA damage of EMCA cells dependent on the phosphorylation of KIFC1. Moreover, the CDK1-KIFC1 axis further activated PI3K/AKT pathway. Finally, CDK1 knockdown repressed tumor formation of EMCA in vivo. Conclusion: We report that increased CDK1 promotes tumor progression and identified it as a potential prognostic marker and therapeutic target of EMCA. [ABSTRACT FROM AUTHOR]

Simple Summary: The inactivation of apoptotic signaling by inhibitors of apoptosis proteins (IAPs) is one of the important hallmarks of cancer cells. Survivin, a 16.5 kDa member of the IAP family, is commonly enriched in many cancers and is a potential therapeutic target. We investigated the Survivin-targeting potential of Withaferin-A (Wi-A) and Withanone (Wi-N), two major withanolides from Withania somnifera (Ashwagandha), using computational assays. The results were validated in various in vitro experimental assays using Wi-A-rich extracts from Ashwagandha leaves, suggesting their use as an important bioresource for cancer drug development. Survivin, a member of the IAP family, functions as a homodimer and inhibits caspases, the key enzymes involved in apoptosis. Several Survivin inhibitors, including YM-155, Debio1143, EM1421, LQZ-7I, and TL32711, have emerged as potential anticancer drugs awaiting validation in clinical trials. Due to the high cost and adverse side effects of synthetic drugs, natural compounds with similar activity have also been in demand. In this study, we conducted molecular docking assays to evaluate the ability of Wi-A and Wi-N to block Survivin dimerization. We found that Wi-A, but not Wi-N, can bind to and prevent the homodimerization of Survivin, similar to YM-155. Therefore, we prepared a Wi-A-rich extract from Ashwagandha leaves (Wi-AREAL). Experimental analyses of human cervical carcinoma cells (HeLa and ME-180) treated with Wi-AREAL (0.05–0.1%) included assessments of viability, apoptosis, cell cycle, migration, invasion, and the expression levels (mRNA and protein) of molecular markers associated with these phenotypes. We found that Wi-AREAL led to growth arrest mediated by the upregulation of p21WAF1 and the downregulation of several proteins (CDK1, Cyclin B, pRb) involved in cell cycle progression. Furthermore, Wi-AREAL treatment activated apoptosis signaling, as evidenced by reduced PARP-1 and Bcl-2 levels, increased procaspase-3, and elevated Cytochrome C. Additionally, treating cells with a nontoxic low concentration (0.01%) of Wi-AREAL inhibited migration and invasion, as well as EMT (epithelial–mesenchymal transition) signaling. By combining computational and experimental approaches, we demonstrate the potential of Wi-A and Wi-AREAL as natural inhibitors of Survivin, which may be helpful in cancer treatment. [ABSTRACT FROM AUTHOR]

Simple Summary: Abemaciclib is an important addition to the care of women with hormone receptor-positive breast cancer. To qualify for abemaciclib treatment, some women are advised to undergo axillary node clearance surgery as finding more than three axillary nodes with metastatic cancer allows access to abemaciclib. This paper explores the balance between the benefits of axillary node clearance in permitting access to abemaciclib and the harms of surgery. We examine how many women need to undergo axillary node clearance before one woman clinically benefits from the procedure. We show that for every 10 women undergoing axillary node clearance surgery, only one eventually qualifies for abemaciclib. The remaining nine would have axillary surgery but still not qualify for abemaciclib as less than four metastatic axillary nodes are found despite full axillary clearance. However, these women could still suffer the complications of axillary node clearance surgery. The monarchE study added the CDK4/6 inhibitor abemaciclib to the care of women with oestrogen-positive (ER+) breast cancers. Eligibility required meeting monarchE criteria—either >3 positive axillary nodes, or 1–3 positive sentinel nodes (SNB+) with tumour size >50 mm or grade 3 cancers. Women were advised to proceed to completion axillary node clearance (cANC) if size/grade criteria were not fulfilled for >3 positive nodes to be identified. However, cANC is associated with significant morbidity, conflicting with the potential benefits of abemaciclib. We analysed data of 229 consecutive women (2016-2022) with ER+ breast cancer and SNB+ who proceeded to cANC, keeping with contemporary treatment guidelines. We used this cohort to assess numbers that, under national guidance in place currently, would be advised to undergo cANC solely to check eligibility for abemaciclib treatment. Using monarchE criteria, 90 women (39%) would have accessed abemaciclib based on SNB+ and size/grade, without cANC. In total, 139 women would have been advised to proceed to cANC to check eligibility, with only 15/139 (11%) having >3 positive nodes after sentinel node biopsy and cANC. The remaining 124 (89%) would have undergone cANC but remained ineligible for abemaciclib. Size, age, grade, and Ki67 did not predict >3 nodes at cANC. Following cANC, a large majority of women with ER+, <50 mm, and grade 1–2 tumours remain ineligible for abemaciclib yet are subject to significant morbidity including lifelong lymphoedema risk. The monarchE authors state that 15 women need abemaciclib therapy for 1 to clinically benefit. Thus, in our cohort, 139 women undergoing cANC would lead to one woman benefitting. [ABSTRACT FROM AUTHOR]

Cyclin-dependent kinase 8 (CDK8) is highly expressed in various cancers and common complex human diseases, and an important therapeutic target for drug discovery and development. The CDK8 inhibitors are actively sought after, especially among natural products. We performed a virtual screening using the ZINC library comprising approximately 90,000 natural compounds. We applied Lipinski's rule of five, absorption, distribution, metabolism, excretion, and toxicity properties, and pan-assay interference compounds filter to eliminate promiscuous binders. Subsequently, the filtered compounds underwent molecular docking to predict their binding affinity and interactions with the CDK8 protein. Interaction analysis were carried out to elucidate the interaction mechanism of the screened hits with binding pockets of the CDK8. The ZINC02152165, ZINC04236005, and ZINC02134595 were selected with appreciable specificity and affinity with CDK8. An all-atom molecular dynamic (MD) simulation followed by essential dynamics was performed for 200 ns. Taken together, the results suggest that ZINC02152165, ZINC04236005, and ZINC02134595 can be harnessed as potential leads in therapeutic development. Moreover, the binding of the molecules brings change in protein conformation in a way that blocks the ATP-binding site of the protein, obstructing its kinase activity. These new findings from natural products offer insights into the molecular mechanisms underlying CDK8 inhibition. CDK8 was previously associated with behavioral and neurological diseases such as autism spectrum disorder, and cancers, for example, colorectal, prostate, breast, and acute myeloid leukemia. Hence, we call for further research and experimental validation, and with an eye to inform future clinical drug discovery and development in these therapeutic fields. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to quantitatively compare the efficacy and safety of CDK4/6 inhibitors and PI3K/AKT/mTOR inhibitors for ER+/HER2− metastatic breast cancer. Methods: A parametric survival function was used to analyze the time course of overall survival (OS) and progression-free survival (PFS). The objective response rate (ORR) and the incidence of any grade and grade 3–4 adverse events were summarized using the random-effects model of a single-arm meta-analysis. Results: This study included 44 arms from 48 publications, with a total sample size of 7881 patients. Our study revealed that CDK4/6 inhibitors had a median OS of 40.7 months, a median PFS of 14.8 months, and an ORR of 40%, whereas PI3K/AKT/mTOR inhibitors had a median OS of 29.8 months, a median PFS of 8.3 months, and an ORR of 20%. Additionally, this study also found that the proportion of patients with visceral metastases and specific endocrine therapy used in combination significantly impact OS and PFS. In terms of adverse events, CDK4/6 inhibitors exhibited a relatively high incidence of hematological adverse events. Conclusion: Our study provides solid quantitative evidence for the first-line recommendation of CDK4/6 inhibitors combined with endocrine therapy for ER+/HER2− metastatic breast cancer in clinical guidelines. [ABSTRACT FROM AUTHOR]

Background: Soft tissue tumors with fusions or amplifications of the GLI1 gene have distinctive molecular characteristics and have recently been considered a unique pathological entity, thus named " GLI1 -altered soft tissue tumors." It is a rare mesenchymal neoplasm that involves soft tissues at any site. Case presentation: We report an example of this condition in a 13-year-old Chinese male patient who presented with a mass in the tongue. The tumor was multilobulated; the tumor cells were arranged in nests and sheets, had a rich, delicate fibrovascular network, and were separated by a hyalinized fibrous stroma. The tumor cells were epithelioid to ovoid, with variable eosinophilic to pale vacuolated cytoplasm and round to oval nuclei. Immunostaining revealed that the tumor cells were positive for CDK4 and CD56. Fluorescence in situ hybridization (FISH) for GLI1 translocation was positive, with a high level of amplification of the translocated segment. Literature review: We present a comprehensive literature review of this condition, focusing on its clinical presentation, histological features, immunohistochemical profile, molecular characteristics, and prognosis. [ABSTRACT FROM AUTHOR]

The biological heterogeneity of neuroblastoma underscores the need for an in vitro model of each molecularly defined subgroup to investigate tumorigenesis and develop targeted therapies. We have established a permanently growing cell line from a 12-year-old girl who developed a late recurrent stage MS, MDM2-amplified neuroblastoma arising in the liver and performed histological, molecular, cytogenetic, exome, and telomere analyses of the recurrent tumor and the cell line. On histology, the recurrent tumor was immunoreactive for TP53, CDKN1A, and MDM2. A molecular cytogenetic study of the recurrent tumor revealed the amplification of MDM2 but no amplification of MYCN. The established cell line, NBM-SHIM, showed amplification of both MDM2 and MYCN on double-minute chromosomes. A copy number evaluation based on exome data confirmed the finding for MYCN and MDM2 and further identified high ploidy on CDK4 and GLI2 loci in the recurrent tumor and the cell line. The telomere maintenance mechanism on the cell line is unusual in terms of the low expression of TERT despite MYCN amplification and alternative lengthening of telomeres suggested by positive value for C-circle assay and telomere contents quantitative assay. The cell line is unique because it was established from a MYCN-nonamplified, MDM2-amplified, late-relapsed stage MS neuroblastoma, and MYCN amplification was acquired during cell culture. Therefore, the cell line is a valuable tool for investigating neuroblastoma tumorigenesis and new molecular targeted therapies for disrupted ARF–TP53–MDM2 pathway and amplification of MDM2 and CDK4. [ABSTRACT FROM AUTHOR]

Glioblastoma, the most common malignant brain tumor in adults, is associated with a median overall survival duration of less than 2 years. Extraneural metastases occur in less than 1% of all patients with glioblastoma. The mechanism of extraneural metastasis is unclear. We present a case of extensive extraneural, extraosseous, epidural, and soft-tissue metastasis of glioblastoma. The diagnosis of metastatic glioblastoma was made only after next-generation sequencing (NGS) of the metastatic paraspinal lesions was completed. The CDK4, pTERT, PTEN, and TP53 molecular alterations seen in the initial intracranial glioblastoma were found in the paraspinal tumor, along with the addition of MYC, which is implicated in angiogenesis and epidermal-to-mesenchymal transition. Immunohistochemical stains showed that neoplastic cells were negative for GFAP. In conclusion, this case raises awareness about the role of NGS in the diagnosis of extraneural glioblastoma. This diagnosis was not possible with histology alone and only became evident after molecular profiling of the metastatic lesions and its comparison to the original tumor. [ABSTRACT FROM AUTHOR]

This letter to the editor responds to comments by Sartor et al regarding recent findings on the clinical relevance of CDK12 pathogenic mutations.

BACKGROUND: Disparities in survival and clinical outcomes between African American and White patients with breast cancer (BC) are well documented, but African American patients have not been well represented in randomized clinical trials of CDK4/6 inhibitors. Real-world studies can provide evidence for effective treatment strategies for underreported patient populations. PATIENTS AND METHODS: This retrospective analysis of African American patients with HR+/HER2- metastatic breast cancer (mBC) from the Flatiron Health longitudinal database evaluated treatments for patients with BC in routine clinical practice in the US. Patients initiated first-line therapy with palbociclib plus an aromatase inhibitor (AI) or AI alone between February 2015 and March 2020. Outcomes assessed included overall survival (OS) and real-world progression-free survival (rwPFS) until September 2020. RESULTS: Of 270 eligible patients, 127 (median age 64 years) were treated with palbociclib + AI, and 143 (median age 68 years) were treated with an AI. Median follow-up was 24.0 months for palbociclib + AI and 18.2 months for AI-treated patients. Median OS was not reached (NR; 95% CI, 38.2-NR) in the palbociclib + AI group versus 28.2 months (95% CI, 19.2-52.8) in the AI group (adjusted HR, 0.56; 95% CI, 0.36-0.89; P = .013). Median rwPFS was 18.0 months (95% CI, 12.4-26.7) in the palbociclib + AI group and 10.5 months (95% CI, 7.0-13.4) in the AI group (adjusted HR, 0.74; 95% CI, 0.47-1.17; P = .199). CONCLUSION: This comparative analysis of palbociclib + AI versus AI alone indicates that palbociclib combined with endocrine therapy in the first line is associated with improved effectiveness for African American patients with HR+/HER2- mBC in real-world settings. TRIAL NUMBER: NCT05361655.

Background: Appropriate adverse event (AE) management and maintenance of therapeutic intensity are necessary to achieve therapeutic benefits of CDK4/6 inhibitors (palbociclib and abemaciclib) in hormone receptor-positive, HER2-negative metastatic/recurrent breast cancer. Objective: This study was aimed at clarifying the effect of AEs associated with palbociclib and abemaciclib on treatment. Methods: A total of 62 and 49 patients were prescribed palbociclib and abemaciclib, respectively, at our hospital from January 1, 2018 to June 30, 2023. The rate and reasons for treatment discontinuation, interruption of administration, and changes in dose and dosing schedule, treatment duration, and relative dose intensity (RDI) were compared between the groups of patients prescribed the 2 treatments. Results: Treatment discontinuation due to AEs occurred more frequently with abemaciclib (12 patients) because of interstitial lung disease and hepatic and renal events than with palbociclib (5 patients; P =.008). Administration was interrupted in 57 (91.9%) and 35 (71.4%) patients treated with palbociclib and abemaciclib, respectively (P =.004). Dose reduction occurred in 37 (67.3%) and 19 (47.5%) patients treated with palbociclib and abemaciclib, respectively (P =.053). The median [range] treatment duration was 301 [21-1643] days for palbociclib and 238 [70-1526] days for abemaciclib (log-rank test, P =.581). The median RDI was 59.7% and 59.6% for palbociclib and abemaciclib, respectively (P =.539). Although the AEs of palbociclib and abemaciclib affected the treatment considerably, the treatment duration and RDI were similar. Conclusion: CDK4/6 inhibitors should be selected based on the tolerability and manageability of each AE. [ABSTRACT FROM AUTHOR]

The components of the mediator kinase module are highly conserved across all eukaryotic lineages, and cyclin‐dependent kinase 8 (CDK8) is essential for correct cell proliferation and differentiation in diverse eukaryotic systems. We show that CDK8 couples leaf development with the establishment of correct stomata patterning for prevailing CO2 conditions. In Arabidopsis, the basic helix‐loop‐helix (bHLH) transcription factor SPEECHLESS (SPCH) controls cellular entry into the stomatal cell lineage, and CDK8 interacts with and phosphorylates SPCH, controlling SPCH protein levels and thereby also expression of the SPCH target genes encoding key regulators of cell fate and asymmetric cell divisions. The lack of the CDK8‐mediated control of SPCH results in an increased number of meristemoid and guard mother cells, and increased stomata index in the cdk8 mutants. Increasing atmospheric CO2 concentrations trigger a developmental programme controlling cell entry into stomatal lineage by limiting the asymmetric divisions. In cdk8, the number of meristemoids and guard mother cells remains the same under ambient and high CO2 concentrations, as the accumulated levels of SPCH caused by the lack of CDK8 appear to override the negative regulation of increased CO2. Thus, our work provides novel mechanistic understanding of how plants alter critical leaf properties in response to increasing atmospheric CO2. [ABSTRACT FROM AUTHOR]

PURPOSE: Outcomes data for DNA-damaging therapeutics for men with prostate cancer (PC) and non- BRCA1/2 homologous recombination repair (HRR) mutations are limited. We evaluated outcomes by HRR alteration in men with PC treated with poly(ADP-ribose)polymerase inhibitors (PARPi) and/or platinum chemotherapy. METHODS: Retrospective data from the PROMISE consortium were used. Clinical outcomes differences were assessed between patients with BRCA1 / 2 mutations (cohort A) and those with HRR mutations without direct BRCA complex interaction (cohort B: ATM , CDK12 , CHEK1 , CHEK2 , and FANCL). Outcomes in patients with HRR mutations with direct BRCA complex interaction were also explored (cohort C: RAD51B/C/D , RAD54L2 , BARD1 , GEN1 , PALB2 , FANCA , and BRIP1). RESULTS: One hundred and forty-six patients received PARPi (cohort A: 94, cohort B: 45, cohort C: 7) and 104 received platinum chemotherapy (cohort A: 48, cohort B: 44, cohort C: 10). PSA50 response rate to PARPi was higher in cohort A (61%) than cohort B (5%), P <.001. Median clinical/radiographic progression-free survival (crPFS) with PARPi in cohort A was significantly longer than in cohort B: 15.9 versus 8.7 months, P =.005. PSA50 response rate to platinum therapy was higher in cohort A (62%) than in cohort B (32%), P =.024, although crPFS was not significantly different. PSA50 response rate to PARPi and platinum was 40% and 32%, respectively, in cohort C. In multivariable analysis, cohort A had significantly improved overall survival and crPFS compared with cohort B with PARPi but not platinum chemotherapy. CONCLUSION: Patients with BRCA1/2 -mutated PC had significantly improved outcomes to PARPi but not platinum chemotherapy compared with those with HRR mutations without direct BRCA complex interaction. [ABSTRACT FROM AUTHOR]

Purpose: This study seeks to contribute real-world data on the prevalence of BRCA1/2 and HRR gene mutations in prostate cancer. Methods: We compiled sequencing data of 197 cases of primary and metastatic prostate cancer, in which HRR mutation analysis was performed upon clinical request within the last 5 years. All cases were analyzed using a targeted NGS BRCAness multigene panel, including 8 HRR genes (ATM, BRCA1, BRCA2, CDK12, CHEK2, FANCA, HDAC2, PALB2). Results: Our findings reveal a prevalence of potentially targetable mutations based on FDA criteria of 20.8%, which is comparable to the literature. However, the frequency of targetable BRCA2 mutations within our cohort was lower than reported for mCRPC and ATM and CHEK2 mutations were more prevalent instead. Thus, while 20.8% (n = 38) of the cases meet the criteria for olaparib treatment per FDA approval, only 4.9% (n = 9) align with the eligibility criteria according to the EMA approval. Conclusion: This study offers valuable real-world insights into the landscape of BRCA1/2 and HRR gene mutations and the practical clinical management of HRR gene testing in prostate cancer, contributing to a better understanding of patient eligibility for PARPi treatment. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma (GB) is recognized as one of the most aggressive brain tumors, with a median survival of 14.6 months. However, there are still some patients whose survival time was greater than 3 years, and the biological reasons behind this clinical phenomenon arouse our research interests. By conducting proteomic analysis on tumor tissues obtained from GB patients who survived over 3 years compared to those who survived less than 1 year, we identified a significant upregulation of SelK in patients with shorter survival times. Therefore, we hypothesized that SelK may be an important indicator related to the occurrence and progression of GBM. Methods: Proteomics and immunohistochemistry from GB patients were analyzed to investigate the correlation between SelK and clinical prognosis. Cellular phenotypes were evaluated by cell cycle analysis, cell viability assays, and xenograft models. Immunoblots and co-immunoprecipitation were conducted to verify SelK-mediated ubiquitin-dependent degradation of CDK4. Results: SelK was found to be significantly upregulated in GB samples from short-term survivors (≤ 1 year) compared to those from long-term survivors (≥ 3 years), and its expression levels were negatively correlated with clinical prognosis. Knocking down of SelK expression reduced GB cell viability, induced G0/G1 phase arrest, and impaired the growth of transplanted glioma cells in nude mice. Down-regulation of SelK-induced ER stress leads to a reduction in the expression of SKP2 and an up-regulation of β-TrCP1 expression. Up-regulation of β-TrCP1, thereby accelerating the ubiquitin-dependent degradation of CDK4 and ultimately inhibiting the malignant proliferation of the GB cells. Conclusion: This study discovered a significant increase in SelK expression in GB patients with poor prognosis, revealing a negative correlation between SelK expression and patient outcomes. Further mechanistic investigations revealed that SelK enhances the proliferation of GB cells by targeting the endoplasmic reticulum stress/SKP2/β-TrCP1/CDK4 axis. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated one of the treatment options for advanced breast cancer patients after they completed standard therapy that combines hormone therapy and specific targeted agents called cyclin-dependent kinase 4/6 inhibitors. We wanted to understand why in real-world patients start chemotherapy after finishing standard initial treatment, how they respond to it, and what factors might affect their outcomes. We found that chemotherapy was often used when patients faced dissemination to internal organs with the risk of further progression, but it provided limited benefits. We suggest that modern drugs recommended by guidelines before chemotherapy should be better reimbursed in Poland. This research could help doctors make better treatment decisions and improve future clinical trials. The standard therapy for hormone-receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer includes the use of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) with endocrine therapy. The optimal post-CDK4/6i treatment sequence is unclear. This cohort study evaluated the initiation, characteristics, and outcomes of chemotherapy following CDK4/6i-based treatment. Among the 227 patients who began CDK4/6i therapy, 114 completed it. Seventy-nine female patients received further treatment, including 55 receiving chemotherapy. The average age was 60.1 years. Post-CDK4/6i chemotherapy was typically (69.1%) first-line due to an impending visceral crisis. The median progression-free survival (mPFS) was 3.0 months (range 0.5–18.9), and the median overall survival (mOS) was 8.3 months (0.5–26.1). The median OS from the end of CDK4/6i treatment was 12.4 months (1.5–26.8). In univariate analysis, neither mPFS nor mOS was associated with age, tumor grade, receptor status, Ki67 status, time from diagnosis to CDK4/6i cessation, therapy line, or CDK4/6i type. Dose reduction occurred in 12 patients (21.8%), and chemotherapy was ceased due to adverse events in 8 patients (14.6%). Chemotherapy showed limited benefit regardless of the regimen. The role of chemotherapy may evolve with broader CDK4/6i use in adjuvant treatment. [ABSTRACT FROM AUTHOR]

Simple Summary: CDK4/6 inhibitors are recommended as first-line therapy for treating patients with hormone receptor-positive metastatic breast cancer. The most commonly reported adverse events of CDK4/6 inhibitors include neutropenia, leukopenia, and diarrhea. Recent case reports and retrospective studies show that CDK4/6 inhibitors may be more frequently associated with cardiovascular adverse events. This study comprehensively analyzed the FDA Adverse Event Reporting System and provided the frequency and onset of cardiovascular adverse events, including heart failure, hypertension, myocardial infarction, QT prolongation, pericarditis, and cardiomyopathy. Hypertension and heart failure were frequently reported among the analyzed adverse events. Further research is warranted to investigate the underlying mechanisms of cardiovascular events. Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors are approved for the treatment of human epidermal growth factor receptor 2 (HER-2)-negative, hormone receptor-positive breast cancer. The cardiovascular toxicity of CDK4/6 inhibitors is not well understood. This study aims to profile the cardiac events associated with CDK4/6 inhibitors. Reports from 2015Q1 to 2024Q1 were obtained from the FDA Adverse Event Reporting System (FAERS). Reports identifying palbociclib, ribociclib, and abemaciclib as the primary suspect were examined for cardiovascular toxicity, including hypertension, cardiac failure, cardiomyopathy, arrhythmia, myocardial infarction, and myocarditis. Signal detection was performed using the proportional reporting ratio (PRR), reporting odds ratio (ROR), and information component (IC). A total of 69,139 reports were analyzed. The median time to adverse events was 69 days (interquartile range [IQR], 18–260 days). Of these, 2065 reports documented cardiac adverse events. Ribociclib and QT prolongation were re-confirmed as a signal (PRR 8.43, ROR 8.65, IC025 2.86). Hypertension and cardiac failure were the most frequently reported cardiovascular toxicities. This study demonstrates that the use of CDK4/6 inhibitors is associated with cardiovascular adverse events, such as heart failure and hypertension. Further research is needed to understand the mechanisms and risk factors contributing to the cardiovascular toxicity of CDK4/6 inhibitors. [ABSTRACT FROM AUTHOR]

The identification of genes involved in replicative stress is key to understanding cancer evolution and to identify therapeutic targets. Here, we show that CDK12 prevents transcription-replication conflicts (TRCs) and the activation of cytotoxic replicative stress upon deregulation of the MYC oncogene. CDK12 was recruited at damaged genes by PARP-dependent DDR-signaling and elongation-competent RNAPII, to repress transcription. Either loss or chemical inhibition of CDK12 led to DDR-resistant transcription of damaged genes. Loss of CDK12 exacerbated TRCs in MYC-overexpressing cells and led to the accumulation of double-strand DNA breaks, occurring between co-directional early-replicating regions and transcribed genes. Overall, our data demonstrate that CDK12 protects genome integrity by repressing transcription of damaged genes, which is required for proper resolution of DSBs at oncogene-induced TRCs. This provides a rationale that explains both how CDK12 deficiency can promote tandem duplications of early-replicated regions during tumor evolution, and how CDK12 targeting can exacerbate replicative-stress in tumors. CDK12 is a therapeutic target and cancer gene required for genome integrity. Here, the Authors show that loss or inhibition of CDK12 leads to persistent transcription of damaged genes, and triggers transcription replication conflicts leading to selective cell death in Myc- driven tumors. [ABSTRACT FROM AUTHOR]

Soft tissue sarcomas represent an heterogeneous group of rare mesenchymal tumors comprising 1% of all solid malignancies. Among them, liposarcoma is one of the most common histotypes with atypical lipomatous tumor/well differentiated liposarcoma and dedifferentiated liposarcoma (ALT/WDLPS and DDLPS) as the major sub-entities. The unavailability of predictive, prognostic and druggable biomarkers makes the management of these lesions challenging. In recent years CDK4 and its inhibitors have emerged as potential agents for these lesions especially for ALT/WDLPS and DDLPS but the results are not conclusive and need to be elucidated. This study involved 21 ALT/WDLPS and DDLPS patients. Histological analyses of MDM2 and CDK4 were carried out. Moreover, a DDLPS patient-derived cancer model was established in vitro and in vivo assessing the efficacy of palbociclib in combination and sequential treatment. Finally, in silico analyses on CDK4 expression were carried out. The results showed a higher expression of CDK4 and MDM2 in DDLPS compared to ALT/WDLPS. Moreover, no correlation between MDM2 expression and CDK4 was observed. Next, in vitro analysis of CDK4 inhibitor palbociclib showed an antagonistic effect when combined to other chemotherapeutics, while it exhibited a significant synergy when administered in sequential schedule with lenvatinib. Next, in vivo analysis on DDLPS xenotransplanted embryos assessing the efficacy and safety profile of the in vitro tested schedules confirmed the observed data. This proof-of-concept study sheds light on the natural history of ALT/WDLPS and DDLPS and provides the rationale for the clinical applicability of sequential treatment with palbociclib in the management of DDLPS. [ABSTRACT FROM AUTHOR]

Aims Although the cannabinoid CB1 receptor has been implicated in atherosclerosis, its cell-specific effects in this disease are not well understood. To address this, we generated a transgenic mouse model to study the role of myeloid CB1 signalling in atherosclerosis. Methods and results Here, we report that male mice with myeloid-specific Cnr1 deficiency on atherogenic background developed smaller lesions and necrotic cores than controls, while only minor genotype differences were observed in females. Male Cnr1 -deficient mice showed reduced arterial monocyte recruitment and macrophage proliferation with less inflammatory phenotype. The sex-specific differences in proliferation were dependent on oestrogen receptor (ER)α-oestradiol signalling. Kinase activity profiling identified a CB1-dependent regulation of p53 and cyclin-dependent kinases. Transcriptomic profiling further revealed chromatin modifications, mRNA processing, and mitochondrial respiration among the key processes affected by CB1 signalling, which was supported by metabolic flux assays. Chronic administration of the peripherally restricted CB1 antagonist JD5037 inhibited plaque progression and macrophage proliferation, but only in male mice. Finally, CNR1 expression was detectable in human carotid endarterectomy plaques and inversely correlated with proliferation, oxidative metabolism, and inflammatory markers, suggesting a possible implication of CB1-dependent regulation in human pathophysiology. Conclusion Impaired macrophage CB1 signalling is atheroprotective by limiting their arterial recruitment, proliferation, and inflammatory reprogramming in male mice. The importance of macrophage CB1 signalling appears to be sex-dependent. [ABSTRACT FROM AUTHOR]

Purpose. Endocrine therapy combined with cyclin‐dependent kinase (CDK) 4/6 inhibitors (CDK4/6i) is the preferred treatment for hormone receptor‐positive (HR+)/human epidermal growth factor receptor 2‐negative (HER2–) metastatic breast cancer (MBC). However, there are currently no recommendations for therapeutic strategies after progression on CDK4/6i‐based treatment. This study aimed to examine the efficacy and safety of anlotinib plus chemotherapy in HR+/HER2– MBC after progression on CDK4/6 inhibitors. Methods. We collected data from 32 patients with HR+/HER2– MBC treated with anlotinib plus chemotherapy after progressing on CDK4/6i at Jiangsu Cancer Hospital from March 2020 to October 2023. The median follow‐up was 9.1 months (range, 2.0–19.7 months) as of the data cutoff date in October 2023. The primary endpoint was median progression‐free survival (PFS); secondary endpoints included objective response rate (ORR), disease control rate (DCR), and adverse events. Results. The median PFS (mPFS) of all patients was 7.6 months (95% confidence interval (CI), 5.75–9.45). There was no significant difference in mPFS between patients who responded to prior CDK4/6i treatment and those who did not (8.3 months vs. 6.8 months, p = 0.580). Besides, the ORR was 34.4% and DCR was 93.8%. The most frequently observed adverse events were anemia (50.0%), neutropenia (40.6%), thrombocytopenia (34.4%), and epistaxis (34.4%). Dose interruption or reductions due to adverse events occurred in 2 (6.3%) and 5 (15.6%) patients, respectively. Conclusions. The study preliminarily demonstrates that anlotinib combined with chemotherapy may be an optional recommendation for patients with HR+/HER2– metastatic breast cancer who have progressed after CDK4/6i. [ABSTRACT FROM AUTHOR]

The consensus linear view of G1/S regulation has served the research community for many years. Recent data indicate considerable heterogeneity in cancer cycles as controlled by distinct cyclin-dependent kinase (CDK) and cyclin complexes. Adaptation and unexpected dependencies reveal emerging themes that support a malleable model for cancer cell division. The growing complexity of the cell cycle offers challenges and opportunities in rationally targeting proliferative control. In the commonly accepted paradigm for control of the mammalian cell cycle, sequential cyclin-dependent kinase (CDK) and cyclin activities drive the orderly transition from G1 to S phase. However, recent studies using different technological approaches and examining a broad range of cancer cell types are challenging this established paradigm. An alternative model is evolving in which cell cycles utilize different drivers and take different trajectories through the G1/S transition. We are discovering that cancer cells in particular can adapt their drivers and trajectories, which has important implications for antiproliferative therapies. These studies have helped to refine an understanding of how CDK inhibition impinges on proliferation and have significance for understanding fundamental features of cell biology and cancer. [ABSTRACT FROM AUTHOR]

Simple Summary: Pancreatic ductal adenocarcinoma has a low 5-year survival rate due to delayed diagnosis, rapid growth, tumor complexity, and difficulties in surgical resection. Treatments involving new targeted chemotherapeutic options are required due to challenges such as drug resistance, low efficacy, severe toxicity, high metastatic potential, and clinical trial failures. This study demonstrates the preclinical efficacy and potential of the novel combination of abemaciclib and panobinostat in multiple pancreatic cancer cell lines. Our results depict that a novel combination of these agents aids in synergistic effects, causing cell death in pancreatic cancer cells. The current 5-year survival rate of pancreatic cancer is about 12%, making it one of the deadliest malignancies. The rapid metastasis, acquired drug resistance, and poor patient prognosis necessitate better therapeutic strategies for pancreatic ductal adenocarcinoma (PDAC). Multiple studies show that combining chemotherapeutics for solid tumors has been successful. Targeting two distinct emerging hallmarks, such as non-mutational epigenetic changes by panobinostat (Pan) and delayed cell cycle progression by abemaciclib (Abe), inhibits pancreatic cancer growth. HDAC and CDK4/6 inhibitors are effective but are prone to drug resistance and failure as single agents. Therefore, we hypothesized that combining Abe and Pan could synergistically and lethally affect PDAC survival and proliferation. Multiple cell-based assays, enzymatic activity experiments, and flow cytometry experiments were performed to determine the effects of Abe, Pan, and their combination on PDAC cells and human dermal fibroblasts. Western blotting was used to determine the expression of cell cycle, epigenetic, and apoptosis markers. The Abe-Pan combination exhibited excellent efficacy and produced synergistic effects, altering the expression of cell cycle proteins and epigenetic markers. Pan, alone and in combination with Abe, caused apoptosis in pancreatic cancer cells. Abe-Pan co-treatment showed relative safety in normal human dermal fibroblasts. Our novel combination treatment of Abe and Pan shows synergistic effects on PDAC cells. The combination induces apoptosis, shows relative safety, and merits further investigation due to its therapeutic potential in the treatment of PDAC. [ABSTRACT FROM AUTHOR]

Aaptamine (8,9-dimethoxy-1H-benzo[de][1,6]naphthyridine), an alkaloid obtained from marine sponges of the genus Aaptos (Demospongiae, Suberitida, Suberitidae), has attracted significant attention as a promising scaffold for the development of antioxidant, antibacterial, and anticancer agents. This review offers an extensive overview of updated research on aaptamine, focusing on its multifaceted pharmacological properties. The antioxidant potential of aaptamine reflects its potential ability for use in the DPPH free radical scavenging assay, for suppressing ROS, and subsequently deactivating the MAPK and AP-1 signaling pathway. Moreover, it demonstrates notable antibacterial activity against pathogenic bacteria, including mycobacterial active and dormant states, making it a potential candidate for combating bacterial infections. Additionally, aaptamine shows promising anticancer activity by inhibiting cancer cell proliferation, apoptosis induction, and suppressing tumor growth through various signaling pathways, including the regulation of PTEN/PI3K/Akt and CDK2/4, and the regulation of cyclin D1/E in cell cycle arrest. The unique chemical structure of aaptamine offers opportunities for structural modifications aimed at enhancing its antioxidant, antibacterial, and anticancer activities. The exploration of aaptamine as a scaffold in the development of novel therapeutic agents offers great promise for addressing various challenges associated with oxidative stress, bacterial infections, and cancer. This article underscores the potential of aaptamine as a valuable marine-derived scaffold in the fields of antioxidant, antibacterial, and anticancer therapy. [ABSTRACT FROM AUTHOR]

Context: Cyclin-dependent kinase 9 (CDK9) plays a significant role in gene regulation and RNA polymerase II transcription under basal and stimulated conditions. The upregulation of transcriptional homeostasis by CDK9 leads to various malignant tumors and therefore acts as a valuable drug target in addressing cancer incidences. Ongoing drug development endeavors targeting CDK9 have yielded numerous clinical candidate molecules currently undergoing investigation as potential CDK9 modulators, though none have yet received Food and Drug Administration (FDA) approval. Methods: In this study, we employ in silico approaches including the molecular docking and molecular dynamics simulations for the virtual screening over the natural compounds library to identify novel promising selective CDK9 inhibitors. The compounds derived from the initial virtual screening were subsequently employed for molecular dynamics simulations and binding free energy calculations to study the compound's stability under virtual physiological conditions. The first-generation CDK inhibitor Flavopiridol was used as a reference to compare with our novel hit compound as a CDK9 antagonist. The 500-ns molecular dynamics simulation and binding free energy calculation showed that two natural compounds showed better binding affinity and interaction mode with CDK9 receptors over the reference Flavopiridol. They also showed reasonable figures in the predicted absorption, distribution, metabolism, excretion, and toxicity (ADMET) calculations as well as in computational cytotoxicity predictions. Therefore, we anticipate that the proposed scaffolds could contribute to developing potential and selective CDK9 inhibitors subjected to further validations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Neutrophilic inflammation is a critical pathogenic hallmark in ARDS. • Ribociclib, a clinically-used CDK4/6 inhibitor, acts as a novel PDE4 inhibitor to regulate neutrophilic inflammation. • Ribociclib shows therapeutic potential in ARDS. • The drug repurposing of ribociclib provides a promising opportunity for neutrophil-associated diseases, including ARDS. Overwhelming neutrophil activation and oxidative stress significantly contribute to acute respiratory distress syndrome (ARDS) pathogenesis. However, the potential of repurposing ribociclib, a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor used clinically in cancer treatment, for treating neutrophilic ARDS remains uncertain. This study illustrated the ability and underlying mechanism of ribociclib for treating ARDS and neutrophilic inflammation. Primary human neutrophils were used to determine the therapeutic effects of ribociclib on respiratory bursts, chemotactic responses, and inflammatory signaling. In vitro and silico analyses were performed to determine the underlying molecular mechanisms. The potential of ribociclib repurposing was evaluated using an in vivo ARDS model in lipopolysaccharide (LPS)-primed mice. We found that treatment using ribociclib markedly limited overabundant oxidative stress (reactive oxygen species [ROS]) production and chemotactic responses (integrin levels and adhesion) in activated human neutrophils. Ribociclib was also shown to act as a selective inhibitor of phosphodiesterase 4 (PDE4), thereby promoting the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway, leading to the inhibition of extracellular signal-regulated kinase (ERK), c-Jun N -terminal kinase (JNK) phosphorylation, and calcium influx. Notably, prophylactic administration and post-treatment with ribociclib ameliorated neutrophil infiltration, lung inflammation, accumulation of oxidative stress, pulmonary destruction, and mortality in mice with LPS-induced ARDS. We demonstrated for the first time that ribociclib serves as a novel PDE4 inhibitor for treating neutrophilic inflammation and ARDS. The repurposing ribociclib and targeting neutrophilic PDE4 offer a potential off-label alternative for treating lung lesions and other inflammatory conditions. [ABSTRACT FROM AUTHOR]

Objective: This article aims to discuss elacestrant, an oral selective estrogen receptor downregulator approved by the Food and Drug Administration (FDA) in January 2023 for the treatment of hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2−) advanced breast cancer. Data sources: PubMed, Embase, Medline, Clinicaltrials.gov, and the National Comprehensive Cancer Network (NCCN) were searched from inception to August 31, 2023. Study selection and data extraction: Clinical trials published in English were included and relevant information regarding methodology and results were extracted. Data synthesis: Phase 1 and 3 trials showed elacestrant was safe and improved progression-free survival in patients with endocrine receptor 1 (ESR1) mutations who failed cyclin-dependent kinase 4/6 inhibitor (CDK 4/6i) plus 1 prior endocrine therapy compared with standard of care (SOC) (fulvestrant, anastrozole, letrozole, or exemestane monotherapy). Relevance to patient care and clinical practice in comparison to existing drugs: Elacestrant maintains a comparable adverse event profile with other endocrine therapies and offers an alternative to typical sequential therapy which can delay the use of or be used after traditional chemotherapy. Elacestrant is currently being studied in CDK 4/6 inhibitor naïve patients and as a component of combination therapy for first-line use which could lead to future indications. Conclusions: Elacestrant gained FDA approval in January 2023 and can be considered in patients with HR+ HER2− advanced breast cancer and ESR1 mutations who have progressed despite therapy with either CDK 4/6i plus aromatase inhibitors (AI) or fulvestrant or chemotherapy. [ABSTRACT FROM AUTHOR]