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Background/Objectives: In Romania, breast cancer is the second most common cancer, the third leading cause of cancer death, and the most prevalent cancer overall. De novo advanced-stage breast cancer often presents in clinical practice, and treatment decisions are best made in a multidisciplinary tumor board (MTD) involving surgeons, radiotherapists, and medical oncologists. Significant advances in systemic therapies, particularly in progression-free survival (PFS) and overall survival (OS), have surpassed traditional palliative mastectomy and radiotherapy for local control. Therefore, the purpose of this study is to emphasize the importance of the initial choice of treatment for patient prognosis. Methods: We expose two cases of patients with de novo severe, advanced-stage, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer and their management and outcome using cyclin-dependent kinase (CDK) 4/6 inhibitor and radiotherapy. An extensive review of the literature from the past five years was also conducted. Results: The role of palliative mastectomy is diminishing, as many patients are opting for novel therapies, including cyclin-dependent kinase (CDK) 4/6 inhibitors, which may improve quality of life. Conclusions: First-line therapy for locally advanced breast cancer has suffered changes due to the implementation of systemic targeted therapy. However, drug resistance—either de novo or acquired—remains a critical consideration. MTD discussions and informed patient decisions are essential to achieving a personalized, evidence-based treatment outcome. [ABSTRACT FROM AUTHOR]

Simple Summary: Breast cancer continues to pose significant treatment challenges, driving the search for new therapeutic agents with innovative mechanisms of action. Ruthenium-based compounds are emerging as promising anticancer agents due to their unique properties, which differ from those of traditional platinum-based therapies. This study investigates the effects of the ruthenium complex Bis(quinolin-8-olato)bis(triphenylphosphine)ruthenium(II) (Ru(quin)2) in hormone receptor-positive and triple-negative breast cancer cell models. Our results demonstrate that this compound effectively reduces cancer cell viability by inducing programmed cell death, stimulating autophagy, and causing cell cycle arrest. These findings highlight the potential of Ru(quin)2 as a novel therapeutic candidate for breast cancer, warranting further exploration to evaluate its in vivo efficacy and potential for clinical application. Background/Objectives: Breast cancer (BC) remains one of the most prevalent and deadly cancers worldwide, with limited access to advanced treatments in developing regions. There is a critical need for novel therapies with unique mechanisms of action, especially to overcome resistance to conventional platinum-based drugs. This study investigates the anticancer potential of the ruthenium complex Bis(quinolin-8-olato)bis(triphenylphosphine)ruthenium(II) (Ru(quin)2) in ER-positive (T47D) and triple-negative (MDA-MB-231) BC cell lines. Results: Ru(quin)2 demonstrated dose-dependent cytotoxicity, with IC50 values of 48.3 μM in T47D cells and 45.5 μM in MDA-MB-231 cells. Its cytotoxic effects are primarily driven by apoptosis, as shown by increased BAX expression, enhanced caspase-3 activity, reduced Aurora B kinase levels, and elevated histone release. Ru(quin)2 also induced autophagy, evidenced by LC3-I to LC3-II conversion and reduced SQSTM1, partially mediated through MAPK signaling. Furthermore, Ru(quin)2 induced G0/G1 cell cycle arrest by downregulating cyclin D1, CDK4, and CDK6, alongside upregulation of the CDK inhibitor p21. Conclusions: Ru(quin)2 emerges as a potent candidate for BC treatment, with multiple mechanisms of action involving apoptosis, autophagy, and cell cycle arrest. Further studies are warranted to elucidate its detailed molecular mechanisms and evaluate its therapeutic potential in vivo, moving toward clinical applications for both ER-positive and triple-negative BC management. [ABSTRACT FROM AUTHOR]

Cancer remains a leading cause of morbidity and mortality worldwide, highlighting the urgent need for novel therapeutic agents. This study investigated the synthesis and biological evaluation of O-alkyl (E)-chalcone derivatives (4a–4v) as potential anticancer agents. The compounds were synthesized via aldol condensation of substituted aldehydes and acetophenones, with structures confirmed by IR, NMR, and mass spectrometry. In vitro cytotoxicity assays revealed varying effectiveness, with compounds 4a, 4b, 4q, and 4v exhibiting potent activity against MDA-MB-231 and MCF-7, showing IC50 values between 2.08 and 13.58 µM, besides HCT-116 and HeLa cancer cell lines (IC50 values between 6.59 and 22.64 µM). Notably, compound 4b displayed remarkable selectivity, with an IC50 of 54.59 µM against the non-cancerous WI-38 cell line. Additionally, protein kinase inhibition assays indicated that compounds 4b and 4q effectively inhibited EGFR and VEGFR-2, with 4b outperforming the standard inhibitor erlotinib. Molecular docking studies of compound 4q showed strong binding affinities in the ATP-binding pockets of EGFR, HER2, VEGFR2, and CDK2. In silico analyses further highlighted the favorable pharmacokinetic properties of compound 4q, underscoring its potential as a selective tyrosine kinase inhibitor. These findings suggest the therapeutic promise of O-alkyl (E)-chalcone derivatives in cancer treatment. [ABSTRACT FROM AUTHOR]

Cyclin-dependent kinases 4 and 6 (CDK4/6) are crucial regulators of cell cycle progression and represent important therapeutic targets in breast cancer. This study employs a comprehensive computational approach to identify novel CDK4/6 inhibitors from marine natural products. We utilized structure-based virtual screening of the CMNPD database and MNP library, followed by rigorous filtering based on drug-likeness criteria, PAINS filter, ADME properties, and toxicity profiles. From an initial hit of 9,497 compounds, 2,344 passed drug-likeness and PAINS filters. Further ADME filtering yielded 50 compounds, of which 25 exhibited non-toxic profiles. These 25 candidates underwent consensus molecular docking using seven distinct algorithms: AutoDockTools 4.2, idock, LeDock, Qvina 2, Smina, AutoDock Vina 1.2.0, PLANTS, and rDock. Based on these results, six top-scoring compounds were selected for comprehensive 500 nanosecond all-atom molecular dynamics simulations to evaluate their structural stability and interactions with CDK4/6. Our analysis revealed that compounds CMNPD11585 and CMNPD2744 demonstrated superior stability in their interactions with CDK4/6, exhibiting lower RMSD and RMSF values, more favorable binding free energies, and persistent hydrogen bonding patterns. These compounds also showed lower Solvent Accessible Surface Area values, indicating better compatibility with the CDK4/6 active site. Subsequent in-vitro studies using MTT assays on MCF-7 breast cancer cells confirmed the cytotoxic effects of these compounds, with CMNPD11585 showing the highest potency, followed by CMNPD2744. [ABSTRACT FROM AUTHOR]

Introduction: Chemotherapy combined with anti-human epidermal growth factor receptor 2 (HER2)-targeted therapy is currently a standard treatment for advanced HER2/HR-positive breast cancer (BC), although evidences showed that HR expression compromised effectiveness of the treatment. While cyclin-dependent kinase (CDK) 4/6 inhibitors combined with endocrine therapy is a key therapy for the BC with HR expression, data on the effectiveness and safety of CDK 4/6 inhibitors combined with trastuzumab and endocrine therapy as a first-line treatment for HER2-positive and HR-positive metastatic BC are limited. Case Presentation: Here, we report a case of a 46-year-old premenopausal woman diagnosed with stage 4 HER2/HR-positive invasive ductal carcinoma from both right and left breast with hypermetabolic activities in multiple lymph nodes, adrenal, bone, and skin. Interventions: Due to the patient’s refusal to use chemotherapy, she was started on goserelin, abemaciclib, letrozole, and trastuzumab. Outcomes: The patient’s symptoms were relieved with near resolution of the primary breast mass and nearly all of the metastatic sites. Metabolic resolution was observed in bone lesions. The disease was under control for 57 weeks. During the treatment, neutropenia (grade 1–2) and anemia (grade 1) occurred, which spontaneously recovered. Additionally, diarrhea improved after symptomatic treatment. Conclusion: We believe that the combination of trastuzumab, hormone suppression, and abemaciclib is a practicable and effective treatment for HER2-positive and HR-positive metastatic BC in premenopausal patients who cannot tolerate the first-line chemotherapy. [ABSTRACT FROM AUTHOR]

Background: Although CDK4/6 inhibitors combined with endocrine therapies have improved outcomes in HR+ HER2-negative metastatic breast cancer, predictive biomarkers for treatment response and adverse effects remain limited. This study assessed the prognostic and predictive value of large unstained cells (LUC), a subset of white blood cells that may reflect immune status or treatment response. Methods: A retrospective analysis of 210 patients with HR+ HER2-negative metastatic breast cancer treated with CDK 4/6 inhibitors between 2021 and 2024 was conducted. Clinical data, including demographics, tumor characteristics, and treatment regimens, were analyzed. Based on LUC levels, progression-free survival (PFS), overall survival (OS), and adverse events were evaluated. Results: The cohort had a median age of 57, of which 78% were postmenopausal. Common metastatic sites included bone (67%) and liver (24%). At a median follow-up of 18.5 months, the PFS and OS rates were 65% and 83%. Patients with low LUC levels had significantly shorter PFS (OR: 1.91; p = 0.014) and OS (OR: 2.39; p = 0.012), while high LUC levels correlated with a lower incidence of grade 3 neutropenia (OR: 0.49; p = 0.017). Liver metastasis and prior treatments were also linked to shorter survival. Conclusions: LUC levels emerge as a promising biomarker for predicting survival outcomes and the risk of neutropenia in HR+ HER2-negative metastatic breast cancer patients treated with CDK 4/6 inhibitors and endocrine therapy, showing their potential to guide personalized treatment approaches. [ABSTRACT FROM AUTHOR]

Objective: Hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer is the most common subtype. Abemaciclib, an inhibitor of cyclin-dependent kinases 4 and 6, was approved to reduce risk of recurrence in high-risk, HR+, HER2-, early breast cancer based on the monarchE trial. The most common adverse events reported in monarchE were diarrhea, neutropenia, and fatigue. Real-world tolerability data and incidence of adverse events with abemaciclib in the adjuvant setting versus the metastatic setting is lacking. Data Sources: This is a retrospective analysis of HR+, HER2- breast cancer patients on abemaciclib from March 2018 to September 2021 at Robert H. Lurie Comprehensive Cancer Center in Chicago, Illinois. Incidence, grade of adverse events, dose reductions, and discontinuations were evaluated in patients taking abemaciclib in the adjuvant setting and the metastatic setting. Data Summary: Of the 30 patients included in this analysis, 100% experienced an adverse event of any grade. During treatment, 12.5% treated in the adjuvant setting and 35.7% in the metastatic setting experienced grade ≥3 adverse events. Adverse events leading to discontinuation of abemaciclib occurred in 18.8% of patients in the adjuvant setting and 57.1% in the metastatic setting. Conclusions: This data suggests abemaciclib is better tolerated in high-risk, HR+, HER2-, node-positive, early breast cancer treated in the adjuvant setting compared to the metastatic setting. Management of adverse events is crucial to help patients stay on therapy to improve clinical outcomes. Real-world tolerability of abemaciclib in both the adjuvant and metastatic settings is of importance. [ABSTRACT FROM AUTHOR]

As a member of peroxisome proliferator-activated receptor (PPAR) family, PPARG has been reported to be involved in glucolipid metabolism in various species. However, the function of PPARG in estradiol (E2) synthesis, apoptosis, and proliferation in goat ovarian granulosa cells (GCs) is unclear. In this study, we found that goat PPARG was expressed in GCs of all grades of follicles, and localized in the cytoplasm and nucleus of GCs. Transfection of small interfering RNA-PPARG2 (si-PPARG2) decreased E2 synthesis and the abundances of HSD3B and CYP19A1 mRNA and protein. It also promoted cell apoptosis with significant increases in the ratio of BAX/BCL-2 and Caspase3 mRNA and protein. Meanwhile, cell cycle was inhibited by si-PPARG2 transfection, accompanied by decreased mRNA levels of CDK4 , CKD6 , MYC , CCND1 , CCND2 , PCNA , and CCNB , increased mRNA level of P53 , and decreased protein levels of CDK4, MYC, and CCND1. Furthermore, PPARG interference affected the mRNA and protein abundances of CREB as well as the phosphorylation of CREB but not PKA. In conclusion, our data suggest that PPARG plays an important role in regulating E2 synthesis, cell apoptosis, and proliferation of goat GCs, including the CREB expression and phosphorylation. These results provide evidences for the in-depth study of PPARG in the regulation of goat GCs function. • PPARG interference decreased E2 synthesis and the mRNA and protein abundances of HSD3B and CYP19A1 in goat granulosa cells. • PPARG2 interference affected cell cycle and cell apoptosis in goat granulosa cells. • PPARG interference affected the mRNA and protein abundances and the phosphorylation of CREB in goat granulosa cells. [ABSTRACT FROM AUTHOR]

AbstractAim: To explore the clinical value of miR-193a-5p in neonatal acute respiratory distress syndrome (ARDS) and its role in ARDS cell model in vitro. Methods: RT-qPCR was utilized to detect miR-193a-5p level. Correlation analysis was implemented to assess the correlation between miR-193a-5p and clinical indicators (IL-6, IL-1β, TNF-α, LUS). Human lung epithelial cells induced by LPS were used to construct ARDS cell model. The effects of miR-193a-5p on cell viability, apoptosis and inflammation were evaluated by CCK-8, flow cytometry and ELISA. The target gene of miR-193a-5p was predicted and verified by StarBaseV2.0 and luciferase reporter gene, respectively. Results: MiR-193a-5p level in the ARDS group was down-regulated. MiR-193a-5p levels were negatively correlated with clinical indicators. In vitro studies revealed that up-regulation of miR-193a-5p significantly improved LPS-induced apoptosis, inflammation and viability inhibition. Conclusion: The expression of miR-193a-5p was decreased in neonatal ARDS, it is negatively correlated with the pro-inflammatory factors levels. [ABSTRACT FROM AUTHOR]

In this study, we applied comparative transcriptomics and proteomics techniques to systematically investigate the dynamic expression patterns of genes and proteins at various stages of early embryonic development of the gastropod Neptunea arthritica cumingii. Twelve cyclin-dependent kinase (CDKs) genes and five downstream proteins associated with these CDKs were identified. Through techniques such as qRT-PCR, our data elucidate for the first time the regulatory functions of CDK family genes and establish CDKs as a pivotal gene cluster in the early embryonic development of N. cumingii. These findings not only enhance the understanding of molecular developmental biology in N. cumingii and marine gastropods in general but also provide significant insights into the mechanisms involved in early embryonic development in N. cumingii. Furthermore, our results provide theoretical guidance for advancing artificial breeding technology for N. cumingii. [ABSTRACT FROM AUTHOR]

Simple Summary: In Romania, around 12,000 new cases of breast cancer are diagnosed each year, making it the second most common cause of cancer-related deaths, after lung cancer. The objective of this study is to evaluate the efficacy, safety, and adherence to Palbociclib in combination with either an aromatase inhibitor or fulvestrant in a real-world cohort of HR+/HER2− breast cancer patients from Romania. By examining clinical outcomes, such as time to treatment discontinuation, overall survival, and adherence, this study aims to contribute to the growing body of real-world data that support the use of Palbo in routine clinical practice. Understanding these factors in a real-world setting is essential for optimizing treatment strategies and improving patient outcomes globally, particularly in underrepresented regions where trial data are scarce. Our findings confirm pre-existing trial and real-world data, showing no significant differences in overall survival between the two treatment options. Background/Objectives: The first reimbursed prescription for palbociclib (Palbo) in breast cancer patients in Romania was issued in July 2018. The objective of this study is to assess the efficacy, safety, and adherence to Palbo in combination with aromatase inhibitor (AI) or fulvestrant in a real-world cohort of HR+/HER2− breast cancer patients from Romania. Methods: A retrospective analysis of reimbursed Palbo prescriptions was conducted using data extracted from the electronic database of the Romanian Health Insurance House, Dolj County, for disease code 124 (breast cancer), covering the period from 2018 to 2023. The primary outcome assessed was time to treatment discontinuation (TTD), with secondary outcomes including overall survival (OS) and Palbo adherence (which was measured by medication possession ratio). Results: A total of 125 patients were identified, with a median age of 62 years (IQR, 53–70), and 98% were female. Two treatment combinations were observed: Palbo + Aromatase Inhibitor (AI) in 104 patients (83.2%) and Palbo + fulvestrant in 21 patients (16.8%). The median TTD for the entire cohort was 19 months (95%CI, 19.3–24.9 months). In patients treated with Palbo + AI, the median TTD was not available/reached [NA] (95%CI, 36.0-NA months). For those receiving Palbo+fulvestrant, the median TTD was 25.0 months (95%CI, 13.0-NR months). No significant differences in TTD were observed among the two treatment combinations (χ2 = 1.33, df = 1, log-rank p = 0.249). The 12- and 36-month TTD rates were higher for Palbl combined with AI than combined with fulvestrant: 77.8% [95%CI, 69.7–86.7%] vs. 71.8% [95%CI, 53.6–96.2%], and 56.3% [95%CI, 45.9–69%] vs. 49.7% [95%CI, 29.7–83.2%], respectively. The median OS was 38 months (95%CI, 25.5–50.9). When treatment involved Palbo + AI, the median OS was NA (95%CI, 54.8-NA) months. When treatment involved Palbo + fulvestrant, the median was 50.8 (95%CI, 34.1-NA) months. Related to OS, no significant differences were found between the two types of treatments (log-rank p = 0.638). The 24- and 36-month OS rates were higher for Palbo combined with AI than combined with fulvestrant: 76.9% [95%CI, 69.2–85.5%] vs. 81% [95%CI, 65.8–99.6%], and 67.9% [95%CI, 59.2–77.8%] vs. 65.3% [95%CI, 47.4–90.0%], respectively. The mean adherence in our study was 0.91 ± 0.1. We found no correlation between adherence to Palbo and OS (Spearman's rho = 0.04, p = 0.593). Conclusions: While both AI and fulvestrant remain viable options, the lack of significant differences in survival between these combinations suggests that treatment choice can be tailored to individual patient needs. [ABSTRACT FROM AUTHOR]

Meriolins (3-(pyrimidin-4-yl)-7-azaindoles) are synthetic hybrids of the naturally occurring alkaloids variolin and meridianin and display a strong cytotoxic potential. We have recently shown that the novel derivative meriolin 16 is highly cytotoxic in several lymphoma and leukemia cell lines as well as in primary patient-derived lymphoma and leukemia cells and predominantly targets cyclin-dependent kinases (CDKs). Here, we efficiently synthesized nine novel 2-aminopyridyl meriolin congeners (3a–3i), i.e., pyrimeriolins, using a one-pot Masuda borylation-Suzuki coupling (MBSC) sequence, with eight of them bearing lipophilic alkoxy substituents of varying length, to systematically determine the influence of the alkoxy sidechain length on the biological activity. All the synthesized derivatives displayed a pronounced cytotoxic potential, with six compounds showing IC50 values in the nanomolar range. Derivatives 3b–3f strongly induced apoptosis and activated caspases with rapid kinetics within 3–4 h in Jurkat leukemia and Ramos lymphoma cells. The induction of apoptosis by the most potent derivative 3e was mediated by the intrinsic mitochondrial death pathway, as it was blocked in caspase-9 deficient and Apaf-1 knockdown Jurkat cells. However, as recently shown for meriolin 16, derivative 3e was able to induce apoptosis in the Jurkat cells overexpressing the antiapoptotic protein Bcl-2. Since tumor cells often inactivate the intrinsic mitochondrial apoptosis pathway (e.g., by overexpression of Bcl-2), these meriolin congeners represent promising therapeutic agents for overcoming therapeutic resistance. [ABSTRACT FROM AUTHOR]

Isothiocyanates (ITCs) are naturally occurring sulfur-containing compounds with diverse biological effects. This study investigated the effects of sulforaphane (SFN, an aliphatic ITC) and benzyl isothiocyanate (BITC, an aromatic ITC) on human acute myeloid leukemia SKM-1 cells, focusing on cell proliferation, cell death, and drug resistance. Both drug-sensitive SKM-1 cells and their drug-resistant SKM/VCR variant, which overexpresses the drug transporter P-glycoprotein, were used. SFN and BITC reduced cell viability in a dose-dependent manner, with BITC showing greater potency. IC50 values ranged from 7.0–8.0 µM for SFN and 4.0–5.0 µM for BITC in both cell types, with only slight differences between the variants. Both ITCs induced autophagy as evidenced by increased LC3-II production and caused a significant increase in the sub-G0/G1 cell population, especially with BITC. Apoptosis was more pronounced after BITC treatment, whereas SFN had a weaker effect. These results suggest that autophagy may act as a defense mechanism in response to ITC-induced apoptosis in human AML cells. [ABSTRACT FROM AUTHOR]

Background: Metastatic breast cancer especially in disseminated carcinomatosis of bone marrow (DCBM) poses a life-threatening risk, often requiring systemic chemotherapy. This situation lacks a cure, emphasizing symptom relief and quality of life. The documented occurrence of DCBM is merely 0.17% in metastatic breast cancer and ranges from 0.6 to 1.7% in solid tumors. Until now, there is no official medical guideline for treating patients with luminal breast cancer (LBC) who have DCBM. This case report highlights LBC patient with DCBM, treated at diagnosis with first-line therapy combining endocrine therapy (ET) and a CDK4/6 inhibitor. Case presentation: A 36-year-old premenopausal female of Javanese ethnicity with advanced de novo luminal breast cancer diagnosed in 2020. The immunohistochemistry showed estrogen receptor (ER)+ (90%), progesterone receptor (PR)+ (20%), human epidermal growth factor receptor 2 (HER-2) negative, and a high Ki-67 staining result at 60%. The patient had visceral crisis, which involved bone marrow infiltration and liver metastasis with preserved liver function. After intolerance of side effects from first line treatment with tamoxifen, the treatment plan was adjusted to letrozole, ribociclib, and leuprorelin injection. After completing the sixth cycle of treatment, blood parameters in the laboratory were found to have returned to normal. The patient's response to this regimen was remarkable, with significant alleviation of symptoms and improvement in quality of life observed. Conclusion: Notably, the combined approach of ET and CDK4/6 inhibitor represents a novel intervention in managing DCBM in patients with LBC. [ABSTRACT FROM AUTHOR]

From numerous threats, malignancies are outstanding as one of the most hazardous diseases facing human life in the current time. Thus, novel medicines that selectively target tumor cells will inevitably add to the therapeutic arsenal already possessed for curing these malignancies. In light of this, the current study strives to create a novel class of small compounds with the advantageous benzimidazole scaffold that may be used as CDK2 inhibitors versus cancer. The synthesized candidates 2a–2c and 4 markedly impeded the development of the four cell lines under investigation with IC50 values of 4.36 ± 0.27 to 11.54 ± 0.29 μM against MCF-7, 9.48 ± 0.28 to 25.94 ± 0.33 μM against HCT-15, 41.76 ± 0.76 to 70.61 ± 1.45 against K-562, and 15.04 ± 0.70 to 32.38 ± 1.13 against HepG2. Moreover, compounds 2a–2c and 4 showed robust CDK2 inhibitory effect (IC50 = 0.76 ± 0.28, 1.26 ± 0.049, 0.84 ± 0.075, and 1.37 ± 0.062 μM, respectively). In order to assess the selectivity towards cancer cells, their cytotoxicity against normal kidney epithelial cells Vero was evaluated. The examined compounds were found to be more selective toward cancer cells when compared to the reference standard (SI = 2.13), and compound 2a demonstrated higher selectivity for the breast cancer MCF-7 cell line with the highest selectivity index (SI = 14.98), followed by compound 2c (SI = 8.42). Ultimately, a molecular docking study was performed to examine the potential binding pattern and interactions of benzimidazole derivatives with CDK2 kinase, suggesting it as an enzymatic target. In the final result, benzimidazole derivatives 2a–2c and 4, especially compound 2a, showed significant anticancer efficacy in addition to their ability to inhibit CDK2. [ABSTRACT FROM AUTHOR]

It has been reported that CDK8 plays a key role in acute myeloid leukaemia. Here, a total of 40 compounds were rational designed and synthesised based on the previous SAR. Among them, compound 12 (3-(3-(furan-3-yl)-1H-pyrrolo[2,3-b]pyridin-5-yl)benzamide) showed the most potent inhibiting activity against CDK8 with an IC50 value of 39.2 ± 6.3 nM and anti AML cell proliferation activity (molm-13 GC50 = 0.02 ± 0.01 μM, MV4-11 GC50 = 0.03 ± 0.01 μM). Mechanistic studies revealed that this compound 12 could inhibit the phosphorylation of STAT-1 and STAT-5. Importantly, compound 12 showed relative good bioavailability (F = 38.80%) and low toxicity in vivo. This study has great significance for the discovery of more efficient CDK8 inhibitors and the development of drugs for treating AML in the future. [ABSTRACT FROM AUTHOR]

O-GlcNAc transferase (OGT) coordinates with regulators of transcription, including cyclin-dependent kinase 12 (CDK12), the major transcription elongation kinase. Here, we use inhibitor- and knockdown-based strategies to show that co-targeting of OGT and CDK12 is toxic to prostate cancer cells. OGT catalyzes all nucleocytoplasmic O-GlcNAcylation and due to its essentiality in higher eukaryotes, it is not an ideal drug target. Our glycoproteomics-data revealed that short-term CDK12 inhibition induces hyper-O-GlcNAcylation of the spliceosome-machinery in different models of prostate cancer. By integrating our glycoproteomics-, gene essentiality- and clinical-data from CDK12 mutant prostate cancer patients, we identify the non-essential serine-arginine protein kinase 1 (SRPK1) as a synthetic lethal partner with CDK12 -inactivation. Both normal and cancer cells become highly sensitive against inhibitors of OGT and SRPK1 if they have lowered activity of CDK12. Inactivating mutations in CDK12 are enriched in aggressive prostate cancer, and we propose that these patients would benefit from therapy targeting the spliceosome. [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. [ABSTRACT FROM AUTHOR]

PURPOSE: Targeted Agent and Profiling Utilization Registry (TAPUR) is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. Results of a cohort of patients with soft tissue sarcoma with cyclin-dependent kinase 4 (CDK4) amplification treated with palbociclib are reported. METHODS: Eligible patients had measurable disease, Eastern Cooperative Oncology Group performance status 0 to 2, adequate organ function, and no standard treatment options. The primary end point was disease control (DC), defined as objective response (OR) or stable disease (SD) of at least 16+ weeks duration (SD16+) according to RECIST v1.1. The DC rate was estimated with a 90% CI. Secondary end points included OR, progression-free survival (PFS), overall survival (OS), duration of response, duration of SD, and safety. RESULTS: Forty-two patients with CDK4 amplification were enrolled. One patient was not evaluable for efficacy. One patient with partial response and 18 with SD16+ were observed for DC and OR rates of 46% (90% CI, 36 to 100) and 2% (95% CI, <1 to 13), respectively. Median PFS was 16 weeks (95% CI, 9 to 28) and median OS was 69 weeks (95% CI, 31 to 111) for evaluable patients. Twenty patients had at least one grade 3 to 4 adverse event (AE) at least possibly related to palbociclib, including alanine aminotransferase increase, anemia, fatigue, hypophosphatemia, leukopenia, neutropenia, and thrombocytopenia. No serious AEs were reported. CONCLUSION: Palbociclib met prespecified criteria to declare a signal of antitumor activity in patients with sarcoma and CDK4 amplification. [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: Genomic alterations have been identified in patients with breast cancer brain metastases (BCBMs), but large structural rearrangements have not been extensively studied. MATERIALS AND METHODS: We analyzed the genomic profiles of 822 BCBMs and compared them with 11,988 local, breast-biopsied breast cancers (BCs) and 15,516 non-CNS metastases (Non-CNS M) derived from formalin-fixed paraffin-embedded material using targeted capture sequencing. RESULTS: Nine genes with structural rearrangements were more prevalent within BCBMs as compared with local BCs and Non-CNS M (adjusted- P <.05) and displayed a prevalence of >0.5%. The most common rearrangements within BCBMs involves cyclin-dependent kinase 12 (CDK12 ; 3.53%) as compared with the local BC (0.86%; adjusted- P = 7.1 × 10–8) and Non-CNS M specimens (0.68%; adjusted- P = 3.7 × 10–10). CDK12 rearrangements had a significantly higher frequency within human epidermal growth factor receptor 2 (HER2)–positive BCBMs (14.59%) compared with HER2-positive BCs (7.80%; P = 4.6 × 10–3) and HER2-positive Non-CNS M (7.87%; P = 4.8 × 10–3). CONCLUSION: The most common structural rearrangements involve CDK12 with the higher prevalence in HER2-positive BCBMs. These data support more detailed investigation of the role and importance of CDK12 rearrangements in BCBMs. CDK12 the most common gene rearranged in breast cancer brain mets, with the highest prevalence in HER2+ disease. [ABSTRACT FROM AUTHOR]

Background: Cutaneous melanoma (CM) is the most common type in Caucasians, while acral melanoma (AM) and mucosal melanoma (MM), which are resistant to immunotherapies and BRAF/MEK-targeted therapies, are more common in East Asians. Genomic profiling is essential for treating melanomas, but such data are lacking in Japan. Methods: Comprehensive genomic profiling data compiled in the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) were analyzed. Results: A total of 380 melanomas was analyzed, including 136 CM, 46 AM, 168 MM, and 30 uveal melanoma (UM). MM included conjunctival, sinonasal, oral, esophageal, anorectal, and vulvovaginal melanomas. No significant difference in the median tumor mutational burden (TMB) of CM (3.39 mutations/megabase), AM (2.76), and MM (3.78) was the key finding. Microsatellite instability-high status was found in one case. BRAF V600E/K was found in only 45 patients (12%). Key driver mutations in CM were BRAF (38%), NRAS (21%), NF1 (8%), and KIT (10%), with frequent copy number alterations (CNAs) of CDKN2A, CDKN2B, and MYC. AM was characterized by altered KIT (30%), NRAS (26%), and NF1 (11%) and CDKN2A, CDKN2B, CDK4, MDM2, and CCND1 CNAs. MM was characterized by altered NRAS (24%), KIT (21%), and NF1 (17%) and MYC, KIT, and CDKN2A CNAs, with differences based on anatomical locations. UM bore GNAQ or GNA11 driver mutations (87%) and frequent mutations in SF3B1 or BAP1. Conclusion: The distinct genomic profiling in Japanese patients, including lower TMB, compared to Caucasians, is associated with poorer treatment outcomes. This result underscores the need for more effective therapeutic agents. [ABSTRACT FROM AUTHOR]

Introduction: Cyclin-dependent kinase (CDK) 4/6 inhibitors have significantly changed the treatment strategy for patients with locally advanced or metastatic hormone receptor positive (HR+), human epidermal growth factor 2 negative (HER2) breast cancer. The purpose of the study was to determine the prevalence of drug-drug interactions (DDI) in breast cancer patients using CDK 4/6 inhibitors and the extent of DDI reflected in the clinic and to increase clinical awareness among physicians. Method: The data of 115 metastatic breast cancer patients using CDK 4/6 inhibitors who were admitted to the Medical Oncology outpatient clinic between July 2021 and July 2023 were retrospectively reviewed. The Drugs.com® Drug Interaction Checker application was used for the interaction between the CDK 4/6 inhibitor and other drugs. Results: Among patients included in the study, 97.3% had at least one additional drug use. We have identified a total of 170 potential DDI risks in 63.5 % of patients. Among these, 50.5% had a major potential DDI. In our study, there was a potential risk of QT prolongation in 45.2% of 170 DDI, an increase in the potential toxicity of the additional drug in 44.1%, an increase in the potential toxicity of the CDK 4/6 inhibitor in 5.3%, a decrease in the potential efficacy of the CDK 4/6 inhibitor in 2.9%, a decrease in the potential efficacy of the additional drug in 1.1%, and a serious potential infection risk in 1.1%. Most of the drug interactions were QT prolongation and increased toxicity of the additional drug. In terms of cardiovascular events, grade-2 and grade-3 QTc prolongation was found in 4.3% and 1.7% of these interactions, respectively. When evaluated in terms of CDK 4/6 inhibitor subtype, there was a potential risk of DDI at major level with Ribocilib and at moderate level with Palbociclib. Conclusion: If CDK 4/6 inhibitors interact with concomitant drugs, they may cause an increase in the incidence of cardiac side effects and a decrease in the effect of the CDK 4/6 inhibitor or additional drug or an increase in toxicity. Increasing awareness of this issue will help to reduce the rates of side effects or toxicity and provide effective antitumour therapy. [ABSTRACT FROM AUTHOR]

Background: With the widespread use of CDK4/6 inhibitors, the number of discontinuations and reductions due to adverse events is increasing. Therefore, we examined the risk of dose reduction, discontinuation, and occurrence of serious adverse events and death due to adverse events when CDK4/6 inhibitors are combined with endocrine drugs. Methods: We searched English-language articles published up to February 10, 2024, using RR values (risk ratio) to indicate the risk of discontinuation, dose reduction, death, and the risk of serious adverse events. Results: When CDK4/6 inhibitors were used in combination with endocrine drugs, abemaciclib resulted in the highest risk of discontinuation, dose reduction, and serious adverse events. Ribociclib caused the highest risk of death. Conclusion: When using CDK4/6 inhibitors in the clinical setting, a comprehensive evaluation should be performed to avoid dosage reductions and discontinuations and to choose the most appropriate treatment regimen. [ABSTRACT FROM AUTHOR]

Background/Objectives: Tonsil-derived mesenchymal stem cells (TMSCs) are in the limelight in regenerative medicine due to their high proliferation and differentiation potential. It is important to conduct studies to determine the optimal conditions for achieving the maximum yield while maintaining the optimal differentiation capacity of TMSCs. Methods: This study explores the impact of serial subculture on TMSCs by analyzing gene expression at passages 2, 4, 6, and 8. For each culture passage, genes with significant differences in RNA expression from previous passages were selected and their characteristics were observed performing enrichment analysis including KEGG (Kyoto Encyclopedia of Genes and Genomes) and Reactome pathway. Results: At each passage, a "cell cycle" term was ranked high with statistical significance in the KEGG and Reactome pathway. Cell cycle gene expression, including Cyclin-dependent kinases (CDKs) and cyclins, increased until passage 6, then decreased by passage 8. The cell cycle is known to be important not only for proliferation but also for determining whether stem cells maintain pluripotency or differentiate into various lineages. Conclusions: The results suggest that cell cycle gene expression can guide the timing for differentiation induction, with passage 6 potentially being a critical point for initiating differentiation. [ABSTRACT FROM AUTHOR]

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]

Background/Objectives: Palbociclib, an oral CDK 4/6 inhibitor, was evaluated in a Pediatric Brain Tumor Consortium (PBTC) phase 1 (NCT02255461; PBTC-042) study to treat children and young adults with recurrent, progressive, or refractory brain tumors. The objectives of this study were to characterize the palbociclib population pharmacokinetics in children enrolled on PBTC-042, to conduct a population pharmacodynamic analysis in this patient population, and to perform a simulation study to assess the role of palbociclib exposure on neutropenia and thrombocytopenia. Methods: The palbociclib population pharmacokinetics and pharmacodynamics were characterized in this patient population (n = 34 patients; 4.9–21.6 years old). Population pharmacokinetics were modeled using a one-compartment model with first-order absorption and elimination. Covariate analysis was performed, evaluating demographics, laboratory values, and concomitant medications. A pharmacodynamic model was used to describe the relation between palbociclib plasma exposure and changes in the ANC and platelet counts. Results: The population estimates for the apparent oral volume, apparent oral clearance, and absorption rate constant were 664.5 L/m2, 36.8 L/h/m2, and 0.48 h−1, respectively. The palbociclib apparent oral clearance was decreased in patients with higher AST values (p = 0.0066). The ANC and platelet pharmacodynamic models estimated that the median (5th–95th percentile) time individuals had grade 3 or greater neutropenia was 4 (0, 21) days. Simulations showed that given 75 mg/m2 palbociclib, 49% of the individuals were expected to have grade 3 or greater neutropenia. Conclusions: Palbociclib pharmacokinetics and pharmacodynamics were adequately characterized in this patient population, no unexpected adverse reactions were noted, and the drug was well tolerated. [ABSTRACT FROM AUTHOR]

Background: The increasing prevalence of drug resistance in cancer therapy underscores the urgent need for novel therapeutic approaches. Dual enzyme inhibitors, targeting critical kinases such as CDK2 and TRKA, represent a promising strategy. The goal of this investigation was to design, synthesize, and evaluate a set of pyrazolo[1,5-a]pyrimidine derivatives for their dual inhibition potential toward CDK2 and TRKA kinases, along with their potential antiproliferative against cancer cell lines. Methods: A set of pyrazolo[1,5-a]pyrimidine derivatives (6a–t, 11a–g, and 12) was synthesized and subjected to in vitro enzymatic assays to determine their inhibitory activity against CDK2 and TRKA kinases. Selected compounds were further assessed for antiproliferative effects across the set of 60 cell lines from the NCI, representing various human cancer types. Additionally, simulations of molecular docking were conducted to explore the modes of binding for the whole active compounds and compare them with known inhibitors. Results: Compounds 6t and 6s exhibited potent dual inhibitory activity, showing an IC50 = 0.09 µM and 0.23 µM against CDK2, and 0.45 µM against TRKA, respectively. These results were comparable to reference inhibitors ribociclib (CDK2, IC50 = 0.07 µM) and larotrectinib (TRKA, IC50 = 0.07 µM). Among the studied derivatives, compound 6n displayed a notable broad-spectrum anticancer activity, achieving a mean growth inhibition (GI%) of 43.9% across 56 cell lines. Molecular docking simulations revealed that the synthesized compounds adopt modes of binding similar to those of the lead inhibitors. Conclusions: In this study, prepared pyrazolo[1,5-a]pyrimidine derivatives demonstrated significant potential as dual CDK2/TRKA inhibitors, and showed potent anticancer activity toward diverse cancer cell lines. These findings highlight their potential as key compounds for the design of novel anticancer therapeutics. [ABSTRACT FROM AUTHOR]

Dysregulation of the cell cycle is a molecular hallmark of cancer, which leads to uncontrolled proliferation and self-renewal of neoplastic cells. To maintain this phenotype, cells acquire multiple molecular alterations and bypass several cellular checkpoints that are involved in the prevention of genomic instability and uncontrolled cell proliferation. Therefore, targeting cell cycle regulators could prove to be a promising anti-cancer approach. Recent advancements in the understanding of cancer cell susceptibilities have revealed a therapeutic opportunity to selectively target the cell cycle in malignant cells. This review highlights major cell cycle dysregulation in cancerous cells and the latest developments on anti-cancer agents that target cell cycle factors which are either in clinical practice or in clinical trials at present. In light of increasing drug resistance in cancer patients, the article also discusses mechanistic insights for the exploration of probable therapies that could be used to target these cell cycle factors. Additionally, it outlines the future research necessary to develop new therapies and optimize existing ones to achieve maximum efficacy. Thus, this article aims to provide a comprehensive understanding of the advancements in cancer therapies targeting dysregulated cell cycle factors. [ABSTRACT FROM AUTHOR]

The Mediator complex plays a pivotal role in facilitating RNA polymerase II-dependent transcription in eukaryotes. Within this complex, the CDK8 kinase module (CKM), comprising CDK8, Cyclin C (CycC), Med12 and Med13, serves as a dissociable subcomplex that modulates the activity of the small Mediator complex. Genetic studies in Drosophila have revealed distinct phenotypes associated with mutations inCKM subunits, but the underlying mechanisms have remained unclear. Using Drosophila as a model, we generated transgenic strains to deplete individually or simultaneously the four CKM subunits in all possible combinations, uncovering unique phenotypes in the eyes and wings. Depletion of CDK8-CycC enhanced E2F1 target gene expression and promoted cell-cycle progression, whereas Med12-Med13 depletion had no significant impact on these processes. Instead, depleting Med12-Med13 altered the expression of ribosomal protein genes and fibrillarin, and reduced nascent protein synthesis, indicating a severe reduction in ribosome biogenesis and cellular growth compared to the loss of CDK8-CycC. These findings reveal distinct in vivo roles for CKM subunits, with Med12-Med13 disruption having a more pronounced effect on ribosome biogenesis and protein synthesis than CDK8-CycC loss. [ABSTRACT FROM AUTHOR]

SAYP and Bap170, subunits of the SWI/SNF remodeling complex, have the ability to support enhancer-dependent transcription when artificially recruited to the promoter on a transgene. We found that the phenomenon critically depends on two subunits of the Mediator kinase module, Med12 and Med13 but does not require the two other subunits of the module (Cdk8 and CycC) or other subunits of the core part of the complex. A cooperation of the above proteins in active transcription was also observed at endogenous loci, but the contribution of the subunits to the activity of a particular gene differed in different loci. The factors SAYP/Bap170 and Med12/Med13 did not form sufficiently stable interactions in the extract, and their cooperation was apparently local at regulatory elements, the presence of SAYP and Bap170 in a locus being necessary for stable recruitment of Med12 and Med13 to the locus. In addition to the above factors, the Nelf-A protein was found to participate in the process. The cooperation of the factors, independent of enzymatic activities of the complexes they are part of, appears to be a novel mechanism that maintains promoter activity and may be used in many loci of the genome. Extended intrinsically disordered regions of the factors were assumed to sustain the mechanism. [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. Summary Statement: The components of the mediator kinase module are highly conserved across eukaryotic lines and cyclin‐dependent kinase 8 (CDK8) is essential for correct cell proliferation and development. We show here that control of leaf development is closely linked to the establishment of correct stomata patterning through the impact of CDK8. Comprehending the plasticity of plant morphology and the mechanisms behind it is essential for our understanding of plant environmental responses and the consequences of climate change. [ABSTRACT FROM AUTHOR]

• Thrombotic risk from CDK 4/6 inhibitors is higher in practice than in RCT data. • This risk appears to be significant if the drug used is abemaciclib. • VTE/AT secondary to this treatment does not seem to impact patient survival. • Healthcare professionals should address this effect with proper prevention and management. • Patients with CNS metastases may have a higher risk of developing this complication. Thrombosis may be included in the profile of side effects associated with CDK4/6 inhibitors. Its significance might be greater than reported in randomized clinical trials. To investigate this, a retrospective, multicenter study was conducted. The primary objective was to calculate the incidence of thrombosis associated with CDK4/6 inhibitors. Secondary objectives included examining the impact of thrombosis on survival and identifying predictor variables for the development of venous thromboembolism (VTE) or arterial thrombosis (AT). A total of 986 patients were recruited. The incidence of VTE/AT associated with CDK4/6 inhibitor treatment during the follow-up period was 5.48 %. Survival analysis did not indicate that the development of VTE/AT during CDK4/6 inhibitor treatment significantly impacted patient survival (p = 0.133). In our analysis, two variables were found to be statistically significant (p < 0.05) as predictors of VTE/AT in breast cancer patients receiving CDK4/6 inhibitor therapy. These variables were the presence of central nervous system (CNS) metastasis with an odds ratio (OR) of 3.68 (95 % CI 1.18 - 11.49) and the use of abemaciclib with an OR of 2.3 (95 % CI 1.16 - 4.57). [ABSTRACT FROM AUTHOR]

Background: Lipomatous tumors represent the most common type of soft tissue neoplasms. Mouse double minute 2 homolog (MDM2)/cyclin-dependent kinase 4 (CDK4) immunostaining is considered effective in differentiating between benign lipomas and intermediate malignant atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLPSs). However, these tumors have traditionally been diagnosed histopathologically using hematoxylin and eosin-stained specimens, which is referred to here as morphological diagnosis. In this study, the accuracy of morphological diagnoses that had been made before MDM2/CDK4 immunostaining became available for distinguishing between lipoma and ALT/WDLPS was examined. Methods: The study participants were 109 patients with a morphological diagnosis of lipoma (68 patients) or ALT/WDLPS (41 patients) who had undergone surgical resection of the tumor in our hospital between 2009 and 2012. Tissue samples from all patients were used for MDM2/CDK4 immunostaining and the confirmation of MDM2/CDK4 amplification by fluorescence in situ hybridization (FISH). Results: Of the 41 patients with a morphological diagnosis of ALT/WDLPS, only 17 were positive for MDM2 FISH. In addition, one of the 68 patients with a morphological diagnosis of lipoma showed MDM2 amplification by FISH. When the definitive diagnosis of ALT/WDLPS was made by the positive results of MDM2 FISH, the sensitivity and specificity of morphological diagnosis were 41.5% and 98.5%, respectively. The sensitivity of MDM2 and CDK4 immunostaining was 55.6% and 40.0%, respectively, and their specificity was 87.0% and 84.6%, respectively. This indicates that the diagnostic accuracy of these immunostaining assays was not particularly high. The clinical features suggesting ALT/WDLPS were: patient age (older), maximum tumor diameter (large, cut-off value of 125 mm), tumor location (lower limb), and tumor depth (deep-seated). Conclusions: Morphological diagnosis alone can accurately diagnose lipomas. However, it has a propensity to overdiagnose ALT/WDLPS. Thus, MDM2 FISH should be used more proactively, not only for lesions with obvious morphological abnormalities, but also for lipomatous tumors that are clinically suggestive of ALT/WDLPS. [ABSTRACT FROM AUTHOR]

Simple Summary: In real-life applications, lenvatinib has been found to have a better tumor response than sorafenib in patients with HBV-related HCC, showing that treatment with lenvatinib may be useful in individuals with HBV infections. However, in this study, we show that HBV confers resistance to lenvatinib at an even deeper level than its resistance to sorafenib. It is highly likely that the mechanisms of resistance to these two medications are distinct. Our findings may explain why lenvatinib and sorafenib have had equal effects on overall survival and progression-free survival in patients with HBV-related HCC, despite the apparent potential benefit of sorafenib. However, additional research is required to identify the processes that drive this resistance and to develop more effective therapies for HBV-associated HCC. These findings highlight the need for tailored therapeutic strategies to overcome HBV-induced resistance in HCC treatment. Background/Objectives: Sorafenib and lenvatinib are tyrosine kinase inhibitors used in hepatocellular carcinoma (HCC) treatment. This study investigates how hepatitis B virus (HBV) infection affects their efficacy in HepG2 hepatoma cells. Methods: HepG2 and HBV-infected HepG2/2215 cells were treated with varying concentrations of both drugs. The cell viability, cell cycle gene expression, cycle progression, and phosphorylation levels of ERK and AKT were analyzed. Results: The HBV-infected cells showed significant alterations in their cell cycle gene expressions, with an 80-fold increase in CCND2 expression and a higher proportion of cells in the G2/M phase, indicating enhanced proliferation. While both drugs decreased HepG2 cell viability in a concentration-dependent manner, HBV infection conferred resistance, as evidenced by the increased viable cells in the HepG2/2215 cultures. Sorafenib and lenvatinib decreased key cyclin and cyclin-dependent kinase expressions in uninfected cells, with less effect on the HBV-infected cells. Both drugs lowered the pERK and pAKT levels in the HepG2 cells. In the HBV-infected cells, sorafenib reduced the pERK and pAKT levels to a lesser extent. However, treatment with lenvatinib elevated the levels of pERK and pAKT. Conclusions: In conclusion, HBV infection increases resistance to both sorafenib and lenvatinib in hepatoma cells by influencing the cell cycle regulatory genes and critical signaling pathways. However, the resistance mechanisms likely differ between the two medications. [ABSTRACT FROM AUTHOR]

Background: Ferroptosis, a form of cell death characterized by lipid peroxidation, plays a crucial role in tumor suppression, offering novel avenues for cancer therapy. Previous studies have indicated that high levels of cyclin-dependent kinase subunit 2 (CKS2) promote the progression of various cancers. However, the potential interplay between CKS2 and ferroptosis in colon cancer (CC) remains unclear. Methods: Bioinformatics and RNA-seq analyses were employed to study genes associated with the ferroptosis signaling pathway. CKS2 expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot (WB). The in vitro and in vivo effects of CKS2 on CC cells were assessed through the CCK-8 assay, colony formation assay, propidium iodide (PI) staining, BODIPY staining, DCFH-DA staining, and animal experiments. Additionally, the impact of CKS2 on autophagy and glutathione (GSH) metabolism was investigated using a transmission electron microscope (TEM), immunofluorescence (IF) assays, WB experiments, and relevant assay kits. Results: CKS2 expression was elevated in CC, indicating a poor clinical outcome. Knockdown of CKS2 significantly enhanced Erastin-induced ferroptosis in CC cells, leading to reduced GSH metabolism. Conversely, CKS2 overexpression produced opposite effects. Mechanistically, CKS2-induced autophagy reinforced GSH metabolism, thereby increasing resistance to ferroptosis in CC cells. Furthermore, inhibiting CKS2 promoted tumor ferroptosis by downregulating GPX4 expression. Additionally, CKS2 knockdown effectively increased sorafenib-induced ferroptosis both in vitro and in vivo. Conclusion: CKS2 suppresses ferroptosis in CC by modulating GSH metabolism in both in vitro and in vivo settings. These findings offer new insights into targeting CKS2 for CC treatment and shed light on the mechanism of ferroptosis in CC. [ABSTRACT FROM AUTHOR]

Neoplastic cells are characterized by uncontrolled cell divisions caused by cell cycle dysregulation. Key regulatory proteins governing the transition from the G1 to the S phase are the CDK4 and CDK6 kinases, which are controlled by D-type cyclins. The CDK4/6 kinases enable the use of these proteins as targets for anticancer therapy because they prevent the growth and the development of malignant cells by inhibiting their activity. This paper surveys the clinical trial results concerning palbociclib, the first in-class FDA-approved anticancer drug for hormone-dependent breast cancer. It discusses the therapeutic applications in breast cancer as well as in solid tumors and hematopoietic malignancies. Additionally, the paper presents an analysis of palbociclib resistance acquired during therapy and explores new approaches, such as modifications to palbociclib that enhance its desired activity or open up new therapeutic possibilities (PROTACs). [ABSTRACT FROM AUTHOR]

Melanoma occurs in various forms and body areas, not only in the cutis, but also in mucous membranes and the uvea. Rarer subtypes of that cancer differ in genomic aberrations, which cause their minor sensibility to regular cutaneous melanoma therapies. Therefore, it is essential to discover new strategies for treating rare forms of melanoma. In recent years, interest in applying CDK inhibitors (CDKIs) in cancer therapy has grown, as they are able to arrest the cell cycle and inhibit cell proliferation. Current studies highlight selective CDK4/6 inhibitors, like palbociclib or abemaciclib, as a very promising therapeutic option, since they were accepted by the FDA for advanced breast cancer treatment. However, cells of every subtype of melanoma do not react to CDKIs the same way, which is partly because of the genetic differences between them. Herein, we discuss the past and current research relevant to targeting various CDKs in mucosal, uveal and acral melanomas. We also briefly describe the issue of amelanotic and desmoplastic types of melanoma and the need to do more research to discover cell cycle dysregulations, which cause the growth of the mentioned forms of cancer. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a single mutation in the huntingtin gene (HTT). Normal HTT has a CAG trinucleotide repeat at its N-terminal within the range of 36. However, once the CAG repeats exceed 37, the mutant gene (mHTT) will encode mutant HTT protein (mHTT), which results in neurodegeneration in the brain, specifically in the striatum and other brain regions. Since the mutation was discovered, there have been many research efforts to understand the mechanism and develop therapeutic strategies to treat HD. HTT is a large protein with many post-translational modification sites (PTMs) and can be modified by phosphorylation, acetylation, methylation, sumoylation, etc. Some modifications reduced mHTT toxicity both in cell and animal models of HD. We aimed to find the known kinase inhibitors that can modulate the toxicity of mHTT. We performed an in vitro kinase assay using HTT peptides, which bear different PTM sites identified by us previously. A total of 368 kinases were screened. Among those kinases, cyclin-dependent kinases (CDKs) affected the serine phosphorylation on the peptides that contain S1181 and S1201 of HTT. We explored the effect of CDK1 and CDK5 on the phosphorylation of these PTMs of HTT and found that CDK5 modified these two serine sites, while CDK5 knockdown reduced the phosphorylation of S1181 and S1201. Modifying these two serine sites altered the neuronal toxicity induced by mHTT. Roscovitine, a CDK inhibitor, reduced the p-S1181 and p-S1201 and had a protective effect against mHTT toxicity. We further investigated the feasibility of the use of roscovitine in HD mice. We confirmed that roscovitine penetrated the mouse brain by IP injection and inhibited CDK5 activity in the brains of HD mice. It is promising to move this study to in vivo for pre-clinical HD treatment. [ABSTRACT FROM AUTHOR]

Inhibition of CDK4/6 kinases has led to improved outcomes in breast cancer. Nevertheless, only a minority of patients experience long-term disease control. Using a large, clinically annotated cohort of patients with metastatic hormone receptor-positive (HR+) breast cancer, we identify TP53 loss (27.6%) and MDM2 amplification (6.4%) to be associated with lack of long-term disease control. Human breast cancer models reveal that p53 loss does not alter CDK4/6 activity or G1 blockade but instead promotes drug-insensitive p130 phosphorylation by CDK2. The persistence of phospho-p130 prevents DREAM complex assembly, enabling cell-cycle re-entry and tumor progression. Inhibitors of CDK2 can overcome p53 loss, leading to geroconversion and manifestation of senescence phenotypes. Complete inhibition of both CDK4/6 and CDK2 kinases appears to be necessary to facilitate long-term response across genomically diverse HR+ breast cancers. [Display omitted] • TP53 mutation is associated with lack of long-term disease control on CDK4/6i • p53 deficiency suppresses DREAM complex in BC cells, enabling cell-cycle re-entry • Disruption of DREAM complex is sufficient to promote long-term CDK4/6i resistance • Inhibition of CDK2 overcomes p53 loss, promoting geroconversion and disease control Kudo et al. demonstrate that TP53 loss in HR+ breast cancer is clinically associated with long-term failure of CDK4/6i due to cellular escape from quiescence via impaired DREAM complex assembly. Selective CDK2 inhibition is found to reinforce p130 dephosphorylation in p53 mutant models and facilitate durable tumor growth suppression. [ABSTRACT FROM AUTHOR]

Acute leukemia has rapid onset and severe complications. Anticancer peptides from natural sources have demonstrated efficacy in eliminating various cancers through apoptosis signaling pathways. Additionally, extracellular vesicles containing microRNAs play pivotal roles in promoting tumorigenesis. Therefore, this study aimed to investigate the impact of PG2, a pomegranate peptide that regulates extracellular vesicles, on the induction of acute leukemia cell apoptosis. NB4 and MOLT-4 leukemia cell lines were treated with PG2 alone or in combination with daunorubicin to assess cell viability using the MTT assay. Extracellular vesicles were extracted from PG2-treated NB4 and MOLT-4 cells. Bioinformatic tools were utilized to predict target proteins and microRNAs, following which mRNA and protein expression were determined by using RT‒qPCR and western blotting, respectively. PG2 significantly reduced the viability of NB4 and MOLT-4 cells. Furthermore, the combination of PG2 with daunorubicin had a synergistic effect on NB4 and MOLT-4 cells. Subsequent treatment with PG2 or PG2-treated extracellular vesicles decreased CDK2 expression while increasing microRNA-339-5p and caspase-3 expression in NB4 and MOLT-4 cells. Our findings revealed that the anticancer activity of PG2 through the CDK2/miR-339-5p/caspase-3 pathway is mediated by extracellular vesicles, ultimately inducing apoptosis. PG2 holds promise as a potential antileukemic drug. [ABSTRACT FROM AUTHOR]

Due to the limited effeteness and safety concerns associated with current cancer treatments, there is a pressing need to develop novel therapeutic agents. 4‐(3,4‐Dimethoxyphenyl)−3‐(4‐methoxyphenyl)−1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine (3) was synthesized and Initially screened on 59 cancer cell lines showed promising anticancer activity, so, it was chosen for a 5‐dose experiment by the NCI/USA. The GI50 values ranged from 1.04 to 8.02 μM on the entire nine panels (57 cell lines), with a GI50 of 2.70 μM for (MG‐MID) panel, indicating an encouraging action. To further explore the molecular attributes of compound 3, we optimized its structure using DFT with the B3LYP/6‐31 + + G(d,p) basis set. We have considered vibrational analysis, bond lengths and angles, FMOs, and MEP for the structure. Additionally, pharmacokinetic assessments were conducted using various in‐silico platforms to evaluate the compound safety. A molecular modeling study created a kinase profile on 44 different kinases. This allowed us to study our compound's binding affinity to these kinases and compare it to the co‐crystallized one. Our findings revealed compound 3 exhibited better binding for half of the tested kinases, suggesting its potential as a multi‐kinase inhibitor. To further validate our computational results, we tested compound 3 for its inhibitory effects on CDK2 and PIM1. Compound 3 exhibited an IC50 of 0.30 µM for CDK2 inhibition, making it five times less active than Roscovitine, which has an IC50 of 0.06 µM. However, compound 3 demonstrated slightly better inhibition of PIM1 compared to Staurosporine. These findings suggest that compound 3 is a promising anticancer agent with the potential for further development into a highly active compound. [ABSTRACT FROM AUTHOR]

Cyclin-dependent kinases (CDKs) are generally involved in the progression of cell cycle and cell division in normal cells, while abnormal activations of CDKs are deemed to be a driving force for accelerating cell proliferation and tumorigenesis. Therefore, CDKs have become ideal therapeutic targets for cancer treatment. The U.S FDA has approved three CDK4/6 inhibitors (CDK4/6is) for the treatment of patients with hormone receptor-positive (HR+) or human epidermal growth factor receptor 2-negative (HER2−) advanced or metastatic breast cancer, and these drugs showed impressive results in clinics. Besides cell-cycle arrest, there is growing evidence that CDK4/6is exert paradoxical roles on cancer treatment by altering the immune system. Indeed, clinical data showed that CDK4/6is could change the immune system to exert antitumor effects, while these changes also caused tumor resistance to CDK4/6i. However, the molecular mechanism for the regulation of the immune system by CDK4/6is is unclear. In this review, we comprehensively discuss the paradoxical immunological effects of CDK4/6is in cancer treatment, elucidating their anticancer mechanisms through immunomodulatory activity and induction of acquired drug resistance by dysregulating the immune microenvironment. More importantly, we suggest a few strategies including combining CDK4/6is with immunotherapy to overcome drug resistance. [ABSTRACT FROM AUTHOR]

Introduction: Angiosarcoma is an exceedingly rare entity in pediatric population. Herein, we report two pediatric angiosarcoma with novel phenotypic and genotypic profile. Methods: The two patients' information was summarized by clinical data, histopathology, immunohistochemistry, genetic, treatment, and prognosis. Results: Two Chinese children presented with abdominal mass or consumptive hypothyroidism at 2 and 6 years. A patient presented with a unique histopathology of epithelioid AS with smooth muscle hyperplasia, and carried a novel somatic mutation in FAT1 (c.3929C > T/p. Ser1310Leu) along with germ-line variants in CDK8 (c.895A > C/p. Lys299Gln), FANCI (c.3906-07inv/p. Glu1303Lys), and MST1R (c.3581-83delinsACG/p. Arg1194-Ser1195delinsHisGly). The other patient presented with a novel -clinical phenotype of consumptive hypothyroidism. They received postoperative treatment and were monitored for 20 and 26 months, showing good recovery. Conclusion: The phenotypic and genotypic spectrum of AS in pediatric population was expanded by these two patients, which requires the accumulating more cases to gain a deeper understanding. [ABSTRACT FROM AUTHOR]

Background: Transforming growth factor beta (TGFβ) is important for the morphogenesis and secretory function of the mammary gland. It is one of the main activators of the epithelial–mesenchymal transition (EMT), a process important for tissue remodeling and regeneration. It also provides cells with the plasticity to form metastases during tumor progression. Noncancerous and cancer cells respond differently to TGFβ. However, knowledge of the cellular signaling cascades triggered by TGFβ in various cell types is still limited. Methods: MCF10A (noncancerous, originating from fibrotic breast tissue) and MCF7 (cancer, estrogen receptor-positive) breast epithelial cells were treated with TGFB1 directly or through conditioned media from stimulated cells. Transcriptional changes (via RNA-seq) were assessed in untreated cells and after 1–6 days of treatment. Differentially expressed genes were detected with DESeq2 and the hallmark collection was selected for gene set enrichment analysis. Results: TGFB1 induces EMT in both the MCF10A and MCF7 cell lines but via slightly different mechanisms (signaling through SMAD3 is more active in MCF7 cells). Many EMT-related genes are expressed in MCF10A cells at baseline. Both cell lines respond to TGFB1 by decreasing the expression of genes involved in cell proliferation: through the repression of MYC (and the protein targets) in MCF10A cells and the activation of p63-dependent signaling in MCF7 cells (CDKN1A and CDKN2B, which are responsible for the inhibition of cyclin-dependent kinases, are upregulated). In addition, estrogen receptor signaling is inhibited and caspase-dependent cell death is induced only in MCF7 cells. Direct incubation with TGFB1 and treatment of cells with conditioned media similarly affected transcriptional profiles. However, TGFB1-induced protein secretion is more pronounced in MCF10A cells; therefore, the signaling is propagated through conditioned media (bystander effect) more effectively in MCF10A cells than in MCF7 cells. Conclusions: Estrogen receptor-positive breast cancer patients may benefit from high levels of TGFB1 expression due to the repression of estrogen receptor signaling, inhibition of proliferation, and induction of apoptosis in cancer cells. However, some TGFB1-stimulated cells may undergo EMT, which increases the risk of metastasis. Plain English summary: Transforming growth factor beta (TGFβ) is a multifaceted cytokine that controls numerous physiological and pathological processes during development and carcinogenesis. Its best-known function is the activation of epithelial–mesenchymal transition (EMT), a process crucial for tissue remodeling and regeneration. During EMT, epithelial cells lose their connections to adjacent cells and acquire mesenchymal characteristics, such as migratory ability. Compared with cancer cells, normal (nontumorigenic) cells usually respond differently to TGFβ stimulation. Typically, TGFβ inhibits the proliferation of epithelial cells and may promote cell death. In cancer cells, TGFβ often promotes tumor progression. TheTGFβ-mediated induction of EMT increases cell mobility, which is associated with the formation of metastases and tumor invasion. In this work, we compared the transcriptional response of noncancerous (MCF10A) and cancerous (MCF7; estrogen receptor-positive) breast epithelial cells to direct stimulation by TGFB1 and its indirect effect through conditioned media. Some of TGFB1-induced changes, including inhibition of proliferation and induction of EMT, were similar in both cell lines. However, these changes were associated with different upstream signaling pathways. Other changes were more specific, such as disruption of estrogen-related signaling or induction of cell death in MCF7 cells. Direct incubation with TGFB1 and treatment of cells with conditioned media similarly affected target cells, indicating the presence of a bystander effect. Moreover, transcript profiling by RNA-seq revealed that the TGFβ signaling pathway is already active in untreated MCF10A cells, which may be due to their origination from a fibrotic lesion. [ABSTRACT FROM AUTHOR]

Introduction: Uterine adenosarcoma (UA) is a rare malignant mesenchymal neoplasm characterized by benign epithelial and malignant stromal components. Comprehensive genomic profiling has identified a high frequency of murine double-minute type 2 (MDM2) and cyclin-dependent kinase 4 (CDK4) amplification in UA. However, the significance of these genetic alterations in tumor biology remains poorly understood. This report presents a case of UA with immunohistochemically positive MDM2 and CDK4 expression. Case Presentation: The patient was a 72-year-old woman with a history of genital bleeding. Magnetic resonance imaging revealed an 11 × 5 × 7 cm mass in the endometrial cavity, extending into the uterine cervix. Biopsy of the tumor showed no malignant findings. The patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. Microscopically, the tumor consisted of benign glandular epithelial components and low-grade sarcoma. The diagnosis was UA stage IA, pT1aNxM0. No sarcomatous overgrowth and no myometrial or lymphovascular invasions were observed. Immunohistochemistry confirmed MDM2 and CDK4 expression in the mesenchymal tissue. No recurrence was observed 12 months post-surgery. Conclusion: The pathological diagnosis of UA was based on histomorphological features. This study demonstrates that immunohistochemistry for MDM2 and CDK4 can help elucidate the molecular genetic features of UA. Further studies are needed to correlate the expression of these genes with the biological behavior of UA. [ABSTRACT FROM AUTHOR]

Simple Summary: This study explores the effectiveness and safety of a common breast cancer treatment in elderly patients, a group often overlooked in clinical trials. Specifically, it focuses on using CDK4/6 inhibitors with hormone therapy for treating metastatic HR+/HER2- breast cancer in patients aged 70 and older. This research aims to understand how well this treatment works and how tolerable it is for this vulnerable population, which faces unique challenges due to age and other health conditions. The results of this study may provide valuable insights for clinicians, enabling more informed treatment decisions which optimize therapeutic outcomes and enhance the quality of life for elderly patients with breast cancer. Background: Metastatic HR+/HER2- breast cancer is commonly treated with CDK4/6 inhibitors in combination with endocrine therapy. However, the efficacy and safety of this approach in elderly patients (≥70 years) remain unclear, particularly in the context of real-world clinical practice. This study aims to evaluate the clinical outcomes and tolerability of CDK4/6 inhibitor treatments in this fragile population, which is often under-represented in randomized clinical trials. Patients and methods: This retrospective multicenter study included elderly patients with metastatic HR+/HER2-negative breast cancer receiving first-line CDK4/6 inhibitors. The primary endpoint was progression-free survival (PFS). The secondary endpoints focused on the overall survival (OS), safety, and tolerability, considering variables such as tumor subtype, age, comorbidities, and treatment specifics. Results: The median PFS and OS were slightly lower than those reported in clinical trials, reflecting the inclusion of a more fragile population. The luminal B subtype was linked to a poorer PFS, while other factors like age, BMI, and ECOG status did not significantly affect the outcomes. A safety analysis indicated a higher incidence of grade 3 or higher toxicities, especially in frail patients, leading to dose reductions. Despite these challenges, CDK4/6 inhibitors were generally well-tolerated, allowing most patients to continue therapy. Conclusions: CDK4/6 inhibitors with endocrine therapy are effective in elderly patients with metastatic HR+/HER2- breast cancer, though careful management is crucial to balance efficacy and minimize adverse events. [ABSTRACT FROM AUTHOR]

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]

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]