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The migration of breast cancer cells is the main cause of death and significantly regulated by physical factors of the extracellular matrix (ECM). To be specific, the curvature and stiffness of the ECM were discovered to effectively guide cell migration in velocity and direction. However, it is not clear what the extent of effect is when these dual-physical factors regulate cell migration. Moreover, the mechanobiology mechanism of breast cancer cell migration in the molecular level and analysis of cell traction force (CTF) are also important, but there is a lack of systematic investigation. Therefore, we employed a microfluidic platform to construct hydrogel microspheres with an independently adjustable curvature and stiffness as a three-dimensional substrate for breast cancer cell migration. We found that the cell migration velocity was negatively correlated to curvature and positively correlated to stiffness. In addition, curvature was investigated to influence the focal adhesion expression as well as the assignment of F-actin at the molecular level. Further, with the help of a motor-clutch mathematical model and hydrogel microsphere stress sensors, it was concluded that cells perceived physical factors (curvature and stiffness) to cause changes in CTF, which ultimately regulated cell motility. In summary, we employed a theoretical model (motor-clutch) and experimental strategy (stress sensors) to understand the mechanism of curvature and stiffness regulating breast cancer cell motility. These results provide evidence of force driven cancer cell migration by ECM physical factors and explain the mechanism from the perspective of mechanobiology.

Therapeutic advancements in treatments for cancer, a leading cause of mortality worldwide, have lagged behind the increasing incidence of this disease. There is a growing interest in multifaceted approaches for cancer treatment, such as chemotherapy, targeted therapy, and immunotherapy, but due to their low efficacy and severe side effects, there is a need for the development of new cancer therapies. Recently, the human microbiome, which is comprised of various microorganisms, has emerged as an important research field due to its potential impact on cancer treatment. Among these microorganisms, Bifidobacterium infantis has been shown to significantly improve the efficacy of various anticancer drugs. However, research on the role of B. infantis in cancer treatment remains insufficient. Thus, in this study, we explored the anticancer effect of treatment with B. infantis DS1685 supernatant (BI sup) in colorectal and breast cancer cell lines. Treatment with BI sup induced SMAD4 expression to suppress cell growth in colon and breast cancer cells. Furthermore, a decrease in tumor cohesion was observed through the disruption of the regulation of EMT-related genes by BI sup in 3D spheroid models. Based on these findings, we anticipate that BI sup could play an adjunctive role in cancer therapy, and future cotreatment of BI sup with various anticancer drugs may lead to synergistic effects in cancer treatment.

Breast cancer (BC) represents a paradigm of heterogeneity, manifesting as a spectrum of molecular subtypes with divergent clinical trajectories. It is fundamentally characterized by the aberrant proliferation of malignant cells within breast tissue, a process modulated by a myriad of factors that govern its progression. Recent endeavors outline the interplay between BC and the nervous system, illuminate the complex symbiosis between neural structures and neoplastic cells, and elucidate nerve dependence as a cornerstone of BC progression. This includes the neural modulations on immune response, neurovascular formation, and multisystem interactions. Such insights have unveiled the critical impact of neural elements on tumor dynamics and patient prognosis. This revelation beckons a deeper exploration into the neuro-oncological interface, potentially unlocking novel therapeutic vistas. This review endeavors to delineate the intricate mechanisms between the nervous system and BC, aiming to accentuate the implications and therapeutic strategies of this intersection for tumor evolution and the formulation of innovative therapeutic approaches., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: Estrogen receptor-positive (ER+) breast cancer represents about 80% of cases, tamoxifen is the election neoadjuvant chemotherapy. However, a large percentage of patients develop chemoresistance, compromising recovery. Clinical evidence suggests that high plasmatic levels of low-density lipoproteins (LDL) could promote cancer progression. The present study analyzed the effect of LDL on the primary plasmatic active Tamoxifen's metabolites resistance acquisition, 4-hydroxytamoxifen (4OH-Tam) and 4-hydroxy-N-desmethyl-tamoxifen (endoxifen), in breast cancer ERα + cells (MCF-7)., Methods: Two resistant cellular variants, MCF-7Var-H and MCF-7Var-I, were generated by a novel strategy and their phenotype features were evaluated. Phenotypic assessment was performed by MTT assays, cytometry, immunofluorescence microscopy, zymography and protein expression analysis., Results: MCF-7Var-H, generated only with tamoxifen metabolites, showed a critical down-regulation in hormone receptors, augmented migration capacity, metalloprotease 9 extracellular medium excretion, and a mesenchymal morphology in contrast with native MCF-7, suggesting the transition towards Triple-negative breast cancer (TNBC) phenotype. In contrast, MCF-7Var-I which was generated in a high LDL media, showed only a slight upregulation in ER and other less noticeable metabolic adaptations. Results suggest a potential role of transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in phenotypic differences observed among variants., Conclusion: LDL high or low concentrations during Tamoxifen´s metabolites chemoresistance acquisition leads to different cellular mechanisms related to chemoresistance. A novel adaptative cellular response associated with Nrf2 activity could be implicated., (© 2024 The Author(s).)

Background: In prior research employing iTRAQ (Isobaric Tags for Relative and Absolute Quantitation) technology, we identified a range of proteins in breast cancer tissues exhibiting high levels of acetylation. Despite this advancement, the specific functions and implications of these acetylated proteins in the context of cancer biology have yet to be elucidated. This study aims to systematically investigate the functional roles of these acetylated proteins with the objective of identifying potential therapeutic targets within breast cancer pathophysiology., Methods: Acetylated targets were identified through bioinformatics, with their expression and acetylation subsequently confirmed. Proteomic analysis and validation studies identified potential acetyltransferases and deacetylases. We evaluated metabolic functions via assays for catalytic activity, glucose consumption, ATP levels, and lactate production. Cell proliferation and metastasis were assessed through viability, cycle analysis, clonogenic assays, PCNA uptake, wound healing, Transwell assays, and MMP/EMT marker detection., Results: Acetylated proteins in breast cancer were primarily involved in metabolism, significantly impacting glycolysis and the tricarboxylic acid cycle. Notably, PGK1 showed the highest acetylation at lysine 323 and exhibited increased expression and acetylation across breast cancer tissues, particularly in T47D and MCF-7 cells. Notably, 18 varieties acetyltransferases or deacetylases were identified in T47D cells, among which p300 and Sirtuin3 were validated for their interaction with PGK1. Acetylation at 323 K enhanced PGK1's metabolic role by boosting its activity, glucose uptake, ATP production, and lactate output. This modification also promoted cell proliferation, as evidenced by increased viability, S phase ratio, clonality, and PCNA levels. Furthermore, PGK1-323 K acetylation facilitated metastasis, improving wound healing, cell invasion, and upregulating MMP2, MMP9, N-cadherin, and Vimentin while downregulating E-cadherin., Conclusion: PGK1-323 K acetylation was significantly elevated in T47D and MCF-7 luminal A breast cancer cells and this acetylation could be regulated by p300 and Sirtuin3. PGK1-323 K acetylation promoted cell glycolysis, proliferation, and metastasis, highlighting novel epigenetic targets for breast cancer therapy., (© 2024. The Author(s).)

HER2+ breast tumors have abundant immune-suppressive cells, including M2-type tumor-associated macrophages (TAMs). Although TAMs consist of the immune-stimulatory M1 type and immune-suppressive M2 type, the M1/M2-TAM ratio is reduced in immune-suppressive tumors, contributing to their immunotherapy refractoriness. M1- versus M2-TAM formation depends on differential arginine metabolism, where M1-TAMs convert arginine to nitric oxide (NO) and M2-TAMs convert arginine to polyamines (PAs). We hypothesize that such distinct arginine metabolism in M1- versus M2-TAMs is attributed to different availability of BH 4 (NO synthase cofactor) and that its replenishment would reprogram M2-TAMs to M1-TAMs. Recently, we reported that sepiapterin (SEP), the endogenous BH 4 precursor, elevates the expression of M1-TAM markers within HER2+ tumors. Here, we show that SEP restores BH 4 levels in M2-like macrophages, which then redirects arginine metabolism to NO synthesis and converts M2 type to M1 type. The reprogrammed macrophages exhibit full-fledged capabilities of antigen presentation and induction of effector T cells to trigger immunogenic cell death of HER2+ cancer cells. This study substantiates the utility of SEP in the metabolic shift of the HER2+ breast tumor microenvironment as a novel immunotherapeutic strategy., (© 2024 Fernando et al.)

In many countries, hormone receptor status assessment of ductal carcinoma in situ (DCIS) is routinely performed, as hormone receptor-positive DCIS patients are eligible for adjuvant anti-hormonal treatment, aiming to reduce the ipsilateral and contralateral breast cancer risk. Although HER2 gene amplification and its associated HER2 protein overexpression constitute a major prognostic and predictive marker in invasive breast carcinoma, its use in the diagnosis and treatment of DCIS is less straightforward. HER2 immunohistochemistry is not routinely performed yet, as the role of HER2-positivity in DCIS biology is unclear. Nonetheless, recent data challenge this practice. Here, we discuss the value of routine HER2 assessment for DCIS. HER2-positivity correlates strongly with DCIS grade: around four in five HER2-positive DCIS show high grade atypia. As morphological DCIS grading is prone to interobserver variability, HER2 immunohistochemistry could render grading more robust. Several studies showed an association between HER2-positive DCIS and ipsilateral recurrence risk, albeit currently unclear whether this is for overall, in situ or invasive recurrence. HER2-positive DCIS tends to be larger, with a higher risk of involved surgical margins. HER2-positive DCIS patients benefit more from adjuvant radiotherapy: it substantially decreases the local recurrence risk after lumpectomy, without impact on overall survival. HER2-positivity in pure biopsy-diagnosed DCIS is associated with increased upstaging to invasive carcinoma after surgery. HER2 immunohistochemistry on preoperative biopsies might therefore provide useful information to surgeons, favoring wider excisions. The time seems right to consider DCIS subtype-dependent treatment, comprising appropriate local treatment for HER2-positive DCIS patients and de-escalation for hormone receptor-positive, HER2-negative DCIS patients., (© 2024. The Author(s).)

Globally, the prevalence of breast cancer (BC) is increasing at an alarming level, despite early detection and technological improvements. Alkaloids are diverse chemical groups, and many within this class have been reported as potential anticancer compounds. Chabamide F (F) and chabamide G (G) are two dimeric amide alkaloids found in a traditional medicinal plant, Piper chaba, and possess significant cytotoxic effects. However, their scientific rationalization in BC remains unknown. Here, we aimed to investigate their potential and molecular mechanisms for BC through in silico approaches. From network pharmacology, we identified 64 BC-related genes as targets. GO and KEGG studies showed that they were involved in various biological processes and mostly expressed in BC-related pathways such as RAS, PI3K-AKT, estrogen, MAPK, and FoxO pathways. However, PPI analysis revealed SRC and AKT1 as hub genes, which play key roles in BC tumorigenesis and metastasis. Molecular docking revealed the strong binding affinity of F (- 10.7 kcal/mol) and G (- 9.4 and - 11.7 kcal/mol) for SRC and AKT1, respectively, as well as the acquisition of vital residues to inhibit them. Their long-term stability was evaluated using 200 ns molecular dynamics simulation. The RMSD, RMSF, Rg, and SASA analyses showed that the G-SRC and G-AKT1 complexes were excellently stable compared to the control, dasatinib, and capivasertib, respectively. Additionally, the PCA and DCCM analyses revealed a significant reduction in the residual correlation and motions. By contrast, the stability of the F-SRC complex was greater than that of the control, whereas it was moderately stable in complex with AKT1. The MMPBSA analysis demonstrated higher binding energies for both compounds than the controls. In particular, the binding energy of G for SRC and AKT1 was - 120.671 ± 16.997 and - 130.437 ± 19.111 kJ/mol, respectively, which was approximately twice as high as the control molecules. Van der Waal and polar solvation energies significantly contributed to this energy. Furthermore, both of them exhibited significant interactions with the binding site residues of both proteins. In summary, this study indicates that these two molecules could be a potential ATP-competitive inhibitor of SRC and an allosteric inhibitor of AKT1., (© 2024. The Author(s).)

Background: Pathologists commonly employ the Ki67 immunohistochemistry labelling index (LI) when deciding appropriate therapeutic strategies for patients with breast cancer. However, despite several attempts at standardizing the Ki67 LI, inter-observer and inter-laboratory bias remain problematic. We developed a flow cytometric assay that employed tissue dissociation, enzymatic treatment and a gating process to analyse Ki67 in formalin-fixed paraffin-embedded (FFPE) breast cancer tissue., Results: We demonstrated that mechanical homogenizations combined with thrombin treatment can be used to recover efficiently intact single-cell nuclei from FFPE breast cancer tissue. Ki67 in the recovered cell nuclei retained reactivity against the MIB-1 antibody, which has been widely used in clinical settings. Additionally, since the method did not alter the nucleoskeletal structure of tissues, the nuclei of cancer cells can be enriched in data analysis based on differences in size and complexity of nuclei of lymphocytes and normal mammary cells. In a clinical study using the developed protocol, Ki67 positivity was correlated with the Ki67 LI obtained by hot spot analysis by a pathologist in Japan (rho = 0.756, P < 0.0001). The number of cancer cell nuclei subjected to the analysis in our assay was more than twice the number routinely checked by pathologists in clinical settings., Conclusions: The findings of this study showed the application of this new flow cytometry method could potentially be used to standardize Ki67 assessments in breast cancer., (© 2024. The Author(s).)

Despite advances in breast cancer screening and treatment, prognosis for metastatic disease remains dismal at 30% five-year survival. This is due, in large, to the failure of current therapeutics to target properties unique to metastatic cells. One of the drivers of metastasis is miR-10b, a small noncoding RNA implicated in cancer cell invasion, migration, viability, and proliferation. We have developed a nanodrug, termed MN-anti-miR10b, that delivers anti-miR-10b antisense oligomers to cancer cells. In mouse models of metastatic triple-negative breast cancer, MN-anti-miR10b has been shown to prevent onset of metastasis and eliminate existing metastases in combination with chemotherapy, even after treatment has been stopped. Recent studies have implicated miR-10b in conferring stem cell-like properties onto cancer cells, such as chemoresistance. In this study, we show transcriptional evidence that inhibition of miR-10b with MN-anti-miR10b activates developmental processes in cancer cells and that stem-like cancer cells have increased miR-10b expression. We then demonstrate that treatment of breast cancer cells with MN-anti-miR10b reduces their stemness, confirming that these properties make metastatic cells susceptible to the nanodrug actions. Collectively, these findings indicate that inhibition of miR-10b functions to impair breast cancer cell stemness, positioning MN-anti-miR10b as an effective treatment option for stem-like breast cancer subtypes.

Breast cancer is a prevalent malignancy affecting women globally, necessitating effective treatment strategies. This study explores the potential of ergosterol, a bioactive compound found in edible mushrooms, as a candidate for breast cancer treatment. Breast cancer cell lines (MCF-7 and MDA-MB-231) were treated with ergosterol, revealing its ability to inhibit cell viability, induce cell cycle arrest, and suppress spheroid formation. Mechanistically, ergosterol demonstrated significant inhibitory effects on the Wnt/beta-catenin signaling pathway, a critical regulator of cancer progression, by attenuating beta-catenin translocation in the nucleus. This suppression was attributed to the inhibition of AKT/GSK-3beta phosphorylation, leading to decreased beta-catenin stability and activity. Additionally, ergosterol treatment impacted protein synthesis and ubiquitination, potentially contributing to its anti-cancer effects. Moreover, the study revealed alterations in metabolic pathways upon ergosterol treatment, indicating its influence on metabolic processes critical for cancer development. This research sheds light on the multifaceted mechanisms through which ergosterol exerts anti-tumor effects, mainly focusing on Wnt/beta-catenin pathway modulation and metabolic pathway disruption. These findings provide valuable insights into the potential of ergosterol as a therapeutic candidate for breast cancer treatment, warranting further investigation and clinical application., (© 2024. The Author(s).)

Background: p63 is a transcription factor with intrinsic pioneer factor activity and pleiotropic functions. Transforming growth factor β (TGFβ) signaling via activation and cooperative action of canonical, SMAD, and non-canonical, MAP-kinase (MAPK) pathways, elicits both anti- and pro-tumorigenic properties, including cell stemness and invasiveness. TGFβ activates the ΔNp63 transcriptional program in cancer cells; however, the link between TGFβ and p63 in unmasking the epigenetic landscape during tumor progression allowing chromatin accessibility and gene transcription, is not yet reported., Methods: Small molecule inhibitors, including protein kinase inhibitors and RNA-silencing, provided loss of function analyses. Sphere formation assays in cancer cells, chromatin immunoprecipitation and mRNA expression assays were utilized in order to gain mechanistic evidence. Mass spectrometry analysis coupled to co-immunoprecipitation assays revealed novel p63 interactors and their involvement in p63-dependent transcription., Results: The sphere-forming capacity of breast cancer cells was enhanced upon TGFβ stimulation and significantly decreased upon ΔNp63 depletion. Activation of TGFβ signaling via p38 MAPK signaling induced ΔNp63 phosphorylation at Ser 66/68 resulting in stabilized ΔNp63 protein with enhanced DNA binding properties. TGFβ stimulation altered the ratio of H3K27ac and H3K27me3 histone modification marks, pointing towards higher H3K27ac and increased p300 acetyltransferase recruitment to chromatin. By silencing the expression of ΔNp63, the TGFβ effect on chromatin remodeling was abrogated. Inhibition of H3K27me3, revealed the important role of TGFβ as the upstream signal for guiding ΔNp63 to the TGFβ/SMAD gene loci, as well as the indispensable role of ΔNp63 in recruiting histone modifying enzymes, such as p300, to these genomic regions, regulating chromatin accessibility and gene transcription. Mechanistically, TGFβ through SMAD activation induced dissociation of ΔNp63 from NURD or NCOR/SMRT histone deacetylation complexes, while promoted the assembly of ΔNp63-p300 complexes, affecting the levels of histone acetylation and the outcome of ΔNp63-dependent transcription., Conclusions: ΔNp63, phosphorylated and recruited by TGFβ to the TGFβ/SMAD/ΔNp63 gene loci, promotes chromatin accessibility and transcription of target genes related to stemness and cell invasion., (© 2024. The Author(s).)

The high-affinity IgE receptor, FcεRI, is typically associated with type 2 effectors such as mast cells (MC). The relatively unique expression profile of FcεRI and accumulating evidence from pre-clinical and clinical settings, such as MC interactions with tumors, have led us to study MCs as a potential therapeutic target in breast cancer. Our work identified MCs interacting with tumor cells at primary sites using the 4T1 (BALB/c) adenocarcinoma model in vivo. However, this analysis was complicated by a surprising finding that the tumor cells intrinsically and strongly expressed FcεRI. We further studied the expression and function of FcεRI in breast cancer cells in vitro. The 4T1 cells expressed FcεRI to a level similar to mouse bone marrow-derived MC (BMMC). Additionally, two established breast cancer cultures derived from human T-47D cells, one estrogen-dependent (E3) and the other estrogen-withdrawn (EWD8), also expressed FcεRI with EWD8 cells showing the greatest abundance. Functional analyses indicated that IgE-mediated antigen stimulation did not elicit classic Ca 2+ flux in breast cancer cells as seen in the respective species' MCs; however, FcεRI crosslinking could stimulate IL-6 production from the T-47D derivatives. Preliminary analysis of primary breast cancer biopsy datasets using R2: Genomics Analysis and Visualization Platform was discordant with our in vivo model and in vitro observations. Indeed, FcεRI mRNA abundance declined in metastatic breast cancers compared to non-cancerous breast tissue. Altogether, we report a previously unidentified and immunologically substantive difference between breast cancer models and human primary tumors. Investigators pursuing FcεRI-relevant therapeutics in this context should be aware of this translational barrier.

Emerging studies support that the polycomb repressive complex 2 (PRC2) regulates phenotypic changes of carcinoma cells by modulating their shifts among metastable states within the epithelial and mesenchymal spectrum. This new role of PRC2 in cancer has been recently proposed to stem from the ability of its catalytic subunit EZH2 to bind and modulate the transcription of mesenchymal genes during epithelial-mesenchymal transition (EMT) in lung cancer cells. Here, we asked whether this mechanism is conserved in other types of carcinomas. By combining TGF-β-mediated reversible induction of epithelial to mesenchymal transition and inhibition of EZH2 methyltransferase activity, we demonstrate that EZH2 represses a large set of mesenchymal genes and favours the residence of breast cancer cells towards the more epithelial spectrum during EMT. In agreement, analysis of human patient samples supports that EZH2 is required to efficiently repress mesenchymal genes in breast cancer tumours. Our results indicate that PRC2 operates through similar mechanisms in breast and lung cancer cells. We propose that PRC2-mediated direct transcriptional modulation of the mesenchymal gene expression programme is a conserved molecular mechanism underlying cell dissemination across human carcinomas., (© 2024. The Author(s).)

Objectives: STAT3 is a transcriptional activator of breast cancer oncogenes, suggesting that it could be a potential therapeutic target for breast cancer. Therefore, this study investigated the potential application of C188-9, a STAT3 signal pathway inhibitor, in the treatment of breast cancer through a novel pre-clinical platform with patient-specific primary cells (PSPCs)., Methods: PSPCs were isolated from breast cancer samples obtained via biopsy or surgery from fifteen patient donors with their full acknowledgements. PSPCs were treated with C188-9 or other chemotherapeutic agents, and then analyzed with cell viability assay. Western blot assay and real-time quantitative PCR were also used to determine the expression and activity of STAT3 signaling pathway of corresponding PSPCs., Results: C188-9 treatment at normal (experimental) concentration had valid inhibition on PSPCs proliferation. Meanwhile, treatment at a low (clinic-relevant) concentration of C188-9 for an extended period reduced cell viability of PSPCs still more than some of other traditional chemotherapy drugs. In addition, C188-9 decreased expression level of pSTAT3 in PSPCs from some, but not all patient samples. The treatment of C188-9 reduced cell viability of the breast cancer samples through inhibiting the STAT3 to C-myc signaling pathway., Conclusions: In this study, we tested a novel drug C188-9 at a low, clinic-relevant concentration, together with several traditional chemotherapy agents. PSPCs from ten out of fifteen patient donors were sensitive to C188-9, while some of traditional chemotherapy agents failed. This finding suggested that C188-9 could have treatment effects only on those ten PSPC patient donors, indicating the future personalized utilization of PSPCs., (© 2024. The Author(s).)

Identifying novel breast cancer biomarkers will improve patient stratification, enhance therapeutic outcomes, and help develop non-invasive diagnostics. We compared the proteomic profiles of whole-cell and exosomal samples of representative breast cancer cell subtypes to evaluate the potential of extracellular vesicles as non-invasive disease biomarkers in liquid biopsies. Overall, differentially-expressed proteins in whole-cell and exosome samples (which included markers for invasion, metastasis, angiogenesis, and drug resistance) effectively discriminated subtypes; furthermore, our results confirmed that the proteomic profile of exosomes reflects breast cancer cell-of-origin, which underscores their potential as disease biomarkers. Our study will contribute to identifying biomarkers that support breast cancer patient stratification and developing novel therapeutic strategies. We include an open, interactive web tool to explore the data as a molecular resource that can explain the role of these protein signatures in breast cancer classification., (© 2024. The Author(s).)

Immune tolerance mechanisms are shared in cancer and pregnancy. Through cross-analyzing single-cell RNA-sequencing data from multiple human cancer types and the maternal-fetal interface, we found B7-H4 (VTCN1) is an onco-fetal immune tolerance checkpoint. We showed that genetic deficiency of B7-H4 resulted in immune activation and fetal resorption in allogeneic pregnancy models. Analogously, B7-H4 contributed to MPA/DMBA-induced breast cancer progression, accompanied by CD8 + T cell exhaustion. Female hormone screening revealed that progesterone stimulated B7-H4 expression in placental and breast cancer cells. Mechanistically, progesterone receptor (PR) bound to a newly identified -58 kb enhancer, thereby mediating B7-H4 transcription via the PR-P300-BRD4 axis. PR antagonist or BRD4 degrader potentiated immunotherapy in a murine B7-H4 + breast cancer model. Thus, our work unravels a mechanistic and biological connection of a female sex hormone (progesterone) to onco-fetal immune tolerance via B7-H4 and suggests that the PR-P300-BRD4 axis is targetable for treating B7-H4 + cancer., Competing Interests: Declaration of interests W.Z. has served as a scientific advisor or consultant for Cstone, NextCure, and Hanchorbio. S. Wang is a co-founder and paid consultant of Ascentage Pharma Group International and owns stock in Ascentage. L.C. has been a scientific founder, consultant, and/or board observer for NextCure, Normunity, Tayu, Zai Lab, Tpioneer, Vcanbio, OncoC4, and GenomiCare and has sponsored research funds from NextCure, Normunity, and DynamiCure. This research is conducted independently and has not received resources from and is unrelated to the scientific and commercial pursuits of these industrial entities, including NextCure., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The FRG1(FSHD region gene 1) gene has emerged as a pivotal tumor suppressor in both breast and prostate cancer. HPF1 (Histone PARylation Factor 1), a gene crucial in the base excision repair (BER) mechanism for single-stranded DNA (ssDNA) lesions, showcases a robust correlation with FRG1. This implies that FRG1 might have the capacity to influence BER via HPF1, potentially playing a role in tumorigenesis. Using a comprehensive approach that integrates in-silico analyses involving differential gene expression, KEGG (Kyoto Encyclopedia of Genes and Genomes), GO (Gene Ontology), and STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) databases, we unravelled the intricate network of genes and pathways influenced by FRG1, which includes BER. Our linear regression analysis unveiled a positive relationship between FRG1 and key genes crucial for BER. Notably, breast cancer patients with low FRG1 expression exhibited a significantly higher frequency of mutation in TP53. To enhance the accuracy of our analysis, we conducted qRT-PCR assays, which demonstrated that FRG1 affects the transcription of DNA base excision repair genes, showing differential expression in breast cancer cells. Moreover, through the Alkaline Comet Assay, a technique that quantifies DNA damage at the single-cell level, we observed diminished DNA repair capabilities when FRG1 levels are low. Risk scores were calculated using the Cox regression coefficients, and we found notable differences in Overall Survival (OS) and mRNA expression of DEGs in the low and high-risk groups. In summary, our findings shed light on the pivotal role of FRG1 in maintaining DNA repair efficiency within breast cancer cells., (© 2024. The Author(s).)

Background: Breast cancer (BC) ranks as the third most fatal malignant tumor worldwide, with a strong reliance on fatty acid metabolism. CLDN6, a candidate BC suppressor gene, was previously identified as a regulator of fatty acid biosynthesis; however, the underlying mechanism remains elusive. In this research, we aim to clarify the specific mechanism through which CLDN6 modulates fatty acid anabolism and its impact on BC growth and metastasis., Methods: Cell function assays, tumor xenograft mouse models, and lung metastasis mouse models were conducted to evaluate BC growth and metastasis. Human palmitic acid assay, triglyceride assay, Nile red staining, and oil red O staining were employed to investigate fatty acid anabolism. Reverse transcription polymerase chain reaction (RT-PCR), western blot, immunohistochemistry (IHC) assay, nuclear fractionation, immunofluorescence (IF), immunoprecipitation and acyl-biotin exchange (IP-ABE), chromatin immunoprecipitation (ChIP), dual luciferase reporter assay, and co-immunoprecipitation (Co-IP) were applied to elucidate the underlying molecular mechanism. Moreover, tissue microarrays of BC were analyzed to explore the clinical implications., Results: We identified that CLDN6 inhibited BC growth and metastasis by impeding RAS palmitoylation both in vitro and in vivo. We proposed a unique theory suggesting that CLDN6 suppressed RAS palmitoylation through SREBP1-modulated de novo palmitic acid synthesis. Mechanistically, CLDN6 interacted with MAGI2 to prevent KLF5 from entering the nucleus, thereby restraining SREBF1 transcription. The downregulation of SREBP1 reduced de novo palmitic acid synthesis, hindering RAS palmitoylation and subsequent endosomal sorting complex required for transport (ESCRT)-mediated plasma membrane localization required for RAS oncogenic activation. Besides, targeting inhibition of RAS palmitoylation synergized with CLDN6 to repress BC progression., Conclusions: Our findings provide compelling evidence that CLDN6 suppresses the palmitic acid-induced RAS palmitoylation through the MAGI2/KLF5/SREBP1 axis, thereby impeding BC malignant progression. These results propose a new insight that monitoring CLDN6 expression alongside targeting inhibition of palmitic acid-mediated palmitoylation could be a viable strategy for treating oncogenic RAS-driven BC., (© 2024. The Author(s).)

The clinical studies for breast cancer (BC) are now assessing the efficacy of 2-Methoxyestradiol (2-ME), a naturally occurring derivative of estradiol. Our study aimed to explore the potential of combining the 2-ME and tamoxifen (TAM) on sensitization of TAM-resistant cells using LCC2 the TAM-resistant cells as a model and comparing the results to the sensitive cells MCF-7. Sulphorhodamine-B (SRB) assay is used to examine the 2-ME chemo-sensitizing impact on the cytotoxicity of TAM on LCC2 cells. Colorimetric assay kits were used to assess the level of the apoptosis-related markers caspases 3, Bcl2, and Bax in cell lysate. Hypoxia-inducible factor 1 alpha (HIF-1α) expression was measured using western blotting. Total cholesterol and triglyceride (TG) levels were examined colorimetrically, using the BIOLABO kit. The use of 2-ME enhanced the cytotoxic effects of TAM and effectively reversed TAM resistance. This was achieved by inhibiting the expression of HIF-1α, while concurrently increasing the levels of apoptotic marker caspase-3, as well as the pro-apoptotic protein Bax. Additionally, there was a reduction in the levels of Bcl2, an anti-apoptotic protein. Furthermore, a reduction in TG and cholesterol levels was noted. Our findings show that HIF-1α plays an important role in TAM resistance and that suppression of HIF-1α by 2-ME-mediated sensitization of BC-resistant cells to TAM. Therefore, the concurrent administration of TAM/2-ME might potentially serve as a viable therapeutic approach to address TAM resistance and enhance the overall therapy efficacy for patients with BC., (© 2024. The Author(s).)

Background: Does incorporating Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors into endocrine therapy (ET) effectively enhance survival outcomes, notably overall survival (OS), among individuals with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer? This remains a clinical controversy. We compared the antitumor efficacy and adverse effects (AEs) between CDK4/6 inhibitors + ET (CET) and placebo + ET (PET) by conducting a phase III randomized controlled trials (RCTs) based meta-analysis., Methods: Seven databases were searched to identify eligible studies, comprising Phase III RCTs comparing CET to PET. The primary endpoints were OS and progression-free survival (PFS), with secondary endpoints including responses and adverse events (AEs)., Results: Seven RCTs (DAWNA-2, MONALEESA-2, MONALEESA-3, MONALEESA-7, MONARCH-3, PALOMA-2, and PALOMA-4) were included. The CET group exhibited significantly improved OS (HR: 0.81 [0.74, 0.88]), PFS (HR: 0.57 [0.52, 0.63]), objective response rate (RR: 1.31 [1.20, 1.43]), and clinical benefit rate (RR: 1.11 [1.07, 1.15]). These benefits were consistent across almost all subgroups. Additionally, the CET group showed better overall survival rates (OSR) from 24 to 60 months (OSR 24-60 m) and progression-free survival rates (PFSR) from 6 to 60 months (PFSR 6-60 m). However, more total AEs, grade 3-5 AEs, and serious AEs were found in CET group. The top 5 grade 3-5 AEs in the CET group were neutropenia (59.39%), leukopenia (24.11%), decreased white blood cell count (12.99%), hypertension (7.03%), and increased alanine aminotransferase (5.91%)., Conclusions: The superiority of CET over PET in HR+/HER2- advanced breast cancer is evident, showing improved survival and responses. Nonetheless, the higher incidence of AEs, specifically hematologic AEs, requires cautious attention., (© 2024. The Author(s).)

The most devastating feature of cancer cells is their ability to metastasize to distant sites in the body. HER2 + and TN breast cancers frequently metastasize to the brain and stay potentially dormant for years until favorable conditions support their proliferation. The sheltered and delicate nature of the brain prevents, however, early disease detection and effective delivery of therapeutic drugs. Moreover, the challenges associated with the acquisition of brain biopsies add compounding difficulties to exploring the mechanistic aspects of tumor development. To provide insights into the determinants of cancer cell behavior at the brain metastatic site, this study was aimed at exploring the early response of HER2 + breast cancer cells (SKBR3) to factors present in the brain perivascular niche. The neural microenvironment was simulated by using the secretome of a set of brain cells that come first in contact with the cancer cells upon crossing the blood brain barrier, i.e., endothelial cells, astrocytes, and microglia. Cytokine microarrays were used to investigate the secretome mediators of intercellular communication, and proteomic technologies for assessing the changes in the behavior of cancer cells upon exposure to the brain cell-secreted factors. The cytokines detected in the brain secretomes were supportive of inflammatory conditions, while the SKBR3 cells secreted numerous cancer-promoting growth factors that were either absent or present in lower abundance in the brain cell cultures, indicating that upon exposure the SKBR3 cells may have been deprived of favorable conditions for optimal growth. Altogether, the results suggest that the exposure of SKBR3 cells to the brain cell-secreted factors altered their growth potential and drove them toward a state of quiescence, with broader overall outcomes that affected cellular metabolism, adhesion and immune response processes. The findings of this study underscore the key role played by the neural niche in shaping the behavior of metastasized cancer cells, provide insights into the cellular cross-talk that may lead cancer cells into dormancy, and highlight novel opportunities for the development of metastatic breast cancer therapeutic strategies., (© 2024. The Author(s).)

Background: TCbHP (taxane + carboplatin + trastuzumab + pertuzumab) is the preferred neoadjuvant therapy regimen for human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, no consensus exists regarding whether specific populations may be exempt from carboplatin, allowing for de-escalation to the THP (taxane + trastuzumab + pertuzumab) regimen. Additionally, the optimal number of cycles for neoadjuvant THP remains unclear. We compared the efficacy and safety of neoadjuvant TCbHP and THP regimens, providing clinicians with a nuanced perspective to guide their treatment regimen selection., Methods: This multicenter real-world study included patients with HER2-positive breast cancer undergoing neoadjuvant TCbHP or THP between March 2019 and February 2023. Efficacy was assessed through the pathological complete response (pCR) rate, while safety was evaluated through monitoring adverse events., Results: Among 220 patients, 103 received 6 cycles of TCbHP (TCbHP×6), 83 received 6 cycles of THP (THP×6), and 34 received 4 cycles of THP (THP×4). The TCbHP×6 cohort exhibited a 66% pCR rate compared with 53% in the THP×6 cohort (P = 0.072). Subgroup analysis revealed that in patients aged ≤ 50 years, those with hormone receptor (HR)-negative status, and those with clinical stage T2, the pCR rate of the TCbHP×6 regimen was significantly higher than the THP×6 regimen (P < 0.05). The TCbHP×6 cohort reported higher frequencies of any-grade adverse events (99% versus 86.7%) and grade 3-4 events (49.5% versus 12%) than the THP×6 cohort. Propensity score matching identified 27 patient pairs between the THP×6 and THP×4 cohorts, indicating a significantly higher pCR rate for the THP×6 regimen than the THP×4 regimen (63% versus 29.6%, P = 0.029)., Conclusions: The TCbHP×6 regimen is favored for individuals aged ≤ 50 years and those aged > 50, ≤60 years with HR-negative status or clinical stage T2-4. For patients in compromised general condition or lacking the specified indications, the THP×6 regimen emerges as a lower-toxicity alternative with satisfactory efficacy. To ensure treatment efficacy, a minimum of 6 cycles of neoadjuvant THP is required., (© 2024. The Author(s).)

Background: Anti-HER2 therapies, including the HER2 antibody-drug conjugates (ADCs) trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd), have led to improved survival outcomes in patients with HER2-overexpressing (HER2+) metastatic breast cancer. However, intrinsic or acquired resistance to anti-HER2-based therapies remains a clinical challenge in these patients, as there is no standard of care following disease progression. The purpose of this study was to elucidate the mechanisms of resistance to T-DM1 and T-DXd in HER2+ BC patients and preclinical models and identify targets whose inhibition enhances the antitumor activity of T-DXd in HER2-directed ADC-resistant HER2+ breast cancer in vitro and in vivo., Methods: Targeted DNA and whole transcriptome sequencing were performed in breast cancer patient tissue samples to investigate genetic aberrations that arose after anti-HER2 therapy. We generated T-DM1 and T-DXd-resistant HER2+ breast cancer cell lines. To elucidate their resistance mechanisms and to identify potential synergistic kinase targets for enhancing the efficacy of T-DXd, we used fluorescence in situ hybridization, droplet digital PCR, Western blotting, whole-genome sequencing, cDNA microarray, and synthetic lethal kinome RNA interference screening. In addition, cell viability, colony formation, and xenograft assays were used to determine the synergistic antitumor effect of T-DXd combinations., Results: We found reduced HER2 expression in patients and amplified DNA repair-related genes in patients after anti-HER2 therapy. Reduced ERBB2 gene amplification in HER2-directed ADC-resistant HER2+ breast cancer cell lines was through DNA damage and epigenetic mechanisms. In HER2-directed ADC-resistant HER2+ breast cancer cell lines, our non-biased RNA interference screening identified the DNA repair pathway as a potential target within the canonical pathways to enhance the efficacy of T-DXd. We validated that the combination of T-DXd with ataxia telangiectasia and Rad3-related inhibitor, elimusertib, led to significant breast cancer cell death in vitro (P < 0.01) and in vivo (P < 0.01) compared to single agents., Conclusions: The DNA repair pathways contribute to HER2-directed ADC resistance. Our data justify exploring the combination treatment of T-DXd with DNA repair-targeting drugs to treat HER2-directed ADC-resistant HER2+ breast cancer in clinical trials., (© 2024. The Author(s).)

Centrosomal Protein 55 (CEP55) exhibits various oncogenic activities; it regulates the PI3K-Akt-pathway, midbody abscission, and chromosomal instability (CIN) in cancer cells. Here, we analyzed the mechanism of how CEP55 controls CIN in ovarian and breast cancer (OvCa) cells. Down-regulation of CEP55 reduced CIN in all cell lines analyzed, and CEP55 depletion decreased spindle microtubule (MT)-stability in OvCa cells. Moreover, recombinant CEP55 accelerated MT-polymerization and attenuated cold-induced MT-depolymerization. To analyze a potential relationship between CEP55-controlled CIN and its impact on MT-stability, we identified the CEP55 MT-binding peptides inside the CEP55 protein. Thereafter, a mutant with deficient MT-binding activity was re-expressed in CEP55-depleted OvCa cells and we could show that this mutant did not restore reduced CIN in CEP55-depleted cells. This finding strongly indicates that CEP55 regulates CIN by controlling MT dynamics.

To compare the magnetic resonance imaging (MRI) features of different immunophenotypes of breast carcinoma of no special type (NST), with special attention to estrogen receptor (ER)-low-positive breast cancer. This retrospective, single-centre, Institutional Review Board (IRB)-approved study included 398 patients with invasive breast carcinoma. Breast carcinomas were classified as ER-low-positive when there was ER staining in 1-10% of tumour cells. Pretreatment MRI was reviewed to assess the tumour imaging features according to the 5th edition of the Breast Imaging Reporting and Data System (BI-RADS) lexicon. Of the 398 cases, 50 (12.6%) were luminal A, 191 (48.0%) were luminal B, 26 (6.5%) were luminal ER-low positive, 64 (16.1%) were HER2-overexpressing, and 67 (16.8%) were triple negative. Correlation analysis between MRI features and tumour immunophenotype showed statistically significant differences in mass shape, margins, internal enhancement and the delayed phase of the kinetic curve. An oval or round shape and rim enhancement were most frequently observed in triple-negative and luminal ER-low-positive tumours. Spiculated margins were most common in luminal A and luminal B tumours. A persistent kinetic curve was more frequent in luminal A tumours, while a washout curve was more common in the triple-negative, HER2-overexpressing and luminal ER-low-positive immunophenotypes. Multinomial regression analysis showed that luminal ER-low-positive tumours had similar results to triple-negative tumours for almost all variables. Luminal ER-low-positive tumours present with similar MRI findings to triple-negative tumours, which suggests that MRI can play a fundamental role in adequate radiopathological correlation and therapeutic planning in these patients., (© 2024. The Author(s).)

Breast cancer is a malignant tumor, with various subtypes showing different behaviors. Endogenous H 2 O 2 is an important marker of tumor progression, which makes it important to study the relationship between breast cancer subtypes and H 2 O 2 for pathogenesis and treatment strategies, but this has rarely been reported so far. In this work, we constructed a three-dimensional (3D) electrochemiluminescence (ECL) sensing platform for the detection of H 2 O 2 released from two typical subtypes of breast cancer cells (MCF-7 cells for luminal A-type and MDA-MB-231 cells for three negative breast cancers, TNBCs). To adequately replicate the tumor microenvironment, the peptide hydrogel was introduced as a scaffold for 3D cell culture. The titanium foam (TF) was used as a 3D electrode to better match the 3D culture substrate. N -(4-Aminobutyl)- N -ethylisoluminol (ABEI) was selected as the ECL emitter and assembled into the peptide hydrogel by hydrogen bonding and π-stacking, which resulted in a stable and homogeneous distribution of ABEI along the hydrogel fibers. Furthermore, basic amino acids were introduced to provide alkaline microenvironment for ABEI. Therefore, ABEI exhibited high ECL efficiency, resulting in a high sensitivity with an ultralow detection limit of 0.023 nM (S/N = 3) for H 2 O 2 of the proposed ECL biosensor. MCF-7 and MDA-MB-231 cells were cultured in a 3D peptide hydrogel/ABEI/TF electrode, respectively, and endogenous H 2 O 2 was successfully monitored. A notably significant difference of H 2 O 2 released between MDA-MB-231 cells and MCF-7 cells without stimulation but similar extra release with stimulation were observed. These findings may help understand the physiological mechanisms behind the various subtypes and reactive oxygen species (ROS)-related treatment for breast cancer.

Breast cancer, a heterogeneous and intricate disease, ranks among the leading causes of mortality in women. Restricted therapeutic choices, drug resistance, recurrence, and metastasis are the predominant conditions that lead to mortality. Accumulating evidence has shown breast cancer initiation and progression happen through a multifaceted and intricate process that involves numerous genetic and epigenetic alterations. The modulation of gene expression through epigenetic modifications, encompassing DNA methylation, histone alterations, and non-coding RNA regulation, has emerged as a fascinating field that represents a new avenue for breast cancer therapy. This review emphasizes various aberrant epigenetic regulations implicated in the onset and advancement of breast cancer. The critical epigenetic modifications closely associated with estrogen signaling, epithelial-to-mesenchymal transition (EMT), cancer stemness, and drug resistance have been discussed extensively. Moreover, it highlights current epi-drugs, including DNA modifying agents, histone acetyltransferase inhibitors, histone deacetylase inhibitors, histone methyltransferase inhibitors, and histone demethyltransferase inhibitors used for breast cancer treatment. Nonetheless, we described current investigations pertaining to combination therapy employing epi-drugs and future challenges., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

Background: Human epidermal growth factor receptor 2 (HER2)-low breast cancer has emerged as a new subtype of tumor, for which novel antibody-drug conjugates have shown beneficial effects. Assessment of HER2 requires several immunohistochemistry tests with an additional in situ hybridization test if a case is classified as HER2 2+. Therefore, novel cost-effective methods to speed up the HER2 assessment are highly desirable., Methods: We used a self-supervised attention-based weakly supervised method to predict HER2-low directly from 1437 histopathological images from 1351 breast cancer patients. We built six distinct models to explore the ability of classifiers to distinguish between the HER2-negative, HER2-low, and HER2-high classes in different scenarios. The attention-based model was used to comprehend the decision-making process aimed at relevant tissue regions., Results: Our results indicate that the effectiveness of classification models hinges on the consistency and dependability of assay-based tests for HER2, as the outcomes from these tests are utilized as the baseline truth for training our models. Through the use of explainable AI, we reveal histologic patterns associated with the HER2 subtypes., Conclusion: Our findings offer a demonstration of how deep learning technologies can be applied to identify HER2 subgroup statuses, potentially enriching the toolkit available for clinical decision-making in oncology., (© 2024. The Author(s).)

Breast cancer is a common invasive tumor in women, and the most common subtype of breast cancer is luminal A. Hormonal therapies are the primary treatment for luminal A, but treatment options are limited. Vulpinic acid (VA), a lichen compound, inhibited cancer cells. Here, we aimed to reveal the functional role and mechanism of VA in luminal A breast cancer. Experiments associated with the ferroptosis mechanism were performed to reveal the role of vulpinic acid on luminal A-breast cancer and the underlying mechanisms. The results showed that VA induced the ferroptosis pathway by decreasing glutathione (GSH) levels while increasing lipid reactive oxygen species (ROS), lipid peroxidation (MDA), and intracellular Fe 2+ levels in MCF-7 cells. After treatment of MCF-7 cells with VA, the ferroptosis-related gene expression profile was significantly altered. Western blot analysis showed that GPX4 protein levels were down-regulated and LPCAT3 protein levels were up-regulated after VA treatment. Our study suggests that apoptosis and ferroptosis act together in VA-mediated tumor suppression in MCF-7 breast cancer cells. These findings suggest that VA, an anti-neoplastic agent, could potentially treat luminal A targeted breast cancer via the ferroptosis pathway., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Luminal breast cancer has a high incidence worldwide and poses a severe health threat. Estrogen receptor alpha (ER-α) is activated by 17β-estradiol (E2), and its overexpression promotes cancerous characteristics. Luminal breast cancer is an epithelial type; however, the cytokine IL-6, secreted by cells within the tumor microenvironment, stimulates the epithelial-to-mesenchymal transition (EMT) and promotes metastasis. Also, IL-6 decreases ER-α levels, favoring the tamoxifen (TMX) resistance development. However, genes under E2 regulation continue to be expressed even though this receptor is absent. GPR30 is an alternative E2 receptor present in both luminal and aggressive triple-negative breast cancer and is related to TMX resistance and cancer progression. The roles of GPR30 and IL-6 in metastasis have been individually established; however, their interplay remains unexplored. This study aims to elucidate the role of GPR30 in IL-6-induced metastatic properties of MCF-7 luminal breast cancer cells. Results showed that GPR30 contributes to the E2-induced MCF-7 proliferation because its inhibition with the antagonist G15 and the Pertussis toxin (PTX) reduced it. Besides, GPR30 upregulated vimentin and downregulated E-cadherin levels in MCF-7 and TMX-resistant (R-TMX) cells and is also involved in the IL-6-induced migration, invasion, and TMX resistance in MCF-7 cells. In addition, in MDA-MB-231 triple-negative cells, both basal and IL-6-induced metastatic properties were related to GPR30 activity. These results indicate that the GPR30 receptor regulates the EMT induced by IL-6 in breast cancer cells.

Invasive lobular carcinoma exhibits unique morphological features frequently associated with alterations in CDH1 . Although some studies have identified abnormalities in adhesion factors other than E-cadherin, the molecular mechanisms underlying E-cadherin abnormalities in CDH1 -unaltered invasive lobular carcinoma remain poorly understood. In this study, we investigated the molecular underpinnings of E-cadherin dysregulation in invasive lobular carcinoma in the absence of CDH1 gene alterations, using comprehensive bioinformatic analyses. We conducted a comparative study of CDH1 -mutated and non-mutated invasive lobular carcinoma and evaluated the differences in mRNA levels, reverse-phase protein array, methylation, and miRNAs. We observed that invasive lobular carcinoma cases without CDH1 alterations exhibited a significantly higher incidence of the Claudin-low subtype ( p < 0.01). The results of the reverse-phase protein array indicate no significant difference in E-cadherin expression between CDH1 -mutated and non-mutated cases. Therefore, abnormalities in E-cadherin production also exist in CDH1 non-mutated invasive lobular carcinoma. Considering that there are no differences in mRNA levels and methylation status, post-translational modifications are the most plausible explanation for the same. Hence, future studies should focus on elucidating the mechanism underlying E-cadherin inactivation via post-translational modifications in CDH1 non-mutated invasive lobular carcinoma.

The metastasis-associated protein (MTA) family plays a crucial role in the development of breast cancer, a common malignancy with a high incidence rate among women. However, the mechanism by which each member of the MTA family contributes to breast cancer progression is poorly understood. In this study, we aimed to investigate the roles of MTA1, MTA3, and tripartite motif-containing 21 (TRIM21) in the proliferation, invasion, epithelial-mesenchymal transition (EMT), and stem cell-like properties of breast cancer cells in vivo and in vitro. The molecular mechanisms of the feedback loop between MTA1 and MTA3/TRIM21 regulated by estrogen were explored using Chromatin immunoprecipitation (ChIP), luciferase reporter, immunoprecipitation (IP), and ubiquitination assays. These findings demonstrated that MTA1 acts as a driver to promote the progression of breast cancer by repressing the transcription of tumor suppressor genes, including TRIM21 and MTA3. Conversely, MTA3 inhibited MTA1 transcription and TRIM21 regulated MTA1 protein stability in breast cancer. Estrogen disrupted the balance between MTA1 and MTA3, as well as between MTA1 and TRIM21, thereby affecting stemness and the EMT processes in breast cancer. These findings suggest that MTA1 plays a vital role in stem cell fate and the hierarchical regulatory network of EMT through negative feedback loops with MTA3 or TRIM21 in response to estrogen, supporting MTA1, MTA3, and TRIM21 as potential prognostic biomarkers and MTA1 as a treatment target for future breast cancer therapies., (© 2024. The Author(s).)

Aim : To synthesize new hybrid cinnamic acids ( 10a , 10b and 11 ) and ester derivatives ( 7 , 8 and 9 ) and investigate their anti-breast cancer activities. Materials & methods: Compounds 7-11 were evaluated ( in vitro ) for their cytotoxic activities against the MCF-7 cell line. A flow cytometry examination was performed. Protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2), topoisomerase II and caspase-9 were measured by qRT-PCR. Molecular docking studies were conducted. Results : Several components were discovered to be active, mainly component 11 , which induced arrest in the cell cycle at phase S, greatly decreased the expression of Nrf2 and topoisomerase II; and upregulated the expression of caspase-9. Conclusion: The newly thiohydantoin-cinnamic acid hybrids can contribute to creating promising candidates for cancer drugs.

Iron is an essential element for human health. In humans, dysregulated iron homeostasis can result in a variety of disorders and the development of cancers. Enhanced uptake, redistribution, and retention of iron in cancer cells have been suggested as an "iron addiction" pattern in cancer cells. This increased iron in cancer cells positively correlates with rapid tumor growth and the epithelial-to-mesenchymal transition, which forms the basis for tumor metastasis. However, the source of iron and the mechanisms cancer cells adopt to actively acquire iron is not well understood. In the present study, we report, for the first time, that the peptide hormone, prolactin, exhibits a novel function in regulating iron distribution, on top of its well-known pro-lactating role. When stimulated by prolactin, breast cancer cells increase CD44, a surface receptor mediating the endocytosis of hyaluronate-bound iron, resulting in the accumulation of iron in cancer cells. In contrast, macrophages, when treated by prolactin, express more ferroportin, the only iron exporter in cells, giving rise to net iron output. Interestingly, when co-culturing macrophages with pre-stained labile iron pools and cancer cells without any iron staining, in an iron free condition, we demonstrate direct iron flow from macrophages to cancer cells. As macrophages are one of the major iron-storage cells and it is known that macrophages infiltrate tumors and facilitate their progression, our work therefore presents a novel regulatory role of prolactin to drive iron flow, which provides new information on fine-tuning immune responses in tumor microenvironment and could potentially benefit the development of novel therapeutics.

Chronic stress-induced epinephrine (EPI) accelerates breast cancer progression and metastasis, but the molecular mechanisms remain unclear. Herein, we found a strong positive correlation between circulating EPI levels and the tumoral expression of ubiquitin-specific peptidase 22 (USP22) in patients with breast cancer. USP22 facilitated EPI-induced breast cancer progression and metastasis by enhancing adipose triglyceride lipase (ATGL)-mediated lipolysis. Targeted USP22 deletion decreased ATGL expression and lipolysis, subsequently inhibiting EPI-mediated breast cancer lung metastasis. USP22 acts as a bona fide deubiquitinase for the Atgl gene transcription factor FOXO1, and EPI architects a lipolysis signaling pathway to stabilize USP22 through AKT-mediated phosphorylation. Notably, USP22 phosphorylation levels are positively associated with EPI and with downstream pathways involving both FOXO1 and ATGL in breast cancers. Pharmacological USP22 inhibition synergized with β-blockers in treating preclinical xenograft breast cancer models. This study reveals a molecular pathway behind EPI's tumor-promoting effects and provides a strong rationale for combining USP22 inhibition with β-blockers to treat aggressive breast cancer.

IL-32 expression is important for pathogen clearance but detrimental in chronic inflammation, autoimmunity, and cancer. T cells are major IL-32 producers in these diseases and key mediators of pathogen and tumor elimination but also autoimmune destruction. However, their contribution to IL-32 biology during immune responses is hardly understood due to several isoforms with divergent inflammatory properties. Here, we identified IL-32β as the predominant isoform in various T cell subsets of healthy individuals and breast cancer patients with the highest levels detected in intratumoral regulatory T cells. We show that IL-32β is induced by IL-2 but IL-32β release requires T Cell Receptor rather than IL2R stimulation. Using inhibitors of protein secretion pathways and serial (ultra)centrifugation of T cell supernatants, we demonstrate that T cells actively secrete IL-32β unconventionally, as a free protein and, to a minor degree, through exosomes. Thus, our data identify activated T cells as major IL-32β secretors in health and cancer., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Sanna, Benešová, Pervan, Krenz, Wurzel, Lohmayer, Mühlbauer, Wöllner, Köhl, Menevse, Stamova, Volpin, Beckhove and Xydia.)

Distant metastasis is the major cause of death in patients with breast cancer. Epithelial-mesenchymal transition (EMT) contributes to breast cancer metastasis. Regulator of G protein-signaling (RGS) proteins modulates metastasis in various cancers. This study identified a novel role for RGS10 in EMT and metastasis in breast cancer. RGS10 protein levels were significantly lower in breast cancer tissues compared to normal breast tissues, and deficiency in RGS10 protein predicted a worse prognosis in patients with breast cancer. RGS10 protein levels were lower in the highly aggressive cell line MDA-MB-231 than in the poorly aggressive, less invasive cell lines MCF7 and SKBR3. Silencing RGS10 in SKBR3 cells enhanced EMT and caused SKBR3 cell migration and invasion. The ability of RGS10 to suppress EMT and metastasis in breast cancer was dependent on lipocalin-2 and MIR539-5p . These findings identify RGS10 as a tumor suppressor, prognostic biomarker, and potential therapeutic target for breast cancer., Competing Interests: YL, YJ, PQ, TM, YB, JB, YH, MJ, TZ, XG No competing interests declared, (© 2024, Liu, Jiang, Qiu et al.)

Breast cancer is a common malignant tumor in women. Ferroptosis, a programmed cell death pathway, is closely associated with breast cancer and its resistance. The transferrin receptor (TFRC) is a key factor in ferroptosis, playing a crucial role in intracellular iron accumulation and the occurrence of ferroptosis. This study investigates the influence and significance of TFRC and its upstream transcription factor hypoxia-inducible factor-1α (HIF1α) on the efficacy of neoadjuvant therapy in breast cancer. The differential gene obtained from clinical samples through genetic sequencing is TFRC. Bioinformatics analysis revealed that TFRC expression in breast cancer was significantly greater in breast cancer tissues than in normal tissues, but significantly downregulated in Adriamycin (ADR)-resistant tissues. Iron-responsive element-binding protein 2 (IREB2) interacts with TFRC and participates in ferroptosis. HIF1α, an upstream transcription factor, positively regulates TFRC. Experimental results indicated higher levels of ferroptosis markers in breast cancer tissue than in normal tissue. In the TAC neoadjuvant regimen-sensitive group, iron ion (Fe 2+ ) and malondialdehyde (MDA) levels were greater than those in the resistant group (all p < .05). Expression levels of TFRC, IREB2, FTH1, and HIF1α were higher in breast cancer tissue compared to normal tissue. Additionally, the expression of the TFRC protein in the TAC neoadjuvant regimen-sensitive group was significantly higher than that in the resistant group (all p < .05), while the difference in the level of expression of IREB2 and FTH1 between the sensitive and resistant groups was not significant (p > .05). The dual-luciferase assay revealed that HIF1α acts as an upstream transcription factor of TFRC (p < .05). Overexpression of HIF1α in ADR-resistant breast cancer cells increased TFRC, Fe 2+ , and MDA content. After ADR treatment, the cell survival rate decreased significantly, and ferroptosis could be reversed by the combined application of Fer-1 (all p < .05). In conclusion, ferroptosis and chemotherapy resistance are correlated in breast cancer. TFRC is a key regulatory factor influenced by HIF1α and is associated with chemotherapy resistance. Upregulating HIF1α in resistant cells may reverse resistance by activating ferroptosis through TFRC overexpression., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Background: Protein misfolding and aggregation can lead to various diseases. Recent studies have shed light on the aggregated protein in breast cancer pathology, which suggests that it is crucial to design chemical sensors that visualize protein aggregates in breast cancer, especially in clinical patient-derived samples. However, most reported sensors are constrained in cultured cell lines., Results: In this work, we present the development of two isophorone-based crystallization-induced-emission fluorophores for detecting proteome aggregation in breast cancer cell line and tissues biopsied from diseased patients, designated as A1 and A2. These probes exhibited viscosity sensitivity and recovered their fluorescence strongly at crystalline state. Moreover, A1 and A2 exhibit selective binding capacity and strong fluorescence for various aggregated proteins. Utilizing these probes, we detect protein aggregation in stressed breast cancer cells, xenograft mouse model of human breast cancer and clinical patient-derived samples. Notably, the fluorescence intensity of both probes light up in tumor tissues., Significance: The synthesized isophorone-based crystallization-induced-emission fluorophores, A1 and A2, enable sensitive detection of protein aggregation in breast cancer cells and tissues. In the future, aggregated proteins are expected to become indicators for early diagnosis and clinical disease monitoring of breast cancer., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Stromal-epithelial communication is an absolute necessity when it comes to the morphogenesis and pathogenesis of solid tissues, including the prostate and breast. So far, signalling pathways of several growth factors have been investigated. Besides such chemical factors, non-coding RNAs such as miRNAs have recently gained much interest because of their variety and complexity of action. Prostate and breast tissues being highly responsive to steroid hormones such as androgen and estrogen, respectively, it is not surprising that a huge set of available literature critically investigated the interplay between such hormones and miRNAs, especially in carcinogenesis. This review showcases our effort to highlight hormonally-related miRNAs that also somehow perturb the regular stromal-epithelial interactions during carcinogenesis in the prostate and breast. In future, we look forward to exploring how hormonal changes in the tissue microenvironment bring about miRNA-mediated changes in stromal-epithelial interactome in carcinogenesis and cancer progression., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Breast cancer (BC) is the most frequently diagnosed cancer and a leading cause of cancer-related mortality among women globally. Resistin, omentin and ghrelin, adipokines involved in inflammation and metabolic regulation, have been implicated in cancer development, yet their associations with BC remain unclear. This systematic review and meta-analysis aimed to elucidate the relationships between resistin, omentin, and ghrelin concentrations and BC, while exploring potential moderators such as body mass index (BMI) and menopausal status. A comprehensive search of electronic databases up to 13 May 2024 identified studies comparing resistin and omentin, but not ghrelin, concentrations in BC patients and healthy controls. Standardized mean differences (SMDs) were calculated using random-effects models, and meta-regression and subgroup analyses were performed to investigate sources of heterogeneity. Analysis of 11 studies showed that BC patients exhibited significantly higher resistin concentrations compared to controls, with a pooled SMD of 2.05 (95 % CI 1.24 to 2.86, p < 0.001). Meta-regression indicated that BMI significantly moderated the resistin-BC association (p = 0.003). In contrast, omentin concentrations presented a complex picture, with a pooled SMD of -0.27 (95 % CI -1.39 to 0.84, I^ 2  = 96.2 %, p < 0.001), indicating substantial heterogeneity and inconclusive results, whereas only one study investigated ghrelin. Our findings support a significant association between elevated resistin concentrations and BC, suggesting a potential role of resistin in BC pathophysiology. The data on omentin and ghrelin remain inconclusive, warranting further investigation. Future research should focus on large, longitudinal studies with standardized methodologies to validate these findings and clarify the role of adipokines in BC., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: Estrogen receptor (ER) alpha signaling is a known driver of ER-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer. Combining endocrine therapy (ET) such as fulvestrant with CDK4/6, mTOR, or PI3K inhibitors has become a central strategy in the treatment of ER+ advanced breast cancer. However, suboptimal ER inhibition and resistance resulting from the ESR1 mutation dictates that new therapies are needed., Experimental Design: A medicinal chemistry campaign identified vepdegestrant (ARV-471), a selective, orally bioavailable, and potent small molecule PROteolysis-TArgeting Chimera (PROTAC) degrader of ER. We used biochemical and intracellular target engagement assays to demonstrate the mechanism of action of vepdegestrant, and ESR1 wild-type (WT) and mutant ER+ preclinical breast cancer models to demonstrate ER degradation-mediated tumor growth inhibition (TGI)., Results: Vepdegestrant induced ≥90% degradation of wild-type and mutant ER, inhibited ER-dependent breast cancer cell line proliferation in vitro, and achieved substantial TGI (87%-123%) in MCF7 orthotopic xenograft models, better than those of the ET agent fulvestrant (31%-80% TGI). In the hormone independent (HI) mutant ER Y537S patient-derived xenograft (PDX) breast cancer model ST941/HI, vepdegestrant achieved tumor regression and was similarly efficacious in the ST941/HI/PBR palbociclib-resistant model (102% TGI). Vepdegestrant-induced robust tumor regressions in combination with each of the CDK4/6 inhibitors palbociclib, abemaciclib, and ribociclib; the mTOR inhibitor everolimus; and the PI3K inhibitors alpelisib and inavolisib., Conclusions: Vepdegestrant achieved greater ER degradation in vivo compared with fulvestrant, which correlated with improved TGI, suggesting vepdegestrant could be a more effective backbone ET for patients with ER+/HER2- breast cancer., (©2024 The Authors; Published by the American Association for Cancer Research.)

Receptor tyrosine kinases (RTKs) are cell surface receptors with kinase activity that play a crucial role in diverse cellular processes. Among the RTK family members, Human epidermal growth factor receptor 2 (HER2) and HER3 are particularly relevant to breast cancer. The review delves into the complexities of receptor tyrosine kinase interactions, resistance mechanisms, and the potential of anti-HER3 drugs, offering valuable insights into the clinical implications and future directions in this field of study. It assesses the potential of anti-HER3 drugs, such as pertuzumab, in overcoming resistance observed in HER2-positive breast cancer therapies. The review also explores the resistance mechanisms associated with various drugs, including trastuzumab, lapatinib, and PI3K inhibitors, providing insights into the intricate molecular processes underlying resistance development. The review concludes by emphasizing the necessity for further clinical trials to assess the efficacy of HER3 inhibitors and the potential of developing safe and effective anti-HER3 treatments to improve treatment outcomes for patients with HER2-positive breast cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Drugs that perturb microtubules are commonly used to treat breast cancers of all subtypes in both early stage and metastatic disease, but they are effective in only approximately 50% of patients. High concentrations of microtubule-targeting agents can elicit mitotic arrest in cell culture models; however, recent evidence from primary and metastatic breast cancers has revealed that these agents only accumulate at intratumoral levels capable of inducing abnormal multipolar mitotic spindles, not mitotic arrest. Although the maintenance of multipolar spindles can generate cytotoxic rates of chromosomal instability (CIN), focusing of aberrant multipolar spindles into normal bipolar spindles can dramatically reduce CIN and confer resistance to microtubule poisons. Here, we showed that inhibition of the mitotic kinesin centromeric-associated protein-E (CENP-E) overcomes resistance caused by focusing multipolar spindles. Clinically relevant microtubule-targeting agents used a mechanistically conserved pathway to induce multipolar spindles without requiring centrosome amplification. Focusing could occur at any point in mitosis, with earlier focusing conferring greater resistance to antimicrotubule agents. CENP-E inhibition increased CIN on focused spindles by generating chromosomes that remained misaligned at spindle poles during anaphase, which substantially increased death in the resulting daughter cells. CENP-E inhibition synergized with diverse, clinically relevant microtubule poisons to potentiate cell death in cell lines and suppress tumor growth in orthotopic tumor models. These results suggest that primary resistance to microtubule-targeting drugs can be overcome by simultaneous inhibition of CENP-E. Significance: The increased incidence of polar chromosomes induced by inhibition of the mitotic kinesin CENP-E exacerbates chromosomal instability, reduces daughter cell viability, and improves sensitivity to microtubule-targeting therapies., (©2024 American Association for Cancer Research.)

Scutebarbatine B (SBT-B) is a neo-clerodane diterpenic compound isolated from Scutellaria barbata D. Don (S. barbata), which has been reported to exhibit inhibitory P-glycoprotein (P-gp) property in MCF-7/ADR cells. However, its metabolism and molecular mechanism of reversal multidrug resistance (MDR) in breast cancer remains unclear. This study investigated the metabolite profile of SBT-B in rats by UHPLC-Q-Orbitrap-MS/MS, and explored its mechanism of reversal MDR through network pharmacology and molecular docking studies. A total of 16 Phase I metabolites and 2 Phase II metabolites were identified, and 18 metabolites were all newly discovered metabolites as novel compounds. The metabolic pathway of SBT-B mainly includes oxidization, reduction, hydrolysis, acetylation and glycination. Meanwhile, network pharmacology analyses showed that SBT-B mainly regulated p27 phosphorylation during cell cycle progression, p53 signaling pathway, influence of Ras and Rho proteins on G1 to S Transition. Molecular docking studies revealed that SBT-B exhibits the potential to inhibit P-gp expression by selectively binding to GLN721 and ALA981 residue sites at the interface of P-gp. In addition, SBT-B exhibits moderate binding affinity with CDK2 and E2F1. This study illustrated the major metabolic pathways of SBT-B in vivo, clarified detailed information on SBT-B metabolites in rats, and uncovered the potential mechanism of SBT-B reversal MDR in breast cancer, providing new insights for the development of P-gp inhibitors., Competing Interests: Declaration of Competing Interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “Identification of Scutebarbatine B metabolites in rats using UHPLC-Q-Orbitrap-MS/MS and exploration of its mechanism of reversal multidrug resistance in breast cancer by network pharmacology and molecular docking studies”, (Copyright © 2024 Elsevier B.V. All rights reserved.)

Breast cancer is the most common cancer diagnosed in women worldwide. Early-stage breast cancer is curable in ~70-80% of patients, while advanced metastatic breast cancer is considered incurable with current therapies. Breast cancer is a highly heterogeneous disease categorized into three main subtypes based on key markers orientating specific treatment strategies for each subtype. The complexity of breast carcinogenesis is often associated with epigenetic modification regulating different signaling pathways, involved in breast tumor initiation and progression, particularly by the methylation of arginine residues. Protein arginine methyltransferases (PRMT1-9) have emerged, through their ability to methylate histones and non-histone substrates, as essential regulators of cancers. Here, we present an updated overview of the mechanisms by which PRMT1 and PRMT5, two major members of the PRMT family, control important signaling pathways impacting breast tumorigenesis, highlighting them as putative therapeutic targets.

The dense extracellular matrix (ECM) in the tumor microenvironment forms an abnormal physical barrier, which impedes the delivery and penetration of nanomedicines and hinders their therapeutic efficacy. Herein, we synthesize matrix-degrading soft-nanocapsules composed of human serum albumin (HSA) and hyaluronidase (HAase) for overcoming the obstruction of ECM in the tumor microenvironment. The matrix-degrading human serum albumin/hyaluronidase soft-nanocapsules, referred to as HSA/HAase SNCs, possess a uniform diameter, inward hollow structure, and wrinkled morphology. In vitro biocompatibility results indicate that the HSA/HAase SNCs display no adverse effects on the viability of human umbilical vein endothelial cells (HUVECs), smooth muscle cells (SMCs), and mouse breast cancer (4T1) cells and do not induce hemolysis towards red blood cells (RBCs). The HSA/HAase SNCs exhibit a 1.4-fold increase in tumor cellular uptake compared to the stiff-counterparts and enhanced penetration in 4T1-, mouse colon carcinoma 26- (CT26-), and mouse pancreatic cancer- (PanO 2 -) multicellular spheroids. Thanks to the advanced biological properties, a photodynamic platform prepared by loading Ce6 in the HSA/HAase SNCs (HSA/HAase@Ce6) shows improved reactive oxygen species production, a stronger killing effect for cancer cells, and deeper penetration in tumor tissues. In vivo experiments show that HSA/HAase@Ce6 effectively inhibits tumor growth in breast cancer mouse models. RNA-seq analysis of the mice that received the treatment of HSA/HAase@Ce6 shows enrichment of signaling pathways associated with ECM-degradation, which demonstrates that the matrix-degrading nanocapsules overcome the ECM-induced physical barriers in tumors. Overall, the matrix-degrading soft-nanoplatform represents a highly promising strategy to overcome ECM-induced physical barriers and enhance the therapeutic efficacy of nanomedicines.

Background: A better understanding of ductal carcinoma in situ (DCIS) is urgently needed to identify these preinvasive lesions as distinct clinical entities. Semaphorin 3F (SEMA3F) is a soluble axonal guidance molecule, and its coreceptors Neuropilin 1 (NRP1) and NRP2 are strongly expressed in invasive epithelial BC cells., Methods: We utilized two cell line models to represent the progression from a healthy state to the mild-aggressive or ductal carcinoma in situ (DCIS) stage and, ultimately, to invasive cell lines. Additionally, we employed in vivo models and conducted analyses on patient databases to ensure the translational relevance of our results., Results: We revealed SEMA3F as a promoter of invasion during the DCIS-to-invasive ductal carcinoma transition in breast cancer (BC) through the action of NRP1 and NRP2. In epithelial cells, SEMA3F activates epithelialmesenchymal transition, whereas it promotes extracellular matrix degradation and basal membrane and myoepithelial cell layer breakdown., Conclusions: Together with our patient database data, these proof-of-concept results reveal new SEMA3F-mediated mechanisms occurring in the most common preinvasive BC lesion, DCIS, and represent potent and direct activation of its transition to invasion. Moreover, and of clinical and therapeutic relevance, the effects of SEMA3F can be blocked directly through its coreceptors, thus preventing invasion and keeping DCIS lesions in the preinvasive state., (© 2024. The Author(s).)