Sprouty genes regulate activated fibroblasts in mammary epithelial development and breast cancer.

Stromal fibroblasts are a major stem cell niche component essential for organ formation and cancer development. Fibroblast heterogeneity, as revealed by recent advances in single-cell techniques, has raised important questions about the origin, differentiation, and function of fibroblast subtypes. In this study, we show in mammary stromal fibroblasts that loss of the receptor tyrosine kinase (RTK) negative feedback regulators encoded by Spry1, Spry2, and Spry4 causes upregulation of signaling in multiple RTK pathways and increased extracellular matrix remodeling, resulting in accelerated epithelial branching. Single-cell transcriptomic analysis demonstrated that increased production of FGF10 due to Sprouty (Spry) loss results from expansion of a functionally distinct subgroup of fibroblasts with the most potent branching-promoting ability. Compared to their three independent lineage precursors, fibroblasts in this subgroup are "activated," as they are located immediately adjacent to the epithelium that is actively undergoing branching and invasion. Spry genes are downregulated, and activated fibroblasts are expanded, in all three of the major human breast cancer subtypes. Together, our data highlight the regulation of a functional subtype of mammary fibroblasts by Spry genes and their essential role in epithelial morphogenesis and cancer development.

Peptide Inhibitor Targeting the Extraterminal Domain in BRD4 Potently Suppresses Breast Cancer Both In Vitro and In Vivo.

BRD4 is associated with a variety of human diseases, including breast cancer. The crucial roles of amino-terminal bromodomains (BDs) of BRD4 in binding with acetylated histones to regulate oncogene expression make them promising drug targets. However, adverse events impede the development of the BD inhibitors. BRD4 adopts an extraterminal (ET) domain, which recruits proteins to drive oncogene expression. We discovered a peptide inhibitor PiET targeting the ET domain to disrupt BRD4/JMJD6 interaction, a protein complex critical in oncogene expression and breast cancer. The cell-permeable form of PiET, TAT-PiET, and PROTAC-modified TAT-PiET, TAT-PiET-PROTAC, potently inhibits the expression of BRD4/JMJD6 target genes and breast cancer cell growth. Combination therapy with TAT-PiET/TAT-PiET-PROTAC and JQ1, iJMJD6, or Fulvestrant exhibits synergistic effects. TAT-PiET or TAT-PiET-PROTAC treatment overcomes endocrine therapy resistance in ERα-positive breast cancer cells. Taken together, we demonstrated that targeting the ET domain is effective in suppressing breast cancer, providing a therapeutic avenue in the clinic.

Crocin enhances the sensitivity to paclitaxel in human breast cancer cells by reducing BIRC5 expression.

Paclitaxel (PTX) is one of the first-line chemotherapeutic agents for treating breast cancer. However, PTX resistance remains a major hurdle in breast cancer therapy. Crocin, the main chemical constituent of saffron, shows anti-cancer activity against various types of cancer. However, the effect of crocin on the resistance of PTX in breast cancer is still unknown. CCK-8 and TUNEL assays were employed to detect cell viability and apoptosis, respectively. The targets of crocin were predicted using HERB database and the targets associated with breast cancer were acquired using GEPIA database. The Venn diagram was utilized to identify the common targets between crocin and breast cancer. Baculoviral inhibitor of apoptosis repeat containing 5 (BIRC5) expression was detected by qRT-PCR and western blot analysis. The correlation between BIRC5 expression and survival was analyzed by Kaplan-Meier plotter and PrognoScan databases. Our data suggested that crocin aggravated PTX-induced decrease of viability and increase of apoptosis in MCF-7 and MCF-7/PTX cells. BIRC5 was identified as the target of crocin against breast cancer. Crocin inhibited BIRC5 expression in MCF-7 and MCF-7/PTX cells. BIRC5 is overexpressed in breast cancer tissues, as well as PTX-sensitive and PTX-resistant breast cancer cells. BIRC5 expression is related to the poor survival of patients with breast cancer. Depletion of BIRC5 strengthened PTX-induced viability reduction and promotion of apoptosis in MCF-7 and MCF-7/PTX cells. Moreover, BIRC5 overexpression reversed the inhibitory effect of crocin on PTX resistance in breast cancer cells. In conclusion, crocin enhanced the sensitivity of PTX in breast cancer cells partially through inhibiting BIRC5 expression.

[Chinese expert consensus on the management of clinical pathway and adverse events of trastuzumab deruxtecan (2024 edition)].

Trastuzumab deruxtecan (T-DXd) is one of the new generation antibody-drug conjugates (ADCs) targeting human epidermal growth factor receptor 2 (HER-2) with bystander effect. T-DXd can not only significantly improve the survival of HER-2-positive advanced breast cancer patients, but also enable advanced breast cancer patients with low HER-2 expression to benefit from HER-2-targeted therapy. T-DXd has been approved by the National Medical Products Administration (NMPA) for the treatment of HER-2-positive or HER-2-low breast cancer patients. It is foreseeable that T-DXd will be widely used in clinical practice in the future. However, T-DXd has also shown different safety characteristics compared to previous HER-2 targeted drugs in clinical trials. How to manage T-DXd adverse events more reasonably and fully utilize the efficacy of T-DXd is an urgent clinical problem. Based on the existing clinical evidence and guideline consensus, combined with clinical practice experience, the expert group finally reached the consensus of clinical care pathway and adverse reaction management of trastuzumab deruxtecan after many discussions. This consensus content includes the clinical use method of T-DXd, pre-treatment patient education, and management of common or noteworthy adverse events of T-DXd. The adverse events include infusion related adverse events, digestive system adverse events (nausea/vomiting, constipation, diarrhea, and decreased appetite), hematological adverse events (neutropenia, febrile neutropenia, anemia, thrombocytopenia), respiratory adverse events (interstitial lung disease/pneumonia), cardiovascular adverse events (decreased left ventricular ejection fraction), adverse events in liver function (elevated transaminases) and other common adverse events (alopecia, fatigue, etc). This consensus focuses on the prevention of adverse events, dose adjustment and treatment when adverse events occur, and recommendations for patients' lifestyle, aiming to improve clinicians' understanding of T-DXd and provide practical guidance for clinical oncologists on T-DXd clinical management.

Factors affecting heterogeneity in breast cancer microenvironment: A narrative mini review.

Breast cancer (BC) heterogeneity is a key trait of BC tumors with crucial implications on tumorigenesis, diagnosis, and therapeutic modalities. It is influenced by tumor intrinsic features and by the tumor microenvironment (TME) composition of different intra-tumoral regions, which in turn affect cancer progression within patients. In this mini review, we will highlight the mechanisms that generate cancer heterogeneity in BC and how they affect the responses to cancer therapies.

siRNA treatment targeting integrin α11 overexpressed via EZH2-driven axis inhibits drug-resistant breast cancer progression.

BACKGROUND: Breast cancer, the most prevalent cancer in women worldwide, faces treatment challenges due to drug resistance, posing a serious threat to patient survival. The present study aimed to identify the key molecules that drive drug resistance and aggressiveness in breast cancer cells and validate them as therapeutic targets. METHODS: Transcriptome microarray and analysis using PANTHER pathway and StemChecker were performed to identify the most significantly expressed genes in tamoxifen-resistant and adriamycin-resistant MCF-7 breast cancer cells. Clinical relevance of the key genes was determined using Kaplan-Meier survival analyses on The Cancer Genome Atlas dataset of breast cancer patients. Gene overexpression/knockdown, spheroid formation, flow cytometric analysis, chromatin immunoprecipitation, immunocytochemistry, wound healing/transwell migration assays, and cancer stem cell transcription factor activation profiling array were used to elucidate the regulatory mechanism of integrin α11 expression. Tumour-bearing xenograft models were used to demonstrate integrin α11 is a potential therapeutic target. RESULTS: Integrin α11 was consistently upregulated in drug-resistant breast cancer cells, and its silencing inhibited cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) while restoring sensitivity to anticancer drugs. HIF1α, GLI-1, and EZH2 contributed the most to the regulation of integrin α11 and EZH2 expression, with EZH2 being more necessary for EZH2 autoinduction than HIF1α and GLI-1. Additionally, unlike HIF1α or EZH2, GLI-1 was the sole transcription factor activated by integrin-linked focal adhesion kinase, indicating GLI-1 as a key driver of the EZH2-integrin α11 axis operating for cancer stem cell survival and EMT. Kaplan-Meier survival analysis using The Cancer Genome Atlas (TCGA) dataset also revealed both EZH2 and integrin α11 could be strong prognostic factors of relapse-free and overall survival in breast cancer patients. However, the superior efficacy of integrin α11 siRNA therapy over EZH2 siRNA treatment was demonstrated by enhanced inhibition of tumour growth and prolonged survival in murine models bearing tumours. CONCLUSION: Our findings elucidate that integrin α11 is upregulated by EZH2, forming a positive feedback circuit involving FAK-GLI-1 and contributing to drug resistance, cancer stem cell survival and EMT. Taken together, the results suggest integrin α11 as a promising prognostic marker and a powerful therapeutic target for drug-resistant breast cancer.

Context-dependent roles for ubiquitous mitochondrial creatine kinase CKMT1 in breast cancer progression.

Metabolic reprogramming is a hallmark of cancer, enabling cancer cells to rapidly proliferate, invade, and metastasize. We show that creatine levels in metastatic breast cancer cell lines and secondary metastatic tumors are driven by the ubiquitous mitochondrial creatine kinase (CKMT1). We discover that, while CKMT1 is highly expressed in primary tumors and promotes cell viability, it is downregulated in metastasis. We further show that CKMT1 downregulation, as seen in breast cancer metastasis, drives up mitochondrial reactive oxygen species (ROS) levels. CKMT1 downregulation contributes to the migratory and invasive potential of cells by ROS-induced upregulation of adhesion and degradative factors, which can be reversed by antioxidant treatment. Our study thus reconciles conflicting evidence about the roles of metabolites in the creatine metabolic pathway in breast cancer progression and reveals that tight, context-dependent regulation of CKMT1 expression facilitates cell viability, cell migration, and cell invasion, which are hallmarks of metastatic spread.

RAD52-dependent mitotic DNA synthesis is required for genome stability in Cyclin E1-overexpressing cells.

Overexpression of Cyclin E1 perturbs DNA replication, resulting in DNA lesions and genomic instability. Consequently, Cyclin E1-overexpressing cancer cells increasingly rely on DNA repair, including RAD52-mediated break-induced replication during interphase. We show that not all DNA lesions induced by Cyclin E1 overexpression are resolved during interphase. While DNA lesions upon Cyclin E1 overexpression are induced in S phase, a significant fraction of these lesions is transmitted into mitosis. Cyclin E1 overexpression triggers mitotic DNA synthesis (MiDAS) in a RAD52-dependent fashion. Chemical or genetic inactivation of MiDAS enhances mitotic aberrations and persistent DNA damage. Mitosis-specific degradation of RAD52 prevents Cyclin E1-induced MiDAS and reduces the viability of Cyclin E1-overexpressing cells, underscoring the relevance of RAD52 during mitosis to maintain genomic integrity. Finally, analysis of breast cancer samples reveals a positive correlation between Cyclin E1 amplification and RAD52 expression. These findings demonstrate the importance of suppressing mitotic defects in Cyclin E1-overexpressing cells through RAD52.

Characterizing heterogeneous single-cell dose responses computationally and experimentally using threshold inhibition surfaces and dose-titration assays.

Single cancer cells within a tumor exhibit variable levels of resistance to drugs, ultimately leading to treatment failures. While tumor heterogeneity is recognized as a major obstacle to cancer therapy, standard dose-response measurements for the potency of targeted kinase inhibitors aggregate populations of cells, obscuring intercellular variations in responses. In this work, we develop an analytical and experimental framework to quantify and model dose responses of individual cancer cells to drugs. We first explore the connection between population and single-cell dose responses using a computational model, revealing that multiple heterogeneous populations can yield nearly identical population dose responses. We demonstrate that a single-cell analysis method, which we term a threshold inhibition surface, can differentiate among these populations. To demonstrate the applicability of this method, we develop a dose-titration assay to measure dose responses in single cells. We apply this assay to breast cancer cells responding to phosphatidylinositol-3-kinase inhibition (PI3Ki), using clinically relevant PI3Kis on breast cancer cell lines expressing fluorescent biosensors for kinase activity. We demonstrate that MCF-7 breast cancer cells exhibit heterogeneous dose responses with some cells requiring over ten-fold higher concentrations than the population average to achieve inhibition. Our work reimagines dose-response relationships for cancer drugs in an emerging paradigm of single-cell tumor heterogeneity.

AMD1 promotes breast cancer aggressiveness via a spermidine-eIF5A hypusination-TCF4 axis.

BACKGROUND: Basal-like breast cancer (BLBC) is the most aggressive subtype of breast cancer due to its aggressive characteristics and lack of effective therapeutics. However, the mechanism underlying its aggressiveness remains largely unclear. S-adenosylmethionine decarboxylase proenzyme (AMD1) overexpression occurs specifically in BLBC. Here, we explored the potential molecular mechanisms and functions of AMD1 promoting the aggressiveness of BLBC. METHODS: The potential effects of AMD1 on breast cancer cells were tested by western blotting, colony formation, cell proliferation assay, migration and invasion assay. The spermidine level was determined by high performance liquid chromatography. The methylation status of CpG sites within the AMD1 promoter was evaluated by bisulfite sequencing PCR. We elucidated the relationship between AMD1 and Sox10 by ChIP assays and quantitative real-time PCR. The effect of AMD1 expression on breast cancer cells was evaluated by in vitro and in vivo tumorigenesis model. RESULTS: In this study, we showed that AMD1 expression was remarkably elevated in BLBC. AMD1 copy number amplification, hypomethylation of AMD1 promoter and transcription activity of Sox10 contributed to the overexpression of AMD1 in BLBC. AMD1 overexpression enhanced spermidine production, which enhanced eIF5A hypusination, activating translation of TCF4 with multiple conserved Pro-Pro motifs. Our studies showed that AMD1-mediated metabolic system of polyamine in BLBC cells promoted tumor cell proliferation and tumor growth. Clinically, elevated expression of AMD1 was correlated with high grade, metastasis and poor survival, indicating poor prognosis of breast cancer patients. CONCLUSION: Our work reveals the critical association of AMD1-mediated spermidine-eIF5A hypusination-TCF4 axis with BLBC aggressiveness, indicating potential prognostic indicators and therapeutic targets for BLBC.

A high-cholesterol diet promotes the intravasation of breast tumor cells through an LDL-LDLR axis.

Most metastases in breast cancer occur via the dissemination of tumor cells through the bloodstream. How tumor cells enter the blood (intravasation) is, however, a poorly understood mechanism at the cellular and molecular levels. Particularly uncharacterized is how intravasation is affected by systemic nutrients. High levels of systemic LDL-cholesterol have been shown to contribute to breast cancer progression and metastasis in various models, but the cellular and molecular mechanisms involved are still undisclosed. Here we show that a high- cholesterol diet promotes intravasation in two mouse models of breast cancer and that this could be reverted by blocking LDL binding to LDLR in tumor cells. Moreover, we show that LDL promotes vascular invasion in vitro and the intercalation of tumor cells with endothelial cells, a phenotypic change resembling vascular mimicry (VM). At the molecular level, LDL increases the expression of SERPINE2, previously shown to be required for both VM and intravasation. Overall, our manuscript unravels novel mechanisms by which systemic hypercholesterolemia may affect the onset of metastatic breast cancer by favouring phenotypic changes in breast cancer cells and increasing intravasation.

Multimodal joint deconvolution and integrative signature selection in proteomics.

Deconvolution is an efficient approach for detecting cell-type-specific (cs) transcriptomic signals without cellular segmentation. However, this type of methods may require a reference profile from the same molecular source and tissue type. Here, we present a method to dissect bulk proteome by leveraging tissue-matched transcriptome and proteome without using a proteomics reference panel. Our method also selects the proteins contributing to the cellular heterogeneity shared between bulk transcriptome and proteome. The deconvoluted result enables downstream analyses such as cs-protein Quantitative Trait Loci (cspQTL) mapping. We benchmarked the performance of this multimodal deconvolution approach through CITE-seq pseudo bulk data, a simulation study, and the bulk multi-omics data from human brain normal tissues and breast cancer tumors, individually, showing robust and accurate cell abundance quantification across different datasets. This algorithm is implemented in a tool MICSQTL that also provides cspQTL and multi-omics integrative visualization, available at https://bioconductor.org/packages/MICSQTL .

H4K20me3, H3K4me2 and H3K9me2 mediate the effect of ER on prognosis in breast cancer.

Previous studies have indicated that histone methylations act as mediators in the relationship between oestrogen receptor (ER) and breast cancer prognosis, yet the mediating role has never been assessed. Therefore, we investigated seven histone methylations (H3K4me2, H3K4me3, H3K9me1, H3K9me2, H3K9me3, H3K27me3 and H4K20me3) to determine whether they mediate the prognostic impact of ER on breast cancer. Tissue microarrays were constructed from 1045 primary invasive breast tumours, and the expressions of histone methylations were examined by immunohistochemistry. Multifactorial logistic regression was used to analyse the associations between ER and histone methylations. Cox proportional hazard model was performed to assess the relationship between histone methylations and breast cancer prognosis. The mediation effects of histone methylations were evaluated by model-based causal mediation analysis. High expressions of H3K9me1, H3K9me2, H3K4me2, H3K27me3, H4K20me3 were associated with ER positivity, while high expression of H3K9me3 was associated ER negativity. Higher H3K9me2, H3K4me2 and H4K20me3 levels were associated with better prognosis. The association between ER and breast cancer prognosis was most strongly mediated by H4K20me3 (29.07% for OS; 22.42% for PFS), followed by H3K4me2 (11.5% for OS; 10.82% for PFS) and least by H3K9me2 (9.35% for OS; 7.34% for PFS). H4K20me3, H3K4me2 and H3K9me2 mediated the relationship between ER and breast cancer prognosis, which would help to further elucidate the impact of ER on breast cancer prognosis from an epigenetic perspective and provide new ideas for breast cancer treatment.

NSABP FB-10: a phase Ib/II trial evaluating ado-trastuzumab emtansine (T-DM1) with neratinib in women with metastatic HER2-positive breast cancer.

BACKGROUND: We previously reported our phase Ib trial, testing the safety, tolerability, and efficacy of T-DM1 + neratinib in HER2-positive metastatic breast cancer patients. Patients with ERBB2 amplification in ctDNA had deeper and more durable responses. This study extends these observations with in-depth analysis of molecular markers and mechanisms of resistance in additional patients. METHODS: Forty-nine HER2-positive patients (determined locally) who progressed on-treatment with trastuzumab + pertuzumab were enrolled in this phase Ib/II study. Mutations and HER2 amplifications were assessed in ctDNA before (C1D1) and on-treatment (C2D1) with the Guardant360 assay. Archived tissue (TP0) and study entry biopsies (TP1) were assayed for whole transcriptome, HER2 copy number, and mutations, with Ampli-Seq, and centrally for HER2 with CLIA assays. Patient responses were assessed with RECIST v1.1, and Molecular Response with the Guardant360 Response algorithm. RESULTS: The ORR in phase II was 7/22 (32%), which included all patients who had at least one dose of study therapy. In phase I, the ORR was 12/19 (63%), which included only patients who were considered evaluable, having received their first scan at 6 weeks. Central confirmation of HER2-positivity was found in 83% (30/36) of the TP0 samples. HER2-amplified ctDNA was found at C1D1 in 48% (20/42) of samples. Patients with ctHER2-amp versus non-amplified HER2 ctDNA determined in C1D1 ctDNA had a longer median progression-free survival (PFS): 480 days versus 60 days (P = 0.015). Molecular Response scores were significantly associated with both PFS (HR 0.28, 0.09-0.90, P = 0.033) and best response (P = 0.037). All five of the patients with ctHER2-amp at C1D1 who had undetectable ctDNA after study therapy had an objective response. Patients whose ctHER2-amp decreased on-treatment had better outcomes than patients whose ctHER2-amp remained unchanged. HER2 RNA levels show a correlation to HER2 CLIA IHC status and were significantly higher in patients with clinically documented responses compared to patients with progressive disease (P = 0.03). CONCLUSIONS: The following biomarkers were associated with better outcomes for patients treated with T-DM1 + neratinib: (1) ctHER2-amp (C1D1) or in TP1; (2) Molecular Response scores; (3) loss of detectable ctDNA; (4) RNA levels of HER2; and (5) on-treatment loss of detectable ctHER2-amp. HER2 transcriptional and IHC/FISH status identify HER2-low cases (IHC 1+ or IHC 2+ and FISH negative) in these heavily anti-HER2 treated patients. Due to the small number of patients and samples in this study, the associations we have shown are for hypothesis generation only and remain to be validated in future studies. Clinical Trials registration NCT02236000.

Decorin (DCN) Downregulation Activates Breast Stromal Fibroblasts and Promotes Their Pro-Carcinogenic Effects through the IL-6/STAT3/AUF1 Signaling.

Decorin (DCN), a member of the small leucine-rich proteoglycan gene family, is secreted from stromal fibroblasts with non-cell-autonomous anti-breast-cancer effects. Therefore, in the present study, we sought to elucidate the function of decorin in breast stromal fibroblasts (BSFs). We first showed DCN downregulation in active cancer-associated fibroblasts (CAFs) compared to their adjacent tumor counterpart fibroblasts at both the mRNA and protein levels. Interestingly, breast cancer cells and the recombinant IL-6 protein, both known to activate fibroblasts in vitro, downregulated DCN in BSFs. Moreover, specific DCN knockdown in breast fibroblasts modulated the expression/secretion of several CAF biomarkers and cancer-promoting proteins (α-SMA, FAP- α, SDF-1 and IL-6) and enhanced the invasion/proliferation abilities of these cells through activation of the STAT3/AUF1 signaling. Furthermore, DCN-deficient fibroblasts promoted the epithelial-to-mesenchymal transition and stemness processes in BC cells in a paracrine manner, which increased their resistance to cisplatin. These DCN-deficient fibroblasts also enhanced angiogenesis and orthotopic tumor growth in mice in a paracrine manner. On the other hand, ectopic expression of DCN in CAFs suppressed their active features and their paracrine pro-carcinogenic effects. Together, the present findings indicate that endogenous DCN suppresses the pro-carcinogenic and pro-metastatic effects of breast stromal fibroblasts.

ZMIZ1 enhances ERα-dependent expression of E2F2 in breast cancer.

The estrogen receptor-α (ER) drives 75% of breast cancers. On activation, the ER recruits and assembles a 1-2 MDa transcriptionally active complex. These complexes can modulate tumour growth, and understanding the roles of individual proteins within these complexes can help identify new therapeutic targets. Here, we present the discovery of ER and ZMIZ1 within the same multi-protein assembly by quantitative proteomics, and validated by proximity ligation assay. We characterise ZMIZ1 function by demonstrating a significant decrease in the proliferation of ER-positive cancer cell lines. To establish a role for the ER-ZMIZ1 interaction, we measured the transcriptional changes in the estrogen response post-ZMIZ1 knockdown using an RNA-seq time-course over 24 h. Gene set enrichment analysis of the ZMIZ1-knockdown data identified a specific delay in the response of estradiol-induced cell cycle genes. Integration of ENCODE data with our RNA-seq results identified that ER and ZMIZ1 both bind the promoter of E2F2. We therefore propose that ER and ZMIZ1 interact to enable the efficient estrogenic response at subset of cell cycle genes via a novel ZMIZ1-ER-E2F2 signalling axis. Finally, we show that high ZMIZ1 expression is predictive of worse patient outcome, ER and ZMIZ1 are co-expressed in breast cancer patients in TCGA and METABRIC, and the proteins are co-localised within the nuclei of tumour cell in patient biopsies. In conclusion, we establish that ZMIZ1 is a regulator of the estrogenic cell cycle response and provide evidence of the biological importance of the ER-ZMIZ1 interaction in ER-positive patient tumours, supporting potential clinical relevance.

Overexpression of WT1 in all molecular subtypes of breast cancer and its impact on survival: exploring oncogenic and tumor suppressor roles of distinct WT1 isoforms.

BACKGROUND: Breast cancer is a highly heterogeneous solid tumor, posing challenges in developing targeted therapies effective for all mammary carcinoma subtypes. WT1 emerges as a promising target for breast cancer therapy due to its potential oncogenic role in various cancer types. Previous works have yielded inconsistent results. Therefore, further studies are needed to clarify the behavior of this complex gene in breast cancer. METHODS AND RESULTS: In this study, we examined WT1 expression in both Formalin Fixed Paraffin Embedded breast tumors (n = 41) and healthy adjacent tissues (n = 41) samples from newly diagnosed cases of ductal invasive breast cancer. The fold change in gene expression between the tumor and healthy tissue was determined by calculating 2-∆∆Ct. Disease-free survival analysis was computed using the Kaplan-Meier method. To identify the expression levels of different WT1 isoforms, we explored the ISOexpresso database. Relative quantification of the WT1 gene revealed an overexpression of WT1 in most cases. The percentage of patients surviving free of disease at 8 years of follow-up was lower in the group overexpressing WT1 compared to the group with down-regulated WT1. CONCLUSIONS: Interestingly, this overexpression was observed in all molecular subtypes of invasive breast cancer, underscoring the significance of WT1 as a potential target in all these subtypes. The observed WT1 down-expression in a few cases of invasive breast cancer, associated with better survival outcomes, may correspond to the down-regulation of a particular WT1-KTS (-) isoform: the WT1 A isoform (EX5-/KTS-). The co-expression of this WT1 oncogenic isoform with a regulated WT1- tumor suppressor isoform, such as the major WT1 F isoform (EX5-/KTS +), could also explain such survival outcomes. Due to its capacity to adopt dual roles, it becomes imperative to conduct individual molecular expression profiling of the WT1 gene. Such an approach holds great promise in the development of personalized treatment strategies for breast cancer.

The endonuclease FEN1 mediates activation of STAT3 and facilitates proliferation and metastasis in breast cancer.

BACKGROUND: The metastasis accounts for most deaths from breast cancer (BRCA). Understanding the molecular mechanisms of BRCA metastasis is urgently demanded. Flap Endonuclease 1 (FEN1), a pivotal factor in DNA metabolic pathways, contributes to tumor growth and drug resistance, however, little is known about the role of FEN1 in BRCA metastasis. METHODS AND RESULTS: In this study, FEN1 expression and its clinical correlation in BRCA were investigated using bioinformatics, showing being upregulated in BRCA samples and significant relationships with tumor stage, node metastasis, and prognosis. Immunohistochemistry (IHC) staining of local BRCA cohort indicated that the ratio of high FEN1 expression in metastatic BRCA tissues rose over that in non-metastatic tissues. The assays of loss-of-function and gain-of-function showed that FEN1 enhanced BRCA cell proliferation, migration, invasion, xenograft growth as well as lung metastasis. It was further found that FEN1 promoted the aggressive behaviors of BRCA cells via Signal Transducer and Activator of Transcription 3 (STAT3) activation. Specifically, the STAT3 inhibitor Stattic thwarted the FEN1-induced enhancement of migration and invasion, while the activator IL-6 rescued the decreased migration and invasion caused by FEN1 knockdown. Additionally, overexpression of FEN1 rescued the inhibitory effect of nuclear factor-κB (NF-κB) inhibitor BAY117082 on phosphorylated STAT3. Simultaneously, the knockdown of FEN1 attenuated the phosphorylation of STAT3 promoted by the NF-κB activator tumor necrosis factor α (TNF-α). CONCLUSIONS: These results indicate a novel mechanism that NF-κB-driven FEN1 contributes to promoting BRCA growth and metastasis by STAT3 activation.

Breast cancer therapy: from the perspective of glucose metabolism and glycosylation.

Breast cancer is a leading cause of mortality and the most prevalent form of malignant tumor among women worldwide. Breast cancer cells exhibit an elevated glycolysis and altered glucose metabolism. Moreover, these cells display abnormal glycosylation patterns, influencing invasion, proliferation, metastasis, and drug resistance. Consequently, targeting glycolysis and mitigating abnormal glycosylation represent key therapeutic strategies for breast cancer. This review underscores the importance of protein glycosylation and glucose metabolism alterations in breast cancer. The current research efforts in developing effective interventions targeting glycolysis and glycosylation are further discussed.

Identification of miR-125a and miR-106b signature as a potential diagnostic biomarker in breast cancer tissues.

MicroRNAs (miRNAs) have essential roles in the etiology of breast cancer and are regarded as possible markers in this malignancy. In order to find new markers for breast cancer, the current study has measured expression level of four miRNAs, namely miR-125a, miR-106b, miR-96 and miR-92a-3p in the paired breast samples. Expression levels of miR-125a and miR-106b were higher in tumoral tissues compared with control tissues (Expression ratios (95% CI) = 4.01 (1.96-8.19) and 3.9 (1.95-7.81); P values = 0.0005 and 0.0003, respectively). miR-106b and miR-125a differentiated between malignant and non-malignant tissues with AUC values of 0.7 and 0.67, respectively. We detected association between expression of miR-106b and clinical stage (P = 0.03), in a way that its expression was the lowest in the advanced stages. Finally, significant relationships were found between miR-96 and miR-125a in both tumoral and non-tumoral specimens (ρ = 0.76 and 0.69, respectively). This nonparametric measure of rank correlation also showed relationship between miR-106b and miR-96 in both sets of samples (ρ = 0.63 and 0.61, respectively). Cumulatively, the assessed miRNAs, particularly miR-125a and miR-106b are putative targets for further expression and functional assays in breast cancer.