This retrospective study evaluated the applicability of radiomics analysis to mammographic images of patients with triple-negative breast cancer (TNBC) to identify features differentiating BRCA gene's mutational status. The mammographic images of 52 patients histologically diagnosed with TNBC, (13 BRCA-mutated patients and 39 BRCA wild-type ones), were included and 53 tumor lesions were manually segmented in the mammographic projection where they were better demarcable. An additional elliptical ROI of standard size was drawn in the most homogeneous area of the contralateral healthy gland, using the analogue mammographic projection of the same date or, if not available, of the corresponding bilateral mammographic investigation closer to the time of diagnosis. Lesions consisted of 36 masses, 2 pathological microcalcifications, and 15 masses with microcalcifications. Radiomic features were extracted using Pyradiomics-3D. Preliminary analysis confirmed feasibility and showed differences in texture features, particularly GLCM SumEntropy, between BRCA-mutated and non-mutated patients. Moreover, the study enhanced the role of healthy glandular tissue in distinguishing the two groups, supporting and reinforcing previous MRI-based radiomics findings in the same population. The study concludes that radiomics analysis of diagnostic mammograms in TNBC patients is feasible and may help build predictive models to discriminate between BRCA mutated and non-mutated patients.

Early-onset breast cancer (EOBC) is disproportionately common in Saudi Arabia, where women present nearly a decade earlier than in Western countries, suggesting unique inherited susceptibility. While BRCA1/2 explain part of the hereditary risk, the contribution of rare coding variants in Arab EOBC remains unclear. Whole-exome sequencing was performed on germline DNA from 102 unrelated Saudi EOBC patients and 1395 cancer-free controls recruited from the same national Saudi cohort. Rare variants were defined by stringent frequency and quality thresholds and classified as rare loss-of-function (RLOF) or rare predicted damaging variants (RPDVs). Gene-level case–control analyses were conducted using burden tests, with exome-wide significance set at p < 2.5 × 10−6. RLOF variants in BRCA1 (6.9% of EOBC vs. 0.14% of controls; OR = 51.3; p < 1.0 × 10−10) and RPDVs in TP53 (4.9% vs. 0.36%; OR = 14.3; p = 5.39 × 10−8) demonstrated strong associations. Sequence Kernel Association Test (SKAT) analysis identified NOTCH4 and OR12D3 and reinforced burden-based significance in GUCY2F, FRMPD3, and SHROOM2. No enriched signaling pathway emerged, indicating heterogeneous rare-variant mechanisms. This first germline exome-wide rare-variant association study in Saudi EOBC identifies substantial enrichment driven by BRCA1, TP53, and additional candidate genes, supporting population-specific genetic risk evaluation and the need for replication in larger Arab cohorts.

Many women carrying pathogenic variants (pvs) of BRCA1 and BRCA2 genes (pvBRCA1/2) elect to undergo bilateral risk-reducing mastectomy (BRRM) in the belief that it will improve their overall survival (OS). Although many are satisfied with their decision to undergo BRRM a significant minority exhibit regret. We compared long-term oncology outcomes in women with pvBRCA1/2 choosing BRRM with those choosing a program of imaging surveillance. All participants were attendees at a regional family history/genetics service and had undergone genetic testing for pvBRCA1/2. Carriers of pvBRCA1/2 elected either to undergo BRRM or imaging surveillance as directed by UK national guidance. A prospective cohort design examined OS, breast cancer-specific death, and breast cancer incidence between the study groups. A total of 460 women elected to undergo BRRM, while 745 chose surveillance (median age, 37.2 years and 38.5 years, respectively; P = .06). Follow-up totaled 4,652 woman-years after BRRM. Overall annual incidence rate of breast cancer was 2.4%, falling to 0.15% after BRRM, a 94% reduction compared with surveillance alone (log-rank chi-square = 86.1; P < .001). There were nine occult cancers diagnosed at BRRM (2%). Breast cancer-specific deaths were similar in the BRRM and surveillance groups (two and four deaths, respectively; P = .36; 4,634 and 5,419 woman-years of follow-up, respectively). Proportionately, deaths from breast cancer were similar to deaths from ovarian cancer in both treatment groups. For women electing imaging surveillance over risk-reducing surgery, our results may offer reassurance that their breast cancer-specific survival and OS are unlikely to be compromised. However, breast cancer incidence rates are significantly reduced after BRRM compared with imaging surveillance, which may be important information for women with pvBRCA1/2 considering BRRM.

The Role of Genetic Testing in Localized Prostate Cancer.

Light-responsive α-TOS liposomal nanocarriers Co-delivering TiO2 and doxorubicin for the treatment of breast cancer.

A novel BRCA mutation classification system reveals differential responses to PARP inhibition and prognostic outcomes in epithelial ovarian cancer: a multicenter study.

Oral squamous cell carcinoma (OSCC) is the most prevalent form of squamous cell carcinomas of the head and neck (SCCHN), accounting for over 90 % of all oral cavity malignancies (approximately 275,000 new cases are worldwide diagnosed annually). Early-stage oral squamous cell carcinoma (T1 and T2) has a 5-year survival rate of up to 80 %. Survival rates decrease to 20-30 % at later stages (T3-T4). Each year, there are between 275,000 and 300,000 new cases of OSCC, and over 150,000 deaths worldwide. OSCC are usually non-hereditary tumors, although familial epidemiology has been recently reported. From 2022 to 2024, we enrolled 56 patients from the complex structure of maxillofacial surgery and ORL, National Cancer Institute-IRCCS-Fondazione G. Pascale. The individuals enrolled underwent molecular testing via a multigene panel of 56 genes related to cancer predisposition customized in our laboratory. The panel included BRCA1 and BRCA2. We identified a total of 7 pathogenic mutations annotated in clinical databases as ClinVar, in BRCA2 (two different variants), BRCA1, MUTYH, BRIP1, FANCM and FANCC genes (approximately 12.5 % of our patients). The results show a frequent predisposition to head and neck tumors similar to or even greater than that observed in other types of neoplasia, such as breast and ovarian cancers or colon cancer), with a predisposition of approximately 10 %. Our results confirm that, similarly to other more studied tumors, predictive genomic medicine can play a crucial role in the early identification of germline mutations in head and neck cancers. This approach should be considered for the early detection of OSCC particularly for individuals at increased risk, e.g., those with a family history of the disease, who may also be candidates for targeted molecular therapies based on their genetic profile.

The article presents the current state of knowledge on genetic modifiers of ovarian cancer risk in women carrying pathogenic variants (PVs) in the BRCA1 and BRCA2 genes, which are major contributors to hereditary susceptibility to this malignancy. Although PV carriers have high disease penetrance (BRCA1: ~40% and BRCA2: 11-27%), substantial variability in individual risk is observed, suggesting the influence of additional genetic variants. Background: Ovarian cancer is characterized by late detection and high mortality, and a significant portion of risk among BRCA1/2 carriers is shaped by reproductive and environmental factors as well as genetic modifiers. The article emphasizes that carriers of the same BRCA PV can exhibit markedly different risk levels depending on additional variants that modulate key biological processes, such as DNA repair, cell cycle regulation, and apoptosis. Methods: A systematic literature search covering the years 1996-2025 was conducted in the PubMed database. Initially, 734 publications were identified; after removing duplicates, thematically irrelevant articles, non-full-text papers, and studies not meeting the inclusion criteria, 47 articles were included in the review. These studies covered candidate gene analyses, GWAS, and data from the CIMBA consortium, which enables the examination of large cohorts of PV carriers. Results: The review identified numerous variants associated with increased or decreased ovarian cancer risk in BRCA1 carriers, including the following: OGG1, DR4, MDM2, CYP2A7, CASP8, ITGB3, HRAS1, TRIM61, and MTHFR. The reviewed studies also identified both protective and risk-increasing variants among BRCA2 PV carriers: UNG, TDG, and PARP2, and haplotypes in ATM, BRIP1, BARD1, MRE11, RAD51, and 9p22.2. The analysis identified 11 variants affecting both BRCA1 and BRCA2 carriers, most of which increase risk, including the following: IRS1, RSPO1, SYNPO2, BABAM1, MRPL34, PLEKHM1, and TIPARP. Protective variants include BNC2 and LINC00824. The only SNP reaching genome-wide significance (p < 5 × 10-8) was in BNC2. Conclusions: The article summarizes the growing number of genetic modifiers of ovarian cancer risk among BRCA1/2 carriers and highlights their potential to improve individualized risk assessment, enhance patient stratification, support personalized prevention and surveillance strategies, deepen the understanding of disease biology, and identify potential therapeutic targets.

Abstract Triphenyl phosphate (TPHP) is a high-production-volume flame retardant and plasticizer that is widely detected in the environment and in biomonitoring studies. TPHP exposure has been linked to endocrine disruption, metabolic disruption, genotoxicity, and neurodevelopmental effects in vitro and in vivo. The diverse toxicological outcomes across studies suggest disruption of fundamental regulatory processes, such as epigenetic control of gene expression. Here, we used an immortalized embryonic cell line derived from steelhead trout (STE-137) to investigate coordinated transcriptional and epigenetic responses to TPHP exposure. Cells were exposed to 0 or 80 μM TPHP for 24 h, followed by RNA sequencing (RNA-seq) or whole-genome bisulfite sequencing (WGBS). Differential expression analysis identified 1,622 significant genes, with significant enrichment of DNA replication and repair, cell cycle regulation, and endocrine signaling pathways and prominent lipid metabolism genes. Weighted Gene Co-expression Network Analysis (WGCNA) revealed modules highly correlated with exposure, including those enriched for protein and amino acid metabolism, ion transport, and genomic stability. WGBS methylome analysis detected 382 differentially methylated regions (DMRs), the majority hypermethylated and within gene bodies. Notable alterations included a DMR in the htr2cl1 gene, encoding a serotonin receptor, and the brca2 gene, a key DNA damage enzyme. Integration of RNA-seq and WGBS datasets identified nine genes with both expression and methylation changes, alongside altered gene expression of several key epigenetic regulators. Our results provide molecular evidence for early initiating events relevant to adverse outcome pathways and highlight the importance of epigenetic endpoints in developmental toxicity assessment.

Astragalus polysaccharide (APS) has recently emerged as a potent antitumor agent, however its impact on breast cancer (BC) remains inadequately understood. The current research aimed to examine the regulatory mechanism of APS in the pathogenesis of BC examining its influence on N6-methyladenosine (m6A) modification of MAL2. The effect of APS on the malignant phenotypes of BC was assessed by CCK8, EdU, transwell and tumor xenograft model assays. The differentially expressed genes (DEGs) in BC were identified by GEPIA-BC database, and their expression levels were determined by qRT-PCR in the BC cells. The role of MAL2 in BC malignancy was examined by EdU and transwell assays. Furthermore, bioinformatics analysis was first employed to explore the m6A modification site of MAL2 mediated by METTL3, which was then validated through MeRIP, western blotting, and qRT-PCR assays. APS was found to significantly reduce the cell proliferation, migration, as well as invasion of MCF-7 (IC50: 1014 μg/ml) and MDA-MB-231 (IC50: 685 μg/ml) cell lines. Additionally, it effectively suppressed tumor growth in vivo. The bioinformatics analysis revealed that among the five DEGs, MAL2 was significantly downregulated upon APS treatment both BC cell lines. Furthermore, the overexpression of MAL2 partially reversed the anti-tumor effects of APS. Notably, METTL3 modulates the m6A modification of MAL2 to regulate tumorigenesis in BC. APS prevents BC progression in association with reduced METTL3 expression and altered m6A modification of MAL2, suggesting that MAL2 may represent a potential therapeutic target to enhance the efficacy of APS.

Understanding the molecular mechanisms underlying the pathogenesis of lung cancer is critical for developing effective therapeutic strategies. It is important to study the role of key DNA repair genes, such as BRCA1, CHEK1, etc., in the context of the presence of aberrations in them and their influence on long-term treatment outcomes. Thus , the aim of the work was to assess the presence of chromosomal aberrations and expression in the main genes of the homologous recombination system in lung tumor. Materials and methods. The study included 111 patients with non-small cell lung cancer (NSCLC) stage IIA-IIIB. RNA and DNA were isolated from the surgical material of normal and tumor tissue. The expression level of HR genes was assessed using RTPCR. The presence of chromosomal aberrations and loss of heterozygosity sites was determined using microarray analysis. Results. Evaluation of the expression level showed that the presence of hyperexpression (more than 1) of the RAD51D gene is associated with 100 % metastasis-free survival (MFS) compared to the group with low expression (67.5 %), log-rank test p = 0.05. The effect of amplification in the ATM, BRIP1, BRCA1 genes on the increase in their expression was established (at p &lt; 0.05). For the BRCA1 gene, an association was established between the presence of a deletion and gene hypoexpression (p = 0.00006). According to Kaplan – Meier curves, in the presence of amplifications in the PPP2R2A gene in the tumor, the 5-year survival rate is only 50 %, compared to normal copy number with 85 % survival (p = 0.02). The opposite picture is observed for the BRCA2 gene: with a deletion, the survival rate is 54 % versus 88 % in the norm (p = 0.001). Conclusion. It remains important to further research to better understand the interaction between aberrations in the genes of the HR system and the assessment of the expression profile of these genes and therapeutic responses, which may ultimately lead to more effective and individualized treatment strategies for NSCLC.

BackgroundThe complexities of nucleotide metabolism in breast cancer (BC) cells are not yet fully understood. A deeper exploration of the various tumor subpopulations and their interactions with the tumor microenvironment (TME) could provide important insights into these clinically relevant signaling pathways.MethodsWe integrated five distinct single-cell enrichment scoring methodologies to conduct a comprehensive enrichment analysis of BC cell populations. The analytical findings underwent subsequent validation using an independent single-cell cohort. Tumor cell clusters were categorized based on their average enrichment scores. Functional analyses were carried out using several tools, including CellChat, Monocle, CopyKAT, SCENIC, and CytoTRACE. The RCTD method was then employed to map the single-cell clusters onto spatial transcriptomics data, facilitating the evaluation of cellular dependencies and pathway activities to differentiate tumor cell subtypes. A prognostic framework was subsequently established using large-scale transcriptomic datasets, enabling prediction of immunotherapy responsiveness. Experimental validation further confirmed expression patterns of pivotal genes implicated in therapeutic outcomes.ResultsTumor cells exhibit significantly upregulated nucleotide metabolic activity, enabling their classification into two distinct subgroups: NUhighepi and NUlowepi. Cells within the NUhighepi subgroup demonstrate pronounced malignant phenotypes. Intercellular communication analysis performed with the stLearn platform revealed robust interactions between NUhighepi cells and fibroblasts. Supporting this finding, spatial transcriptomic analysis via MISTy revealed a distinct dependency of NUhighepi on fibroblasts. A robust prognostic model, developed using various machine learning algorithms, was able to predict survival outcomes and responses to immunotherapy. Furthermore, targeted drugs were identified for both the high and low scoring groups. Experimental investigations confirmed the expression of core genes in different breast cancer cells.DiscussionIn conclusion, we developed a nucleotide metabolism-derived prognostic signature for BC, with DCTPP1 highlighted as a promising biomarker and therapeutic target. These findings provide a valuable framework for early clinical intervention and show promising potential for predicting responses to immunotherapy in BC patients.

BackgroundTriple-negative breast cancer (TNBC) is recognized as one of the most aggressive and prognostically adverse subtypes of breast cancer. The lack of effective therapeutic targets presents substantial challenges, including impediments in early diagnosis, restricted treatment options, and a pronounced tendency for drug resistance. Despite recent advancements in the diagnosis and management of TNBC, the overall survival rate for patients remains suboptimal. Consequently, gaining a more profound understanding of its biological mechanisms and developing novel therapeutic strategies are imperative scientific priorities in this domain.MethodsOLFML2A was identified as a potential therapeutic target in TNBC through analyses of the Human Protein Atlas and Kaplan-Meier databases. Its functional role was investigated using OLFML2A knockout (KO) and overexpression (OE) models in MDA-MB-231 cells. Effects on proliferation, cell cycle, and apoptosis were assessed by EdU assays, flow cytometry, RT-qPCR, western blotting, and immunofluorescence. Tumor growth and body weight were monitored in vivo, and tumor tissues were examined by H&E staining, RT-qPCR, and western blotting. Proteomic profiling integrated with literature mining identified EZH2 as a key downstream candidate. Their interaction was validated by co-immunoprecipitation, and EZH2 expression and localization under different OLFML2A conditions were analyzed. Rescue experiments using the EZH2 inhibitor GSK126 assessed the functional output of the OLFML2A-EZH2 axis via CCK-8, EdU assays.ResultsOLFML2A acts as an oncogenic gene in triple-negative breast cancer. The silencing of OLFML2A markedly reduced the proliferation of MDA-MB-231 cells, induced cell cycle arrest at the G1 phase, and inhibited tumor growth. In contrast, overexpression of OLFML2A reversed these effects. Comprehensive proteomic and molecular biology analyses further indicated that OLFML2A may play a role in cell cycle regulation through the modulation of EZH2.ConclusionsOur findings suggest that OLFML2A may facilitate cell cycle progression by regulating EZH2, implicating it as a potential therapeutic target for triple-negative breast cancer.

Circadian disruption affects various physiological processes, including male fertility. However, the effects and mechanism of circadian disruption on sperm DNA fragmentation (SDF) remain largely unexplored. In this study, we investigated this relationship using a mouse model of circadian disruption to assess in vivo effects, human sperm samples to evaluate clinical associations, and GC2 spermatocyte cells for mechanistic insights. A model of circadian disruption was established using C57BL/6J male mice subjected to a weekly 12-h inversion of the light-dark cycle for 8weeks, which resulted in significant sperm DNA damage in mice. Analysis of differentially expressed genes from RNA sequencing of testes from circadian-disrupted mice revealed that the homologous recombination (HR) repair pathway was significantly affected. Potential correlations between CREB1 expression and SDF were explored in human sperm (n = 40). CREB1 mRNA expression detected using droplet digital PCR was lower in patients with high sperm DNA damage than in the control group. In GC2 germ cells, Creb1 knockdown reduced cell proliferation and increased sensitivity to oxidative stress; moreover, it increased double-strand breaks and decreased protein levels of the DNA repair genes BRCA1, MRE11, and RAD51. Luciferase reporter and ChIP assay confirmed the transcriptional regulation of CREB1 on BRCA1 expression. Overall, circadian disruption suppressed CREB1 expression, which contributed to deficient HR repair and ultimately led to SDF. CREB1 expression was associated with sperm DNA damage in human. Our findings may have implications for understanding male health under circadian disruption and could provide novel avenues for therapeutic strategies to address SDF.

To enhance breast cancer (BC) management, there is an urgent need for molecular prognostic markers and therapeutic targets. This study investigates the role of chondroadherin (CHAD) in BC prognosis and its potential as a therapeutic target, focusing on its correlation with cancer severity and patient survival. CHAD expression at both mRNA and protein levels was analyzed in multiple datasets, and survival analysis was conducted. Comparisons were made between groups with different metastasis tendencies, and associations with clinical and pathological stages were examined. CHAD knockdown in T47D and ZR75-30 cell lines was performed to assess effects on proliferation and migration. Overexpression of CHAD in the MDA-MB-231 cell line reduced cell proliferation capability. GO/KEGG enrichment analysis identified CHAD's roles in molecular functions, cellular components, and biological processes. Western blotting evaluated CHAD's impact on the PI3K/Akt signaling pathway. Results indicated that CHAD expression is significantly lower in high malignancy BC groups and is associated with poorer survival outcomes. Increased CHAD levels correlate with lower metastasis propensity and are typically seen in lower-grade BC patients. CHAD knockdown increased proliferation and migration in T47D and ZR75-30 cells. Enrichment analyses highlighted pathways like "focal adhesion," "ECM receptor interaction," "regulation of actin cytoskeleton," and "PI3K/Akt pathway." Western blotting confirmed that CHAD inhibits PI3K and Akt phosphorylation. In summary, CHAD serves as a tumor suppressor gene and potential prognostic biomarker in breast cancer by inhibiting cell migration and proliferation through cell adhesion and PI3K/Akt pathway inhibition. Reduced CHAD expression correlates with worse prognosis, suggesting its potential as a therapeutic target.

Since the discovery of the BRCA1 and BRCA2 (hereafter referred to as BRCA1/2) hereditary breast and ovarian cancer genes three decades ago, genetically engineered and patient-derived mouse models have been instrumental in advancing our understanding of BRCA1/2 biology, particularly their roles in normal development, tumor suppression and therapy response. Brca1/2-mutant mouse models and derivative cell lines have facilitated in vivo dissection of BRCA1/2 functions and identification of the cellular origin and (epi)genetic drivers of BRCA1/2-associated cancer. Genetically engineered and patient-derived mouse tumor models have also been instrumental in developing new (combination) therapies for patients with BRCA1/2-mutated cancers and to study mechanisms of therapy resistance. In this Perspective, we highlight the crucial insights into the complex biology of BRCA1/2 these models have afforded and emphasize those aspects that remain to be elucidated. We also propose next-generation mouse models to further advance our understanding of BRCA1/2 and improve the quality of life of mutation carriers.

IntroductionBreast cancer is the most prevalent malignancy among women worldwide. A significant portion of patients possess homologous recombination deficiency (HRD), often caused by BRCA1/2 mutations, which may sensitize tumors to PARP inhibitors and platinum-based chemotherapy through synthetic lethality. Since mutations in BRCA genes have been previously suggested in association with impaired biology of telomeres, in the present study we investigated leukocyte telomere length (LTL) to evaluate its potential utility as a biomarker for BRCA1 mutations and HRD.MethodologyLTL was measured using multiplex monochrome real-time qPCR in four groups: breast cancer patients with pathogenic hereditary BRCA1 mutations (n = 99), age-matched non-cancerous controls carrying the same BRCA1 mutations (n = 99), breast cancer patients with wild-type BRCA1 (n = 105), and age-matched non-cancerous controls with wild-type BRCA1 (n = 107). BRCA1 mutations were tested by the DNA sequencing approach.ResultsA significant negative correlation between age and LTL was observed across all studied groups, except in breast cancer patients carrying pathogenic hereditary BRCA1 mutations. Interestingly, after adjusting for age, BRCA1 mutation carriers had shorter LTL compared to non-carriers, regardless of the presence of cancer (P = 0.024).ConclusionLTL shortening is associated with BRCA1 mutations, regardless of cancer status. Further validation studies are needed.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12672-025-04007-8.

Background:The efficacy and safety of poly (ADP-ribose) polymerase inhibitors (PARPis) in the Chinese real-world setting have not been well characterized.Design:This is a retrospective analysis of PARPis efficacy in metastatic breast cancer (MBC) patients with homologous recombination repair (HRR) gene pathogenic variants (PVs).Objectives:We aimed to evaluate the efficacy and toxicities of PARPis in real-world MBC patients.Methods:Patients who received PARPi for MBC at the National Cancer Center and two other centers between January 1, 2019, and December 31, 2024, were consecutively included. The primary endpoint was progression-free survival (PFS). Univariable and multivariable Cox proportional hazard models were used to evaluate the predictive impact of clinicopathologic characteristics on PFS.Results:In total, 62 MBC patients treated with olaparib (N = 55), talazoparib (N = 4), pamiparib (N = 2), and fluzoparib (N = 1) were enrolled. The median PFS (mPFS) in all patients was 6.0 months (95% confidence interval: 4.1–7.9). mPFS in the germline BRCA1 (gBRCA1; N = 19), gBRCA2 (N = 30), gBRCA (N = 4), somatic BRCA2 (sBRCA2; N = 1), gPALB2 (N = 4), and other HRR gene (N = 4) PVs carriers were 3.7, 8.0, 2.8, 2.7, 5.3, and 7.1 months, respectively (p = 0.334). In multivariate analysis, ⩽40 years old (hazard ratio (HR): 2.281, p = 0.008), third-line or later therapy (HR: 2.429, p = 0.019), and prior platinum-based treatment (HR: 2.172, p = 0.014) were independently associated with shorter PFS. The incidence of adverse events (AEs) of all grades was 62.5% (35/56). The most common AEs in all grades were anemia (30.4%), nausea (21.4%), and leukopenia (17.9%). Hematologic toxicity was the most common grade ⩾3 AEs.Conclusion:PARPis showed promising PFS and tolerable toxicity in the real-world treatment of Chinese MBC patients with HRR-related gene mutations.

Digital PCR has seen increasing adoption in recent years since it overcomes most of the main technical limitations of real-time PCR. However, the level of multiplexing remains limited when facing the need to develop approaches that can detect multiple targets in a single reaction with a high sensitivity to obtain a more complete genetic characterization of samples. This need concerns most molecular biology applications, but it is especially valuable in fields such as oncology, for which it is often necessary to detect numerous specific mutations, particularly those involving hotspots, in order to adapt a treatment, monitor the efficacy of a drug, and detect resistance mutations. This is the case of the ESR1 gene in breast cancer, where numerous mutations can be responsible for mechanisms of resistance to the backbone therapy. In this sense, the implementation of color combination using Crystal Digital PCR® allows high levels of multiplexing to be achieved, while maintaining simplicity and robustness of analysis. This approach has been successfully applied to the detection of 17 ESR1 mutations in a single assay.

Drug resistance remains a major obstacle to successful chemotherapy, leading to treatment failure and tumor recurrence. Recent studies indicate that mutations in FAT Atypical Cadherin 1 (FAT1) contribute to drug resistance in cancer cells. However, the precise role and underlying mechanisms of FAT1 in breast cancer (BC) remain insufficiently explored. Here, we conducted a comprehensive genomic and transcriptomic analysis, identifying FAT1 as a crucial tumor suppressor gene in BC. Our study demonstrates that genomic alterations in FAT1 are associated with the Wnt/β-catenin pathway activation. We further show that FAT1 loss induces cyclophosphamide (CTX) resistance and leads to the upregulation of the Wnt signaling cascade, accompanied by the accumulation of CTNNB1 transcription factors. Notably, combination therapy effectively alleviates drug resistance by suppressing the Wnt pathway. These findings highlight the critical role of FAT1 loss in mediating CTX resistance in BC and provide insights into potential therapeutic strategies targeting the Wnt pathway.