BRCA1 and BRCA2: different roles in a common pathway of genome protection

Predictors of olaparib discontinuation owing to adverse drug events in patients with ovarian, peritoneal, or fallopian tube cancer: a retrospective observational study

We investigated predictors of olaparib discontinuation owing to adverse effects. Patients with ovarian, peritoneal, or fallopian tube cancers treated with olaparib at Osaka Medical and Pharmaceutical University Hospital between April 2018 and September 2022 were included in this study. The exclusion criteria were as follows: discontinuation of treatment due to disease progression, use of anaemia medications, and use of cytochrome P450 (CYP3A4) inhibitors. The follow-up period was 90 d. Of the 46 eligible patients, 21 patients discontinued olaparib, including 15 patients with grade 3 or higher anaemia, eight patients with grade 3 or higher neutropenia, and four patients with non-haematological toxicity (including multiple onset). Multivariate logistic regression analysis showed that grade 4 neutropenia and anaemia progression to grades 2-3 due to chemotherapy administered before olaparib administration were predictors of olaparib discontinuation. The severity of neutropenia and anaemia due to chemotherapy before olaparib administration may be a potential marker for its discontinuation.

Increased Synthetic Cytotoxicity of Combinatorial Chemoradiation Therapy in Homologous Recombination Deficient Tumors

PURPOSE

Homologous recombination deficient (HRD) tumors are exquisitely sensitive to platinum-based chemotherapy and when combined with radiation therapy (RT), leads to improved overall survival in multiple cancer types. Whether a subset of tumors with distinct molecular characteristics demonstrate increased benefit from cisplatin and RT (c-RT) is unclear. We hypothesized that HRD tumors, whether associated with BRCA mutations or genomic scars of HRD, exhibit exquisite sensitivity to c-RT, and that HRD may be a significant driver of c-RT benefit.

METHODS AND MATERIALS

Sensitivity to c-RT was examined using isogenic and sporadic breast cancer cell lines. HRD was assessed using 4 assays: RT-induced Rad51 foci, a DR-GFP reporter assay, a genomic scar score (large-scale state transitions [LST]), and clonogenic survival assays. Whole-genome sequencing of 4 breast tumors from a phase 2 clinical trial of neoadjuvant c-RT in triple-negative breast cancer was performed and HRD was defined using HRDetect.

RESULTS

BRCA1/2 deficient cell lines displayed functional HRD based on the Rad51 functional assay, with c-RT to RT or cisplatin interaction ratios (IR) of 1.11 and 26.84 for the BRCA1 isogenic pair at 2 μM cisplatin and 6 Gy, respectively. The highest LST lines demonstrated HRD and synthetic cytotoxicity to c-RT with IR at 2 Gy and cisplatin 20 μM of 7.50, and the lowest LST line with IR of 0.65. Of 4 evaluable patients in the phase 2 trial, one achieved a pathologic complete response with corresponding HRD based on multiple genomic scar scores including HRDetect and LST scores, compared with patients without a pathologic complete response.

CONCLUSIONS

HRD breast cancers, whether identified by BRCA1/2 mutation status, functional tests, or mutational signatures, appear to be significantly more sensitive to c-RT compared with isogenic controls or tumors without HRD mutational signatures. HRD tumors may be exquisitely sensitive to c-RT which warrants further clinical investigation to guide a precision oncology approach.

Biophysical investigation of the molecular interaction between minichromosome maintenance protein 6 and Bloom syndrome helicase

The minichromosome maintenance protein (MCM) complex and Bloom syndrome helicase (BLM) are crucial components in DNA replication and cell division. MCM, a hexameric helicase that unwinds double-stranded DNA, serves as an important diagnostic and prognostic biomarker for cancer cells and a target for anticancer drug development. BLM, associated with G-quadruplex structures, is another key helicase in maintaining genomic stability. In this study, we investigate the interaction between MCM6 and BLM at the atomic level, as their expression levels are highly correlated in various cancer types, with elevated levels indicating poor prognosis. To elucidate the molecular basis of MCM6/BLM interaction, we employed fluorescence polarization anisotropy analysis, NMR chemical shifts perturbation analysis (CSP), and paramagnetic relaxation enhancement (PRE) experiments. MCM6 binding domain (MBD) C and D exhibit similar binding affinities to MCM6 winged-helix domain (WHD). However, significant CSPs with MBD-D and PRE experiments suggested that MBD-D is closer to MCM6 WHD than MBD-C. Despite both proteins containing numerous negatively charged residues, hydrophobic interactions govern the association between MCM6 WHD and BLM MBD-D. This biophysical characterization of the MCM6/BLM interaction provides new insights into their functional relationship and challenges existing models. Our findings reveal that MCM6 binds BLM at a different site than its other known partner chromatin licensing and DNA replication factor. Understanding these protein-protein interactions at the molecular level may contribute to the development of novel anticancer therapies targeting the MCM6/BLM interaction.

Overview of splicing variation in ovarian cancer

Ovarian cancer remains one of the deadliest gynecological malignancies, with a persistently high mortality rate despite promising advancements in immunotherapy. Aberrant splicing events play a crucial role in cancer heterogeneity and treatment resistance. Many splicing variants, especially those involving key molecular markers such as BRCA1/2, are closely linked to disease progression and treatment outcomes. These variants and related splicing factors hold significant clinical value as diagnostic and prognostic biomarkers and therapeutic targets. This review provides a comprehensive overview of splicing variants in ovarian cancer, emphasizing their role in metastasis and resistance, and offers insights to advance biomarker development and treatment strategies.

Exploring the differences between BRCA mutated and HRwild-type high grade serous ovarian cancer: A multiomic analysis

OBJECTIVE

The purpose of this study was to evaluate the transcriptomic profile of BRCA1 mutant (BRCA1mut) and BRCA2 mutant (BRCA2mut) HGSOC compared to homologous recombination wild-type (HRwt) tumors utilizing the CARIS database.

METHODS

Next-generation and Whole Transcriptome Sequencing (WTS; Caris Life Sciences, Phoenix, AZ) was performed on a total of 2745 HGSOC tumor samples. BRCA mutations were defined as variants resulting in loss-of-function of the protein and HRwt was defined as samples wildtype for aberrations in both BRCA1 and BRCA2, as well as for 28 other HR genes. HRwt group was further classified into HRwt/LOH-low (<16 %) and HRwt/LOH-high (≥16 %). Genomic analysis consists of mutation analysis and measurements of TMB and MSI. Transcriptomic analysis included identification of Differentially expressed genes (DEGs), GSEA and immune deconvolution.

RESULTS

We identified 519 (19 %) BRCA1-mut, 302 (11 %) BRCA2-mut, and 739 (27 %) HRwt/LOH high and 1181 (43 %) HRwt/LOH low HGSOC. TP53 was the most commonly mutated gene in all groups. Mutations in PIK3CA were most common in HRwt/LOH-low compared to BRCA1-mut and BRCA2-mut HGSOC. TMB-H was highest in BRCA2-mut compared to BRCA1-mut, HRwt/LOH high and HRwt/LOH low tumors. In contrast, higher NKT cell infiltration, higher T cell inflamed and IFNγ scores, and higher PDL1 expression were observed in BRCA1-mut tumors.

CONCLUSION

Our findings emphasize the differential immune profiles based on BRCA1 and BRCA2 mutations and suggest potential therapeutic targets, including treatment strategies that incorporate immunotherapy and target specific genomic alterations.

Case report: Deciphering the clinical significance of a novel partial BRCA1 exon 10 duplication in a patient with triple-negative breast cancer

Pathogenic/likely pathogenic germline variants in the BRCA1 and BRCA2 genes are associated with an increased risk of developing cancer, particularly breast and/or ovarian tumors. The identification and correct classification of these variants is crucial to find individuals with an increased risk of cancer and to support physicians in their clinical and therapeutic decisions. In addition, the status of BRCA1 and BRCA2 variants is important for appropriate management of patients' family members. Here, we describe the case of a woman who developed triple-negative breast cancer at the age of 49 years. NGS analysis of BRCA1 and BRCA2 genes revealed the presence of a new partial BRCA1 exon 10 duplication of 2.012 bp. The identified duplication comprises 395 nucleotides from the final portion of intron 9 and 1617 nucleotides from the beginning of exon 10. Using specific primers, we were able to identify the breakpoint at the DNA level and characterize the alteration as a tandem duplication leading to the formation of a premature stop codon after 10 residues. RNA analysis allowed to confirm the production of an altered mRNA showing the duplicated sequence. In this way, we were able to assign a clinical significance to the new alteration and classify it as a pathogenic variant. Although new ClinGen ENIGMA guidelines have been produced to provide tools for the accurate interpretation of variants in the BRCA1 and BRCA2 genes, defining the clinical significance of copy number variants, particularly duplications, remains a challenging goal that requires complex approaches to accurately determine the role of such variants. Other investigations, such as the detection of breakpoints by RNA analysis, are often essential to classify the identified alteration. Our study suggests that RNA transcript analysis is an ideal methodology to support the accurate classification of variants and clarify their effects.

Genomic Characterization of Chordoma: Insights from the AACR Project GENIE Database

Background: Chordoma is a rare primary tumor originating from embryonic notochord remnants, with limited systemic therapeutic options due to a poor understanding of its genomic landscape. This study aims to characterize the genetic alterations in chordoma using a large national patient-level genomic repository, the AACR Project GENIE, to identify potential therapeutic targets and improve disease modeling. Methods: A retrospective analysis of chordoma samples was conducted using the AACR Project GENIE database. Targeted sequencing data were analyzed for recurrent somatic mutations, tumor mutational burden, and chromosomal copy number variations, with significance set at p < 0.05. Results: Frequent mutations were observed in genes associated with SWI/SNF complex affecting chromatin remodeling (SETD2, PBRM1, ARID1A). Mutations were also common among the TERT promoter regions, and cell cycle regulation (CDKN2A). Significant co-occurrences were identified among PBRM1, BRCA2, and KMT2D mutations. CDKN2A/B deletions were enriched in metastatic tumors, and pediatric cases demonstrated distinct mutation profiles compared to adults. Conclusions: This study provides a genomic profile of chordoma, identifying key mutations and potential therapeutic targets. These findings highlight the roles of chromatin remodeling and cell cycle pathways in chordoma biology, offering insights for future precision medicine approaches and therapeutic interventions.

The Role of Microhomology-Mediated End Joining (MMEJ) at Dysfunctional Telomeres

DNA double-strand break (DSB) repair pathways are crucial for maintaining genome stability and cell viability. However, these pathways can mistakenly recognize chromosome ends as DNA breaks, leading to adverse outcomes such as telomere fusions and malignant transformation. The shelterin complex protects telomeres from activation of DNA repair pathways by inhibiting nonhomologous end joining (NHEJ), homologous recombination (HR), and microhomology-mediated end joining (MMEJ). The focus of this paper is on MMEJ, an error-prone DSB repair pathway characterized by short insertions and deletions flanked by sequence homology. MMEJ is critical in mediating telomere fusions in cells lacking the shelterin complex and at critically short telomeres. Furthermore, studies suggest that MMEJ is the preferred pathway for repairing intratelomeric DSBs and facilitates escape from telomere crisis. Targeting MMEJ to prevent telomere fusions in hematologic malignancies is of potential therapeutic value.

Saturation genome editing-based clinical classification of BRCA2 variants

Sequencing-based genetic tests have uncovered a vast array of BRCA2 sequence variants1. Owing to limited clinical, familial and epidemiological data, thousands of variants are considered to be variants of uncertain significance2-4 (VUS). Here we have utilized CRISPR-Cas9-based saturation genome editing in a humanized mouse embryonic stem cell line to determine the functional effect of VUS. We have categorized nearly all possible single nucleotide variants (SNVs) in the region that encodes the carboxylate-terminal DNA-binding domain of BRCA2. We have generated function scores for 6,551 SNVs, covering 96.4% of possible SNVs in exons 15-26 spanning BRCA2 residues 2479-3216. These variants include 1,282 SNVs that are categorized as missense VUS in the clinical variant database ClinVar, with 77.2% of these classified as benign and 20.4% classified as pathogenic using our functional score. Our assay provides evidence that 3,384 of the SNVs in the region are benign and 776 are pathogenic. Our classification aligns closely with pathogenicity data from ClinVar, orthogonal functional assays and computational meta predictors. We have integrated our embryonic stem cell-based BRCA2-saturation genome editing dataset with other available evidence and utilized the American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines for clinical classification of all possible SNVs. This classification is available as a sequence-function map and serves as a valuable resource for interpreting unidentified variants in the population and for physicians and genetic counsellors to assess BRCA2 VUS in patients.

The cardio-oncologic burden of breast cancer: molecular mechanisms and importance of preclinical models

Breast cancer, the most prevalent cancer affecting women worldwide, poses a significant cardio-oncological burden. Despite advancements in novel therapeutic strategies, anthracyclines, HER2 antagonists, and radiation remain the cornerstones of oncological treatment. However, each carries a risk of cardiotoxicity, though the molecular mechanisms underlying these adverse effects differ. Common mechanisms include DNA damage response, increased reactive oxygen species, and mitochondrial dysfunction, which are key areas of ongoing research for potential cardioprotective strategies. Since these mechanisms are also essential for effective tumor cytotoxicity, we explore tumor-specific effects, particularly in hereditary breast cancer linked to BRCA1 and BRCA2 mutations. These genetic variants impair DNA repair mechanisms, increase the risk of tumorigenesis and possibly for cardiotoxicity from treatments such as anthracyclines and HER2 antagonists. Novel therapies, including immune checkpoint inhibitors, are used in the clinic for triple-negative breast cancer and improve the oncological outcomes of breast cancer patients. This review discusses the molecular mechanisms underlying BRCA dysfunction and the associated pathological pathways. It gives an overview of preclinical models of breast cancer, such as genetically engineered mouse models, syngeneic murine models, humanized mouse models, and various in vitro and ex vivo systems and models to study cardiovascular side effects of breast cancer therapies. Understanding the underlying mechanism of cardiotoxicity and developing cardioprotective strategies in preclinical models are essential for improving treatment outcomes and reducing long-term cardiovascular risks in breast cancer patients.

BRCA functional domains associated with high risk of multiple primary tumors and domain-related sensitivity to olaparib: the Prometheus Study

BACKGROUND

Germline pathogenic variants (gPVs) in the breast cancer susceptibility gene 1/2 (BRCA1/2) genes confer high-penetrance susceptibility to breast cancer (BC) and ovarian cancer (OC). Although most female BRCA carriers develop only a single BRCA-associated tumor in their lifetime, a smaller subpopulation is diagnosed with multiple primary tumors (MPTs). The genetic factors influencing this risk remain unclear. Further, in patients with BRCA-mutated tumors, there appears to be a variability in the effectiveness of olaparib treatment.

PATIENTS AND METHODS

This real-world, multicenter, observational study aimed to determine whether the location of BRCA gPVs within functional domains (FDs) is associated with the development of MPTs and the magnitude of olaparib benefit. The study population comprised consecutive patients with OC who underwent hereditary cancer genetic testing between May 2015 and March 2023. MPT history was assessed based on mutated genes (BRCA1 or BRCA2) and the location of the PVs within the FDs. Clinical outcomes of olaparib first-line maintenance therapy were evaluated according to BRCA1/2 FD location.

RESULTS

The frequency of MPT history in the overall population was 13.3% (118/882), and 20.4% in the BRCA-mutated subpopulation (68/333; P < 0.001). We observed a significant association between the DNA-binding domain (DBD) FD of BRCA2 and MPT. Specifically, 55.6% of BRCA2-mutated patients with PVs in the DBD had a history of BC as a second tumor. At a median follow-up of 48.5 months (95% confidence interval 10-70 months), the 48-month progression-free survival rates were 100.0% for patients with PVs in DBD, 91.7% for those with PVs in other FDs, and 36.4% for those with PVs in the RAD51-binding domain (RAD51-BD) of BRCA2 (P = 0.01). Results in the BRCA1 cohort were not statistically significant.

CONCLUSIONS

The results suggest that the location of PVs within BRCA FDs may influence the onset of multiple tumors and the benefit of olaparib in patients with BRCA-mutated OC. These findings could be relevant for cancer prevention efforts, particularly given the increasing number of cancer survivors. However, further understanding is needed before these results can inform clinical decisions.

Positive Selection Shapes Breast Cancer Tumor Suppressor Genes: Unveiling Insights into BRCA1, BRCA2, and MDC1 Stability

Worldwide, breast cancer is the leading cause of death in women with cancers. Given this situation, new approaches to treatment are urgently needed. Tumor Suppressor Genes (TSGs) defects play a crucial role in tumor development, and recent studies propose their reactivation as a promising way for clinical intervention in breast cancer. Here, we performed detailed evolutionary analyses of 241 breast cancer TSGs across 25 mammalian genomes, revealing 28 genes under strong positive selection. These genes exhibit elevated molecular pressure in codons corresponding to amino acids located in crucial protein domains and motifs. Notably, one positively selected site in the BRCA1 C-terminal domain is known for its role in DNA damage response, suggesting potential interference with DNA repair mechanisms. Moreover, the substitution of some other sites found in important key motifs, namely two codons in BRCA2 (752 and 939) localized within the phosphoinositide-3-OH-kinase-related and playing a crucial role in the DNA repair and the DNA damage checkpoints. Our findings could be inspirational to foster future recommendations for drug-targeting sites and further illuminate the function of these proteins. Finally, the code developed in our study is delivered in the Automated tool for positive selection (ATPs) ( https://github.com/APS-P/Automated-Tool-for-Positive-Selection-ATPS-/wiki ) to assist the easy reproducibility and support future evolutionary genomics analyses.

Combination strategies with PARP inhibitors in BRCA-mutated triple-negative breast cancer: overcoming resistance mechanisms

Triple-negative breast cancer (TNBC) is a particularly aggressive breast cancer subtype, characterised by a higher incidence in younger women, rapid metastasis, and a generally poor prognosis. Patients with TNBC and BRCA mutations face additional therapeutic challenges due to the cancer's intrinsic resistance to conventional therapies. Poly (ADP-ribose) polymerase inhibitors (PARPis) have emerged as a promising targeted treatment for BRCA-mutated TNBC, exploiting vulnerabilities in the homologous recombination repair (HRR) pathway. However, despite initial success, the efficacy of PARPis is often compromised by the development of resistance mechanisms, including HRR restoration, stabilisation of replication forks, reduced PARP1 trapping, and drug efflux. This review explores latest breakthroughs in overcoming PARPi resistance through combination therapies. These strategies include the integration of PARPis with chemotherapy, immunotherapy, antibody-drug conjugates, and PI3K/AKT pathway inhibitors. These combinations aim to enhance the therapeutic efficacy of PARPis by targeting multiple cancer progression pathways. The review also discusses the evolving role of PARPis within the broader treatment paradigm for BRCA-mutated TNBC, emphasising the need for ongoing research and clinical trials to optimise combination strategies. By tackling the challenges associated with PARPi resistance and exploring novel combination therapies, this review sheds light on the future possibilities for improving outcomes for patients with BRCA-mutated TNBC.

Long Intergenic Non-Coding RNAs and BRCA1 in Breast Cancer Pathogenesis: Neighboring Companions or Nemeses?

Breast cancer is one of the leading causes of mortality among women, primarily due to its complex molecular landscape and heterogeneous nature. The tendency of breast cancer patients to develop metastases poses significant challenges in clinical management. Notably, mutations in the breast cancer gene 1 (BRCA1) significantly elevate breast cancer risk. The current research endeavors employ diverse molecular approaches, including RNA, DNA, and protein studies, to explore avenues for the early diagnosis and treatment of breast cancer. Recent attention has shifted towards long non-coding RNAs (lncRNAs) as promising diagnostic, prognostic, and therapeutic targets in the multifaceted progression of breast cancer. Among these, long intergenic non-coding RNAs (lincRNAs), a specific class of lncRNAs, play critical roles in regulating various aspects of tumorigenesis, including cell proliferation, apoptosis, epigenetic modulation, tumor invasion, and metastasis. Their distinctive expression patterns in cellular and tissue contexts underscore their importance in breast cancer development and progression. Harnessing lincRNAs' sensitivity and precision as diagnostic, therapeutic, and prognostic markers holds significant promise for the clinical management of breast cancer. However, the potential of lincRNAs remains relatively underexplored, particularly in the context of BRCA1-mutated breast cancer and other clinicopathological parameters such as receptor status and patient survival. Consequently, there is an urgent need for comprehensive investigations into novel diagnostic and prognostic breast cancer biomarkers. This review examines the roles of lincRNAs associated with BRCA1 in the landscape of breast cancer, highlighting the potential avenues for future research and clinical applications.

The PST repeat region of MDC1 is a tunable multivalent chromatin tethering domain

DNA double strand breaks (DSBs) are widely considered the most cytotoxic DNA lesions occurring in cells because they physically disrupt the connectivity of the DNA double helix. Homologous recombination (HR) is a high-fidelity DSB repair pathway that copies the sequence spanning the DNA break from a homologous template, most commonly the sister chromatid. How both DNA ends, and the sister chromatid are held in close proximity during HR is unknown. Here we demonstrate that the PST repeat region of MDC1 is a mutlivalent nucleosome binding domain, sufficient to tether chromatin in multiple contexts. In mitotic cells the affinity of the PST repeats for chromatin is downregulated by phosphorylation to prevent chromosome missegregation, while still contributing to DNA break tethering by the MDC1-TOPBP1-CIP2A complex. In interphase, the PST repeat region is critical for RAD51 focus formation but not the recruitment of 53BP1 to DNA breaks, consistent with a chromatin tethering function. In total, this work demonstrates that the PST repeat region of MDC1 is a multivalent chromatin binding domain with tunable affinity that contributes to DNA break tethering during HR and in mitosis.

Heterozygous mutation in BRCA2 induces accelerated age-dependent decline in sperm quality with male subfertility in rats

Tumor suppressor BRCA2 executes homologous recombination to repair DNA double-strand breaks in collaboration with RAD51, involving exon 11 and 27. Exon 11 constitutes a region where pathogenic variants (PVs) accumulate, and mutations in this region are known to contribute to carcinogenesis. However, the impact of the heterozygous PVs of BRCA2 exon 11 on the life quality beyond cancer risk, including male fertility, remains unclear. Here, we established a rat model with a frameshift on the seventh BRC repeat in Brca2 exon 11 (Brca2+/p.T1942fs), which is homologous to human BRCA2+/p.T1974fs, using CRISPR/Cas9 system. Our analyses revealed that the heterozygous rats with the PV in the BRCA2 exon 11 showed increased DNA double-strand breaks and apoptosis in spermatogonia and spermatocytes, accelerated testicular germ cell loss, and deterioration in sperm quality according with aging, ultimately resulting in early male reproductive dysfunction. Of note, these alterations in testes and sperm, including DNA fragmentation in spermatozoa, were observed from completion of sexual maturation. The present findings suggest that it is crucial to consider not only cancer risk but also potential declines in reproductive capacity in men carrying BRCA2 exon 11 PVs. Further investigation is warranted to determine whether similar traits appear in humans.

Application of Gene Editing in Triple-Negative Breast Cancer Research

With the rapid development of gene editing technology, its application in breast cancer has gradually become the focus of research. This article reviews the application of gene editing technology in the treatment of breast cancer, and discusses its challenges and future development directions. The key application areas of gene editing technology in the treatment of breast cancer will be outlined, including the discovery of new therapeutic targets and the development of drugs related to the pathway. Gene editing technology has played an important role in the discovery of new therapeutic targets. Through the use of gene editing technology, breast cancer-related genes are systematically edited to regulate key regulatory factors on related pathways or key tumor suppressor genes such as FOXC1 and BRCA, and the results are analyzed in cell or animal experiments, and the target is obtained from the experimental results, which provides important clues for the development of new drugs. This approach provides an innovative way to find more effective treatment strategies and inhibit tumor growth. In addition, gene editing technology has also promoted the personalization of breast cancer treatment. By analyzing a patient's genomic information, researchers can pinpoint key genetic mutations in a patient's tumor and design personalized treatments. This personalized treatment approach is expected to improve the therapeutic effect and reduce adverse reactions. Finally, the application of gene editing technology also provides support for the development of breast cancer immunotherapy. By editing immune cells to make them more potent against tumors, researchers are trying to develop more effective immunotherapies to bring new treatment options to breast cancer patients.

Multiomics analysis of homologous recombination deficiency across cancer types

There remains ongoing debate regarding the association of homologous recombination deficiency (HRD) with patient survival across various malignancies, highlighting the need for a comprehensive understanding of HRD's role in different cancer types. Based on data from databases, we conducted a multivariable omics analysis on HRD in 33 cancer types, focusing mainly on 23 cancers in which HRD was significantly associated with patient overall survival (OS) rates. This analysis included the mechanisms related to patient prognosis, gene expression, gene mutation, and signaling pathways. In this study, HRD was found to be significantly associated with patient prognosis, but its impact varied among different cancers. HRD was linked to different outcomes for patients with distinct tumor subtypes and was correlated with clinical features such as clinical stage and tumor grade. Driver gene mutations, including TP53, MUC4, KRAS, HRAS, FLG, ANK3, BRCA2, ATRX, FGFR3, NFE2L2, MAP3K1, PIK3CA, CIC, FUBP1, ALB, CTNNB1, and MED12, were associated with HRD across specific cancer types. We also analyzed differentially expressed genes (DEGs) and differentially methylated regions (DMRs) in relation to HRD levels in these cancers. Furthermore, we explored the correlation between HRD and signaling pathways, as well as immune cell infiltration. Overall, our findings contribute to a comprehensive understanding of HRD's multifaceted role in cancer.

BRCA1 & BRCA2 methylation as a prognostic and predictive biomarker in cancer: Implementation in liquid biopsy in the era of precision medicine

BACKGROUND

BReast CAncer gene 1 (BRCA1) and BReast CAncer gene 2 (BRCA2) encode for tumor suppressor proteins which are critical regulators of the Homologous Recombination (HR) pathway, the most precise and important DNA damage response mechanism. Dysfunctional HR proteins cannot repair double-stranded DNA breaks in mammalian cells, a situation called HR deficiency. Since their identification, pathogenic variants and other alterations of BRCA1 and BRCA2 genes have been associated with an increased risk of developing mainly breast and ovarian cancer. Interestingly, HR deficiency is also detected in tumors not carrying BRCA1/2 mutations, a condition termed "BRCAness".

MAIN TEXT

One of the main mechanisms causing the BRCAness phenotype is the methylation of the BRCA1/2 promoters, and this epigenetic modification is associated with carcinogenesis and poor prognosis mainly among patients with breast and ovarian cancer. BRCA1 promoter methylation has been suggested as an emerging biomarker of great predictive significance, especially concerning Poly (ADP-ribose) Polymerase inhibitors (PARP inhibitor-PARPi) responsiveness, along with or beyond BRCA1/2 mutations. However, as its clinical exploitation is still insufficient, the impact of BRCA1/2 promoter methylation status needs to be further evaluated. The current review aims to gather the latest findings about the mechanisms that underline BRCA1/2 function as well as the molecular characteristics of tumors associated with BRCA1/2 defects, by focusing on DNA methylation. Furthermore, we critically analyze their translational meaning and the validity of BRCA methylation biomarkers in predicting treatment response.

CONCLUSIONS

We believe that BRCA1/2 methylation alone or combined with other biomarkers in a clinical setting is expected to change the scenery in prognosis and predicting treatment response in multiple cancer types and is worthy of further attention. The quantitative BRCA1 promoter methylation assessment might predict treatment response in PARPi and analysis of BRCA1/2 methylation in liquid biopsy might define patient subgroups at different time points that may benefit from PARPi. Finally, we suggest a pipeline that could be implemented in liquid biopsy to aid precision pharmacotherapy in BRCA-associated tumors.

Whole‑exome sequencing insights into synchronous bilateral breast cancer with discordant molecular subtypes

The incidence of synchronous bilateral breast cancer (SBBC) is very low, and SBBC with discordant molecular subtypes is even more uncommon. As such, little is known about the pathogenesis of SBBC with discordant molecular subtypes, and reports about this entity are scarce. In the present study, the case of a 72-year-old female patient who presented with SBBC with discordant molecular subtypes is reported, with a stage IA hormone receptor negative {human epidermal growth factor receptor-2 [HER2(+)]} tumor in the left breast and a stage IIIA hormone sensitive tumor [HER2(-)] in the right breast. Whole-exome sequencing was performed to identify the differential genetic variations in the BBC tissues. A total of 8 key mutated cancer susceptibility genes (ALK, BRCA1, FAT1, HNF1A, KDR, PTCH1, SDHA and SETBP1) were screened, and mutations were found in 10 vital cancer driver genes, including BRCA1, EBF1, MET, NF2, NUMA1 RALGAPA1, ROBO2, SMYD4, UBR5 and ZNF844. The high-frequency mutated genes mainly contained missense mutations, among which single nucleotide variants were the most common mutations, with C > T and C > A as the main forms. The pathways associated with the high frequency mutated genes were further elucidated by functional category and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. Heterogeneity in the hormone receptor and HER2 status of SBBC poses unique therapeutic challenges. Future studies should aim to identify the optimal management strategy for this disease.

Monoubiquitinated H2B, a Main Chromatin Target of Formaldehyde, Is Important for S-Phase Checkpoint Signaling and Genome Stability

Formaldehyde (FA) is a human carcinogen with ubiquitous environmental exposures and significant endogenous formation. Genotoxic activity of FA stems from its reactivity with DNA-NH2 groups. Histone lysines are another source of aldehyde-reactive amino groups in chromatin, however, chromatin/histone damage responses to FA and their biological significance are poorly understood. We examined histone posttranslational modifications in FA-treated human lung cells and found that the majority of the most prominent small lysine modifications associated with active or inactive chromatin were unchanged. FA moderately decreased H3K9 and H3K27 acetylation and H2A-K119 monoubiquitination but caused surprisingly severe losses of H2B-K120 monoubiquitination, especially in primary and stem-like cells. H2Aub1 decreases reflected its slower ubiquitination linked to a lower ubiquitin availability due to K48-polyubiquitination of FA-damaged proteins. Depletion of H2Bub1 resulted from its rapid deubiquitination in part by ATXN7L3-associated deubiquitinases and was independent on DNA damage signaling, indicating a direct chromatin damage response. Manipulations of H2Bub1 abundance showed that it was important for robust ATM and ATR signaling, efficient S-phase checkpoint, and suppression of mitotic transmission of unreplicated DNA and formation of micronuclei. Our findings identified H2B deubiquitination as a major FA-induced chromatin damage response that regulates S-phase checkpoint signaling and genome stability.

Predicting BRCA mutation and stratifying targeted therapy response using multimodal learning: a multicenter study

BACKGROUND

The status of BRCA1/2 genes plays a crucial role in the treatment decision-making process for multiple cancer types. However, due to high costs and limited resources, a demand for BRCA1/2 genetic testing among patients is currently unmet. Notably, not all patients with BRCA1/2 mutations achieve favorable outcomes with poly (ADP-ribose) polymerase inhibitors (PARPi), indicating the necessity for risk stratification. In this study, we aimed to develop and validate a multimodal model for predicting BRCA1/2 gene status and prognosis with PARPi treatment.

METHODS

We included 1695 slides from 1417 patients with ovarian, breast, prostate, and pancreatic cancers across three independent cohorts. Using a self-attention mechanism, we constructed a multi-instance attention model (MIAM) to detect BRCA1/2 gene status from hematoxylin and eosin (H&E) pathological images. We further combined tissue features from the MIAM model, cell features, and clinical factors (the MIAM-C model) to predict BRCA1/2 mutations and progression-free survival (PFS) with PARPi therapy. Model performance was evaluated using area under the curve (AUC) and Kaplan-Meier analysis. Morphological features contributing to MIAM-C were analyzed for interpretability.

RESULTS

Across the four cancer types, MIAM-C outperformed the deep learning-based MIAM in identifying the BRCA1/2 genotype. Interpretability analysis revealed that high-attention regions included high-grade tumors and lymphocytic infiltration, which correlated with BRCA1/2 mutations. Notably, high lymphocyte ratios appeared characteristic of BRCA1/2 mutations. Furthermore, MIAM-C predicted PARPi therapy response (log-rank p < 0.05) and served as an independent prognostic factor for patients with BRCA1/2-mutant ovarian cancer (p < 0.05, hazard ratio:0.4, 95% confidence interval: 0.16-0.99).

CONCLUSIONS

The MIAM-C model accurately detected BRCA1/2 gene status and effectively stratified prognosis for patients with BRCA1/2 mutations.

Long non-coding RNAs: roles in cellular stress responses and epigenetic mechanisms regulating chromatin

Most of the genome is transcribed into RNA but only 2% of the sequence codes for proteins. Non-coding RNA transcripts include a very large number of long noncoding RNAs (lncRNAs). A growing number of identified lncRNAs operate in cellular stress responses, for example in response to hypoxia, genotoxic stress, and oxidative stress. Additionally, lncRNA plays important roles in epigenetic mechanisms operating at chromatin and in maintaining chromatin architecture. Here, we address three lncRNA topics that have had significant recent advances. The first is an emerging role for many lncRNAs in cellular stress responses. The second is the development of high throughput screening assays to develop causal relationships between lncRNAs across the genome with cellular functions. Finally, we turn to recent advances in understanding the role of lncRNAs in regulating chromatin architecture and epigenetics, advances that build on some of the earliest work linking RNA to chromatin architecture.

p53-dependent crosstalk between DNA replication integrity and redox metabolism mediated through a NRF2-PARP1 axis

Mechanisms underlying p53-mediated protection of the replicating genome remain elusive, despite the quintessential role of p53 in maintaining genomic stability. Here, we uncover an unexpected function of p53 in curbing replication stress by limiting PARP1 activity and preventing the unscheduled degradation of deprotected stalled forks. We searched for p53-dependent factors and elucidated RRM2B as a prime factor. Deficiency in p53/RRM2B results in the activation of an NRF2 antioxidant transcriptional program, with a concomitant elevation in basal PARylation in cells. Dissecting the consequences of p53/RRM2B loss revealed a crosstalk between redox metabolism and genome integrity that is negotiated through a hitherto undescribed NRF2-PARP1 axis, and pinpoint G6PD as a primary oxidative stress-induced NRF2 target and activator of basal PARylation. This study elucidates how loss of p53 could be destabilizing for the replicating genome and, importantly, describes an unanticipated crosstalk between redox metabolism, PARP1 and p53 tumor suppressor pathway that is broadly relevant in cancers and can be leveraged therapeutically.

Early Onset Colorectal Cancer: Molecular Underpinnings Accelerating Occurrence

The onset of colorectal cancer (CRC) in patients younger than 50 continues to rapidly increase. This study highlights the epidemiologic changes, risk factors, clinical characteristics, and molecular profiles prevalent in early onset CRC patients, and identifies key areas for future research. It has been noted that only a small fraction of early onset CRC cases is attributed to known hereditary mutations and fit the canonical pathway of late-onset colorectal cancer development. To highlight this, we review the genetic and epigenetic modifications specific to early onset CRC. We also discuss the synergetic effect of single-nucleotide polymorphisms and environmental factors on the early onset of CRC. Additionally, we discuss the potential of noninvasive biomarker assays to enhance early detection, screening, diagnosis, and prognostic outcome predictions.

Nuclear porcupine mediates XRCC6/Ku70 S-palmitoylation in the DNA damage response

BACKGROUND

The activation of the DNA damage response (DDR) heavily relies on post-translational modifications (PTMs) of proteins, which play a crucial role in the prevention of genetic instability and tumorigenesis. Among these PTMs, palmitoylation is a highly conserved process that is dysregulated in numerous cancer types. However, its direct involvement in the DDR and the underlying mechanisms remain unclear.

METHODS

CRISPR-Cas9 technology was used to generate the PORCN KO and PORCN NLS KO cell lines. The effects of PORCN NLS in the DDR were verified by colony formation assays, MTT assays, the DR/EJ5 homologous recombination/non-homologous end-joining reporter system, xenograft tumor growth and immunofluorescence. Mechanisms were explored by mass spectrometry, acyl-biotin exchange (ABE) palmitoylation assay, Click-iT assay, cell subcellular fractionation assay, Western blot analysis, and in vivo and in vitro co-immunoprecipitation.

RESULTS

In this study, we introduce evidence that Porcupine (PORCN) is an integral component of and plays a critical role in the DDR. PORCN deficiency hampers nonhomologous end joining (NHEJ) and highly sensitizes cells to ionizing radiation (IR) both in vitro and in vivo. We also provide evidence that PORCN possesses a nuclear fraction (nPORCN) with S-acyltransferase activity, unlike its membrane-bound O-acyltransferase in the endoplasmic reticulum. Furthermore, we show that nPORCN is necessary for the successful activation of NHEJ. Using mass spectrometry, we reveal the existence of an nPORCN complex and show that nPORCN mediates the S-palmitoylation of XRCC6/Ku70 at five specific cysteine sites in response to IR. Mutation of these sites causes a substantial increase in radiosensitivity and delays NHEJ. Additionally, we present evidence that nPORCN-dependent Ku70 palmitoylation is required for DNA-PKcs/Ku70/Ku80 complex formation.

CONCLUSION

Our findings underscore the crucial role of nPORCN-dependent Ku70 S-palmitoylation in the DDR.

Advances in the Understanding of the Pathogenesis of Triple-Negative Breast Cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is a heterogeneous disease characterized by high aggressiveness, high malignancy, and poor prognosis compared to other breast cancer subtypes.

OBJECTIVE

This review aims to explore recent advances in understanding TNBC and to provide new insights and potential references for clinical treatment.

METHODS

We examined current literature on TNBC to analyze molecular subtypes, genetic mutations, signaling pathways, mechanisms of drug resistance, and emerging therapies.

RESULTS

Findings highlight key aspects of TNBC's molecular subtypes, relevant mutations, and pathways, alongside emerging treatments that target drug resistance mechanisms.

CONCLUSION

These insights into TNBC pathogenesis may help guide future therapeutic strategies and improve clinical outcomes for patients with TNBC.

From fallopian tube epithelium to high-grade serous ovarian cancer: A single-cell resolution review of sex steroid hormone signaling

High-grade serous ovarian cancer (HGSOC) represents the most lethal subtype of ovarian cancer, largely due to being commonly diagnosed at advanced stages. The early molecular mechanisms underlying ovarian carcinogenesis remain poorly defined, posing challenges to the development of prevention and early detection strategies. Here we dissect the molecular mechanisms of sex steroid hormone signaling throughout the decades-long evolution of HGSOC precursor lesions, which predominantly originate from secretory epithelial cells of fallopian tubes (FT). We also discuss the prognostic significance of sex steroid receptor isoforms and steroid metabolizing enzymes in HGSOCs. Finally, we provide a comprehensive gene expression atlases of sex steroid receptors, steroidogenic, and steroid-metabolizing enzymes across different cell populations in pre- and postmenopausal FTs, and HGSOCs, using published single-cell RNA sequencing datasets. These atlases reveal that secretory epithelial cells and stromal populations in FTs express sex steroid receptors and enzymes responsible for the formation and inactivation of genotoxic estrogen metabolites. In HGSOC, epithelial cells express various HSD17B isoforms and steroid conjugating enzymes, suggesting an enhanced ability to finely regulate the levels of bioactive sex steroids.

Effects of BRCA variation on prognosis in patients with nonmetastatic breast cancer

BACKGROUND

To compare the clinicopathological characteristics of nonmetastatic breast cancer patients with and without BRCA variations and to investigate the impact of BRCA variations on prognosis.

METHODS

This retrospective single-center study involved an analysis of 938 patients with localized or locally advanced breast cancer who underwent BRCA variation testing. The patients were divided into three groups: 757 were without BRCA variation, 64 were with BRCA1 variation, and 117 were with BRCA2 variation.

RESULTS

In patients with BRCA1 variation, the Ki67, grade, and frequency of triple-negative breast cancer were significantly higher than in patients without BRCA variation and with BRCA2 variation. The 5-year disease-free survival in patients with BRCA1 variation was significantly worse than the other two groups (without BRCA, BRCA1, and BRCA2; 87.7%, 69.9%, and 95.3%, respectively, p = 0.049). Multivariate analysis detected no significant difference between groups. The pathological complete response rates with neoadjuvant therapy were significantly better in patients with BRCA variations than those without BRCA variations (49.2% vs. 29.6%, p = 0.024).

CONCLUSION

Patients with BRCA1 variation had more aggressive tumor characteristics, such as higher Ki67 and higher grade. Also, triple-negative breast cancer was more common. The presence of BRCA1 variation may worsen survival outcomes. Neoadjuvant treatment responses of patients with BRCA variations were significantly better, and neoadjuvant treatment may contribute to survival outcomes in nonmetastatic patients with BRCA variations.

Effects of BRCA1 overexpression via the NRF2 / HO1 / NQO1 pathway on oral cancer cells proliferation, migration, and apoptosis

Objective

Herein, we explored the influences of breast cancer susceptibility gene 1 (BRCA1) overexpression on oral cancer cells proliferation, migration, and apoptosis via evaluation of its interactions with nuclear factor erythroid 2-like 2 (NRF2).

Design

CAL-27 and DOK cells were transfected with a BRCA1 overexpressing lentivirus. Next, we utilized Western blot and quantitative real-time polymerase chain reaction (qRT-PCR) analyses to evaluate BRCA1, NRF2, and their target gene expressions. Using cell counting kit-8 (CCK-8) assessment, we assessed cell proliferation and a scratch test detected CAL-27 cell migration. Additionally, flow cytometry was employed used to examine cell apoptosis, while an enzyme-linked immunosorbent assa (ELISA) was employed for evaluation of 8-hydroxy-2'- deoxyguanosine (8-OHdG) expression. An immunohistochemical analysis was employed to determine the NRF2 target genes and Ki-67 expressions.

Results

BRCA1 overexpression increased the NRF2 and its target gene transcript and protein expressions. CCK-8 and scratch test results showed that BRCA1 overexpression decreased cell proliferation and weakened CAL-27 cell migratory ability. Flow cytometry results showed that BRCA1 overexpression promoted cell apoptosis in a time-dependent manner, while enzyme-linked immunosorbent assay results showed that BRCA1 overexpression decreased 8-OHdG expression levels in CAL-27 and DOK cells. Immunohistochemical analysis results showed higher expression of NRF2 target genes and Ki-67 in oral squamous cell carcinoma cells.

Conclusions

Experiments involving oral cancer cells confirmed that BRCA1 overexpression could up-regulate the NRF2 signalling pathway, reduce oxidative damage, and inhibit cell proliferation and other biological behaviours. The BRCA1 and NRF2 pathways might be associated with oral cancer occurrence and development.

Mitophagy: insights into its signaling molecules, biological functions, and therapeutic potential in breast cancer

Mitophagy, a form of selective autophagy that removes damaged or dysfunctional mitochondria, plays a crucial role in maintaining mitochondrial and cellular homeostasis. Recent findings suggest that defective mitophagy is closely associated with various diseases, including breast cancer. Moreover, a better understanding of the multifaceted roles of mitophagy in breast cancer progression is crucial for the treatment of this disease. Here, we will summarize the molecular mechanisms of mitophagy process. In addition, we highlight the expression patterns and roles of mitophagy-related signaling molecules in breast cancer progression and the potential implications of mitophagy for the development of breast cancer, aiming to provide better therapeutic strategies for breast cancer treatment.

An interpretable deep learning model for detecting BRCA pathogenic variants of breast cancer from hematoxylin and eosin-stained pathological images

Background

Determining the status of breast cancer susceptibility genes (BRCA) is crucial for guiding breast cancer treatment. Nevertheless, the need for BRCA genetic testing among breast cancer patients remains unmet due to high costs and limited resources. This study aimed to develop a Bi-directional Self-Attention Multiple Instance Learning (BiAMIL) algorithm to detect BRCA status from hematoxylin and eosin (H&E) pathological images.

Methods

A total of 319 histopathological slides from 254 breast cancer patients were included, comprising two dependent cohorts. Following image pre-processing, 633,484 tumor tiles from the training dataset were employed to train the self-developed deep-learning model. The performance of the network was evaluated in the internal and external test sets.

Results

BiAMIL achieved AUC values of 0.819 (95% CI [0.673-0.965]) in the internal test set, and 0.817 (95% CI [0.712-0.923]) in the external test set. To explore the relationship between BRCA status and interpretable morphological features in pathological images, we utilized Class Activation Mapping (CAM) technique and cluster analysis to investigate the connections between BRCA gene mutation status and tissue and cell features. Significantly, we observed that tumor-infiltrating lymphocytes and the morphological characteristics of tumor cells appeared to be potential features associated with BRCA status.

Conclusions

An interpretable deep neural network model based on the attention mechanism was developed to predict the BRCA status in breast cancer. Keywords: Breast cancer, BRCA, deep learning, self-attention, interpretability.

Mechanism of BCDX2-mediated RAD51 nucleation on short ssDNA stretches and fork DNA

Homologous recombination (HR) factors are crucial for DSB repair and processing stalled replication forks. RAD51 paralogs, including RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3, have emerged as essential tumour suppressors, forming two subcomplexes, BCDX2 and CX3. Mutations in these genes are associated with cancer susceptibility and Fanconi anaemia, yet their biochemical activities remain unclear. This study reveals a linear arrangement of BCDX2 subunits compared to the RAD51 ring. BCDX2 shows a strong affinity towards single-stranded DNA (ssDNA) via unique binding mechanism compared to RAD51, and a contribution of DX2 subunits in binding branched DNA substrates. We demonstrate that BCDX2 facilitates RAD51 loading on ssDNA by suppressing the cooperative requirement of RAD51 binding to DNA and stabilizing the filament. Notably, BCDX2 also promotes RAD51 loading on short ssDNA and reversed replication fork substrates. Moreover, while mutants defective in ssDNA binding retain the ability to bind branched DNA substrates, they still facilitate RAD51 loading onto reversed replication forks. Our study provides mechanistic insights into how the BCDX2 complex stimulates the formation of BRCA2-independent RAD51 filaments on short stretches of ssDNA present at ssDNA gaps or stalled replication forks, highlighting its role in genome maintenance and DNA repair.

Deletions Rate-Limit Breast and Ovarian Cancer Initiation

Optimizing prevention and early detection of cancer requires understanding the number, types and timing of driver mutations. To quantify this, we exploited the elevated cancer incidence and mutation rates in germline BRCA1 and BRCA2 (gBRCA1/2) carriers. Using novel statistical models, we identify genomic deletions as the likely rate-limiting mutational processes, with 1-3 deletions required to initiate breast and ovarian tumors. gBRCA1/2-driven hereditary and sporadic tumors undergo convergent evolution to develop a similar set of driver deletions, and deletions explain the elevated cancer risk of gBRCA1/2-carriers. Orthogonal mutation timing analysis identifies deletions of chromosome 17 and 13q as early, recurrent events. Single-cell analyses confirmed deletion rate differences in gBRCA1/2 vs. non-carrier tumors as well as cells engineered to harbor gBRCA1/2. The centrality of deletion-associated chromosomal instability to tumorigenesis shapes interpretation of the somatic evolution of non-malignant tissue and guides strategies for precision prevention and early detection.

Real-World Evidence on Prescribing Patterns and Clinical Outcomes of Metastatic Breast Cancer Patients Treated with PARP Inhibitors: The Mayo Clinic Experience

PURPOSE

This study evaluates real-world outcomes, toxicities, and prescribing patterns of PARP inhibitors (PARPis) for the treatment of metastatic breast cancer (MBC).

PATIENTS AND METHODS

Electronic health records of 62 MBC patients treated with olaparib (n = 48) or talazoparib (n = 14) at Mayo Clinic System between 2017 and 2022 were analyzed. Time-to-treatment-failure (TTF) was assessed utilizing the Kaplan-Meier method. Predictors of TTF were identified in a multivariate Cox-proportional hazard regression model adjusting for relevant tumor and demographic characteristics.

RESULTS

Among 62 patients who received PARPis for MBC, 55 had germline (g) pathogenic variants (PVs) (gBRCA1 = 24, gBRCA2 = 26, and gPALB2 = 4) and 8 patients had somatic (s) PVs (sBRCA1 = 4, sBRCA2 = 2, sATM = 1, sCDKN2A = 1). Median TTF in the gBRCA1, gBRCA2, and gPALB2 PV carriers were 7, 8, and 9 months, respectively (P = .37). Complete or partial responses were observed among 51.8% of patients with gBRCA or gPALB2 PVs. In multivariate analysis, HER2 positivity (hazard ratio, HR: 4.9, P = .007) and somatic PVs in homologous recombination repair (HRR) genes other than BRCA (sATM or sCDKN2A) (HR: 11.7, P = .01) were associated with a shorter TTF. No significant difference in TTF was observed by the type of PARPi, estrogen and progesterone receptor status, age, or number of prior therapies. Eight (16.7%) patients receiving olaparib and seven (50%) receiving talazoparib required dose reductions due to toxicities.

CONCLUSIONS

In real-world practice, PARPis are well-tolerated with promising TTF in gBRCA1/2 and gPALB2 carriers. Further studies will delineate the clinical efficacy of PARPis in other MBC subsets, such as sBRCA mutations, HER2-positive disease, and CNS metastasis.

An Analysis of Genetic Polymorphisms in 76 Genes Related to the Development of Ovarian Tumors of Different Aggressiveness

Borderline ovarian tumors (BOTS) are rare neoplasms of intermediate aggressiveness between cystadenomas and low-grade ovarian cancers (lgOvCa), which they share some molecular resemblances with. In contrast to the most frequent and well-described high-grade ovarian carcinomas (hgOvCa), the molecular background of BOTS and lgOvCa is less thoroughly characterized. Here, we aimed to analyze genetic variants in crucial tumor suppressors and oncogenes in BOTS (with or without the BRAF V600E mutation), lgOvCa, and hgOvCa in two gene panels using next-generation sequencing. Then, we verified the existence of selected polymorphisms by Sanger sequencing. Finally, Western blot analyses were carried out to check the impact of the selected polymorphisms on the expression of the corresponding proteins. Our study contributes to the molecular characterization of ovarian neoplasms, demonstrating divergent polymorphic patterns pointing to distinct signaling pathways engaged in their development. Certain mutations seem to play an important role in BOTS without the BRAF V600E variant (KRAS) and in lgOvCa (KRAS and NRAS), but not in hgOvCa. Additionally, based on multivariable regression analyses, potential biomarkers in BOTS (PARP1) and hgOvCa (FANCI, BRCA2, TSC2, FANCF) were identified. Noteworthy, for some of the analyzed genes, such as FANCI, FANCD2, and FANCI, FANCF, TSC2, the status of BRCA1/2 and TP53, respectively, turned out to be crucial. Our results shed new light on the similarities and differences in the polymorphic patterns between ovarian tumors of diverse aggressiveness. Furthermore, the biomarkers identified herein are of potential use as predictors of the prognosis and/or response to therapy.

Deubiquitinating enzyme USP28 inhibitor AZ1 alone and in combination with cisplatin for the treatment of non-small cell lung cancer

Lung cancer is one of the most common malignant tumors. Despite decades of research, the treatment of lung cancer remains challenging. Non-small cell lung cancer (NSCLC) is the primary type of lung cancer and is a significant focus of research in lung cancer treatment. The deubiquitinase ubiquitin-specific protease 28 (USP28) plays a role in the progression of various tumors and serves as a potential therapeutic target. This study aims to determine the role of USP28 in the progression of NSCLC. We examined the impact of the USP28 inhibitor AZ1 on the cell cycle, apoptosis, DNA damage response, and cellular immunogenicity in non-small cell lung cancer. We observed that AZ1 and siUSP28 induce DNA damage, leading to the activation of Noxa-mediated mitochondrial apoptosis. The dsDNA and mtDNA released from DNA damage and mitochondrial apoptosis activate tumor cell immunogenicity through the cGAS-STING signaling pathway. Simultaneously, targeting USP28 promotes the degradation of c-MYC, resulting in cell cycle arrest and inhibition of DNA repair. This further promotes DNA damage-induced cell apoptosis mediated by the Noxa protein, thereby enhancing tumor cell immunogenicity mediated by dsDNA and mtDNA. Moreover, we found that the combination of AZ1 and cisplatin (DDP) can enhance therapeutic efficacy, thereby providing a new strategy to overcome cisplatin resistance in NSCLC. These findings suggest that targeting USP28 and combining it with cisplatin are feasible strategies for treating NSCLC.

Genetics of prostate cancer: a review of latest evidence

Prostate cancer (PrCa) is a largely heritable and polygenic disease. It is the most common cancer in people with prostates (PwPs) in Europe and the USA, including in PwPs of African descent. In the UK in 2020, 52% of all cancers were diagnosed at stage I or II. The National Health Service (NHS) long-term plan is to increase this to 75% by 2028, to reduce absolute incidence of late-stage disease. In the absence of a UK PrCa screening programme, we should explore how to identify those at increased risk of clinically significant PrCa.Incorporating genomics into the PrCa screening, diagnostic and treatment pathway has huge potential for transforming patient care. Genomics can increase efficiency of PrCa screening by focusing on those with genetic predisposition to cancer-which when combined with risk factors such as age and ethnicity, can be used for risk stratification in risk-based screening (RBS) programmes. The goal of RBS is to facilitate early diagnosis of clinically significant PrCa and reduce overdiagnosis/overtreatment in those unlikely to experience PrCa-related symptoms in their lifetime. Genetic testing can guide PrCa management, by identifying those at risk of lethal PrCa and enabling access to novel targeted therapies.PrCa is curable if diagnosed below stage III when most people do not experience symptoms. RBS using genetic profiling could be key here if we could show better survival outcomes (or reduction in cancer-specific mortality accounting for lead-time bias), in addition to more cost efficiency than age-based screening alone. Furthermore, PrCa outcomes in underserved communities could be optimised if genetic testing was accessible, minimising health disparities.

Widening the spectrum of players affected by genetic changes in Wilms tumor relapse

Few studies investigated the genetics of relapsed Wilms tumor (WT), suggesting the SIX1 gene, the microRNA processing genes, and the MYCN network as possibly involved in a relevant percentage of relapses. We investigated 28 relapsing WT patients (10 new cases and 18 cases in which the involvement of SIX and miRNAPG had been excluded) with a panel of ∼5000 genes. We identified variants affecting genes involved in DNA damage prevention and repair in 12/28 relapsing patients (42.9%), and affecting genes involved in chromatin modification and regulation in 6/28 relapsing patients (21.4%), widening the spectrum of anomalies detected in relapsed tumors. The disclosure of molecular pathways possibly underlying tumor progression might allow to use molecularly targeted therapies at relapse. Surprisingly, germline anomalies, mostly affecting DNA damage prevention and repair genes, were identified in 13/28 patients (46.4%), raising the issue of performing a genetic testing to all children presenting with a WT.

Direct DNA binding by BRCA1 on β-hCG promoter and its clinical implications

Objective

The role of β-hCG in breast cancer is largely unknown, this study aims to analyse the gene expression and clinical implications of β-hCG and its isoforms in various cancers focussing particularly in Breast Invasive Carcinoma (BRCA). A mechanistic approach deciphering the transcriptional regulation of β-hCG by BRCA1 was also explored.

Methods

Data from various comprehensive gene expression platforms like UALCAN, GEPIA2, GENT2, TIMER2, LinkedOmics, and STRING were used to analyse the expression of β-hCG and its clinical implications; Immunohistochemistry and ELISA for β-hCG expression analysis from human breast cancer patients; Electrophoretic mobility shift assay (EMSA) to analyse the direct binding of BRCA1 on β-hCG; Immunoblotting and Luciferase assay to understand the regulation of β-hCG by p53 were performed.

Results

Results from UALCAN and GENT2 gene expression cancer database revealed that TNBC subtypes and high-grade metaplastic carcinoma shows elevated expression of β-hCG and infiltration of various immune cells were also identified in BRCA by TIMER2. It was observed that most of the isoforms of β-hCG (CGB) are upregulated in breast cancers irrespective of hormonal status when BRCA1 gene is mutated according to TIMER2. Similar results were observed with Lymphoid neoplasm diffuse large B-cell lymphoma (LGG) and DLBC (Brain lower grade glioma) when BRCA1 is mutated. These results correlate with our earlier reports indicating expression of β-hCG in BRCA1 defective condition. We have also identified direct binding of BRCA1 on β-hCG promoter.

Conclusion

All these findings demonstrate the importance of β-hCG as a potential target in BRCA1-deficient carcinomas.

Hyper-recombination in ribosomal DNA is driven by long-range resection-independent RAD51 accumulation

Ribosomal DNA (rDNA) encodes the ribosomal RNA genes and represents an intrinsically unstable genomic region. However, the underlying mechanisms and implications for genome integrity remain elusive. Here, we use Bloom syndrome (BS), a rare genetic disease characterized by DNA repair defects and hyper-unstable rDNA, as a model to investigate the mechanisms leading to rDNA instability. We find that in Bloom helicase (BLM) proficient cells, the homologous recombination (HR) pathway in rDNA resembles that in nuclear chromatin; it is initiated by resection, replication protein A (RPA) loading and BRCA2-dependent RAD51 filament formation. However, BLM deficiency compromises RPA-loading and BRCA1/2 recruitment to rDNA, but not RAD51 accumulation. RAD51 accumulates at rDNA despite depletion of long-range resection nucleases and rDNA damage results in micronuclei when BLM is absent. In summary, our findings indicate that rDNA is permissive to RAD51 accumulation in the absence of BLM, leading to micronucleation and potentially global genomic instability.

The intersection of homologous recombination (HR) and mismatch repair (MMR) pathways in DNA repair-defective tumors

Homologous recombination (HR) and mismatch repair (MMR) defects are driver mutational imprints and actionable biomarkers in DNA repair-defective tumors. Although usually thought as mutually exclusive pathways, recent preclinical and clinical research provide preliminary evidence of a functional crosslink and crosstalk between HRR and MMR. Shared core proteins are identified as key players in both pathways, broadening the concept of DNA repair mechanism exclusivity in specific tumor types. These observations may result in unexplored forms of synthetic lethality or hypermutable tumor phenotypes, potentially impacting the cancer risk management, and considerably expanding in the future the therapeutic window for DNA repair-defective tumors.

BRCA genetic testing and counseling in breast cancer: how do we meet our patients' needs?

BRCA1 and BRCA2 are tumor suppressor genes that have been linked to inherited susceptibility of breast cancer. Germline BRCA1/2 pathogenic or likely pathogenic variants (gBRCAm) are clinically relevant for treatment selection in breast cancer because they confer sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors. BRCA1/2 mutation status may also impact decisions on other systemic therapies, risk-reducing measures, and choice of surgery. Consequently, demand for gBRCAm testing has increased. Several barriers to genetic testing exist, including limited access to testing facilities, trained counselors, and psychosocial support, as well as the financial burden of testing. Here, we describe current implications of gBRCAm testing for patients with breast cancer, summarize current approaches to gBRCAm testing, provide potential solutions to support wider adoption of mainstreaming testing practices, and consider future directions of testing.

ATR, CHK1 and WEE1 inhibitors cause homologous recombination repair deficiency to induce synthetic lethality with PARP inhibitors

PURPOSE

PARP inhibitors (PARPi) are effective in homologous recombination repair (HRR) defective (HRD) cancers. To (re)sensitise HRR proficient (HRP) tumours to PARPi combinations with other drugs are being explored. Our aim was to determine the mechanism underpinning the sensitisation to PARPi by inhibitors of cell cycle checkpoint kinases ATR, CHK1 and WEE1.

EXPERIMENTAL DESIGN

A panel of HRD and HRP cells (including matched BRCA1 or 2 mutant and corrected pairs) and ovarian cancer ascites cells were used. Rucaparib (PARPi) induced replication stress (RS) and HRR (immunofluorescence microscopy for γH2AX and RAD51 foci, respectively), cell cycle changes (flow cytometry), activation of ATR, CHK1 and WEE1 (Western Blot for pCHK1S345, pCHK1S296 and pCDK1Y15, respectively) and cytotoxicity (colony formation assay) was determined, followed by investigations of the impact on all of these parameters by inhibitors of ATR (VE-821, 1 µM), CHK1 (PF-477736, 50 nM) and WEE1 (MK-1775, 100 nM).

RESULTS

Rucaparib induced RS (3 to10-fold), S-phase accumulation (2-fold) and ATR, CHK1 and WEE1 activation (up to 3-fold), and VE-821, PF-477736 and MK-1775 inhibited their targets and abrogated these rucaparib-induced cell cycle changes in HRP and HRD cells. Rucaparib activated HRR in HRP cells only and was (60-1,000x) more cytotoxic to HRD cells. VE-821, PF-477736 and MK-1775 blocked HRR and sensitised HRP but not HRD cells and primary ovarian ascites to rucaparib.

CONCLUSIONS

Our data indicate that, rather than acting via abrogation of cell cycle checkpoints, ATR, CHK1 and WEE1 inhibitors cause an HRD phenotype and hence "induced synthetic lethality" with PARPi.

The treatment landscape of triple-negative breast cancer

Triple-negative breast cancer (TNBC) tumors are biologically aggressive breast cancer. On the molecular level, TNBC is a highly heterogeneous disease; more biotechnologies are gradually being used to advance the understanding of TNBC subtypes and help establish more targeted therapies. Multiple TNBC target-related agents are already approved by the Food and Drug Administration for clinical use, including PI3K/AKT/mTOR inhibitors, PRAP inhibitors, and antibody-drug conjugates. Some innovative approaches, like peptide strategies, also promise to treat TNBC. Currently, the interplay between TNBC tumors and their tumor microenvironment provides a promising prospect for improving the efficacy of immunotherapy. In this review, we summarize the prevalent TNBC subtype methodologies, discuss the evolving therapeutic strategies, and propose new therapeutic possibilities based on existing foundational theories, with the attempt to serve as a reference to further advance tailoring treatment of TNBC.

Triple-Negative Breast Cancer: Molecular Particularities Still a Challenge

Worldwide, breast cancer (BC) is one of the most common cancers in women and is responsible for the highest number of cancer-related deaths among women, with a special clinical behavior and therapy response. Triple-negative breast cancer (TNBC) is seen as a highly invasive BC, characterized by a short survival, higher mortality, recurrence, and metastasis when it is compared to the other BC subtypes. The molecular subtyping of TNBC based on mRNA expression levels does not accurately reflect protein expression levels, which impacts targeted therapy effectiveness and prognostic predictions. Most TNBC cases exhibit a high frequency of homologous recombination (HR) DNA repair deficiency (HRD) signatures and are associated with a complex genomic profile. Biomarker research in TNBC includes investigating genetic mutations, gene expression patterns, immune system-related markers, and other factors that can provide valuable information for diagnosis, treatment selection, and patient outcomes. Additionally, these biomarkers are often crucial in the development of personalized and precision medicine approaches, where treatments are customized to each patient's unique characteristics. This ongoing research is essential for improving the management and outcomes of TNBC, which is a challenging and heterogeneous form of breast cancer. The findings of this research have practical implications for refining treatment strategies, particularly in selecting appropriate systemic therapies and integrating traditional treatment modalities like surgery and radiotherapy into comprehensive care plans for TNBC patients.

Advancements in targeting tumor suppressor genes (p53 and BRCA 1/2) in breast cancer therapy

Globally, among numerous cancer subtypes, breast cancer (BC) is one of the most prevalent forms of cancer affecting the female population. A female's family history significantly increases her risk of developing breast cancer. BC is caused by aberrant breast cells that proliferate and develop into tumors. It is estimated that 5-10% of breast carcinomas are inherited and involve genetic mutations that ensure the survival and prognosis of breast cancer cells. The most common genetic variations are responsible for hereditary breast cancer but are not limited to p53, BRCA1, and BRCA2. BRCA1 and BRCA2 are involved in genomic recombination, cell cycle monitoring, programmed cell death, and transcriptional regulation. When BRCA1 and 2 genetic variations are present in breast carcinoma, p53 irregularities become more prevalent. Both BRCA1/2 and p53 genes are involved in cell cycle monitoring. The present article discusses the current status of breast cancer research, spotlighting the tumor suppressor genes (BRCA1/2 and p53) along with structural activity relationship studies, FDA-approved drugs, and several therapy modalities for treating BC. Breast cancer drugs, accessible today in the market, have different side effects including anemia, pneumonitis, nausea, lethargy, and vomiting. Thus, the development of novel p53 and BRCA1/2 inhibitors with minimal possible side effects is crucial. We have covered compounds that have been examined subsequently (2020 onwards) in this overview which may be utilized as lead compounds. Further, we have covered mechanistic pathways to showcase the critical druggable targets and clinical and post-clinical drugs targeting them for their utility in BC.

ARTEMIS: An independently validated prognostic prediction model of breast cancer incorporating epigenetic biomarkers with main effects and gene-gene interactions

INTRODUCTION

Breast cancer, a heterogeneous disease, is influenced by multiple genetic and epigenetic factors. The majority of prognostic models for breast cancer focus merely on the main effects of predictors, disregarding the crucial impacts of gene-gene interactions on prognosis.

OBJECTIVES

Using DNA methylation data derived from nine independent breast cancer cohorts, we developed an independently validated prognostic prediction model of breast cancer incorporating epigenetic biomarkers with main effects and gene-gene interactions (ARTEMIS) with an innovative 3-D modeling strategy. ARTEMIS was evaluated for discrimination ability using area under the receiver operating characteristics curve (AUC), and calibration using expected and observed (E/O) ratio. Additionally, we conducted decision curve analysis to evaluate its clinical efficacy by net benefit (NB) and net reduction (NR). Furthermore, we conducted a systematic review to compare its performance with existing models.

RESULTS

ARTEMIS exhibited excellent risk stratification ability in identifying patients at high risk of mortality. Compared to those below the 25th percentile of ARTEMIS scores, patients with above the 90th percentile had significantly lower overall survival time (HR = 15.43, 95% CI: 9.57-24.88, P = 3.06 × 10-29). ARTEMIS demonstrated satisfactory discrimination ability across four independent populations, with pooled AUC3-year = 0.844 (95% CI: 0.805-0.883), AUC5-year = 0.816 (95% CI: 0.775-0.857), and C-index = 0.803 (95% CI: 0.776-0.830). Meanwhile, ARTEMIS had well calibration performance with pooled E/O ratio 1.060 (95% CI: 1.038-1.083) and 1.090 (95% CI: 1.057-1.122) for 3- and 5-year survival prediction, respectively. Additionally, ARTEMIS is a clinical instrument with acceptable cost-effectiveness for detecting breast cancer patients at high risk of mortality (Pt = 0.4: NB3-year = 19‰, NB5-year = 62‰; NR3-year = 69.21%, NR5-year = 56.01%). ARTEMIS has superior performance compared to existing models in terms of accuracy, extrapolation, and sample size, as indicated by the systematic review. ARTEMIS is implemented as an interactive online tool available at http://bigdata.njmu.edu.cn/ARTEMIS/.

CONCLUSION

ARTEMIS is an efficient and practical tool for breast cancer prognostic prediction.

Nutrition Intervention and Microbiome Modulation in the Management of Breast Cancer

Breast cancer (BC) is one of the most common cancers worldwide and a leading cause of cancer-related deaths among women. The escalating incidence of BC underscores the necessity of multi-level treatment. BC is a complex and heterogeneous disease involving many genetic, lifestyle, and environmental factors. Growing evidence suggests that nutrition intervention is an evolving effective prevention and treatment strategy for BC. In addition, the human microbiota, particularly the gut microbiota, is now widely recognized as a significant player contributing to health or disease status. It is also associated with the risk and development of BC. This review will focus on nutrition intervention in BC, including dietary patterns, bioactive compounds, and nutrients that affect BC prevention and therapeutic responses in both animal and human studies. Additionally, this paper examines the impacts of these nutrition interventions on modulating the composition and functionality of the gut microbiome, highlighting the microbiome-mediated mechanisms in BC. The combination treatment of nutrition factors and microbes is also discussed. Insights from this review paper emphasize the necessity of comprehensive BC management that focuses on the nutrition-microbiome axis.

Combination of the PARPi and ARSi in advanced castration resistant prostate cancer: a review of the recent phase III trials

Tumors with an impaired ability to repair DNA double-strand breaks by homologous recombination, including those with alterations in breast cancer 1 and 2 (BRCA1 and BRCA2) genes, are very sensitive to blocking DNA single-strand repair by inhibition of the poly (ADP-ribose) polymerase (PARP) enzyme. This provides the basis for a synthetic deadly strategy in the treatment of different types of cancer, such as prostate cancer (PCa). The phase 3 PROfound study was the first to lead to olaparib approval in patients with metastatic castration resistant PCa (mCRPC) and BRCA genes mutations. In recent years, the benefit of combination therapy consisted of a PARP inhibitor (PARPi) plus an androgen receptor signalling inhibitor (ARSi), was evaluated as first-line treatment of mCRPC, regardless of the mutational state of genes, participating in the homologous recombination repair (HRR). This review explores the role of PARPi in PCa and analyses the data of latest clinical trials exploring the PARPi-ARSi combinations, and how these results could change our clinical practice.