Project description:NGS-based multiple gene panel resequencing in combination with a high resolution CGH-array was used to identify genetic risk factors for hereditary breast and/or ovarian cancer in 237 high risk patients who were previously tested negative for pathogenic BRCA1/2 variants. All patients were screened for pathogenic variants in 94 different cancer predisposing genes. We identified 32 pathogenic variants in 14 different genes (ATM, BLM, BRCA1, CDH1, CHEK2, FANCG, FANCM, FH, HRAS, PALB2, PMS2, PTEN, RAD51C and NBN) in 30 patients (12.7%). Two pathogenic BRCA1 variants that were previously undetected due to less comprehensive and sensitive methods were found. Five pathogenic variants are novel, three of which occur in genes yet unrelated to hereditary breast and/or ovarian cancer (FANCG, FH and HRAS). In our cohort we discovered a remarkably high frequency of truncating variants in FANCM (2.1%), which has recently been suggested as a susceptibility gene for hereditary breast cancer. Two patients of our cohort carried two different pathogenic variants each and ten other patients in whom a pathogenic variant was confirmed also harbored a variant of unknown significance in a breast and ovarian cancer susceptibility gene. We were able to identify pathogenic variants predisposing for tumor formation in 12.3% of BRCA1/2 negative breast and/or ovarian cancer patients.
Project description:Differentially expressed genes between BRCA1/BRCA2 negative and positive mutation driven-tumors. Screening for germline mutations was performed in a cohort of 55 patients under the age of 35 years in the BRCA1, BRCA2, CHEK2 (c.del1,100C) and TP53 genes, and the respective tumors were investigated regarding hormonal receptors status, HER2 expression. Transcriptional profiles were performed using Agilent one color hybridizations in a G4112F platform.
Project description:RNAseq was generated for a cohort of ovarian cancer patients to identify gene expression changes between primary and recurrent ovarian cancer tumors from patients with and without BRCA1/2 mutations
Project description:WGBS was generated for a cohort of ovarian cancer patients to identify DNA methylation changes between primary and recurrent ovarian cancer tumors from patients with and without BRCA1/2 mutations
Project description:BRCA1 functions in multiple biological processes, including double-strand break repair, replication stress suppression, transcriptional regulation, and chromatin reorganization. While non-malignant cells carrying cancer-predisposing BRCA1 mutations exhibit increased genomic instability, it remains unclear whether BRCA1 haploinsufficiency affects transcription and chromatin dynamics. Here we show that primary mammary epithelial cells from women with BRCA1 mutations (BRCA1mut/+) display significant loss of H3K27ac-associated super-enhancers.
Project description:Background: Normal cell BRCA1 epimutations have been associated with increased risk of triple-negative breast cancer (TNBC). However, the fraction of TNBCs that may have BRCA1 epimutations as their underlying cause is unknown. Neither are the time of occurrence and the potential inheritance patterns of BRCA1 epimutations established. Methods: To address these questions, we analyzed BRCA1 methylation status in breast cancer tissue and matched white blood cells (WBC) from 408 patients with 411 primary breast cancers, including 66 TNBCs, applying a highly sensitive sequencing assay, allowing allele-resolved methylation assessment. Further, to assess the time of origin and the characteristics of normal cell BRCA1 methylation, we analyzed umbilical cord blood of 1260 newborn girls and 200 newborn boys. Finally, we assessed BRCA1 methylation status among 575 mothers and 531 fathers of girls with (n = 102) and without (n = 473) BRCA1 methylation. Results: We found concordant tumor and mosaic WBC BRCA1 epimutations in 10 out of 66 patients with TNBC and in four out of six patients with estrogen receptor (ER)-low expression (<10%) tumors (combined: 14 out of 72; 19.4%; 95% CI 11.1–30.5). In contrast, we found concordance in only three out of 220 patients with 221 ER≥10% tumors and zero out of 114 patients with 116 HER2-positive tumors. Intraindividually, BRCA1 epimutations affected the same allele in normal and tumor cells. Assessing BRCA1 methylation in umbilical WBCs from girls, we found mosaic, predominantly monoallelic BRCA1 epimutations, with qualitative features similar to those in adults, in 113/1260 (9.0%) of individuals, but no correlation to BRCA1 methylation status either in mothers or fathers. A significantly lower fraction of newborn boys carried BRCA1 methylation (9 / 200; 4.5%) as compared to girls (p = 0.038). Similarly, WBC BRCA1 methylation was found less common among fathers (16/531; 3.0%), as compared to mothers (46 / 575; 8.0%; p = 0.0003). Conclusions: Our findings suggest prenatal BRCA1 epimutations might be the underlying cause of around 20% of TNBC and low-ER expression breast cancers. Such constitutional mosaic BRCA1 methylation likely arise through gender-related mechanisms in utero, independent of Mendelian inheritance.
Project description:While new defects in BRCA1 are still being found, it is unclear whether current breast cancer diagnostics misses many BRCA1-associated cases. A reliable test that is able to indicate the involvement of BRCA1 deficiency in cancer genesis could support decision making in genetic counselling and clinical management. To find BRCA1-specific markers and explore the effectiveness of the current diagnostic strategy, we designed a classification method, validated it and examined whether we could find BRCA1-like breast tumours in a group of patients initially diagnosed as non-BRCA1/2 mutation carriers. A classifier was built based on array-CGH profiles of 18 BRCA1-related and 32 control breast tumours, and validated on independent sets of 16 BRCA1-related and 16 control breast carcinomas. Subsequently, we applied the classifier to 48 breast tumours of patients from Hereditary Breast and Ovarian Cancer (HBOC) families in whom no germ line BRCA1/BRCA2 mutations were identified. The classifier showed an accuracy of 91% when applied to the validation sets. In 48 non-BRCA1/2 patients, only two breast tumours presented a BRCA1-like CGH profile. Additional evidence for BRCA1 dysfunction was found in one of these tumours. We here describe the specific chromosomal aberrations in BRCA1-related breast carcinomas. We developed a predictive genetic test for BRCA1-association and show that BRCA1-related tumours can still be identified in HBOC families after routine DNA diagnostics.
Project description:Mgbemena et al report that hematopoietic stem cells have an absolute requirement for Brca1 to survive. They also show that humanization of the mouse Brca1 e with a knocked-in BRCA1 cDNA, but not a mutant BRCA1/5382insC cDNA, fully substitutes for the mouse Brca1 during both embryonic development and hematopoiesis.
Project description:We report differential effects of mutations in genes of the homologous recombination (HR) pathway on response after ICB administration in mouse and human tumors, and show that truncating mutations in BRCA2 are associated with superior response to ICB compared to BRCA1-deficient tumors. Immunogenomic analyses demonstrated that mutations in BRCA1 and BRCA2 differentially modulate the tumor-immune microenvironment, with gene expression programs related to both adaptive and innate immune pathways enriched in BRCA2-deficient tumors. Single-cell RNA sequencing further revealed distinct T cell, NK, macrophage, and dendritic cell populations enriched in BRCA2 mutant tumors relative to BRCA1-deficient tumors.
Project description:Although PARP inhibitors (PARPi) now form part of the standard-of-care for the treatment of homologous recombination defective cancers, de novo and acquired resistance limits their overall effectiveness. Previously, overexpression of the BRCA1-∆11q splice variant has been shown to cause PARPi resistance. How cancer cells achieve increased BRCA1-∆11q expression has remained unclear. Using isogenic cells with different BRCA1 mutations, we show that reduction in HUWE1 leads to increased levels of BRCA1-∆11q and PARPi resistance. This effect is specific to cells able to express BRCA1-∆11q (e.g. BRCA1 exon 11 mutant cells) and is not seen in BRCA1 mutants that cannot express BRCA1-∆11q, nor in BRCA2 mutant cells. As well as increasing levels of BRCA1-∆11q protein in exon 11 mutant cells, HUWE1 silencing also restores RAD51 nuclear foci and platinum salt resistance. HUWE1 catalytic domain mutations were also seen in a case of PARPi resistant, BRCA1 exon 11 mutant, high grade serous ovarian cancer. These results suggest how elevated levels of BRCA1-∆11q and PARPi resistance can be achieved, identify HUWE1 as a candidate biomarker of PARPi resistance for assessment in future clinical trials and illustrate how some PARPi resistance mechanisms may only operate in patients with particular BRCA1 mutations.