High BRCA1 gene expression increases the risk of early distant metastasis in ER+ breast cancers

Although the function of the BRCA1 gene has been extensively studied, the relationship between BRCA1 gene expression and tumor aggressiveness remains controversial in sporadic breast cancers. Because the BRCA1 protein is known to regulate estrogen signaling, we selected microarray data of ER+ breast cancers from the GEO public repository to resolve previous conflicting findings. The BRCA1 gene expression level in highly proliferative luminal B tumors was shown to be higher than that in luminal A tumors. Survival analysis using a cure model indicated that patients of early ER+ breast cancers with high BRCA1 expression developed rapid distant metastasis. In addition, the proliferation marker genes MKI67 and PCNA, which are characteristic of aggressive tumors, were also highly expressed in patients with high BRCA1 expression. The associations among high BRCA1 expression, high proliferation marker expression, and high risk of distant metastasis emerged in independent datasets, regardless of tamoxifen treatment. Tamoxifen therapy could improve the metastasis-free fraction of high BRCA1 expression patients. Our findings link BRCA1 expression with proliferation and possibly distant metastasis via the ER signaling pathway. We propose a testable hypothesis based on these consistent results and offer an interpretation for our reported associations.

Long Non-Coding RNA Neighbor of BRCA1 Gene 2: A Crucial Regulator in Cancer Biology

Long non-coding RNAs (lncRNAs) are involved in fundamental biochemical and cellular processes. The neighbor of BRCA1 gene 2 (NBR2) is a long intergenic non-coding RNA (lincRNA) whose gene locus is adjacent to the tumor suppressor gene breast cancer susceptibility gene 1 (BRCA1). In human cancers, NBR2 expression is dysregulated and correlates with clinical outcomes. Moreover, NBR2 is crucial for glucose metabolism and affects the proliferation, survival, metastasis, and therapeutic resistance in different types of cancer. Here, we review the precise molecular mechanisms underlying NBR2-induced changes in cancer. In addition, the potential application of NBR2 in the diagnosis and treatment of cancer is also discussed, as well as the challenges of exploiting NBR2 for cancer intervention.

Genetic and epigenetic profiling of the BRCA1 / 2 genes in solitary ovarian cancer and multiple primary ovarian tumors

Background. Ovarian cancer is a complex and poorly studied disease that kills nearly 70–80 % of patients. Therefore, practitioners are interested in any opportunity of improving survival of these patients. From this point of view, investigation of genetic and epigenetic functions associated with this pathology is quite promising.Objective: to assess clinical and morphological characteristics of tumors in ovarian cancer patients, considering the presence of mutations and methylation in the BRCA1/2 gene.Materials and methods. This study included 180 ovarian cancer patients (FIGO stage I–IV) treated in the N. N. Blokhin Russian Cancer Research Center between 2008 and 2019. Study participants were divided into 3 groups according to their BRCA status and the number of primary tumors. We collected and analyzed venous blood, biopsy samples of ovarian cancer, archived histological sections, and paraffin-embedded tissue blocks. DNA isolated from venous blood was used to identify the following germline mutation by pyrosequencing: BRCA1 5382insC, BRCA1 4153delA, BRCA1 185delAG, and BRCA26174delT. DNA isolated from biopsy specimens and paraffin-embedded tissue specimens was used to analyze methylation in the promoter regions of the BRCA1 and BRCA2 genes by bisulfite sequencing (PyroMark Q24 DNA Sequencer; Qiagen, USA) with specific primers targeting promoter regions of the BRCA1 and BRCA2 genes.Results. Molecular testing demonstrated that the frequency of BRCA1 gene mutations was 21.1 % (38/148) in patients with solitary ovarian cancer and 40.6 % (13/32) in patients with multiple primary ovarian cancers. The frequency of methylation of the BRCA1 gene promoter was 2.2 % (18/148) in patients with solitary ovarian cancer and 3.1 % (1 case) in patients with multiple primary ovarian cancers. All BRCA1 methylated ovarian tumors were serous adenocarcinomas, including high grade tumors in 15 patients (78.9 %) and low-grade tumors in 4 patients (21.1 %).Conclusion. Hypermethylation of the BRCA1 gene promoter was observed only in individuals with sporadic serous ovarian cancer. No methylation was detected in patients with non-serous ovarian cancer, as well as in patients carrying BRCA1 gene mutations (both with solitary ovarian cancer and with primary multiple ovarian tumors).

Cell-Free DNA Variant Sequencing Using Plasma and AR-V7 Testing of Circulating Tumor Cells in Prostate Cancer Patients

Prostate cancer (PCa) is the second most common malignant cancer and is a major cause of morbidity and mortality among men worldwide. There is still an urgent need for biomarkers applicable for diagnosis, prognosis, therapy prediction, or therapy monitoring in PCa. Liquid biopsies, including cell-free DNA (cfDNA) and circulating tumor cells (CTCs), are a valuable source for studying such biomarkers and are minimally invasive. In our study, we investigated the cfDNA of 34 progressive PCa patients, via targeted sequencing, for sequence variants and for the occurrence of CTCs, with a focus on androgen receptor splice variant 7 (AR-V7)-positive CTCs. The cfDNA content was associated with overall survival (OS; p = 0.014), disease-specific survival (DSS; p = 0.004), and time to treatment change (TTC; p = 0.001). Moreover, when considering all sequence variants grouped by their functional impact and allele frequency, a significant association with TTC (p = 0.017) was observed. When investigating only pathogenic or likely pathogenic gene variants, variants of the BRCA1 gene (p = 0.029) and the AR ligand-binding domain (p = 0.050) were associated with a shorter TTC. Likewise, the presence of CTCs was associated with a shorter TTC (p = 0.031). The presence of AR-V7-positive CTCs was associated with TTC (p < 0.001) in Kaplan–Meier analysis. Interestingly, all patients with AR-V7-positive CTCs also carried TP53 point mutations. Altogether, analysis of cfDNA and CTCs can provide complementary information that may support temporal and targeted treatment decisions and may elucidate the optimal choice within the variety of therapy options for advanced PCa patients.

Characterization of Potential Driver Genes Involved in Human Breast Cancer in Maysan Province, Iraq

Background: Breast cancer is a heterogeneous disease regarding its morphology, invasive behaviour, metastatic capacity, hormone receptor expression and clinical outcome. There are many risk factors for breast cancer, including genetic factors that account for 25-30% of the incidence; from this percentage, only 15-30% of the heritable component of breast cancer is due to known familiar highly penetrating genes, and the others are sporadic.Methods: This study was the first to include amplified genes as PCR templates to determine the relationship between their polymorphism and breast cancer incidence using RAPD of amplified genes. The study was designed first to evaluate the association of ABCG2, ABCB1 and BRCA1 gene polymorphisms in addition to miRNA-152 and ER-a using the RAPD technique with breast cancer incidence in Maysan Province women and second to use those genes as indicators for breast cancer prediction and diagnosis. The study included 100 patients with breast cancer and 30 healthy control women, and then all samples were amplified by conventional PCR with specific F and R primers for ABCG2, ABCB1, BRCA1, ER-α, and miRNA-152 genes. Then, the best PCR product (20) was chosen as the template for the RAPD technique.Results: The results revealed that all RAPD primers showed polymorphisms with higher values and more specific bands in patient samples. Our study proved the relationship between genetic polymorphisms of breast cancer-related genes and a higher incidence of cancer.Conclusion: The current study recommends employing these results for the future prediction and diagnosis of breast cancers.

EPCO-22. INHERITED POLYMORPHISM IN CHROMOSOME 8Q24 COOPERATES WITH MUTANT IDH1, Trp53 AND ATRX LOSS TO INDUCE LOW-GRADE GLIOMA

Establishing causal links between genetic polymorphisms and increased heritable risk of developing brain cancer is a major challenge. The non-coding single nucleotide polymorphism rs55705857 (A &gt;G) is associated with a ~6-fold increased risk to develop IDH-mutant low-grade glioma (LGG). The rs55705857 G allele has a minor allele frequency of only ~5% in the general population but is found in ~40% of patients with IDH-mutant LGG and patients carrying risk-alleles are diagnosed on average 7-12 years earlier than those carrying non-risk A alleles. This makes rs55705857 one of the highest reported genetic associations with cancer, comparable with inherited BRCA1 gene mutations and the risk of developing breast cancer or other familial glioma genes such as NF1/2, CDKN2A or p53. To generate a LGG mouse model, we combined clonal activation of IDH1R132H with mutations of Trp53 and Atrx, which resulted in the development of LGG-like brain tumors in 25% of mice. Mutating the highly conserved, orthologous mouse rs55705857 locus to mimic the human risk allele dramatically accelerated tumor development from 463 to 172 days and increased penetrance to 75%. The resulting tumors exhibit elevated R-2-hydroxyglutarate levels, well-differentiated fibrillary neoplastic histology and metabolic rewiring, recapitulating histopathological and molecular hallmarks of human LGG. Mechanistically, we show that the rs55705857 locus resides within a brain-specific enhancer, which shows enhanced activity in IDH-mutant tumors. In addition, we found that the risk allele disrupts OCT2/4 binding, allowing increased interaction with the Myc promoter and increased Myc expression. The hyperactive chromatin status combined with the tissue specificity of this enhancer explains the cooperativity between mutant IDH and rs55705857 and why rs55705857 is associated specifically with IDH-mutant glioma, but not other cancers. Overall, we generated new LGG mouse models, which provide insights into the pathophysiology of this deadly disease and shed light into the heritable predisposition to LGG development.

Identification and Characterization of New Alu Element Insertion in the BRCA1 Exon 14 Associated with Hereditary Breast and Ovarian Cancer

Hereditary breast and ovarian cancer syndrome (HBOC) is an autosomal dominant cancer predisposition syndrome characterized by an increased risk of breast and ovarian cancers. Germline pathogenic variants in BRCA1 are found in about 7–10% of all familial breast cancers and 10% of ovarian cancers. Alu elements are the most abundant mobile DNA element in the human genome and are known to affect the human genome by different mechanisms leading to human disease. We report here the detection, by next-generation sequencing (NGS) analysis coupled with a suitable bioinformatics pipeline, of an AluYb8 element in exon 14 of the BRCA1 gene in a family with HBOC history first classified as BRCA-negative by Sanger sequencing and first NGS analysis. The c.4475_c.4476insAluYb8 mutation impacts splicing and induces the skipping of exon 14. As a result, the produced mRNA contains a premature stop, leading to the production of a short and likely non-functional protein (pAla1453Glyfs*10). Overall, our study allowed us to identify a novel pathogenic variant in BRCA1 and showed the importance of bioinformatics tool improvement and versioning.