Breast Cancer BRCA2 Research Articles

Increased Rate of Phenocopies in All Age Groups in BRCA1/BRCA2 Mutation Kindred, but Increased Prospective Breast Cancer Risk Is Confined to BRCA2 Mutation Carriers

To establish, if among unaffected noncarrier relatives in a family with an established BRCA1/2 mutation, there is an increased risk of breast cancer. We identified 49 women with breast cancer who were first-degree relatives of a pathogenic mutation carrier among 807 BRCA1/2 families but who tested negative for the specific mutation. A prospective analysis of breast cancer from date of family ascertainment was performed for first-degree relatives of proven BRCA1/2 mutation carriers and compared with population-expected incidence rates. Women who prospectively test negative for BRCA1/2 mutations showed excess risk of breast cancer to be confined to BRCA2 noncarriers with an observed:expected (O/E) ratio of 4.57 [95% confidence interval (CI) 2.50-7.67; P < 0.0001; O/E in BRCA1 noncarriers, 1.77]; this dropped to 2.01 for BRCA2 [relative risk (RR), 1.99; 95% CI, 0.54-5.10] from date of predictive test. Genotyping of 18 breast cancer susceptibility single-nucleotide polymorphisms (SNP) defined an RR of 1.31 for BRCA2 breast cancer phenocopies with a breast cancer diagnosis at age less than 60 years. Noncarriers remain at risk in the prospective follow-up of women who tested negative for BRCA1/2. Women testing negative in BRCA2 families may have increased risk of breast cancer compared with population levels, particularly with strong breast cancer history in close relatives. Any increased risk in BRCA1 families is likely to be insufficient to recommend additional interventions. Our work can help with counseling women from BRCA1/2 families who have tested negative, and could impact on how individual breast cancer risk is related back to these women.

MicroRNA signatures in hereditary breast cancer

This study aims to identify signatures of miR associated with hereditary, BRCA1 or BRCA2 mutation positive breast cancer (BC), and non-hereditary BC, either sporadic (SBC) or non-informative (BRCAX). Moreover, we search for signatures associated with tumor stage, immunohistochemistry and tumor molecular profile. Twenty formalin fixed paraffin embedded (FFPE) BCs, BRCA1, BRCA2, BRCAX and SBC, five per group were studied. Affymetrix platform miRNA v.3.0 was used to perform miR expression analysis. ER, PR, HER2 and Ki67 protein expression was analyzed by immunohistochemistry. BRCA1, BRCA2 and RASSF1 methylation analysis, AURKA copy number variations, and BRCA1 and BRCA2 deletions, were studied by MLPA. We validated eight of the miR selected by the arrays in 77 BCs by qRT-PCR. The miR profiles associated with tumor features were studied applying the Sparse Partial Least Squares Discriminant Analysis. MiR discrimination capability to distinguish hereditary and non-hereditary BC was analyzed by the discriminant function. With 15 out of 1,733 hsa-miRs, it was possible to differentiate the four groups. BRCA1, BRCA2 and SBC were associated with clusters of hyper-expressed miRs, and BRCAX with hypo-expressed miRs. Hsa-miR-4417 and hsa-miR-423-3p expressions (included among the eight validated miRs) differentiated 70.1 % of hereditary and non-hereditary BCs. We found miR profiles associated with tumor features like node involvement, histological grade, ER, PR and HER2 expression. Regarding molecular parameters, we only found a weak association of miRs in BC harboring losses in AURKA. We conclude that array miR expression profiles can differentiate the four study groups using FFPE BC. However, miRs expression estimated by qRT-PCR differentiates only hereditary and non-inherited BCs. The miR expression array is a simple and rapid approach that could be useful to facilitate the identification of those SBC carrying genetic or epigenetic changes in BRCA genes responsible of BRCA-like phenotype. These patients could benefit from the treatment with PARP inhibitors.

BRCA1 polymorphisms and breast cancer epidemiology in the Western New York Exposures and Breast Cancer (WEB) study

BRCA1 polymorphisms and breast cancer epidemiology in the Western New York Exposures and Breast Cancer (WEB) study

Genetic Counseling, Cancer Screening, Breast Cancer Characteristics, and General Health among a Diverse Population of BRCA Genetic Testers

Outcomes after genetic testing for hereditary breast and ovarian cancer (HBOC) syndrome have not been well studied in underserved populations. We surveyed 1,123 BRCA testers from a genetic counseling program serving an academic cancer center (n=1,045) and a public county hospital (n=78) a median of 3.7 years after testing for mutations in BRCA1 and BRCA2 (breast cancer susceptibility genes). We compared genetic counseling outcomes, cancer screening rates, and self-reported general health. We found no differences in genetic counseling outcomes between hospitals. Breast cancer screening rates were similarly high at both hospitals, which are warranted in this high-risk population. Screening rates for ovarian, colon, and skin cancer were significantly lower in participants from the public hospital. BRCA results were not a predictor of general health at either hospital. When creating a genetic counseling program that serves women in different hospital settings, providers should emphasize guidelines-based screening recommendations for all patients.

Prophylactic Mastectomy: A Treatment Alternative for Hodgkin Survivors?

The link between mantle (chest) radiation for the treatment of pediatric Hodgkin lymphoma and secondary malignant neoplasms in adulthood, especially breast cancer, has been known for several years.1-4 The elevated risk persists regardless of whether women received only high-dose radiation or the newer treatment regimen of lower dose radiation combined with chemotherapy5; it is highest, however, in those treated in their teens and early twenties with higher doses of radiation. Currently, survivors undergo annual to semiannual breast screenings with mammograms or breast magnetic resonance imaging (MRI), or both, similar to women with BRCA mutations.6-8 Recent publications have highlighted the increased risk of second malignancies in this patient population.9,10 New results from the Childhood Cancer Survivor Study show that women who received chest radiation for Hodgkin lymphoma were at nearly identical risk for the development of breast cancer as women who have BRCA1 mutations (31% vs. 30%) and had 3 times the risk of those with BRCA2 mutations by age 50 years.11 The risk of breast cancer developing in the general population is 4%. This study, one of the first to directly compare these large patient populations, presents the question of how Hodgkin survivors should be most effectively monitored and treated in adulthood in terms of breast cancer risk. Swerdlow et al also demonstrated cumulative risks of > 40% for women treated for Hodgkin lymphoma in their teens, regardless of radiation dosage.12 Although MRI may detect earlier breast cancer, it does not prevent the development of a second cancer. It is also less clear whether breast MRI screening affects mortality in this patient population. Aggressive surgery with mastectomy can be very effective in preventing breast cancer in BRCA1- and BRCA2-positive women. Offering BRCA-positive women the option of prophylactic bilateral mastectomy is becoming increasingly commonplace.13 In contrast, this appears to be more rarely discussed with Hodgkin survivors, based on the absence or extreme paucity of published articles on the subject, despite similarly alarming risks. With these most recent data, we are proposing that the option of prophylactic mastectomy should be discussed with Hodgkin survivors. The psychological toll of losing a sense of “womanhood” would still be a great barrier to overcome for these women, a major reason why many BRCA-positive women forego this treatment. However, unlike BRCA-positive women, Hodgkin survivors have additional complications such as breast tissue changes after radiation and the emotional and physical enduring effects of having already experienced cancer once. One can only hypothesize at this time whether prophylactic mastectomy would gain traction as a feasible preventive treatment alternative for Hodgkin survivors, but this therapeutic option should be explored with more patients. An educated discussion can and should take place between physicians and their patients about this alternative option. Furthermore, additional research into chemoprevention in this patient population is warranted. We wait excitedly for the results of the proposed use of tamoxifen as chemoprevention in this patient population (NCT00165308).14

Short Read (Next-Generation) Sequencing

Rapid advances in DNA sequencing technologies have made it increasingly cost-effective to obtain accurate and timely large-scale genomic sequence data on individuals (short read massively parallel or next generation [next-gen]). A next-gen molecular diagnostic approach that has seen rapid deployment in the clinic over the last year is exome sequencing. Whole exome sequencing covers all protein-coding genes in the genome (≈1.1% of genome), and an exome test for a single patient generates ≈6 gigabases (109 bp) of DNA sequence data. A key challenge facing routine use of next-gen data in patient diagnosis and management is data interpretation. What sequence variant findings are relevant to diagnosis (pathogenic mutations)? What sequence variant findings are relevant to clinical care but not necessarily to patient diagnosis (clinically actionable incidental data)? What sequence information should be stored, and where can it be stored? This review provides a tutorial on current approaches to answering these questions. A recent landmark study showed that application of next-gen sequencing to a large cohort of idiopathic dilated cardiomyopathy patients found ≈27% of patients to show mutations of the titin gene, the most complex gene in the genome (363 exons). We use titin in cardiomyopathy as an exemplar for explaining next-gen sequencing approaches and data interpretation. Decreasing sequencing costs and broad dissemination of next-generation (next-gen) equipment and expertise are increasing availability of massively parallel sequencing of patient DNA samples (short read massively parallel or next-gen sequencing).1,2 Most rapidly expanding is exome sequencing, where all protein-coding sequences (exons) are selected from total genomic DNA and selectively sequenced.3 Alternative approaches to next-gen sequencing include targeted sequencing (TS) and whole genome (complete genome) sequencing. Currently, marketed targeted Sanger sequencing panels using traditional individual exon-by-exon sequencing remain expensive and time consuming, and massively parallel next-gen approaches are beginning to supplant …

Proteomics of Genetically Engineered Mouse Mammary Tumors Identifies Fatty Acid Metabolism Members as Potential Predictive Markers for Cisplatin Resistance

In contrast to various signatures that predict the prognosis of breast cancer patients, markers that predict chemotherapy response are still elusive. To detect such predictive biomarkers, we investigated early changes in protein expression using two mouse models for distinct breast cancer subtypes who have a differential knock-out status for the breast cancer 1, early onset (Brca1) gene. The proteome of cisplatin-sensitive BRCA1-deficient mammary tumors was compared with that of cisplatin-resistant mammary tumors resembling pleomorphic invasive lobular carcinoma. The analyses were performed 24 h after administration of the maximum tolerable dose of cisplatin. At this time point, drug-sensitive BRCA1-deficient tumors showed DNA damage, but cells were largely viable. By applying paired statistics and quantitative filtering, we identified highly discriminatory markers for the sensitive and resistant model. Proteins up-regulated in the sensitive model are involved in centrosome organization, chromosome condensation, homology-directed DNA repair, and nucleotide metabolism. Major discriminatory markers that were up-regulated in the resistant model were predominantly involved in fatty acid metabolism, such as fatty-acid synthase. Specific inhibition of fatty-acid synthase sensitized resistant cells to cisplatin. Our data suggest that exploring the functional link between the DNA damage response and cancer metabolism shortly after the initial treatment may be a useful strategy to predict the efficacy of cisplatin.

Abstract 4316: A dynamic interplay of KSR1, p53 and BRCA1 in breast cancer.

Abstract Background: We have previously performed a human kinome screen and identified kinase suppressor of ras 1 (KSR1) as a potential regulator of estrogen receptor α (ERα) in breast cancer. Recent studies have suggested that KSR1, originally known as a positive modulator interacting with RAS and RAF in the MAPK pathway, may have dual functions as a scaffold protein and a kinase. Although KSR1 has been implicated in Ras-dependent cancers, its role in breast cancer has not been studied. Methods: The clinical significance of KSR1 levels and single nucleotide polymorphisms (SNPs) were assessed by analyzing its expression in tissue microarrays (n=1000) by immunohistochemistry in univariate and multivariate analyses. Expression of KSR1 in a panel of breast cancer cell lines were measured. A KSR1 stable over-expression breast cancer cell line (MCF7-KSR1) was generated to study its effects on growth and colony formation by 3D matrigel and soft agar assays. A xenograft mouse model was used to examine the effects of KSR1 on tumor development in vivo. Stable isotope labelling by amino acids in cell culture (SILAC) was used to analyse KSR1-regulated proteins and pathways. Additional molecular biology techniques (including immunoprecipitation, luciferase reporter and uibiquitination assay) were performed to study the action of KSR1 on p53 and BRCA1. Results: KSR1 was differentially expressed in breast cancer patients. High KSR1 expression correlated significantly with longer DFS (p=0.014) and OS (p=0.012) in &amp;gt; 20 yrs follow-up, independent of tumor stage, grade and size. KSR1 was associated positively with BRCA1 (p=0.002) and inversely with p53 levels (p=0.038). Two KSR1 SNPs’ were identified with no correlations with either DFS or OS. RT-qPCR and western blotting showed that KSR1 is ubiquitously expressed in breast cancer cell lines. In vitro 3D matrigel and soft agar assays revealed that MCF7-KSR1 had a significant decreased number of colonies and formed smaller size colonies compared to MCF7-parental cells. In vivo breast cancer mouse model showed tumor volumes of xenografts over-expressing KSR1 were significantly reduced compared to controls. SILAC analysis revealed various novel KSR1-regulated proteins and phospho-proteins in breast cancer. Our results showed over-expression of KSR1 decreases the transcriptional activity of p53 by reducing DBC1 phosphorylation, which leads to a reduced interaction of DBC1-SIRT1 and therefore allowing SIRT1 to deacetylate p53. Finally, KSR1 stabilizes BRCA1 by up-regulating BARD1 and promoting the interaction of BRCA1-BARD1. Conclusion: KSR1 is an independent prognostic factor in breast cancer; high KSR1 correlates with longer DFS and OS. KSR1 over-expression inhibits tumor formation and growth in vitro and in vivo. KSR1 is part of a dynamic interplay with p53 and BRCA1; it reduces p53 transcriptional activity by abolishing the interaction of SIRT1-DBC1, while it stabilizes BRCA1 by enhancing BRCA1-BARD1 interaction. Citation Format: Hua Zhang, Justin Stebbing, Aleksandra Filipovic, Ian O. Ellis, Heinz-Josef Lenz, Georgios Giamas. A dynamic interplay of KSR1, p53 and BRCA1 in breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4316. doi:10.1158/1538-7445.AM2013-4316

Abstract 1779: BRCA2 interacts with an essential replication factor, MCM10.

Abstract The BRCA2 (Breast Cancer 2, early onset) gene is implicated in a variety of familial cancers. Loss of BRCA2 function results in severe defects in DNA double-strand break repair, DNA damage-induced checkpoint response and the stability of stalled DNA replication forks, all of which are important for genomic stability. About 50% of BRCA2 is associated with PALB2 (partner and localizer of BRCA2), which anchors BRCA2 onto chromatin and directs its recruitment to DNA damage sites. By tandem affinity purification of PALB2 we identified MCM10, an essential DNA replication factor, as a component of the PALB2/BRCA2 complex. MCM10 promotes initiation of DNA replication through binding to MCM2-7 helicase complex and recruiting the initial DNA polymerase, pol α, to replication origins. Interestingly, we found that MCM10 binds to BRCA2 instead of PALB2 in the complex. Cells depleted of BRCA2 or MCM10 showed similar instability of stalled replication forks, indicating possible cooperation between the two proteins in fork stabilization following replication stress. Moreover, DNA damage-induced CHK1 activation is markedly reduced in both BRCA2- and MCM10-depleted cells even though RPA (replication protein A) is hyperphosphorylated. Our findings suggest that BRCA2 checkpoint function may be mediated through MCM10 and their interaction may be important for stalled replication fork stability. Domain mapping experiments showed that an evolutionarily conserved coiled-coil motif in the N-terminus of MCM10 which is required for BRCA2 binding and that BRCA2 has at least two MCM10-binding sites, both in its central region. BRCA2 and MCM10 mutants lacking these interaction domains will be used to further test the functional relevance of their interaction. Citation Format: Allen L. Alcivar, Jianglin Ma, Bing Xia. BRCA2 interacts with an essential replication factor, MCM10. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1779. doi:10.1158/1538-7445.AM2013-1779

Genetic Susceptibility to Triple-Negative Breast Cancer

Triple-negative breast cancers (TNBC), defined by the absence of estrogen receptor, progesterone receptor, and HER-2 expression, account for 12% to 24% of all breast cancers. TNBC is associated with early recurrence of disease and poor outcome. Germline mutations in the BRCA1 and BRCA2 breast cancer susceptibility genes have been associated with up to 15% of TNBC, and TNBC accounts for 70% of breast tumors arising in BRCA1 mutation carriers and 16% to 23% of breast tumors in BRCA2 carriers. Whether germline mutations in other breast cancer susceptibility genes also predispose to TNBC remains to be determined. Common variation in a subset of the 72 known breast cancer susceptibility loci identified through genome-wide association studies and other large-scale genotyping efforts have also been associated with risk of TNBC (TOX3, ESR1, RAD51L1, TERT, 19p13.1, 20q11, MDM4, 2p24.1, and FTO). Furthermore, variation in the 19p13.1 locus and the MDM4 locus has been associated with TNBC, but not other forms of breast cancer, suggesting that these are TNBC-specific loci. Thus, TNBC can be distinguished from other breast cancer subtypes by a unique pattern of common and rare germline predisposition alleles. Additional efforts to combine genetic and epidemiologic data are needed to better understand the etiology of this aggressive form of breast cancer, to identify prevention and therapeutic targets, and to impact clinical practice through the development of risk prediction models.

Involvement of IGF-1R regulation by miR-515-5p modifies breast cancer risk among BRCA1 carriers

Several lines of evidence indicate that sequence alterations within microRNA (miRNA)-binding sites can modify the binding to its target gene resulting in altered expression patterns. We hypothesized that a single nucleotide polymorphism (SNP) located in the miR-515-5p binding site of igf-1r gene may alter IGF-1R regulation, with consequent effects on breast cancer risk in BRCA1 mutation carriers. Computational prediction revealed that the rs28674628 SNP in the igf-1r 3' UTR is located within a predicted binding site for miR-515-5p. The effect of this SNP on breast cancer risk was evaluated by genotyping 115 Jewish Ashkenazi carriers of the 185delAG mutation in the BRCA1 gene using the Sequenom platform followed by Kaplan-Meier analysis. Additional data set of 378 Jewish BRCA1 carriers was analyzed to validate our results. MiRNA transfection, Western blot analysis, luciferase reporter assay, real time PCR, and immunohistochemistry were performed to assess direct regulation of igf-1r by miR-515-5p. We show direct regulation of IGF-1R by miR-515-5p. We identified that disrupting miR-515-5p and igf-1r 3' UTR binding by SNP may cause elevated IGF-1R protein levels. Interestingly, miR-515-5p is downregulated in tumor tissue compared to its non-neoplastic surrounding tissue while IGF-1R levels are elevated. This igf-1r SNP was found to be significantly associated with age at diagnosis of breast cancer in Jewish Ashkenazi BRCA1 mutation carriers. These findings support the hypothesis that a SNP located in igf-1r gene may alter miRNA regulation of IGF-1R, with a putative effect on BRCA1 penetrance and breast cancer risk.

Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk

BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10−8, HR = 1.14, 95% CI: 1.09–1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10−8, HR = 1.27, 95% CI: 1.17–1.38) and 4q32.3 (rs4691139, P = 3.4×10−8, HR = 1.20, 95% CI: 1.17–1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific association. The 17q21.31 locus was also associated with ovarian cancer risk in 8,211 BRCA2 carriers (P = 2×10−4). These loci may lead to an improved understanding of the etiology of breast and ovarian tumors in BRCA1 carriers. Based on the joint distribution of the known BRCA1 breast cancer risk-modifying loci, we estimated that the breast cancer lifetime risks for the 5% of BRCA1 carriers at lowest risk are 28%–50% compared to 81%–100% for the 5% at highest risk. Similarly, based on the known ovarian cancer risk-modifying loci, the 5% of BRCA1 carriers at lowest risk have an estimated lifetime risk of developing ovarian cancer of 28% or lower, whereas the 5% at highest risk will have a risk of 63% or higher. Such differences in risk may have important implications for risk prediction and clinical management for BRCA1 carriers.

A prospective investigation of predictive and modifiable risk factors for breast cancer in unaffected BRCA1 and BRCA2gene carriers

BackgroundBreast cancer is the most common female cancer worldwide. The lifetime risk of a woman being diagnosed with breast cancer is approximately 12.5%. For women who carry the deleterious mutation in either of the BRCA genes, BRCA1 or BRCA2, the risk of developing breast or ovarian cancer is significantly increased. In recent years there has been increased penetrance of BRCA1 and BRCA2 associated breast cancer, prompting investigation into the role of modifiable risk factors in this group. Previous investigations into this topic have relied on participants recalling lifetime weight changes and subjective methods of recording physical activity. The influence of obesity-related biomarkers, which may explain the link between obesity, physical activity and breast cancer risk, has not been investigated prospectively in this group. This paper describes the design of a prospective cohort study investigating the role of predictive and modifiable risk factors for breast cancer in unaffected BRCA1 and BRCA2 gene mutation carriers.Methods/designParticipants will be recruited from breast cancer family risk clinics and genetics clinics. Lifestyle risk factors that will be investigated will include body composition, metabolic syndrome and its components, physical activity and dietary intake. PBMC telomere length will be measured as a potential predictor of breast cancer occurrence. Measurements will be completed on entry to the study and repeated at two years and five years. Participants will also be followed annually by questionnaire to track changes in risk factor status and to record cancer occurrence. Data will be analysed using multiple regression models. The study has an accrual target of 352 participants.DiscussionThe results from this study will provide valuable information regarding the role of modifiable lifestyle risk factors for breast cancer in women with a deleterious mutation in the BRCA gene. Additionally, the study will attempt to identify potential blood biomarkers which may be predictive of breast cancer occurrence.

HIF-1α Overexpression in Ductal Carcinoma In Situ of the Breast in BRCA1 and BRCA2 Mutation Carriers

Recent studies have revealed that BRCA1 and BRCA2 germline mutation-related breast cancers show frequent overexpression of hypoxia inducible factor-1α (HIF-1α), the key regulator of the hypoxia response. However, the question remained whether hypoxia is a late stage bystander or a true carcinogenetic event in patients with hereditary predisposition. We therefore studied HIF-1α overexpression in ductal carcinoma in situ (DCIS), an established precursor of invasive breast cancer.We used immunohistochemistry to examine the expression of the hypoxia markers HIF-1α, CAIX and Glut-1 in DCIS and available invasive carcinoma lesions of 32 BRCA1, 16 BRCA2 and 77 non-BRCA mutation-related cases. HIF-1α expression was detected in 63% of BRCA1 and 62% of BRCA2 as compared to 34% of non-BRCA mutation-related DCIS cases (p = 0.005). CAIX overexpression was present in 56% of BRCA1 and 44% of BRCA2 as compared to 6% of non-BRCA mutation-related DCIS cases (p = 0.000). Glut-1 overexpression was observed in 59% of BRCA1, 75% of BRCA2 and 67% of non-BRCA mutation-related DCIS cases (p = 0.527). Overall, HIF-1α, CAIX and Glut-1 expression in BRCA mutation-related DCIS matched the expression in the accompanying invasive cancers in 60% or more of cases. In non-BRCA mutation-related cases the expression of the hypoxia markers in DCIS matched the expression in the invasive part in 46% or more of the cases.Although BRCA1 and BRCA2 germline mutation-related invasive breast cancers are different in many ways, the hypoxia-related proteins HIF-1α, CAIX and Glut-1 are expressed in both DCIS and invasive lesions of BRCA1 and BRCA2 mutation carriers. This suggests that hypoxia may already play a role in the DCIS stage of BRCA1 and BRCA2 germline mutation related breast carcinogenesis, and may also drive cancer progression. Hypoxia-related proteins are therefore putative targets for therapy and molecular imaging for early detection and monitoring therapy response in BRCA mutation patients.

Whole Exome Sequencing Suggests Much of Non-BRCA1/BRCA2 Familial Breast Cancer Is Due to Moderate and Low Penetrance Susceptibility Alleles

The identification of the two most prevalent susceptibility genes in breast cancer, BRCA1 and BRCA2, was the beginning of a sustained effort to uncover new genes explaining the missing heritability in this disease. Today, additional high, moderate and low penetrance genes have been identified in breast cancer, such as P53, PTEN, STK11, PALB2 or ATM, globally accounting for around 35 percent of the familial cases. In the present study we used massively parallel sequencing to analyze 7 BRCA1/BRCA2 negative families, each having at least 6 affected women with breast cancer (between 6 and 10) diagnosed under the age of 60 across generations. After extensive filtering, Sanger sequencing validation and co-segregation studies, variants were prioritized through either control-population studies, including up to 750 healthy individuals, or case-control assays comprising approximately 5300 samples. As a result, a known moderate susceptibility indel variant (CHEK2 1100delC) and a catalogue of 11 rare variants presenting signs of association with breast cancer were identified. All the affected genes are involved in important cellular mechanisms like DNA repair, cell proliferation and survival or cell cycle regulation. This study highlights the need to investigate the role of rare variants in familial cancer development by means of novel high throughput analysis strategies optimized for genetically heterogeneous scenarios. Even considering the intrinsic limitations of exome resequencing studies, our findings support the hypothesis that the majority of non-BRCA1/BRCA2 breast cancer families might be explained by the action of moderate and/or low penetrance susceptibility alleles.

The Effectiveness of Cucurbitacin B in BRCA1 Defective Breast Cancer Cells

Cucurbitacin B (CuB) is one of the potential agents for long term anticancer chemoprevention. Cumulative evidences has shown that cucurbitacin B provides potent cellular biological activities such as hepatoprotective, anti-inflammatory and antimicrobial effects, but the precise mechanism of this agent is not clearly understood. We examine the biological effects on cancer cells of cucurbitacin B extracted from a Thai herb, Trichosanthes cucumerina L. The wild type (wt) BRCA1, mutant BRCA1, BRCA1 knocked-down and BRCA1 overexpressed breast cancer cells were treated with the cucurbitacin B and determined for the inhibitory effects on the cell proliferation, migration, invasion, anchorage-independent growth. The gene expressions in the treated cells were analyzed for p21/Waf1, p27Kip1 and survivin. Our previous study revealed that loss of BRCA1 expression leads to an increase in survivin expression, which is responsible for a reduction in sensitivity to paclitaxel. In this work, we showed that cucurbitacin B obviously inhibited knocked-down and mutant BRCA1 breast cancer cells rather than the wild type BRCA1 breast cancer cells in regards to the cellular proliferation, migration, invasion and anchorage-independent growth. Furthermore, forcing the cells to overexpress wild type BRCA1 significantly reduced effectiveness of cucurbitacin B on growth inhibition of the endogenous mutant BRCA1 cells. Interestingly, cucurbitacin B promotes the expression of p21/Waf1 and p27Kip1 but inhibit the expression of survivin. We suggest that survivin could be an important target of cucurbitacin B in BRCA1 defective breast cancer cells.

Tumoral Lymphocytic Infiltration and Expression of the Chemokine CXCL10 in Breast Cancers from the Ontario Familial Breast Cancer Registry

Breast carcinomas, including basal and hereditary cases, often present with a prominent tumoral lymphocytic infiltrate. Chemokines could play a role in attracting these cells and contribute to tumor progression. We explored tumoral expression of CXCL10 and determined the relationship between CXCL10 and lymphocytic infiltrate in a cohort of breast cancers. Using tissue microarrays of 364 breast tumors, we evaluated expression of CXCL10 and its receptor, CXCR3, in relation to histopathologic features, biomarkers, and lymphocyte markers. In addition, we overexpressed CXCL10 and CXCR3 in MCF7 breast cancer cells and monitored T-lymphocyte migration and invasion. Forty-five percent of tumors expressed CXCL10, and a significant association was found with CXCR3 and lymphocytic infiltrate. Further characterization of the lymphocytic infiltrate revealed an association with CXCL10 expression for peritumoral CD4+ and CD8+ lymphocytes. CD8+ intratumoral lymphocytes, FOXP3+ regulatory T cells (Tregs), and T-BET+ T(H)1 cells were associated with BRCA1 and basal tumors. Conditioned media from MCF7 cells overexpressing both CXCL10 and CXCR3 increased T-lymphocyte migration and invasion. Our findings suggest that CXCL10 may act in a paracrine manner, affecting the tumor microenvironment, and in an autocrine manner, acting on the tumor cells themselves and may play a role in tumor invasiveness and progression. The CXCL10-CXCR3 axis can serve as a potential target in BRCA1 and basal breast cancers, which present with a prominent lymphocytic infiltrate and a poor prognosis. Clin Cancer Res; 19(2); 336-46. ©2012 AACR.

BRCA-1 and BRCA-2 mutation bedside detection and breast cancer clinical primary prevention.

BRCA-1 and BRCA-2 mutation bedside detection and breast cancer clinical primary prevention.

The role of BRCA1 and BRCA2 in prostate cancer

The familial aggregation of prostate cancer and breast cancer has been observed for almost half a century and about 85% of the inherited breast cancer can be linked to germ-line mutations of BRCA1 (breast cancer 1, early onset) and BRCA2. In this review, we are mainly focusing on the contribution of BRCA1/2 sequence variations to prostate cancer risk and disease progression. We will discuss the biological functions of BRCA1/2 and BRCA1/2-related signaling pathways in prostate cancer biology. The majority of studies supporting the link between BRCA1/2 mutations and prostate cancer are from populations with a high frequency of mutations, such as Ashkenazi Jewish, Icelandic, and U.K. population. BRCA1 can directly interact with the androgen receptor (AR) and Janus kinase (JAK), and can differentially regulate insulin-like growth factor 1 receptor (IGF-IR) expression in an AR-dependent manner. BRCA2 homeostasis in prostate cancer cells has been found to be critical in determining cell fates during prostate cancer progression. This review may be helpful for medical professionals and prostate cancer patients when discussing prostate cancer risks, treatment and prognosis.

Loss of Heterozygosity at Tumor Suppressor Genes Detectable on Fractionated Circulating Cell-Free Tumor DNA as Indicator of Breast Cancer Progression

LOH on circulating DNA may provide tumor-specific information on breast cancer. As identification of LOH on cell-free DNA is impeded by the prevalence of wild type DNA in blood of cancer patients, we fractionated plasma DNA, and determined the diagnostic and prognostic value of both fractions. Our cohort of 388 patients with primary breast cancer before chemotherapy was selected from a multicenter study (SUCCESS). Postoperative plasma was fractionated in low- and high-molecular weight DNA by two different column systems. In both fractions, LOH was determined by a PCR-based microsatellite analysis using a panel of 8 polymorphic markers. Circulating tumor DNA in plasma from 30 patients after chemotherapy was additionally analyzed. The significance levels were adjusted for multiple comparisons. More patients (38%) had LOH at all markers in the fraction containing short DNA fragments than in the fraction containing the long DNA molecules (28%, P = 0.0001). In both fractions 32.85% of LOH were concordant. LOH at the markers D3S1605, D10S1765, D12S1725, D13S218, and D17S855 significantly correlated with tumor stage, tumor size, and lymph node metastasis, positive progesterone, and HER2 receptor status. Most importantly, LOH at D12S1725 mapping to cyclin D2 correlated with shorter overall survival (P = 0.004). The improved detection of LOH on cell-free DNA provides important information on DNA losses of tumor suppressor genes TIG1, PTEN, cyclin D2, RB1, and BRCA1 in breast cancer. In particular, loss of the cyclin D2 gene might become an important prognostic marker easily detectable in the peripheral blood.