Analysis of BRCA1and BRCA2 large genomic rearrangements in Sri Lankan familial breast cancer patients and at risk individuals

Downregulation of microRNA-30c-5p was responsible for cell migration and tumor metastasis via COTL1-mediated microfilament arrangement in breast cancer

Background

Breast cancer metastasis is the main problem that affects the therapy and prognosis of breast cancer patients. Studies have indicated the role of microRNAs in breast cancer regulation, but the mechanisms are largely unknown.

Methods

In this study, we determined the expression of microRNA-30c-5p (miR-30c-5p) and coactosin-like protein 1 (COTL1) gene in breast cancer tissues, and revealed their effects on breast cancer metastasis regulation. Breast cancer and paracancerous tissues were collected. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to analyze the expression of miR-30c-5p and COTL1, and breast cancer cell line (MCF-7) was employed to verify the relationship between miR-30c-5p and COTL1. Western blot analysis and immunofluorescence were used for proteins analysis and microfilament observation, respectively. A dual-luciferase reporter gene was used for microRNA-gene interaction assay.

Results

The results showed that the expression of miR-30c-5p decreased, while the expression of COTL1 increased in breast cancer tissues. The results of luciferase reporting gene assay showed that, COTL1 was the target of miR-30c-5p. After miR-30c-5p was upregulated, the expression of COTL1 was reduced, microfilament arrangement was in disorder, and cell migration ability was inhibited. After miR-30c-5p was downregulated, the expression of COTL1 was increased, and the cell migration ability was enhanced. COTL1 protein expression levels were significantly higher in cancer tissues with lymph node metastasis.

Conclusions

These findings indicate that miR-30c-5p/COTL1 pathway regulates breast cancer metastasis and can be used as a potential therapy target.

BRCA1/2 mutations, including large genomic rearrangements, among unselected ovarian cancer patients in Korea

Objective

We performed small-scale mutation and large genomic rearrangement (LGR) analysis of BRCA1/2 in ovarian cancer patients to determine the prevalence and the characteristics of the mutations.

Methods

All ovarian cancer patients who visited a single institution between September 2015 and April 2017 were included. Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), and long-range polymerase chain reaction (PCR) were performed to comprehensively study BRCA1/2. The genetic risk models BRCAPRO, Myriad, and BOADICEA were used to evaluate the mutation analysis.

Results

In total, 131 patients were enrolled. Of the 131 patients, Sanger sequencing identified 16 different BRCA1/2 small-scale mutations in 20 patients (15.3%). Two novel nonsense mutations were detected in 2 patients with a serous borderline tumor and a large-cell neuroendocrine carcinoma. MLPA analysis of BRCA1/2 in Sanger-negative patients revealed 2 LGRs. The LGRs accounted for 14.3% of all identified BRCA1 mutations, and the prevalence of LGRs identified in this study was 1.8% in 111 Sanger-negative patients. The genetic risk models showed statistically significant differences between mutation carriers and non-carriers. The 2 patients with LGRs had at least one blood relative with breast or ovarian cancer.

Conclusion

Twenty-two (16.8%) of the unselected ovarian cancer patients had BRCA1/2 mutations that were detected through comprehensive BRCA1/2 genetic testing. Ovarian cancer patients with Sanger-negative results should be considered for LGR detection if they have one blood relative with breast or ovarian cancer. The detection of more BRCA1/2 mutations in patients is important for efforts to provide targeted therapy to ovarian cancer patients.

Frequency of Rearrangements Versus Small Indels Mutations in BRCA1 and BRCA2 Genes in Turkish Patients with High Risk Breast and Ovarian Cancer

Objective

The current rearrangement ratio of BRCA1 and BRCA2 genes is not known in the Turkish population. Rearrangements are not routinely investigated in many Turkish laboratories. This creates problems and contradictions between clinics. Therefore, the aim of this study was to evaluate the distribution and frequency of rearrangements in BRCA1 and BRCA2 genes in high-risk families and to clarify the limits of BRCA1 and BRCA2 testing in Turkey.

Materials and Methods

The study included 1809 patients at high risk of breast cancer or ovarian cancer. All patients were investigated for both small indels and rearrangements of BRCA genes using DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis.

Results

The overall frequency of rearrangements was 2% (25/1262). The frequency of rearrangements was 1.7% (18/1086) and 4% (9/206) in patients with breast cancer and ovarian cancer, respectively. The frequency of rearrangements was 3.7% (8/215) in patients with triple-negative breast cancer. The rearrangement rate was 7.7% (2/26) in patients with both breast and ovarian cancer.

Conclusions

Rearrangements were found with high rates and were strongly associated with bilateral and triple-negative status of patients with breast cancer, which are signs of high risk for breast and ovarian cancer. Analysis of rearrangements should definitely be included in routine clinical practice in Turkey for high-risk families and also for improved cancer risk prediction for families.

Genetic determinants of sporadic breast cancer in Sri Lankan women

Background

While a range of common genetic variants have been identified to be associated with risk of sporadic breast cancer in several Western studies, little is known about their role in South Asian populations. Our objective was to examine the association between common genetic variants in breast cancer related genes and risk of breast cancer in a cohort of Sri Lankan women.

Methods

A case-control study of 350 postmenopausal women with breast cancer and 350 healthy postmenopausal women was conducted. Genotyping using the iPLEX GOLD assay was done for 56 haplotype-tagging single nucleotide polymorphisms (SNPs) in 36 breast cancer related genes. Testing for association was done using an additive genetic model. Odds ratios and 95% confidence intervals were calculated using adjusted logistic regression models.

Results

Four SNPs [rs3218550 (XRCC2), rs6917 (PHB), rs1801516 (ATM), and rs13689 (CDH1)] were significantly associated with risk of breast cancer. The rs3218550 T allele and rs6917 A allele increased breast cancer risk by 1.5-fold and 1.4-fold, respectively. The CTC haplotype defined by the SNPs rs3218552|rs3218550|rs3218536 on chromosome 7 (P = 0.0088) and the CA haplotype defined by the SNPs rs1049620|rs6917 on chromosome 17 (P = 0.0067) were significantly associated with increased risk of breast cancer. The rs1801516 A allele and the rs13689 C allele decreased breast cancer risk by 0.6-fold and 0.7-fold, respectively.

Conclusions

These findings suggest that common genetic polymorphisms in the XRCC2, PHB, CDH1 and ATM genes are associated with risk of breast cancer among Sri Lankan postmenopausal women. The exact biological mechanisms of how these variants regulate overall breast cancer risk need further evaluation using functional studies.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4112-4) contains supplementary material, which is available to authorized users.

Contribution of BRCA1 large genomic rearrangements to early-onset and familial breast/ovarian cancer in Pakistan

BACKGROUND

Germline mutations in BRCA1 and BRCA2 (BRCA1/2) account for the majority of hereditary breast and/or ovarian cancers. Pakistan has one of the highest rates of breast cancer incidence in Asia, where BRCA1/2 small-range mutations account for 17% of early-onset and familial breast/ovarian cancer patients. We report the first study from Pakistan evaluating the prevalence of BRCA1/2 large genomic rearrangements (LGRs) in breast and/or ovarian cancer patients who do not harbor small-range BRCA1/2 mutations.

MATERIALS AND METHODS

Both BRCA1/2 genes were comprehensively screened for LGRs using multiplex ligation-dependent probe amplification in 120 BRCA1/2 small-range mutations negative early-onset or familial breast/ovarian cancer patients from Pakistan (Group 1). The breakpoints were characterized by long-range PCR- and DNA-sequencing analyses. An additional cohort of 445 BRCA1/2 negative high-risk patients (Group 2) was analyzed for the presence of LGRs identified in Group 1.

RESULTS

Three different BRCA1 LGRs were identified in Group 1 (4/120; 3.3%), two of these were novel. Exon 1-2 deletion was observed in two unrelated patients: an early-onset breast cancer patient and another bilateral breast cancer patient from a hereditary breast cancer (HBC) family. Novel exon 20-21 deletion was detected in a 29-year-old breast cancer patient from a HBC family. Another novel exon 21-24 deletion was identified in a breast-ovarian cancer patient from a hereditary breast and ovarian cancer family. The breakpoints of all deletions were characterized. Screening of the 445 patients in Group 2 for the three LGRs revealed ten additional patients harboring exon 1-2 deletion or exon 21-24 deletion (10/445; 2.2%). No BRCA2 LGRs were identified.

CONCLUSIONS

LGRs in BRCA1 are found with a considerable frequency in Pakistani breast/ovarian cancer cases. Our findings suggest that BRCA1 exons 1-2 deletion and exons 21-24 deletion should be included in the recurrent BRCA1/2 mutations panel for genetic testing of high-risk Pakistani breast/ovarian cancer patients.