Hypermethylation of the BRCA2 gene promoter and its co-hypermethylation with the BRCA1 gene promoter in patients with breast cancer.

BACKGROUND: The BRCA2 gene is an important tumour suppressor in breast cancer, and alterations in BRCA2 may lead to cancer progression. The aim of the study was to investigate the association of hypermethylation of the BRCA2 gene promoter and its co-hypermethylation with the BRCA1 gene promoter with the development and course of breast cancer in women. METHODS: This study included 74 women with breast cancer (tumour tissue samples and peripheral blood) and 62 women without oncological pathology (peripheral blood) - control group. RESULTS: Hypermethylation of the BRCA2 gene was significantly more frequently detected in the tumour tissue of women with breast cancer compared to their peripheral blood and peripheral blood of control subjects (p= 0.0006 and p= 0.00001, respectively). Hypermethylation of BRCA2 was more frequently detected in patients with breast cancer over the age of 50 and in patients with higher Ki67 expression levels (p= 0.045 and p= 0.045, respectively). There was a high frequency of unmethylated BRCA1 and BRCA2 gene combination in women of the control group compared to women with breast cancer, both in blood samples and tumour tissue samples (p= 0.014 and p= 0.00001, respectively). CONCLUSION: Our study confirms the hypothesis that BRCA2 hypermethylation plays an important role in the pathogenesis of breast cancer and the importance of assessing its co-hypermethylation with BRCA1 in predicting the course of the disease.

Clinical significance of determining the hypermethylation of the RUNX3 gene promoter and its cohypermethylation with the BRCA1 gene for patients with breast cancer.

PURPOSE: The aim of this study was to assess the clinical significance of RUNX3 gene hypermethylation in the pathogenetic mechanisms of breast cancer in women, taking into account its cohypermethylation with the BRCA1 gene. METHODS: This study included 74 women with newly diagnosed breast cancer (samples from female primary breast carcinomas and paired peripheral blood samples) and 62 women without oncological pathology-control group (peripheral blood samples). Epigenetic testing for hypermethylation status studying was performed in all samples on freshly collected material with the addition of a preservative before the storage and DNA isolation. RESULTS: Hypermethylation of the RUNX3 gene promoter region was detected in 71.6% samples of breast cancer tissue and in 35.13% samples of blood. The RUNX3 gene promoter region hypermethylation was significantly higher among breast cancer patients compared to the control group. The frequency of cohypermethylation in RUNX3 and BRCA1 genes was significantly increased in breast cancer tissues compared to the blood of patients. CONCLUSION: A significantly increased frequency of the hypermethylation of the RUNX3 gene promoter region and its cohypermethylation with the BRCA1 gene promoter region was found in tumor tissue and blood samples from patients with breast cancer, in contrast to the control group. The identified differences indicate the importance of further investigations of suppressor genes cohypermethylation in patients with breast cancer. Further large-scale studies are needed to find out whether the detected hypermethylation and cohypermethylation of the RUNX3 gene promoter region will have an impact on the treatment strategy in patients.

Methylation of promoter region of BRCA1 gene versus pathogenic variants of gene: risk factor or clinical marker of breast cancer.

BACKGROUND: In this study, we compared the contribution of pathogenic variants of the BRCA1/2 genes (5382insC, 185delAG, 6174delT, 4153delA, T300G) and hypermethylation of the BRCA1 gene promoter region to the risk of breast cancer and clinical features in women. METHODS: This study enrolled 74 women (tumor tissue, blood) with newly diagnosed breast cancer and 62 women (blood) without oncological pathology (control group). Molecular genetic testing of samples and determination of hypermethylation status were performed on freshly collected material with the addition of a preservative before the procedure of DNA isolation. RESULTS: Hypermethylation of the BRCA1 gene promoter in women is a risk breast cancer factor (χ2 = 19.10, p = 0.001, OR = 16.25 (3.67-71.92)) and is more common than major pathogenic variants in the BRCA1/2 genes. The patients with the BRCA1 gene promoter hypermethylation were more likely to be diagnosed with late-stage metastatic cancer (χ2 = 4.31, p = 0.038, OR = 4.04 (1.19-13.65)). Hypermethylation of the BRCA1 gene promoter was predominant in tumor tissue among BC patients without family history compared to patients with cancer in relatives. CONCLUSION: We proved that hypermethylation of the BRCA1 gene promoter is a risk factor for breast cancer and possibly an early biological marker of clinical onset, as its presence contributed to rapid disease progression with metastasis. The high frequency of hypermethylation in the examined breast cancer patients may be a consequence of environmental factors pressure on the risk of the disease development. Further large-scale studies are needed for the clinical application of the results.

Contribution of BRCA1 5382insC mutation to triplene-gative and luminal types of breast cancer in Ukraine.

PURPOSE: The gene BRCA1 plays a key role in DNA repair in breast and ovarian cell lines and this is considered one of target tumor suppressor genes in same line of cancers. The 5382insC mutation is among the most frequently detected in patients (Eastern Europe) with triple-negative breast cancer (TNBC). In Ukraine, there is not enough awareness of necessity to test patients with TNBC for BRCA1 mutations. That is why this group of patients is not well-studied, even through is known the mutation may affect the course of disease. METHODS: The biological samples of 408 female patients were analyzed of the 5382insC mutation in BRCA1. We compared the frequency of the 5382insC mutation in BRCA1 gene observed in Ukraine with known frequencies in other countries. RESULTS: For patients with TNBC, BRCA1 mutations frequency was 11.3%, while in patients with luminal types of breast cancers, the frequency was 2.8%. Prevalence of 5382insC among TNBC patients reported in this study was not different from those in Tunisia, Poland, Russia, and Bulgaria, but was higher than in Australia and Germany. CONCLUSION: The BRCA1 c.5382 mutation rate was recorded for the first time for TNBC patients in a Ukrainian population. The results presented in this study underscore the importance of this genetic testing of mutations in patients with TNBC. Our study supports BRCA1/2 genetic testing for all women diagnosed with TNBC, regardless of the age of onset or family history of cancer and not only for women diagnosed with TNBC at <60y.o., as guidelines recommend.

Mutations c.459+1G>A and p.P426L in the ARSA gene: prevalence in metachromatic leukodystrophy patients from European countries.

In this multicentre study, we examined the prevalence of two mutations in the arylsulfatase A (ARSA) gene, i.e., c.459+1G>A and p.P426L, in 384 unrelated European patients presenting with different types of metachromatic leukodystrophy (MLD). In total, c.459+1G>A was found 194 times among the 768 investigated ARSA alleles (25%), whereas p.P426L was identified 143 times (18.6%). Thus, these two mutations accounted for 43.8% of investigated MLD alleles. Mutation c.459+1G>A was most frequent in late-infantile MLD patients (40%), while p.P426L was most frequent in adults (42.5%), which is consistent with earlier observations, although p.P426L was also found in a few late-infantile patients (0.9%), and c.459+1G>A was present in some adults (9%). Mutation c.459+1G>A is more frequent in countries situated at the western edges of Europe, i.e., in Great Britain and Portugal, and also in Belgium, Switzerland, and Italy, which is visible as a strand ranging from North to South, and additionally in Czech and Slovak Republics. Mutation p.P426L is most prevalent in countries assembled in a cluster containing the Netherlands, Germany, and Austria. In other Central European countries, the frequency of both c.459+1G>A and p.P426L ranges from 8 to 37.5%. Our study has confirmed that c.459+1G>A and p.P426L are the most frequently found MLD-causing mutations in Europe. The data about their prevalence reflect the population variability in Europe.

Novel mutations in arylsulfatase A gene in three Ukrainian families with metachromatic leukodystrophy.

Metachromatic leukodystrophy (MLD) is a lysosomal storage disease caused by the deficiency of arylsulfatase A (ARSA) or saposin B. The majority of mutations identified in patients with MLD are unique within individual families. Here, we report on the novel missense mutations (F247S, D381E, and A469G) and the known mutations "A" allele and P136S in the ARSA gene in three unrelated Ukrainian families with MLD. The mutations F247S and P136S were found in compound heterozygous with the "A" allele in two patients with juvenile onset MLD. The clinical features of the typical patient with genotype D381E/A469G (early onset with very rapid manifestation of disease) suggest the reason to distinguish an early infantile MLD variant.