Exosome-Mediated Transfer of Cancer Cell Resistance to Antiestrogen Drugs.

Exosomes are small vesicles which are produced by the cells and released into the surrounding space. They can transfer biomolecules into recipient cells. The main goal of the work was to study the exosome involvement in the cell transfer of hormonal resistance. The experiments were performed on in vitro cultured estrogen-dependent MCF-7 breast cancer cells and MCF-7 sublines resistant to SERM tamoxifen and/or biguanide metformin, which exerts its anti-proliferative effect, at least in a part, via the suppression of estrogen machinery. The exosomes were purified by differential ultracentrifugation, cell response to tamoxifen was determined by MTT test, and the level and activity of signaling proteins were determined by Western blot and reporter analysis. We found that the treatment of the parent MCF-7 cells with exosomes from the resistant cells within 14 days lead to the partial resistance of the MCF-7 cells to antiestrogen drugs. The primary resistant cells and the cells with the exosome-induced resistance were characterized with these common features: decrease in ERα activity and parallel activation of Akt and AP-1, NF-κB, and SNAIL1 transcriptional factors. In general, we evaluate the established results as the evidence of the possible exosome involvement in the transferring of the hormone/metformin resistance in breast cancer cells.

The \textit{BRAF} V600E mutation in single- institution study of Russian melanoma patients.

BACKGROUND: The activating mutation BRAF V600E is considered to be a diagnostic cutaneous melanoma (CM) marker important for prognosis and targeted therapy. OBJECTIVE: The aim of this study was to determine the frequency of the V600E mutation in CM patients in Russia and to estimate the influence of the BRAF gene mutation status on prognosis and clinical outcome. METHODS: To ensure mutation detection in FFPE tissue, interlaboratory validation was performed using three different methods: allele-specific hybridisation on a biochip, allele-specific real-time PCR and, in some cases, direct sequencing. RESULTS: Mutation V600E was detected in 49% of patients. The age of disease manifestation was significantly lower in mutated (MT) BRAF patients, and the median age difference between the wild-type (WT) and MT BRAF groups (P= 0.002) was 10 years. A tumour thickness more than 1 mm was also more frequently observed in the MT BRAF group (P= 0.059). Patients from the MT BRAF group were more likely to have ulceration compared to the WT group (P= 0.088). No statistically significant differences were found between the relapse-free, progression-free or overall survival of CM patients in the MT BRAF and WT BRAF groups. CONCLUSIONS: The data obtained show that the V600E BRAF mutation occurred in about half of melanoma patients; it was associated with earlier manifestation of melanoma and likely with more aggressive clinical features.

The 4154delA mutation carriers in the BRCA1 gene share a common ancestry.

Uncertainty exists whether the 4154delA mutation of the BRCA1 gene detected in unrelated individuals from Latvia, Poland and Russia is a founder mutation with a common ancestral origin. To trace back this problem we analysed the mutation-associated haplotype of the BRCA1 intragenic SNPs as well as intragenic and nearby STR markers in mutation carriers from the aforementioned populations. The mutation-associated SNP alleles were found to be "T-A-A-A-A-G" for six intragenic SNPs of the BRCA1 gene (IVS8-58delT, 3232A/G, 3667A/G, IVS16-68A/G, IVS16-92A/G, IVS18+66G/A, respectively). The alleles 195, 154, 210 and 181 were found to be associated with the 4154delA mutation for STR markers D17S1325, D17S855, D17S1328 and D17S1320, correspondingly. Further analysis of markers in the 4154delA mutation carriers from all three populations allows us to assert that all analysed mutation carriers share a common ancestry.