Genetic and epigenetic bases of prostate tumor cell radioresistance.

Abstract

Radiation therapy plays aleading role in the treatment of prostate cancer, but the emergence of radioresistant forms of this disease dictates the need for apersonalized ap-proach based on the data from genetic and epigenetic markers. Such markers include the copy number variation as well as gene and microRNA expression. The aim of the study was to validate the list of potential predictors of radioresistance of prostate tumor cells in amodel experiment based on the determination of gene copy number variation, gene transcriptional activity and microRNA expression. The study used aPC-3prostate cancer cell culture. The determination of the relative copy number variation and expression of 32genes (BRCA1, BRCA2, PTEN, CASP3, CASP8, BAX, BCL2, CASP9, P53, MDM2, AKT1, ATM, BRIP1, CDK1, CDKN1B, CCND1, CCND3, FGFR2, KU70, RAD50, RAP80, Rif1, RNF168, TopBP1, HIST, H2AX, EXO1, XRCC4, RBBP8, EP300, LIG4, C-FLIP), as well as 15microRNAs (let-7, miR15a/ 16, miR-17, miR-18a, miR-21, miR-24, miR-26b, miR-99a, miR-100, miR-101, miR-106a, miR-663a, miR-143, miR-145) was performed using the real-time quantitative polymerase chain reaction method. It was found that daily irradiation of PC-3cells on aNovalis TX linear accelerator at doses of 6and 7Gy for 5days leads to asignificant decrease in the total number of cells and the number of viable cells. Nevertheless, after 5days of irradiation, about 15% of the initial number of prostate tumor cells retained their viability, which is due to their special genetic and epigenetic characteristics: increased copy number and expression of genes BRCA2, CDK1, CDKN1B, H2AX, RAD50, XRCC4, RBBP8and EP300and reduced copy number and expression of CCND3, TP53, and BCL2genes, as well as differential expression of sixmicroRNAs (hsa-miR-18a-5p, hsa-miR-24-5p, hsa-miR-99a-5p, hsa-miR-100-5p, hsa-miR-145-5p, hsa-let-7a-3p). This study enabled to identify genetic and epigenetic markers of prostate tumor cells resistance to radiation therapy.