Modulation of CT-genes transcriptional activity in HT-29 cells by irradiation with a linear accelerator.

Abstract

e15218 Background: Cancer-testis antigens (CTAs) are used as targets in immunotherapeutic approaches based on gene-cell vaccines (GCV). In some cases, it is possible to use experimental combinatorial therapy regimens that combine radiation and GCV. Despite numerous studies of the expression of CTA in tumors of various locations, including colon tumors, the transcriptional activity of CT-genes in tumor tissue of the colon after radiation therapy remains poorly studied. The aim of the study was to analyze changes in the expression of CT-genes in HT-29 cells after irradiation with a linear accelerator. Methods: The study used human cell culture HT-29. For the model experiment, 7 Gy fractionation option was used (irradiation was carried out 5 times every 24 hours). Irradiation was performed on a Novalis TX linear accelerator (Varian, USA). The ratio of living and dead cells was calculated in a Goryaev chamber using a 0.4% trypan blue dye solution. After microscopy on the 5th day of irradiation, the cell line was removed from the vial substrate by Trypsin/Versen solution. RNA was isolated by the Chomczynski&Sacchi method. For cDNA synthesis a set of "REVERTA-L" reagents used. Expression of 16 CT genes (MAGE-A1, -A2, -A3, -A4, MAGE-B1, -B2, GAGE-1, -3, -4, MAGEC1, BAGE, XAGE3, NYESO1, SSX2, SCP1, PRAME1) was determined using the Real-Time qPCR method (reference genes — GAPDH and B2M). Statistical analysis was performed using univariate analysis of variance (ANOVA) with repeated measurements. Results: After 5 days of exposure at a dose of 7 Gy, only 20% of the initial number of HT-29 cells remained viable. It was found that irradiation was statistically significantly (p < 0.05) influenced the increase in the expression of genes MAGEA1 by 1.8 times, MAGEB1 by 6.8 times, BAGE by 1.6 times, CTAGE1 by 3.3 times and SSX2 by 5.8 times relative to intact cells. Conclusions: Thus, tumor cells exposed to radiation at a dose of 7 Gy show an increase in the expression of 5 CT-genes, which, in turn, can increase their immunogenic potential.