STUDY OF THE DNA DAMAGE IN HeLa CELLS EXPOSED TO THE COMBINATION OF ULTRASOUND AND 5-FLUORURACYL

Abstract

To understand the mechanism of the effect of 5 % 5-fluorouracil (5-FU) gel used simultaneously with ultrasound (US ) on a tumor in patients with cervical cancer, the level of DNA damage was studied in vitro. We used cervical adenocarcinoma HeLa CC L-2 cells cultured under standard conditions in RPMI-1640 medium with 10 % fetal bovine serum and 50 μg / ml gentamicin. Ultrasound exposure lasted 10 min. (frequency of 0.88 MHz and intensity of 0.2 W / cm2). The 5-FU dose was 0.7 мкМ, with the time of exposure of 24 hours. In 24 hours after starting exposure, the level of DNA damage to the cells of the culture was studied using the comet assay in the alkaline version and evaluated by the % DNA parameter in the comet tail (% TDNA). The statistical significance of the differences was evaluated using the Mann-Whitney U test and Fisher’s exact test. The combined exposure to ultrasound / 5-FU led to a 5.2-fold increase in % TDNA compared to the control culture, % TDNA was 1.9 times higher after exposure to 5-FU alone and 3.0 times higher after exposure to ultrasound alone. In 24 hours after the combined exposure, less than 50 % of the culture cells had a low level of DNA damage (<10 % TDNA), i.e. completed the repair process and could continue to proliferate, and more than 30 % of the culture cells still had a high level of damage (>30 % TDNA) and were probably in the process of apoptosis. Thus, the results of the study showed that the combined effect of ultrasound / 5-FU on the HeLa culture helped to overcome resistance to chemotherapy, having a synergistic effect.