Comparison of the effects of various types of beta-irradiation on the cells of human epidermoid carcinoma A431

Targeted radiopharmaceuticals, which mainly include beta-emitting radionuclides, allow for selective action and reduction of the total radiation load. The aim of the study was to assess the viability of human epidermoid carcinoma cells A431 at various intervals after exposure to high-energy electrons in the regime of acute and chronic irradiation.

To simulate chronic or acute irradiation, cells were irradiated with closed Sr-Y-90 sources (STC, Amplituda) and a Novalis Tx linear accelerator (Varian Medical Systems, UK), respectively. At 24 and 72 hours after the start of irradiation, an MTT test was performed for the subsequent determination of LD₅₀.

We registered a difference in the viability of A431 cells 24 and 72 hours after irradiation at the same dose: LD₅₀, estimated 72 hours after irradiation, was 2 times lower than after 24 hours. The observed effect is apparently caused by a pronounced radiation block of mitosis 24 hours after exposure. In addition, 72 hours after irradiation, large numbers of "giant" cells are found, formed from several cells as a result of division attempts. In the case of acute irradiation, the radiosensitivity of A431 cells increases approximately fourfold. Apparently, different types of exposure, at the same dose, cause different levels of oxidative stress, which is suppressed to varying degrees by enzymes and the antioxidant system, which affect the repair systems in the cell, which must be taken into account when forming the dose load for patients undergoing radiotherapy.

The work was supported by the Russian Foundation for Basic Research, No. 20-34-70124