The inhibitory effect of selenium on induction of tetraploidy by dimethylarsinic acid in Chinese hamster cells.

Arsenic is a human carcinogen. On the other hand, selenium supplementation can inhibit induction of carcinogenesis by chemical carcinogens. The effect of selenium compounds on the cytotoxicity of dimethylarsinic acid (DMA) and on the induction of tetraploidy by DMA were studied using Chinese hamster V79 cells. Two selenium compounds were tested, sodium selenite and trimethylselenonium iodide (TMSeI). Trimethylselenonium is a major excretory product of selenite metabolism. The cytotoxicity of sodium selenite was 1000-fold greater than that of TMSeI. The cytotoxicity of DMA was about the same as that of TMSeI. The mitotic index for DMA administration was increased by these selenium compounds at low concentrations and decreased by them at high concentrations. The tetraploid index for DMA decreased with increasing concentrations of these selenium compounds. Tetraploidy is a form of aneuploidy, and aneuploidy is known to induce carcinogenesis. The finding that selenium inhibited induction of tetraploidy by DMA may yield clues to the role of selenium in the chemoprevention of carcinogenesis by chemical carcinogens.