SYNERGETIC CYTOTOXICITY OF BLEOMYCIN AND POLYHYDRIC ALCOHOLS - DNA STRAND BREAKAGE EVALUATED BY COMET ASSAY

DNA strand breakage induced in cultured cells by bleomycin (BLM) was r emarkably enhanced in the presence of glycerol or polyvinyl alcohol wh ich produces an enhancement effect on BLM cytotoxicity, but not in the presence of alcohols such as methanol, ethanol, or polyethylene glyco l which do not produce enhanced cytotoxicity. The comet assay, a usefu l analytical method for evaluating DNA strand breakage, clearly demons trated that combinations of BLM and polyhydric alcohols induced seriou s DNA damage in the,whole cell populations compared with those induced by treatment with BLM alone. The comet assay also successfully showed distributions of cell populations with various degrees of DNA damage. These results suggested that an increase in DNA damage induced in the presence of polyhydric alcohols might be responsible for the enhancem ent of BLM cytotoxicity.