FORMATION OF INTERSTRAND DNA CROSS-LINKS BY BIS-(2-CHLOROETHYL)SULFIDE (BCES) - A POSSIBLE CYTOTOXIC MECHANISM IN RAT KERATINOCYTES

Interstrand cross-links in the DNA of epidermal basal keratinocytes ma y be responsible for cell death and consequent vesication in skin expo sed to BCES. The formation of cross-links and cytotoxicity were compar ed when cells in primary monolayer cultures of rat epidermal keratinoc ytes, synchronized at the G1/S boundary or in the G1 phase of the cell cycle, were exposed to BCES. The dose-responsive formation of cross-l inks, measured with an ethidium bromide-fluorescence assay, was determ ined immediately after exposure of cells at either position of the cyc le. At 24 hr post-exposure, the level of cross-links in cells exposed at the C1/S boundary had not decreased significantly and was still dos e-dependent. However, cells exposed in the G1 phase showed a major dec rease in cross-links. Formation of interstrand DNA cross-links appears to be related to the mustard's cytotoxicity. (C) 1996 Academic Press, Inc.