6,7-dimethoxycoumarin attenuated cisplatin-induced DNA interstrand crosslink and DNA-protein crosslink in primary cultured rabbit kidney proximal tubular cells

AIM: To study the mechanism of cisplatin interaction with DNA, and the atte nuating effects of 6,7-dimethoxycoumarin ( DMOC) on crosslink. METHODS: Pri mary cultured rabbit kidney proximal tubular cells (PTC) were established. DNA interstrand crosslink was assayed with ethidium bromide binding and DNA -protein crosslink with I-125-postlabelling, PTC were incubated with cispla tin for 24 h. DMOC was preincubated with PTC for 24 h, and cisplatin (26 mu mol.L-1) was added into culture and incubated for another 24 h. RESULTS: C isplatin induced formation of DNA interstrand crosslink (13, 26, 52, and 78 mu mol.L-1) and DNA-protein crosslink (26, 52, and 78 mu mol.L-1) (P < 0.0 1). DNA interstrand crosslink in DMOC (0.4, 4, and 8 mg.L-1) and DNA-protei n crosslink in DMOC (4, 8 mg.L-1) were less than those in cisplatin group ( 26 mu mol.L-1), respectively (P < 0.01). CONCLUSION: The mechanisms of cisp latin interaction with DNA in PTC were DNA interstrand crosslink and DNA-pr otein crosslink, and DMOC attenuated these effects in vitro.