Aim: To study the mechanism of cisplatin interaction with DNA, and the attenuating effects of 6,7-dimethoxycoumarin (DMOC) on crosslink.
Methods: Primary cultured rabbit kidney proximal tubular cells (PTC) were established. DNA interstrand crosslink was assayed with ethidium bromide binding and DNA-protein crosslink with 125I-postlabelling. PTC were incubated with cisplatin for 24 h. DMOC was preincubated with PTC for 24 h, and cisplatin (26 mumol.L-1) was added into culture and incubated for another 24 h.
Results: Cisplatin induced formation of DNA interstrand crosslink (13, 26, 52, and 78 mumol.L-1) and DNA-protein crosslink (26, 52, and 78 mumol.L-1) (P < 0.01). DNA interstrand crosslink in DMOC (0.4, 4, and 8 mg.L-1) and DNA-protein crosslink in DMOC (4, 8 mg.L-1) were less than those in cisplatin group (26 mumol.L-1), respectively (P < 0.01).
Conclusion: The mechanisms of cisplatin interaction with DNA in PTC were DNA interstrand crosslink and DNA-protein crosslink, and DMOC attenuated these effects in vitro.