Two recently established human ovarian
carcinoma cell lines (JA-T and TR175) have been used to study the effects of
aphidicolin glycinate (APG), a specific competitive inhibitor of
DNA polymerase alpha (Ikegani et al. (1978) Nature, 275, 458-460), on the formation and removal of four
platinum-
DNA adducts. Logarithmically-growing cells were exposed to
cis-diamminedichloroplatinum (II) (
cisplatin) (10 micrograms, 33.4 microM) in the presence or absence of APG (5 or 50 micrograms/ml, 11.6 or 116 microM).
Platinum-
DNA adducts were quantitated using a competitive ELISA technique. No differences were observed between the initial levels of total
DNA platination and of specific
DNA adducts formed in the presence or absence of APG in either cell line. Following 18 h posttreatment incubation both lines showed some ability to remove each of the three main
platinum-DNA lesions (Pt-GMP, Pt-AG and Pt-GG). However, the levels of these specific
DNA adducts decreased over this time period, by similar rates with or without APG addition. It was also shown that the APG concentrations used had minimal inhibitory effects alone on growth or
DNA synthesis during this 18 h posttreatment incubation period. Furthermore its addition did not significantly modify
cisplatin-induced cytotoxicity, as judged by inhibition of growth or
DNA synthesis over this time period. We therefore conclude that under these experimental conditions APG does not modulate 'repair' of
cisplatin-induced DNA damage in logarithmically-growing cultures of these two apparently 'repair-proficient' human ovarian tumour cell lines.