title: The formation and repair of cisplatin-DNA adducts in wild-type and cisplatin-resistant L1210 cells: comparison of immunocytochemical determination with detection in isolated DNA.
abstract: We have studied the formation and repair of cisplatin-DNA adducts in wild-type mouse leukemia L1210/0 cells and in the sublines L1210/2 and L1210/5, which differ in cisplatin sensitivity. In a colony-formation assay these sublines were 9- and 22-fold more resistant compared to L1210/0, respectively. Cisplatin-induced DNA modification was studied at the cellular level by immunocytochemistry with antiserum NKI-A59 raised against cisplatin-treated DNA. Levels of nuclear staining immediately after a 1-h treatment were similar to those seen after a 24-h post-incubation in drug-free medium. Clear differences in DNA platination were found between the cell lines: immediately after exposure, L1210/2 and L1210/5 showed only 32 and 14%, respectively, of the nuclear staining observed in L1210/0, and 48 and 13% after 24 h. In these experiments, adduct-specific nuclear staining was quantified as the area under the adduct versus concentration curves (AUC). The formation and repair in these cell lines of the bifunctional adducts cis-Pt(NH3)2d(pGpG) (Pt-GG), cis-Pt(NH3)2d(pApG) (Pt-AG) and cis-Pt(NH3)2(dGMP)2 (G-Pt-G) were studied with an enzyme-linked immunosorbent assay (ELISA). No relation between repair and resistance was observed. The results suggest that differences in induced DNA platination levels, rather than in repair, are responsible--at least in part--for the differences in cisplatin resistance. A mechanism such as an increased tolerance of the resistant cells to plantinum-DNA damage may also be involved.
authors.affiliation: Division of Molecular Carcinogenesis, The Netherlands Cancer Institute (Antoni van Leeuwenhoek Huis), Amsterdam, Netherlands.
authors.forename: F A
authors.initials: FA
authors.lastname: Blommaert
authors.forename: B G
authors.initials: BG
authors.lastname: Floot
authors.forename: H C
authors.initials: HC
authors.lastname: van Dijk-Knijnenburg
authors.forename: F
authors.initials: F
authors.lastname: Berends
authors.forename: R A
authors.initials: RA
authors.lastname: Baan
authors.forename: J H
authors.initials: JH
authors.lastname: Schornagel
authors.forename: L
authors.initials: L
authors.lastname: den Engelse
authors.forename: A M
authors.initials: AM
authors.lastname: Fichtinger-Schepman
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001639:Bicarbonates / Q000737:chemistry; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000378:metabolism* / Q000494:pharmacology*; D018736:DNA Adducts / Q000378:metabolism*; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm; D004797:Enzyme-Linked Immunosorbent Assay; D007150:Immunohistochemistry / Q000379:methods; D007939:Leukemia L1210 / Q000188:drug therapy / Q000378:metabolism*; D051379:Mice; D012680:Sensitivity and Specificity; D013890:Thiourea / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D001639:Bicarbonates; D018736:DNA Adducts; D004273:DNA, Neoplasm; C057270:cisplatin-DNA adduct; C027043:ammonium bicarbonate; D013890:Thiourea; D002945:Cisplatin