title: Cross-resistance to cis-diamminedichloroplatinum(II) of a multidrug-resistant lymphoma cell line associated with decreased drug accumulation and enhanced DNA repair.
abstract: HOB1/VCR, a multidrug-resistant subline of the immunoblastic B lymphoma cell line, was established by sequential selection in increasing concentrations of vincristine. The expression of the human mdr l gene, as analyzed by reverse transcription and polymerase-chain reaction (RT-PCR), revealed a 10-15-fold overexpression in this resistant cell line. A complete inhibition of vincristine resistance by verapamil was observed in the vincristine-resistant HOB1/VCR cells, which suggests that acquired resistance may be mainly due to P-glycoprotein. HOB1/VCR cells also developed a 67-fold cross-resistance to the anticancer drug cis-diamminedichloroplatinum (cisplatin). DNA repair of the resistant and the parental cell lines was investigated by in situ detection with a cisplatin-DNA adduct-specific antibody and by measurement of repair-associated host cell reactivation of damaged plasmid DNA. HOB1/VCR cells exhibited a 2-fold decrease in the level of cisplatin-DNA adducts, compared to the parental cells. The DNA repair rate following peak accumulation of cisplatin-DNA adducts (which took approximately 4 h) was also enhanced in the resistant cells. This was supported by the measurement of the cisplatin level remaining in cells by atomic absorption spectrophotometry, which showed a 2.7-fold reduction in the resistant cells. In addition, the acquired resistance and enhanced DNA repair in HOB1/VCR cells were partially reversed by nontoxic aphidicolin, a DNA polymerase-alpha and DNA repair inhibitor. Inhibition of the intracellular level of glutathione by DL-buthionine-[S,R]-sulfoximine demonstrated that cell viability was inhibited 4-fold more in the resistant cells than in the parental cells. The results suggest that the reduced formation of cisplatin-DNA adducts and the increased glutathione content of the multidrug-resistant cells play a major role in phenotypic cross-resistance to cisplatin.
authors.affiliation: Department of Biochemistry, Chang Gung Medical College, Taoyuan, Taiwan, ROC.
authors.forename: C C
authors.initials: CC
authors.lastname: Chao
mesh_terms: D000970:Antineoplastic Agents / Q000378:metabolism*; D016590:Aphidicolin / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000378:metabolism*; D003078:Colchicine / Q000494:pharmacology; D018736:DNA Adducts / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects; D004273:DNA, Neoplasm / Q000302:isolation & purification; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression; D019450:Genes, MDR; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D016685:Mitomycin / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011691:Puromycin / Q000494:pharmacology; D013054:Spectrophotometry, Atomic; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D014700:Verapamil / Q000494:pharmacology; D014750:Vincristine / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D018736:DNA Adducts; D004273:DNA, Neoplasm; D016590:Aphidicolin; D011691:Puromycin; D016685:Mitomycin; D014750:Vincristine; D004317:Doxorubicin; D014700:Verapamil; D002945:Cisplatin; D003078:Colchicine