title: Codominance of cisplatin resistance in somatic cell hybrids.
abstract: Intrinsic or acquired resistance to cisplatin in cancer cells remains a major obstacle to successful chemotherapy. The clinically relevant genetic and molecular mechanisms of resistance have not yet been identified. Cisplatin-resistant (CP-r) human KB epidermoid carcinoma cell lines (HeLa) resistant to varying levels of cisplatin after single and multiple selection steps are cross-resistant to other platinum compounds and to methotrexate. Intraspecies hybrids of the sensitive and KB CP-r cells were fused with HeLa D98(OR) CP-s, hypoxanthine-aminopterin-thymidine (HAT) sensitive, ouabain resistant, to determine whether cisplatin resistance is dominant or recessive. Cell-cell hybridization between the sensitive cells and single-step or two-step KB CP-r cells both indicated codominance of cisplatin resistance compared to hybrids between sensitive cell lines (D98(OR)xKB). The hybrids between sensitive cell lines (D98xKB) and a single-step CP-r KB cell line (D98xKB-CP.5) also were cross-resistant to carboplatin and methotrexate. In addition, the relatively slower growth rate of CP-r cells appears to be dominant. In the two-step CP-r KB cell line, KB-CP1, resistance is no more dominant than in the single-step CP-r KB cell line, KB-CP.5, suggesting that one of the two steps of resistance in KB-CP1 may not be dominant. These dominance data suggest that it might be possible to identify one or more genes responsible for cisplatin resistance by gene transfer from a resistant cell line to a sensitive cell line.
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4254, USA.
authors.forename: Yu-Lan Mary
authors.initials: YL
authors.lastname: Ying
authors.forename: Ding-Wu
authors.initials: DW
authors.lastname: Shen
authors.forename: Xing-Jie
authors.initials: XJ
authors.lastname: Liang
authors.forename: Michael M
authors.initials: MM
authors.lastname: Gottesman
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D016190:Carboplatin / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D005799:Genes, Dominant / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D006822:Hybrid Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007624:KB Cells; D008727:Methotrexate / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D016190:Carboplatin; D002945:Cisplatin; D008727:Methotrexate