Radioresistant derivatives of an X-ray-sensitive CHO cell line exhibit distinct patterns of sensitivity to DNA-damaging agents.
X-ray-resistant clones of the xrs-5 radiosensitive derivative of the CHO-K1 cell line were generated by transfecting cosmid library DNAs into the X-ray-sensitive cells. Transfectants were selected for both a dominant drug resistance marker present in the vector sequences and return to wild-type survival. Three cell lines were isolated which show X-ray survival characteristics similar to parental K1 cells. These revertant lines were examined for their cross-sensitivity to cis-diamminedichloroplatinum(II) (cisplatin) and bleomycin. Although these cell lines reverted with regard to X-ray sensitivity, they retained their sensitivity to cisplatin. Furthermore, changes in bleomycin and X-ray sensitivity did not correlate. There was a positive correlation between return to wild-type radiosensitivity and an increase in the rate of DNA double-strand break rejoining.
Department of Radiation and Cellular Oncology, University of Chicago Medical Center, IL 60637.
D R
DR
Jaffe
D
D
Haraf
J L
JL
Schwartz
R R
RR
Weichselbaum
A M
AM
Diamond
D000818:Animals; D001761:Bleomycin / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002945:Cisplatin / Q000494:pharmacology; D006224:Cricetinae; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D006801:Humans; D011836:Radiation Tolerance; D014162:Transfection; D014965:X-Rays
D001761:Bleomycin; D004247:DNA; D002945:Cisplatin