[Cross-resistance to radiation in human squamous cell carcinoma cells with induced cisplatin resistance].
Accumulated evidence indicates that drug resistance is induced in tumor cells treated with a variety of anti-cancer drugs and that there is a possibility of cross-resistance to ionizing radiation associated with induced drug resistance. Most in vitro studies have shown inconsistent results on cross-resistance probably because of different cell lines used and protocols for drug induction. In this study, TE3 human squamous cell carcinoma cell line was treated with a 4-day cycle of cisplatin (cis-diamminedichloroplatinum (II); CDDP) at a concentration yielding 10% cell survival. The treatment was repeated up to 3 cycles. After treatment, cells were tested for CDDP and X-ray sensitivity. One cycle of CDDP treatment induced CDDP resistance with a factor of 1.41 and 2 cycles of the treatment with a factor of 1.86. The resistance factor reached a plateau at 3 cycles of treatment. For analyzing the correlation of CDDP and X-ray resistance, 30 clones from both untreated and 3-cycle treated cells were isolated and analyzed for CDDP and X-ray sensitivity. The sensitivity was expressed as the concentration of drug or dose of X-ray required to reduce the cell survival to x% (Dx). The correlation coefficient of clones with 3-cycle treatment between CDDP and X-ray sensitivity increased gradually by increasing the end point of Dx from D10 to D90, resulting in significant correlation at D90. The result suggested that there is a certain common repair-related mechanism affecting both CDDP and X-ray resistance in CDDP-treated cells.
Komori
K
K
Department of Dental Radiology and Radiation Research, Faculty of Dentistry, Tokyo Medical and Dental University.
D000970:Antineoplastic Agents / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002945:Cisplatin / Q000494:pharmacology*; D003429:Cross Reactions; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D019008:Drug Resistance, Neoplasm; D004938:Esophageal Neoplasms / Q000473:pathology*; D006801:Humans; D011836:Radiation Tolerance; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000528:radiation effects*
D000970:Antineoplastic Agents; D011838:Radiation-Sensitizing Agents; D002945:Cisplatin