Comparison of the combined action of oxaliplatin or cisplatin and radiation in cervical and lung cancer cells

Background and purpose: To test the combined effects of oxaliplatin and radiation versus cisplatin and radiation using human cervical and lung cancer cell lines. Material and Methods: CaSki cervical cancer cells, and A549 lung cancer cells were cultured under standard conditions. Cells were treated with escalating doses of gamma-irradiation (0 - 6 Gy), and with oxali- and cisplatin for 2 h or 24 h, or a combination of both. Cell survival was measured by a colony-forming assay. Survival curves were fitted to the data using the linear quadratic model. Sensitizer enhancement ratios (SER) were calculated at the 37% survival level, and isobologram analysis was applied to test for the drug-radiation interactions. Results: Oxaliplatin as well as cisplatin alone were cytotoxic in both cell lines. In CaSki cells, oxaliplatin and cisplatin significantly increased radiation toxicity. In A549 cells no increase of radiation toxicity was observed after treatment with cisplatin, however, isobologram analysis revealed supra-additive interaction between oxaliplatin and radiation in A549 cells. Conclusion: Oxaliplatin had the same effectiveness on tumor cells as cisplatin and induced enhanced radiation toxicity in lung cancer cells, where cisplatin was not able to achieve radiosensitization.