Modulation of the sensitivity in Chinese hamster cells to photons and fast neutrons by cisplatin, vinblastine, and bleomycin.

Normal tissue toxicity resulting from chemoradiotherapy is of significant clinical concern. This study used normal Chinese hamster fibroblasts from lung (V79) and ovary (CHO-K1) to assess the modulation of cellular response to photons and neutrons by cisplatin, vinblastine, and bleomycin. Based on the colony formation assay, the drug concentration corresponding to 50% cell survival (EC50) of V79 cells was 1.50 +/- 0.21 micromol/L for cisplatin, 0.97 +/- 0.06 nmol/L for vinblastine, and 1.68 +/- 0.11 micromol/L for bleomycin. The corresponding values for CHO-K1 cells were significantly lower for vinblastine (0.54 +/- 0.02 nmol/L) and bleomycin (0.49 +/- 0.13 micromol/L), but not for cisplatin (1.57 +/- 0.20 micromol/L). No radiosensitivity enhancement was apparent when cells were exposed to p(66)/Be neutrons or photons (60Co gamma-rays) in the presence of these drugs at EC50 concentrations. These data suggest that concurrent use of these drugs with radiation for the treatment of lung and ovarian diseases radiation does not exacerbate radiation-induced normal tissue toxicity, regardless of the quality of radiation. The relatively higher sensitivity of the ovarian cells to vinblastine and bleomycin might constitute a limitation in the use of these drugs for the treatment of lung lesions.