Cellular Chemo-Resistance and Radiosensitivity of Parental and Adriamycin-Selective Human Small-Cell Lung Cancer Cell Lines

Abstract

The radiosensitivity of two small-cell, lung cancer cell lines comprising the adriamycin-selective cell line (GLC4/Adr) and its parental counter cell line (GLC4) was investigated in an aqueous soluble system. A simplified resazurin assay was optimized and used in the cell viability investigation. Cell survival was evaluated after being exposed to cytotoxic agents, deduced from the resazurin reduction using the optical density of a spectrophotometer instead of a fluorescent signal. Compared with their parental counterparts, the GLC4/Adr cells displayed a high resistance capability to doxorubicin with a resistant factor of about 320. No significant resistance to gamma radiation was demonstrated after exposure to gamma radiation from a Cs-137 source. The GLC4/Adr cell line responded to radiation in the same manner as its parental counterpart. This finding suggested that a drug resistance phenotype occurred in the GLC4/Adr cells (plausibly acquired after being cultured in the presence of oxidative stress produced by the step-wise concentration of adriamycin) and it is not responsible for the radioresistance of the cells.