Differential response to gamma radiation of human stomach cancer cells in vitro.

In vitro effects of radiation were studied in two permanent cell lines (AGS and SII) from two patients with adenocarcinoma of the stomach and three permanent sublines from each cell line. Radiation survival parameters for AGS and SII parent cell lines and sublines were determined after in vitro irradiation of their cells with 0.5 to 10 Gy of 60Co gamma rays. The AGS and SII cell lines had different growth properties, DNA contents and radiation survival curves. Surviving fractions of SII parent cells (76 chromosomes) after 2.0 and 10 Gy were 1.22 and 17.8 times greater, respectively, than values for AGS parent cells (47 chromosomes). Sensitivities (D0) were 1.08 and 1.45 Gy for AGS and SII parent lines, respectively. The D0 values for AGS parent cells and sublines were similar (1.01 to 1.08 Gy), but SII parent cells and sublines had D0 values of 1.45, 1.36, 1.37 and 1.12 Gy (for SII-A). Also, the SII parent cells had survival fractions after 2.0 and 10 Gy that were 1.3 and 11.3 times greater, respectively, than values for the SII-A cells. These data show differences in radiation responses among stomach cancer cell lines and sublines that may relate to DNA content, but there was no consistent correlation between radiation response and a particular cell characteristic.