Biological heterogeneity and radiation sensitivity of in vitro propagated lung metastatic lines originated from a transplantable squamous cell carcinoma of BALB/c mouse.

Seven cell lines established from a diethylnitrosamine (DEN)-induced forestomach carcinoma (DEN3) of a BALB/c mouse and its six pulmonary metastatic foci were used to study the biological and functional diversity of tumor cells. DEN3 is a highly tumorigenic line capable of forming lung metastases readily. Six metastatic nodules were isolated from the lungs of syngeneic mice and six cell lines were established. The cell lines differed in characteristics such as tumorigenicity, metastatic capability, and in vivo and in vitro growth properties. Radiation sensitivity of these cell lines was examined by exposure, at near confluency stage of in vitro growth, to doses of 2.5 to 50 Gray (Gy) X-rays (1 Gy = 100 rads). Shortly after exposure (approximately 5 min), the cells were harvested and 10(5) cells were cultured or inoculated into syngeneic mice, or both. Growth of three of the six cell lines tested was prohibited by 5 Gy. However, some populations from the other cell lines were able to survive 5 or 10 Gy. Progenies of the cells that survived primary radiation exposure after several in vitro passages were able to withstand another exposure of the same magnitude but not a higher dose. The X-rayed survivor cells also maintained their tumorigenic potential.