Cell shedding from x-irradiated multicellular spheroids of human lung carcinomas.

We studied the effect of radiation on cell shedding from the surface of multicellular spheroids. Spheroids were produced from two human lung cell lines, one adenocarcinoma (LCT1) and the other small cell carcinoma (LCT2), by using a liquid overlay culture technique. The number of cells shed from both kinds of spheroids did not change significantly when they were irradiated. The number of clonogenic cells shed from both kinds of irradiated spheroids decreased sharply as the dose of irradiation increases. There were no significant differences in clonogenic cell shedding per spheroid between LCT1 and LCT2 spheroids. 400 microns spheroids were more radioresistant to inhibition of clonogenic cell shedding than 250 microns spheroids. Shed cells were more radiosensitive than spheroid cells. In these experiments, we did not obtain any results indicating that radiation enhances metastasis.