Detection of Characteristic Differences in the Irradiation Sensitivity of Four Human Cancer Cell Strains

Abstract

Monolayers of four human cancer cell strains were exposed to various doses of x radiation during different phases of their growth cycles. The effects as measured by changes in cell number were dependent on the radiation dose. The dose-response curve of each strain varied significantly when radiation was administered during different stages of the population cycle. With three strains, HeLa, RP Ca Vu I, and RP Ca Ov I, the cells at the beginning of the logarithmic growth phase were more sensitive to radiation than cells entering the negative growth acceleration phase. With the other strain, RP Ca Cx I, the reverse was true. Highly significant differences in the radiation sensitivity of the four cell lines were detected when radiation was administered during the fourth culture day, a period when the cells were entering the phase of negative growth acceleration. The characteristic differences appear to be consistent with the generally accepted radiotherapeutic susceptibility of the tumors from which the cell lines were originally derived. (auth)