Correlation of Cell Cycle Parameters with Radiation Sensitivity in a Series of Murine L5178Y Cells

Summary

The X-ray dose–response parameters (D₀, n and D_q) of 10 strains of murine L5178Y cells spanning a wide range of radiation sensitivities were characterized. The proportions of cells residing in G₁, S and G₂ + M phases of the cell cycle in exponentially growing cell populations were estimated using DNA microfluorometric techniques. The radiosensitive strains contained a lower proportion of cells in G₁ phase and a somewhat larger proportion of cells in S phase than did the radioresistant strains, reflecting a direct correlation between radioresistance and the duration of G₁ phase (and possibly an inverse correlation with the duration of the S phase) in these closely related cell strains. These results are discussed in terms of the putative role of G₁ in governing radiosensitivity of cells and tumours.