Reduction of proliferative heterogeneity of CHEF18 Chinese hamster cell line during the progression toward tumorigenicity.

Doubling time and generation time represent two parameters by which the proliferation of cultured mammalian cells can be monitored. In this study we report the characterization of CHEF18 Chinese hamster cell line during the progression toward tumorigenicity by analysis of doubling time and generation time. The two parameters reveal that the proliferation was initially different, indicating the presence of a proliferative heterogeneity among the cycling cells. The progressive reduction up to the disappearance of this discrepancy suggests that a modification of the length of some phases of the cell cycle may have occurred during the progression toward tumorigenicity. However, the hypothesis that the shortening of doubling time might be due to a continuous coming out of cells from the cell cycle rather than to a shortening of the cell cycle is presented.