Different responses of polyploidized V79 cells after removal of two drugs,demecolcine and K-252a

To examine whether or not cells polyploidized by different mechanisms behav e in a different manner after drug removal, V79 Chinese hamster cells were assessed by flow cytometry (FCM) after their polyploidization by demecolcin e and K-252a, inhibitors of spindle-fiber formation and protein kinase, res pectively. Cell cycle analysis of DNA histograms of V79 cells before and af ter the drug release was performed. With both drugs, the ploidy of V79 cell s increased just after the drug removal and was maintained for a week. A di fference was evident 10 days after the release. Tetraploid cells were the m ain population from 10 to 18 days after the release of K-252a, but not deme colcine. Cell cycle parameters were almost the same in pseudo diploid and t etraploid V79 cells, except for the tetraploid S phase which was 2 h longer .