Lack of synchrony among multiple nuclei induces partial DNA fragmentation in V79 cells polyploidized by demecolcine

The nuclear morphology of polyploidized cells was examined in V79 Chinese hamster cells polyploidized by demecolcine or K-252a, inhibitors of spindle fibre formation and protein kinases, respectively. A variety of nuclear morphologies, including multinuclei, were observed in V79 cells polyploidized by demecolcine but not by K-252a, which produced mononuclear cells. A lack of synchrony in the nuclear cycle was observed among nuclei in multinuclear polyploidized cells. Partial DNA fragmentation, defined as DNA fragmentation of a nucleus in a multinuclear cell, was detected using the TUNEL method in V79 cells polyploidized by demecolcine but not by K-252a. Apoptosis occurred earlier in cell populations treated with demecolcine than in these treated with K-252a once the drugs were removed from the medium, suggesting that polyploidized cells with separate nuclei tend to apoptose earlier than those with mononuclei.