Activation of a well-behaved cell cycle in araC-treated V79 cells by caffeine

.3-1.0 microM araC (cytosine arabinoside) treatment of V79 cells produced inhibition of multiplication of cells which was accompanied by a large increase of cell size. In presence of 1-2 mM caffeine the inhibition of cell proliferation due to araC treatment was substantially reduced and cell-size increase was prevented; caffeine did not influence the uptake of araC by V79 cells. Flow microfluorometric analysis showed that caffeine induced a wave of cell cycle progression in 0.3 microM araC-treated cells. The cell cycle activated by caffeine in 0.3 microM araC-treated cells was largely well behaved; this was indicated by the fact that (1) prior to cell division cells achieved a tetraploid DNA content and (2) following cell division they had diploid DNA content as a result of which DNA homeostasis was maintained. At 1.0 microM araC concentration, however, extreme micronucleation was observed which gave rise to a substantial fraction of micronuclei with less than G1 DNA content.