Ribonucleotide depletion in glucose-deprived tumor cells - the role of RNA synthesis.

Ribonucleoside triphosphate pools decreased rapidly and profoundly in Ehrlich ascites tumor cells incubated in glucose-free medium. Ribonucleoside triphosphate pools decreased to a lesser degree and total ribonucleotide pools remained normal in cells that were incubated with actinomycin D or with cycloheximide for 30 min before deprivation of glucose. RNA synthesis rates in glucose-deprived cells were 53–70% of the rates in glucose-supplemented cells. These findings suggest that ribonucleoside triphosphate consumption in RNA synthesis is an important factor in the depletion of ribonucleotide pools in tumor cells subjected to glucose starvation. Restriction of ATP regeneration is the other major factor.