Pyrimidine nucleotide metabolism in L5178Y murine leukemia cells: deoxycytidine protection from deoxyguanosine toxicity.

Deoxyguanosine was found to inhibit reduction of uridine phosphate within L5178Y cells. A correlation of this effect with deoxyguanosine-induced inhibition of radioactive incorporation into DNA and inhibition of L5178Y cell growth suggests that depletion of thymidylate pools is involved in the toxicity induced by deoxyguanosine. Deoxycytidine appears to protect from deoxyguanosine toxicity by metabolism to thymidylate via a dCMP deaminase pathway, thus replenishing the thymidylate pools which have been depleted by deoxyguanosine.