Inhibition of ribonucleotide reduction in CCRF-CEM cells by 2',2'-difluorodeoxycytidine.

摘要: The new deoxycytidine analogue 2',2'-difluorodeoxycytidine (dFdC) is a specific inhibitor of DNA synthesis that has marked cytotoxicity and therapeutic activity. A 2-hr incubation with 0.1-10 microM dFdC decreased cellular viability 78-97%. This treatment reduced deoxynucleoside triphosphate pools, similar to the action ribonucleotide reductase hydroxyurea. most pronounced decrease occurred in dCTP pool, quantitatively followed by dATP, dGTP, dTTP. In contrast, inhibition arabinosylcytosine did not affect level, whereas dTTP pools increased, but less than 2-fold. incorporation [5-3H]cytidine into measure activity whole cells, was 3% controls 0.1 dFdC, only 40% ara-C. Each drug extent (greater 94%), suggesting limitation reaction proximal this step. concentration 5'-diphosphate 0.3 at 50% situ reductase. Direct assays partially purified ribonucleoside diphosphate (EC 1.17.4.1) demonstrated 4 5'-diphosphate; 5'-triphosphate much inhibitory. We conclude acts as an