RELATIONSHIPS AMONG ARA-CTP POOLS, FORMATION OF (ARA-C)DNA, AND CYTO-TOXICITY OF HUMAN-LEUKEMIC CELLS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 64  (1) , 54-58
Abstract
Cytosine arabinoside (Ara-C) is the most effective agent in the treatment of acute myelogenous leukemia. This agent incorporates in leukemic cell DNA, and the extent of this incorporation correlates with loss of clonogenic survival. The incorporated Ara-C residue behaves as a relative DNA chain terminator, and the extent of (Ara-C)DNA formation correlates with inhibition of DNA synthesis. The incorporation of Ara-C into DNA requires the formation of Ara-CTP, and previous measurements of this metabolite have also been correlated with cytotoxicity. The present studies were undertaken to determine the relationship among Ara-CTP pools, formation of (Ara-C)DNA and loss of clonogenic survival. The incorporation of Ara-C into DNA is the single most powerful predictor of cell lethality. Although there is a correlation between Ara-CTP pools or continuous cellular exposure to Ara-CTP and cell kill, these relationships are less significant than that obtained with formation of (Ara-C)DNA. The extent of Ara-C incorporation into DNA can be predicted by the product of the Ara-CTP level and time (T), thus supporting the concept that Ara-C incorporation is dependent on continuous exposure to the triphosphate metabolite. These findings support the formation of (Ara-C)DNA as a highly predictive parameter of lethal cellular events.