Effect Of Fmdc On The Cell Cycle Of Some Leukemia Cell Lines

Background: (E)-2'-deoxy-2'-(fluoromethylene)-cytidine (FMdC), an irreversible inhibitor of ribonucleotide reductase, displays a strong toxicity towards many cell Lines derived from human solid tumors, while its activity on leukemia lines is less well-known. The aim of this study was to assess the effect of FMdC on the cell cycle and cell death of human leukemia lines HL-60 and MOLT-4, and murine leukemia L-1210 in vitro. It has been assumed that a prerequisite of FMdC cytotoxicity is intracellular phosphorylation by deoxycytidine kinase (dCK).Methods: Cell cultures in the exponential phase of growth were exposed to different concentrations of FMdC (10 nM to 10 mu M) for 6 and 24 hours. In a parallel set of experiments I mM deoxycytidine was added to prevent phosphorylation of the drug by dCK. The DNA and protein content in the cells, as well as Annexin V/PI binding were assessed by flow cytometry. The cell cycle was analyzed by the MacCycle software.Results: The cytotoxic effects of FMdC, i.e., G(1)/S block and cell death were observed, associated with pronounced changes in the protein content. These effects were of variable intensity among the cell lines studied (HL-60 being the most susceptible), and in some cases, were not completely reversed by deoxycytidine excess.Conclusions: FMdC is a potent cytotoxic/cytostatic agent against human leukemia cell lines in vitro. It also changes the cellular protein content. Unphosphorylated FMdC may slightly influence the cell cycle of some leukemic Lines. Cytometry 37:302-307, 1999. (C) 1999 Wiley-Liss, Inc.