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 microM) for 6 and 24 hours. In a parallel set of experiments 1 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.
Skierski
J S
JS
Flow Cytometry Laboratory, The Drug Institute, Warsaw, Poland. skierski@il.waw.pl
Koronkiewicz
M
M
Grieb
P
P
D000818:Animals; D017304:Annexin A5 / Q000032:analysis; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D004273:DNA, Neoplasm / Q000032:analysis; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects*; D018922:HL-60 Cells / Q000737:chemistry / Q000166:cytology; D006801:Humans; D007945:Leukemia, Lymphoid; D051379:Mice; D009363:Neoplasm Proteins / Q000032:analysis; D010766:Phosphorylation
D017304:Annexin A5; D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D003841:Deoxycytidine; C086432:tezacitabine