title: Recombinant GM-CSF modulates the metabolism of cytosine arabinoside in leukemic cells in bone marrow.
abstract: The effect of human recombinant GM-CSF (rGM-CSF) on the metabolism of high dose ara-C was determined in bone marrow mononuclear cells (BMMCs) from eight normal volunteers and from seven patients with acute myelogenous leukemia (AML). We incubated the cells with rGM-CSF alone, ara-C alone, or a combination of the two drugs. Treatment with rGM-CSF for 16 h increased the percentage of cells in S-phase both in normal BMMCs and leukemic marrow cells. The treatment with rGM-CSF alone produced an approximately two-fold increase in the intracellular dCTP pools in normal BMMCs, but this increment was not observed in leukemic marrow cells. Simultaneous exposure to rGM-CSF in combination with ara-C increased cytosine arabinoside triphosphate (ara-CTP) pools in leukemic blasts. In contrast, this treatment decreased ara-CTP pools in normal BMMCs. Moreover, when the cells were preincubated with rGM-CSF for 16 h prior to the exposure to ara-C, leukemic blasts achieved a 7-fold higher ara-CTP/dCTP ratio as compared with normal marrow cells. Treatment of the cells with rGM-CSF, either simultaneously or sequentially, resulted in significantly greater amounts of ara-C incorporation into DNA in leukemic marrow cells than normal counterparts. The higher accumulation of ara-CTP and subsequent increased incorporation of ara-C into DNA in leukemic cells treated with rGM-CSF lead to the enhanced ara-C-mediated inhibition of DNA synthesis as compared with normal BMMCs. The selective accumulation of ara-CTP in leukemic vs normal cells have implications for the efficacy of the treatment of AML patients with high dose ara-C and rGM-CSF.
authors.affiliation: Nagoya National Hospital, Department of Clinical Research, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D001085:Arabinofuranosylcytosine Triphosphate / Q000378:metabolism; D001853:Bone Marrow / Q000187:drug effects / Q000378:metabolism*; D001854:Bone Marrow Cells; D003561:Cytarabine / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000378:metabolism; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D007700:Kinetics; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects; D014316:Tritium; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D003845:Deoxycytosine Nucleotides; D011994:Recombinant Proteins; D003561:Cytarabine; D014316:Tritium; D001085:Arabinofuranosylcytosine Triphosphate; C024107:2'-deoxycytidine 5'-triphosphate; D016178:Granulocyte-Macrophage Colony-Stimulating Factor