title: CPEC induces erythroid differentiation of human myeloid leukemia K562 cells through CTP depletion and p38 MAP kinase.
abstract: Cyclopentenyl cytosine (CPEC) is a carbocyclic cytidine analog inhibitor of CTP synthetase and experimental drug for combination chemotherapy. CPEC treatment (50 nM) depleted intracellular CTP and induced a specific S-phase arrest and erythroid differentiation of human erythroleukemia K562 cells. The equilibrative nucleoside transporters (ENT1, 2) facilitated uptake of CPEC into K562 cells as evidenced by both NBMPR and dipyridamole inhibition of CPEC-mediated CTP depletion and erythroid differentiation. Incubation with the pyridinylimidazole p38 MAPK inhibitors, SB203580 or SB220025, suppressed both the CPEC-induced cell cycle arrest and differentiation of K562 cells. SB203580 also prevented the cell cycle arrest and erythroid differentiation of K562 cells induced by Leflunomide (LEF), a non-nucleoside inhibitor of the de novo pyrimidine pathway, without affecting LEF-induced depletion of pyrimidine pools. Finally, selective knockdown of p38 MAPK by using Smart Pooltrade mark siRNA to p38 MAPK significantly decreased the CPEC-induced differentiation of K562 cells. These results suggest that endogenous activity of p38 MAP kinases may be required for committing K562 cells to cell cycle arrest and erythroid differentiation under conditions of CTP depletion.
authors.affiliation: Department of Pharmacology and the Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7365, USA.
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Collins
authors.forename: L M
authors.initials: LM
authors.lastname: Graves
mesh_terms: D000345:Affinity Labels / Q000494:pharmacology; D019731:Carbon-Nitrogen Ligases / Q000037:antagonists & inhibitors; D002454:Cell Differentiation / Q000187:drug effects*; D003562:Cytidine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D003570:Cytidine Triphosphate / Q000378:metabolism*; D004176:Dipyridamole / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D033721:Equilibrative Nucleoside Transporter 1 / Q000378:metabolism; D015672:Erythroid Precursor Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D020014:K562 Cells; D000077339:Leflunomide; D007951:Leukemia, Myeloid; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011743:Pyrimidines / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects; D013868:Thioinosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; D004791:Enzyme Inhibitors; D033721:Equilibrative Nucleoside Transporter 1; D007555:Isoxazoles; D010726:Phosphodiesterase Inhibitors; D011743:Pyrimidines; D034741:RNA, Small Interfering; C438649:SLC29A1 protein, human; D013868:Thioinosine; D003562:Cytidine; D004176:Dipyridamole; D003570:Cytidine Triphosphate; C045911:cyclopentenyl cytosine; D048051:p38 Mitogen-Activated Protein Kinases; D019731:Carbon-Nitrogen Ligases; C019951:CTP synthetase; D000077339:Leflunomide; C001789:4-nitrobenzylthioinosine