engleski

The role of AMP-activated kinase (AMPK) in proliferation and differentiation of acute myeloid leukemia cells

Introduction: AMP-activated protein kinase (AMPK) is a serine/threonine kinase that serves as an energy sensor of AMP/ATP ratio. Activated AMPK stimulates tuberous sclerosis complex 1/2 (TSC1 /2), which negatively regulates mammalian target of rapamycin (mTOR) activity. Pharmacological AMPK activators have been recently reported to have antileukemic effects in bcr-abl expressing leukemias. The aim of the present study was to investigate the role of AMPK in cell cycle and differentiation of acute myeloid leukemia (AML) cell lines. Materials and Methods: Myeloblastic HL-60, promyelocytic NB4 and monocytic U937 cell lines were maintained in exponential growth in RPMI-1640 with 10% FBS. N, N-dimethylimidodicarbonimidic diamide (metformin) was purchased from Sigma, 5- aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR), AMPK inhibitor (Compound C), rapamycin and all-trans retionoic acid (ATRA) from Calbiochem. Cells were differentiated in the presence of ATRA (1 and 0.1 µM). The number of viable cells was determined by trypan blue exclusion and hemocytometer. The expression of CD11b, CD14 and CD64 was determined by FACSCalibur and Cell Quest software (Becton Dickinson). For cell cycle analysis, cells were stained directly with propidium iodide and analyzed by FACS and ModFit software (Becton Dickinson). Total cell lysates were analyzed for the level of p70 S6K, phosphorylated p70 S6K (Thr389), AMPKα and phosphorylated AMPKα (Thr172) by Western blot. Results: The presence of AMPK activators (5-15 mM metformin and 0.5 mM AICAR) significantly reduced the number of viable HL-60, NB4 and U937 cells after 96h. Metformin enchanced the ATRA-mediated increase in the expression of CD11b in NB4 cells. In all cell lines tested, 0.5 mM AICAR increased the percentage of subG1. Conclusion: AMPK activators exert antiproliferative and differentiative effects in AML.

AICAR; differentiation; acute myeloid leukemia

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