Erythropoietin inhibits chemotherapy-induced cell death and promotes a senescence-like state in leukemia cells

a DA3/EPOR cells were cultured in the absence of EPO for 1.5？h and then stimulated with EPO (1？U/ml) for the times indicated. JAK2 and AKT kinase activation was determined by western blot analysis using a phospho-specific Tyr 1007/Tyr 1008 antibody (pJAK2) and phospho-specific Ser 473 antibody (pAKT) respectively. b Cells were cultured in the absence of EPO for 1？h followed by 6？h of treatment with Dox (200？ng/ml) or DNR (0.25？μM), with or without EPO (1？U/ml). The proportion of apoptotic cells (cells with <2？N DNA content) was determined by flow cytometry after propidium iodide staining. Error bars represent SEM (N？=？3 biological replicates) and p values were obtained via Student’s two-tailed t test. c Cells were cultured in the absence of EPO for 1.5？h, followed by 20？h treatment with Dox (200？ng/ml) or DNR (0.25？μM) in the presence or absence of EPO (1？U/ml). Caspase-3 activity was measured by flow cytometry. d Cells were cultured in the absence of EPO for 1.5？h, exposed to 6？Gy γ-radiation and cultured for an additional 6？h in the presence or absence of EPO (1？U/ml) before assessment of apoptosis by TUNEL assay. Error bars represent SEM (N？=？3 biological replicates