title: Synergistic effect of retinoic acid and calcium ionophore A23187 on differentiation, c-myc expression, and membrane tyrosine kinase activity in human promyelocytic leukemia cell line HL-60.
abstract: The effect of the combination of retinoic acid (RA) and calcium ionophore A23187 on cellular differentiation was assessed in promyelocytic leukemia cell line HL-60. RA (10(-10)-2.5 X 10(-8) M) or A23187 (4 X 10(-7) M) alone produced 15-22% differentiated cells as assessed by nitroblue tetrazolium reduction. Exposure of cells for 48 hr to the combination of 4 X 10(-7) M A23187 and 10(-10)-2.5 X 10(-8) M RA resulted in 20-86% of the cells capable of reducing nitroblue tetrazolium, but with no measurable level of nonspecific esterase activity. The combination of A23187 and either dimethyl sulfoxide, 1,25-dihydroxyvitamin D3, or immune interferon failed to produce a synergistic effect on differentiation. Addition of either the calmodulin antagonists, N-(6-aminohexyl)-5-chloronaphthalenesulfonamide and trifluoperazine, or the protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine, during treatment with A23187 and RA did not block differentiation. Membrane tyrosine kinase activity was measured in cells treated with A23187 and RA in a nondenaturing gel system using the exogenous substrate poly(Glu:Tyr). Membrane-bound tyrosine kinase activity was not present in untreated or RA-treated cells but was induced by A23187 treatment alone and was markedly increased in cells 48 hr after treatment with the combination of A23187 and RA. Significantly greater reduction in c-myc mRNA levels was also observed 24 hr after treatment with RA and A23187 in comparison to that observed with either agent alone. These results suggest that a Ca2+-mediated process sensitizes cells to the differentiating effect of RA and that this effect is associated with a significant reduction of c-myc expression and the induction of membrane tyrosine kinase activity in this cell line.
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000001:Calcimycin / Q000494:pharmacology*; D002147:Calmodulin / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects; D006410:Hematopoiesis / Q000187:drug effects; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000473:pathology*; D010879:Piperazines / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology*; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D007546:Isoquinolines; D010879:Piperazines; D012333:RNA, Messenger; D013449:Sulfonamides; D014268:Trifluoperazine; D000001:Calcimycin; D014212:Tretinoin; C017967:W 7; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011505:Protein-Tyrosine Kinases