title: Phorbol myristate acetate inhibits phosphoinositol lipid-specific phospholipase C activity via protein kinase C activation in conditions inducing differentiation in HL-60 cells.
abstract: We have studied, in streptolysin O-permeabilized HL-60 cells and in HL-60 membrane preparations, the effects of phorbol 12-myristate 13-acetate (PMA) on polyphosphoinositide-specific phospholipase C (PLC) activity and on terminal differentiation towards macrophagic-like cells. We showed that terminal differentiation was induced when differentiating concentrations of the drug were present for only 1-2 h in the culture medium. Conditions inducing differentiation also inhibited PLC activity for a long lasting period (at least 5 h). When terminal differentiation affected only part of the cell population, inhibition of phospholipase C activity was found to be less marked and reversible over the period studied. Moreover in experiments done in an HL-60 clone resistant to PMA, no inhibition of PLC activity was provoked by this tumour promotor. In order to study the involvement of protein kinase C in this process, we measured modifications of PLC activity by PMA in the presence of two different protein kinase C inhibitors, staurosporine and H-7. They both prevented the inhibition of PLC activity by PMA indicating that this inhibition is likely to be related to the effect of PMA on protein kinase C activity. This was also confirmed by the fact that active protein kinase C, by itself, was able to decrease PLC activity when added to membrane preparations or to streptolysin O-permeabilized control HL-60 cells. These results indicate that PMA acts in inhibiting phospholipase C activity through its effect on protein kinase C activation and/or on protein kinase C translocation to the plasma membrane and that terminal differentiation, might be related to changes in both protein kinase C and PLC activities.
authors.affiliation: INSERM, Unité 204, Hôpital Saint Louis, Paris, France.
authors.forename: H
authors.initials: H
authors.lastname: Cost
authors.forename: P
authors.initials: P
authors.lastname: Barreau
authors.forename: M
authors.initials: M
authors.lastname: Basset
authors.forename: C
authors.initials: C
authors.lastname: Le Peuch
authors.forename: B
authors.initials: B
authors.lastname: Geny
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002999:Clone Cells; D004789:Enzyme Activation / Q000187:drug effects*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007546:Isoquinolines; D007951:Leukemia, Myeloid / Q000378:metabolism; D050356:Lipid Metabolism; D010879:Piperazines; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D019311:Staurosporine; D013301:Streptolysins / Q000494:pharmacology; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D007295:Inositol Phosphates; D007546:Isoquinolines; D010879:Piperazines; D013301:Streptolysins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate