title: Up-regulation of p21WAF1 expression in myeloid cells is activated by the protein kinase C pathway.
abstract: Phorbol-12-myristate-13-acetate (PMA) induces p21WAF-1 expression in human myeloid leukaemic HL-60 cells. We show that this induction is specifically mediated by protein kinase C (PKC). In addition, the PKC inhibitor Ro 31-8220 with predominant PKC-alpha isoform specificity almost completely inhibited PMA-induced up-regulation of p21WAF1 in HL-60 cells as well as in the myelomonocytic leukaemic U937 cells. Pretreatment of HL-60 cells with Ro 31-8220 also inhibited PMA-induced activation of c-raf-1, a known PKC alpha target. In the phorbol ester-tolerant HL-60 subline (PET) with PKC-beta isoform deficiency PMA or bryostatin-1 induced p21WAF1 expression, but to a lesser extent than in wild-type HL-60 cells. In PET cells, Ro 31-8220 also inhibited PMA and bryostatin-1-induced up-regulation of p21WAF1 expression. Our findings indicate that at least in HL-60 cells up-regulation of p21WAF-1 is specifically activated by PKC. We suggest that PKC isoforms other than beta, presumably the PKC-alpha isoform, are involved in this process.
authors.affiliation: The Department of Clinical Research, University of Berne, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Schwaller
authors.forename: U R
authors.initials: UR
authors.lastname: Peters
authors.forename: T
authors.initials: T
authors.lastname: Pabst
authors.forename: G
authors.initials: G
authors.lastname: Niklaus
authors.forename: D E
authors.initials: DE
authors.lastname: Macfarlane
authors.forename: M F
authors.initials: MF
authors.lastname: Fey
authors.forename: A
authors.initials: A
authors.lastname: Tobler
mesh_terms: D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D015973:Gene Expression Regulation, Leukemic; D018922:HL-60 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D007211:Indoles; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; C064758:Ro 31-8220