title: Induction of differentiation in human promyelocytic HL-60 leukemia cells activates p21, WAF1/CIP1, expression in the absence of p53.
abstract: The melanoma differentiation associated gene, mda-6, which is identical to the P53-inducible gene WAF1/CIP1, encodes an M(r) 21,000 protein (p21) that can directly inhibit cell growth by repressing cyclin dependent kinases. mda-6 was identified using subtraction hybridization by virtue of its enhanced expression in human melanoma cells induced to terminally differentiate by treatment with human fibroblast interferon and the anti-leukemic compound mezerein (Jiang and Fisher, 1993). In the present study, we demonstrate that mda-6 (WAF1/CIP1) is an immediate early response gene induced during differentiation of the promyelocytic HL-60 leukemia cell line along the granulocytic or macrophage/monocyte pathway. mda-6 gene expression in HL-60 cells is induced within 1 to 3 h during differentiation along the macrophage/monocyte pathway evoked by 12-0-tetradecanoyl phorbol-13-acetate (TPA) or 1,25-dihydroxyvitamin D3 (Vit D3) or the granulocytic pathway produced by retinoic acid (RA) or dimethylsulfoxide (DMSO). Immunoprecipitation analyses using an anti-p21 antibody indicate a temporal induction of p21 protein following treatment with TPA, DMSO or RA. A relationship between rapid induction of mda-6 gene expression and differentiation is indicated by a delay in this expression in an HL-60 cell variant resistant to TPA-induced growth arrest and differentiation. A similar delay in mda-6 gene expression is not observed in Vit D3 treated TPA-resistant variant cells that are also sensitive to induction of monocytic differentiation. Since HL-60 cells have a null-p53 phenotype, these results demonstrate that p21 induction occurs during initiation of terminal differentiation in a p53-independent manner. In this context, p21 may play a more global role in growth control and differentiation than originally envisioned.
authors.affiliation: Department of Pathology, Columbia University, College of Physicians and Surgeons, New York, NY 10032.
authors.forename: H
authors.initials: H
authors.lastname: Jiang
authors.forename: J
authors.initials: J
authors.lastname: Lin
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Su
authors.forename: F R
authors.initials: FR
authors.lastname: Collart
authors.forename: E
authors.initials: E
authors.lastname: Huberman
authors.forename: P B
authors.initials: PB
authors.lastname: Fisher
mesh_terms: D002454:Cell Differentiation / Q000235:genetics*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D017781:Genes, Immediate-Early; D016158:Genes, p53; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute; D014407:Tumor Cells, Cultured
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D003513:Cycloheximide