title: p53-independent increase in p21WAF1 and reciprocal down-regulation of cyclin A and proliferating cell nuclear antigen in bromodeoxyuridine-mediated growth arrest of human melanoma cells.
abstract: Differentially regulated expression of activators and inhibitors of cyclin-dependent kinases (cdks) modulate cell cycle progression. In normal fibroblasts, these complexes consist of the cdk inhibitor p21WAF1/PCNA/G1 cyclin/cdk. We now show that bromodeoxyuridine (BrdUrd), a thymidine analogue and radiation sensitizer, inhibits growth and activity of cyclin A-cdk2 kinase in metastatic C8161 and nonmetastatic neo 6.3/C8161 human melanoma cells. Inhibition is not due to altered levels of cyclin D or catalytic cdk2 but involves a decrease in cyclin A and proliferating cell nuclear antigen, paralleled by higher levels of p21WAF1 without increases in p53. In contrast to serum starvation, which prevents accumulation of cyclins A and D in normal fibroblasts, such treatment did not down-regulate either cyclin in these melanoma cells, implying an aberrant control for G1 cyclins in these tumor cells. However, cyclin A was decreased by BrdUrd, suggesting that this pyrimidine analogue arrests melanoma cells at a G1 transition point, unlike that of serum starvation. This is the first report indicating that the antitumor therapeutic action of BrdUrd may be mediated by a p53-independent reciprocal effect on activators and inhibitors of cdk kinases.
authors.affiliation: IVIC, Tumor Cell Biology, Caracas, Venezuela. mrieber/pasteur.ivic.ve
authors.forename: M
authors.initials: M
authors.lastname: Strasberg Rieber
authors.forename: D R
authors.initials: DR
authors.lastname: Welch
authors.forename: M E
authors.initials: ME
authors.lastname: Miele
authors.forename: M
authors.initials: M
authors.lastname: Rieber
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001798:Blood Proteins / Q000494:pharmacology; D015153:Blotting, Western; D001973:Bromodeoxyuridine / Q000494:pharmacology; D042846:CDC2-CDC28 Kinases; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000819:agonists / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006801:Humans; D008545:Melanoma / Q000473:pathology*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
chemical_list: D000964:Antimetabolites, Antineoplastic; D001798:Blood Proteins; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D016159:Tumor Suppressor Protein p53; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D001973:Bromodeoxyuridine