title: Retinoic acid-mediated G1 arrest is associated with induction of p27(Kip1) and inhibition of cyclin-dependent kinase 3 in human lung squamous carcinoma CH27 cells.
abstract: Retinoids are promising agents for the prevention and treatment of several human malignancies including lung cancer. In this study, the effect of retinoic acid (RA) on cell growth and the mechanism of growth modulation were examined in human lung squamous carcinoma CH27 cells. Here we report that RA mediated the dose- and time-dependent growth arrest in G1 phase, accompanied by the up-regulation of p27(Kip1) and the down-regulation of the cyclin-dependent kinase 3 (Cdk3) and p21(CIP1/Waf1) proteins. Furthermore, RA-induced growth arrest of CH27 cells was also associated with increased retinoic acid receptor beta (RARbeta) and reduced c-Myc expression. However, RA had no effect on the levels of cyclins A, D1, D3, E, or H, or on Cdk2, Cdk4, Cdk5, CDk6, Cdk7, p16(Ink4A), p15(Ink4B), p53, or pRb proteins in CH27 cells. Evaluation of the kinase activity of cyclin-Cdk complexes showed that RA increases p27(Kip1) expression in CH27 cells leading to markedly reduced cyclin A/Cdk2 kinase activity and slightly reduced cyclin E/Cdk2 kinase activity, with no effect on cyclin D/Cdk4 and cyclin D/Cdk6 activities. Moreover, coincident with the decrease in kinase activity was a drastic increase in cyclin A-bound p27(Kip1). These results suggest that increases in the levels of p27(Kip1) and its binding to cyclin A, as well as reduction of Cdk3 protein expression, are strong candidates for the cell cycle regulator that prevents the entry into the S phase in RA-treated CH27 cells, with prolongation of G1 phase and inhibition of DNA synthesis.
authors.affiliation: Department of Education & Research, Taichung Veterans General Hospital, Taichung, Taiwan. h2326@vghtc.vghtc.gov.tw
authors.forename: S L
authors.initials: SL
authors.lastname: Hsu
authors.forename: J W
authors.initials: JW
authors.lastname: Hsu
authors.forename: M C
authors.initials: MC
authors.lastname: Liu
authors.forename: L Y
authors.initials: LY
authors.lastname: Chen
authors.forename: C D
authors.initials: CD
authors.lastname: Chang
mesh_terms: D042846:CDC2-CDC28 Kinases; D002294:Carcinoma, Squamous Cell; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins; D002455:Cell Division; D002850:Chromatography, Gel; D019925:Cyclin A / Q000096:biosynthesis / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D056849:Cyclin-Dependent Kinase 3; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D016213:Cyclins / Q000378:metabolism; D016193:G1 Phase; D006801:Humans; D008175:Lung Neoplasms; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D000097768:Retinoic Acid Receptor gamma
chemical_list: D042846:CDC2-CDC28 Kinases; D018797:Cell Cycle Proteins; D019925:Cyclin A; D019927:Cyclin E; D051357:Cyclin-Dependent Kinase 2; D056849:Cyclin-Dependent Kinase 3; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D017346:Protein Serine-Threonine Kinases; D016271:Proto-Oncogene Proteins c-myc; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin; D025521:Tumor Suppressor Proteins; D000097768:Retinoic Acid Receptor gamma; C493956:CDKN1A protein, human; C000607071:RARA protein, human; C082925:retinoic acid receptor beta; C495894:CDK2 protein, human; C098776:CDK3 protein, human