title: Inhibition of cell cycle progression by penta-acetyl geniposide in rat C6 glioma cells.
abstract: Penta-acetyl geniposide, (Ac)5-GP, the acetylated compound of geniposide, is able to inhibit the growth of rat C6 glioma cells in culture and in the bearing rats. Our recent data indicated that the induction of cell apoptosis and cell cycle arrest at G0/gap phase 1 (G1) by (Ac)5-GP might be associated with the induction of p53 and c-Myc, and mediated via the apoptosis-related bcl-2 family proteins. In this report, we further investigated the mechanism involved in the cell cycle arrest induced by (Ac)5-GP in C6 glioma cells. The inhibitory effect of (Ac)5-GP on the cell cycle progression of C6 glioma cells which arrested cells at the G0/G1 phase was associated with a marked decrease in the protein expression of cyclin D1, and an induction in the content of cyclin-dependent kinase (cdk) inhibitor p21 protein. This effect was correlated with the elevation in p53 levels. Further immunoprecipitation studies found that, in response to the treatment, the formation of cyclin D1/cdk 4 complex declined, preventing the phosphorylation of retinoblastoma (Rb) and the subsequent dissociation of Rb/E2F complex. These results illustrated that the apoptotic effect of (Ac)5-GP, arresting cells at the G0/G1 phase, was exerted by inducing the expression of p21 that, in turn, repressed the activity of cyclin D1/cdk 4 and the phosphorylation of Rb.
authors.affiliation: Institute of Biochemistry, College of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Yun-Ching
authors.initials: YC
authors.lastname: Chang
authors.forename: Fen-Pi
authors.initials: FP
authors.lastname: Chou
authors.forename: Hui-Pei
authors.initials: HP
authors.lastname: Huang
authors.forename: Jeng-Dong
authors.initials: JD
authors.lastname: Hsu
authors.forename: Chau-Jong
authors.initials: CJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D019938:Cyclin D1 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D005910:Glioma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D005960:Glucosides / Q000494:pharmacology*; D057888:Iridoid Glucosides; D039823:Iridoids / Q000494:pharmacology*; D010766:Phosphorylation; D010936:Plant Extracts / Q000737:chemistry; D011714:Pyrans / Q000494:pharmacology*; D051381:Rats; D016160:Retinoblastoma Protein / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004365:Drugs, Chinese Herbal; D005960:Glucosides; D057888:Iridoid Glucosides; D039823:Iridoids; D010936:Plant Extracts; D011714:Pyrans; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1; C074968:pentaacetyl geniposide; D018844:Cyclin-Dependent Kinases