title: Over-expression of insulin-like growth factor binding protein-related protein-1(IGFBP-rP1/mac25) in the M12 prostate cancer cell line alters tumor growth by a delay in G1 and cyclin A associated apoptosis.
abstract: In the present study, we examined the effects of over-expression of the potential tumor suppressor gene IGFBP-rP1/mac25 on cell-cycle kinetics in prostate cancer cells. The majority of the high expressing IGFBP-rP1/mac25 cell population was located in the G1 and sub-G0/G1 peaks; synchronizing cells in G2/M with nocodazole demonstrated the high expressing IGFBP-rP1/mac25 clones were delayed in the G1 phase of the cell cycle. Unscheduled expression of cyclin A in the sub-G0/G1 peak occurred in the IGFBP-rP1/mac25 clones. Immunoblots showed decreased cyclin D1 and p21 and increased cyclin E, p16, and p27 in the high expressing IGFBP-rP1/mac25 clones compared to the control cells. Cyclin D1/cdk-4,6 and cyclin E/cdk-2 kinase activities decreased but cyclin A/cdk-2 kinase activity increased for the high expressing IGFBP-rP1/mac25 clones compared to control cells. A pRb immunoprecipitation demonstrated more binding of E2F-1 to pRb in the high expressing IGFBP-rP1/mac25 clones than in control cells. Finally, cell senescence, as assessed by senescence-associated beta-galactosidase, demonstrated significantly more staining in the IGFBP-rP1/mac25 cells than control cells. These results suggest that IGFBP-rP1/mac25 alters the cell cycle kinetics of the M12 prostate cell line by delaying the cells in the G1 phase of the cell cycle. In addition, the appearance of cyclin A in the sub-G0/G1 phase of the cell cycle and the increased kinase activity of cyclin A/cdk-2 in the IGFBP-rP1/mac25 clones suggests that cyclin A is associated with the apoptotic cells.
authors.affiliation: Geriatric Research Education and Clinical Center, VAPSHCS, Seattle/Tacoma, Washington, WA 98493, USA.
authors.forename: Cynthia C
authors.initials: CC
authors.lastname: Sprenger
authors.forename: Mary E
authors.initials: ME
authors.lastname: Vail
authors.forename: Karen
authors.initials: K
authors.lastname: Evans
authors.forename: Jerry
authors.initials: J
authors.lastname: Simurdak
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Plymate
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology*; D017209:Apoptosis / Q000235:genetics*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics; D002455:Cell Division; D016922:Cellular Senescence; D019925:Cyclin A / Q000502:physiology*; D003599:Cytoskeleton / Q000187:drug effects; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D016193:G1 Phase / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D046911:Macromolecular Substances; D008297:Male; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015739:Nocodazole / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology*; D011993:Recombinant Fusion Proteins / Q000502:physiology; D016160:Retinoblastoma Protein / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000473:pathology
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D019925:Cyclin A; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D018969:Insulin-Like Growth Factor Binding Proteins; D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D011993:Recombinant Fusion Proteins; D016160:Retinoblastoma Protein; D014157:Transcription Factors; C102529:insulin-like growth factor binding protein-related protein 1; D015739:Nocodazole