title: Prostaglandin A2 blocks the activation of G1 phase cyclin-dependent kinase without altering mitogen-activated protein kinase stimulation.
abstract: Prostaglandin A2 (PGA2) reversibly blocked the cell cycle progression of NIH 3T3 cells at G1 and G2/M phase. When it was applied to cells synchronized in G0 or S phase, cells were blocked at G1 and G2/M, respectively. The G2/M blockage was transient. Microinjected oncogenic leucine 61 Ras protein could not override the PGA2 induced G1 blockage, nor could previous transformation with the v-raf oncogene. The serum-induced activation of mitogen-activated protein kinase was not inhibited by PGA2 treatment. These data suggest that PGA2 blocks cell cycle progression without interfering with the cytosolic proliferative signaling pathway. Combined microinjection of E2F-1 and DP-1 proteins or microinjected adenovirus E1A protein, however, could induce S phase in cells arrested in G1 by PGA2, indicating that PGA2 does not directly inhibit the process of DNA synthesis. In quiescent cells, PGA2 blocked the normal hyperphosphorylation of the retinoblastoma susceptible gene product and the activation of cyclin-dependent kinase (CDK) 2 and CDK4, in response to serum stimulation. PGA2 treatment elevated the p21Waf1/Cip1/Sdi1 protein expression level. These data indicate that PGA2 may arrest the cell cycle in G1 by interfering with the activation of G1 phase CDKs.
authors.affiliation: Department of Molecular Biology, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hitomi
authors.forename: J
authors.initials: J
authors.lastname: Shu
authors.forename: D
authors.initials: D
authors.lastname: Strom
authors.forename: S W
authors.initials: SW
authors.lastname: Hiebert
authors.forename: M L
authors.initials: ML
authors.lastname: Harter
authors.forename: D W
authors.initials: DW
authors.lastname: Stacey
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D002471:Cell Transformation, Neoplastic; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation; D016193:G1 Phase; D016195:G2 Phase; D007700:Kinetics; D051379:Mice; D008845:Microinjections; D008938:Mitosis; D027384:Oncogene Proteins v-raf; D009857:Oncogenes; D010766:Phosphorylation; D011454:Prostaglandins A / Q000494:pharmacology*; D016160:Retinoblastoma Protein / Q000302:isolation & purification / Q000378:metabolism; D015682:Retroviridae Proteins, Oncogenic / Q000096:biosynthesis / Q000235:genetics; D013997:Time Factors; D018631:ras Proteins / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D011454:Prostaglandins A; D016160:Retinoblastoma Protein; D015682:Retroviridae Proteins, Oncogenic; D027384:Oncogene Proteins v-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018844:Cyclin-Dependent Kinases; D018631:ras Proteins; C100008:prostaglandin A2