title: Antimitogenesis linked to regulation of Skp2 gene expression.
abstract: Prostacyclin has many effects in the vasculature; one of the less well understood is the ability to block cell cycle progression through G(1) phase. We previously reported that the prostacyclin mimetic, cicaprost, selectively inhibits cyclin E-cyclin-dependent kinase-2 (Cdk2), and now we show that it acts by regulating the expression of Skp2, the F-box protein that targets p27(Kip1) for ubiquitin-mediated proteolysis. First, we show that cicaprost prevents the late G(1) phase down-regulation of p27(Kip1) and that the inhibitory effect of cicaprost on cyclin E-Cdk2 activity and S phase entry is eliminated by deleting p27(Kip1). Levels of the closely related Cdk2 inhibitor, p21(Cip1), are unaffected by cicaprost. Moreover, we show that cicaprost blocks the induction of Skp2 mRNA and that ectopic expression of a Skp2 cDNA overrides the effect of cicaprost on p27(Kip1) levels and S phase entry. Our data show that inhibition of F-box protein gene expression can underlie the effect of a potent antimitogen.
authors.affiliation: Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6084, USA.
authors.forename: Sheryl A
authors.initials: SA
authors.lastname: Stewart
authors.forename: Devashish
authors.initials: D
authors.lastname: Kothapalli
authors.forename: Yuval
authors.initials: Y
authors.lastname: Yung
authors.forename: Richard K
authors.initials: RK
authors.lastname: Assoian
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D042846:CDC2-CDC28 Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects* / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D019927:Cyclin E / Q000037:antagonists & inhibitors / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D050760:Cyclin-Dependent Kinase Inhibitor p27; D015536:Down-Regulation; D011464:Epoprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects; D044786:S-Phase Kinase-Associated Proteins / Q000235:genetics* / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D019927:Cyclin E; D044786:S-Phase Kinase-Associated Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D015124:8-Bromo Cyclic Adenosine Monophosphate; D011464:Epoprostenol; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; D051357:Cyclin-Dependent Kinase 2; C043867:cicaprost