title: Molecular mechanism of progesterone-induced antiproliferation in rat aortic smooth muscle cells.
abstract: Previously we demonstrated that progesterone at physiologic levels dose dependently inhibited cell proliferation in cultured rat aortic smooth muscle cells (RASMCs). However, the molecular mechanism underlying of progesterone-induced antiproliferation was not clear. Here we demonstrated that progesterone induced a reduction of the [(3)H]thymidine incorporation into RASMCs during the S-phase of the cell cycle. Western blotting analysis revealed that the protein levels of cyclin A, cyclin E, and cyclin-dependent-kinase (CDK) 2 but not cyclin D1 and CDK4 decreased after progesterone treatment, but those of CDK-inhibitory proteins, p21 and p27, increased. Immunoprecipitation showed that the formations of the CDK2-p21 and CDK2-p27 complex were increased and the assayable CDK2 kinase activity was decreased in the progesterone-treated RASMCs. In contrast, the formations of the CDK4-p21 and CDK4-p27 complex and the assayable CDK4 kinase activity were not changed significantly by progesterone treatment. Pretreatment of RASMCs with a p21 or p27 antisense oligonucleotide reduced the progesterone-induced inhibition of [(3)H]thymidine incorporation into RASMCs. In conclusion, these data suggest that progesterone inhibits RASMCs proliferation by increasing the levels of p21 and p27 protein, which in turn inhibit CDK2 kinase activity, and finally interrupt the cell cycle.
authors.affiliation: Department of Physiology, School of Medicine, Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan. wslee@tmu.edu.tw
authors.forename: Wen-Sen
authors.initials: WS
authors.lastname: Lee
authors.forename: Chao-Wei
authors.initials: CW
authors.lastname: Liu
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Juan
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Liang
authors.forename: Pei-Yin
authors.initials: PY
authors.lastname: Ho
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Lee
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D001161:Arteriosclerosis / Q000473:pathology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016196:S Phase / Q000187:drug effects; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C493958:Cdkn1a protein, rat; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016376:Oligonucleotides, Antisense; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D011374:Progesterone