title: Down-Regulation of Protein Kinase C-ε by Prolonged Incubation with PMA Inhibits the Proliferation of Vascular Smooth Muscle Cells.
abstract: OBJECTIVE
  Phorbol myristate acetate (PMA) exerts a pleiotropic effect on the growth and differentiation of various cells. Protein kinase Cs (PKCs) plays a central role in mediating the effects of PMA on cells. The present study investigated whether the down-regulation of protein kinase C-ε (PKC-ε) is involved in the inhibition of vascular smooth muscle cell (VSMC) proliferation caused by prolonged PMA incubation.
  
  
  METHODS
  Using cell counting, Cell Counting Kit-8 (CCK-8) and EdU incorporation assay on VSMCs, we evaluated the inhibitory effects of prolonged incubation of PMA, of lentiviruses carrying the short-hairpin RNAs (shRNA) of PKC-ε and of the PKC-ε inhibitor peptide on the proliferation and viability of cells. The effect of PKC-ε down-regulation on growth of rat breast cancer SHZ-88 cells was also measured.
  
  
  RESULTS
  The prolonged incubation of VSMCs with PMA for up to 72 hours resulted in attenuated cell growth rates in a time-dependent manner. The expression of PKC-ε, as assessed by Western blotting, was also decreased accordingly. Notably, the number of EdU-positive cells and the cell viability of VSMCs were decreased by shRNA of PKC-ε and the PKC-ε inhibitor peptide, respectively. The proliferation of rat breast cancer SHZ-88 cells was also attenuated by lentivirus-induced shRNA silencing of PKC-ε.
  
  
  CONCLUSIONS
  Prolonged incubation of PMA can inhibit the expression of PKC-ε. The effect results in the inhibition of VSMC proliferation. PKC-ε silencing can also attenuate breast cancer cell growth, suggesting that PKC-ε may be a potential target for anti-cancer drugs.
authors.affiliation: Department of Anesthesiology, Shanghai Jiaotong University Affiliated Shanghai Sixth People's Hospital, Shanghai, China.
authors.forename: Huixuan
authors.initials: H
authors.lastname: Zhou
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Quanhong
authors.initials: Q
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.forename: Aizhong
authors.initials: A
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Li
authors.initials: L
authors.lastname: Wang
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D020868:Gene Silencing / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008819:Mice, Nude; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D034741:RNA, Small Interfering; D051744:Protein Kinase C-epsilon; D048049:Extracellular Signal-Regulated MAP Kinases; D013755:Tetradecanoylphorbol Acetate