title: Silibinin induces hepatic stellate cell cycle arrest via enhancing p53/p27 and inhibiting Akt downstream signaling protein expression.
abstract: BACKGROUND
  Proliferation of hepatic stellate cells (HSCs) plays a pivotal role in the progression of liver fibrosis consequent to chronic liver injury. Silibinin, a flavonoid compound, has been shown to possess anti-fibrogenic effects in animal models of liver fibrosis. This was attributed to an inhibition of cell proliferation of activated HSCs. The present study was to gain insight into the molecular pathways involved in silibinin anti-fibrogenic effect.
  
  
  METHODS
  The study was conducted on LX-2 human stellate cells treated with three concentrations of silibinin (10, 50 and 100 μmol/L) for 24 and 96 hours. At the end of the treatment cell viability and proliferation were evaluated. Protein expression of p27, p21, p53, Akt and phosphorylated-Akt was evaluated by Western blotting analysis and Ki-67 protein expression was by immunocytochemistry. Sirtuin activity was evaluated by chemiluminescence based assay.
  
  
  RESULTS
  Silibinin inhibits LX-2 cell proliferation in dose- and time-dependent manner; we showed that silibinin upregulated the protein expressions of p27 and p53. Such regulation was correlated to an inhibition of both downstream Akt and phosphorylated-Akt protein signaling and Ki-67 protein expression. Sirtuin activity also was correlated to silibinin-inhibited proliferation of LX-2 cells.
  
  
  CONCLUSIONS
  The anti-proliferative effect of silibinin on LX-2 human stellate cells is via the inhibition of the expressions of various cell cycle targets including p27, Akt and sirtuin signaling.
authors.affiliation: Institut de Recherche Experimentale et Clinique (IREC), Laboratory of Pediatric Hepatology and Cell Therapy, Universite Catholique de Louvain, 1200, Brussels, Belgium. mustapha.najimi@uclouvain.be.
authors.forename: Devaraj
authors.initials: D
authors.lastname: Ezhilarasan
authors.forename: Jonathan
authors.initials: J
authors.lastname: Evraerts
authors.forename: Brice
authors.initials: B
authors.lastname: Sid
authors.forename: Pedro Buc
authors.initials: PB
authors.lastname: Calderon
authors.forename: Sivanesan
authors.initials: S
authors.lastname: Karthikeyan
authors.forename: Etienne
authors.initials: E
authors.lastname: Sokal
authors.forename: Mustapha
authors.initials: M
authors.lastname: Najimi
mesh_terms: D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D000077385:Silybin; D012838:Silymarin / Q000494:pharmacology*; D037761:Sirtuins / Q000378:metabolism; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C436291:CDKN1B protein, human; D019394:Ki-67 Antigen; D012838:Silymarin; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D050760:Cyclin-Dependent Kinase Inhibitor p27; D000077385:Silybin; D051057:Proto-Oncogene Proteins c-akt; D037761:Sirtuins