PPAR(gamma)/PGC-1(alpha) pathway in E-cadherin expression and motility of HepG2 cells.
BACKGROUND
Peroxisome proliferator-activated receptor gamma (PPARgamma) activation has been proposed as a potential therapeutic strategy for various types of human cancer. The aim of this study was to activate PPARgamma and overexpress PGC-1alpha in HepG2 cells in order to analyze their effects on cell motility and E-cadherin expression.


METHODS
Adenovirus-mediated gene transfer was performed to overexpress PGC-1alpha in HepG2 human hepatoma cells. Small interference RNA (siRNA) was used to silence the expression of E-cadherin and PPARgamma. Cell motility was assessed by transwell cell migration analysis. Measurements of mRNA and protein expression were done by quantitative RT-PCR and Western blotting.


RESULTS
Treatment with synthetic PPARgamma agonists, thiazolidinediones (rosiglitazone; troglitazone), and adenovirus-delivered overexpression of PPARgamma transcriptional coactivator-1alpha (PGC-1alpha) up-regulated E-cadherin expression and reduced motility of HepG2 cells. Using PPARgamma antagonist GW9662, we demonstrated that both PPARgamma-dependent and -independent pathways were involved in PGC-1alpha-induced up-regulation of E-cadherin. In addition, siRNA-mediated knockdown of E-cadherin expression restored the motility of PGC-1alpha-overexpressing HepG2 cells, indicating that up-regulated E-cadherin is responsible for the lower migratory ability of these cells. Intriguingly, siRNA-mediated silencing of PPARgamma abolished E-cadherin protein expression but also reduced the motility of HepG2 cells.


CONCLUSIONS
PPARgamma/PGC-1alpha pathway plays a crucial role in modulating E-cadherin expression and motility of HepG2 cells and may be a potential target for the prevention of HCC metastasis.
Lee
Hui-Ju
HJ
Department and Institute of Pharmacology, School of Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan, R.O.C.
Su
Yeu
Y
Yin
Pen-Hui
PH
Lee
Hsin-Chen
HC
Chi
Chin-Wen
CW
D015153:Blotting, Western; D015820:Cadherins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D045162:Thiazolidinediones / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D015820:Cadherins; D006360:Heat-Shock Proteins; D047495:PPAR gamma; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger; D045162:Thiazolidinediones; D014157:Transcription Factors