Inhibition of extracellular signal-regulated kinase 1 by adenovirus mediated small interfering RNA attenuates hepatic fibrosis in rats.
Extracellular signal-regulated kinase 1 (ERK1) is a critical part of the mitogen-activated protein kinase signal transduction pathway, which is involved in hepatic fibrosis. However, the effect of down-regulation of ERK1 on hepatic fibrosis has not been reported. Here, we induced hepatic fibrosis in rats with dimethylnitrosamine administration or bile duct ligation. An adenovirus carrying small interfering RNA targeting ERK1 (AdshERK1) was constructed to determine its effect on hepatic fibrosis, as evaluated by histological and immunohistochemical examination. Our results demonstrated that AdshERK1 significantly reduced the expression of ERK1 and suppressed proliferation and levels of fibrosis-related genes in hepatic stellate cells in vitro. More importantly, selective inhibition of ERK1 remarkably attenuated the deposition of the extracellular matrix in fibrotic liver in both fibrosis models. In addition, both hepatocytes and biliary epithelial cells were proven to exert the ability to generate the myofibroblasts depending on the insults of the liver, which were remarkably reduced by AdshERK1. Furthermore, up-regulation of ERK1 paralleled the increased expression of transforming growth factor beta1 (TGF-beta1), vimentin, snail, platelet-derived growth factor-BB (PDGF-BB), bone morphogenetic protein 4 (BMP4), and small mothers against decapentaplegic-1 (p-Smad1), and was in reverse correlation with E-cadherin in the fibrotic liver. Nevertheless, inhibition of ERK1 resulted in the increased level of E-cadherin in parallel with suppression of TGF-beta1, vimentin, snail, PDGF-BB, BMP4, and p-Smad1. Interestingly, AdshERK1 treatment promoted hepatocellular proliferation.


CONCLUSIONS
Our study provides the first evidence for AdshERK1 suppression of hepatic fibrosis through the reversal of epithelial-mesenchymal transition of both hepatocytes and biliary epithelial cells without interference of hepatocellular proliferation. This suggests that ERK1 is implicated in hepatic fibrogenesis and selective inhibition of ERK1 by small interfering RNA may present a novel option for hepatic fibrosis treatment.
Zhong
Wei
W
Department of Gastroenterology, Changzheng Hospital, Second Military Medical University, Shanghai, China.
Shen
Wei-Feng
WF
Ning
Bei-Fang
BF
Hu
Ping-Fang
PF
Lin
Yong
Y
Yue
Hai-Yan
HY
Yin
Chuan
C
Hou
Jun-Liang
JL
Chen
Yue-Xiang
YX
Zhang
Jun-Ping
JP
Zhang
Xin
X
Xie
Wei-Fen
WF
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000077214:Becaplermin; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D004128:Dimethylnitrosamine / Q000009:adverse effects; D004195:Disease Models, Animal; D055166:Hepatic Stellate Cells / Q000378:metabolism / Q000473:pathology; D008026:Ligation; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D051898:Smad1 Protein / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
C525811:Bmp4 protein, rat; D055415:Bone Morphogenetic Protein 4; D015820:Cadherins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D034741:RNA, Small Interfering; D051898:Smad1 Protein; C497400:Smad1 protein, rat; D053773:Transforming Growth Factor beta1; D014746:Vimentin; D000077214:Becaplermin; D048052:Mitogen-Activated Protein Kinase 3; D004128:Dimethylnitrosamine