Salvianolic acid B prevents epithelial-to-mesenchymal transition through the TGF-beta1 signal transduction pathway in vivo and in vitro.
BACKGROUND
Salvianolic Acid B (Sal B) is a water-soluble component from Danshen (a traditional Chinese herb widely used for chronic renal diseases) with anti-oxidative and cell protective properties. Sal B also has potential protective effects on renal diseases. Tubular epithelial cells can undergo epithelial-to-mesenchymal transition (EMT), which plays an important role in the pathogenesis of renal interstitial fibrosis (RIF) and is mainly regulated by TGF-beta1/Smads pathway. The aims of the study are to investigate the effect of Sal B on tubular EMT in vivo and in vitro, and to elucidate its underlying mechanism against EMT related to TGF-beta1/Smads pathway.


RESULTS
For in vivo experiments, RIF was induced in rats by oral administration of HgCl2 and prophylaxised with Sal B and vitamin E. The protein expression of E-cadherin was down-regulated, while the expression of alpha-SMA, TGF-beta1, TbetaR-I, p-Smad2/3 and the activity of matrix metalloproteinase-2 (MMP-2) were up-regulated in kidneys of model rats when compared with those of normal rats. In contrast, Sal B and vitamin E significantly attenuated the expression of alpha-SMA, TGF-beta1, TbetaR-I, p-Smad2/3, and MMP-2 activity, but increased E-cadherin expression. For in vitro experiments, HK-2 cells were incubated with TGF-beta1 to induce EMT, and the cells were co-cultured with 1 and 10 microM Sal B or SB-431542 (a specific inhibitor of TbetaR-I kinase). TGF-beta1 induced a typical EMT in HK-2 cells, while it was blocked by Sal B and SB-431542, as evidenced by blocking morphologic transformation, restoring E-cadherin and CK-18 expression, inhibiting alpha-SMA expression and F-actin reorganization, and down-regulating MMP-2/9 activities in TGF-beta1 mediated HK-2 cells. Furthermore, Sal B and SB-431542 profoundly down-regulated the expressions of TbetaR-I and p-Smad2/3 but prevented the decreased expression of Smad7 in TGF-beta1 stimulated HK-2 cells.


CONCLUSIONS
Sal B can prevent tubular EMT in the fibrotic kidney induced by HgCl2 as well as HK-2 cells triggered by TGF-beta1, the mechanism of Sal B is closely related to the regulation of TGF-beta1/Smads pathway, manifested as the inhibition of TGF-beta1 expression, suppression of TbetaR-I expression and function, down-regulation of Smad2/3 phosphorylation, and restoration of the down-regulation of Smad7, as well as inhibition of MMP-2 activity.
Wang
Qing-Lan
QL
Institute of Liver Diseases, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, 528 Zhangheng Road, Shanghai, China.
Tao
Yan-Yan
YY
Yuan
Ji-Li
JL
Shen
Li
L
Liu
Cheng-Hai
CH
D000199:Actins / Q000378:metabolism; D000818:Animals; D001572:Benzofurans / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology*; D005355:Fibrosis / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000473:pathology*; D008648:Mesoderm / Q000166:cytology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction; D051906:Smad7 Protein / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation; D053630:Depsides
D000199:Actins; D001572:Benzofurans; D004365:Drugs, Chinese Herbal; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta; D051906:Smad7 Protein; D053773:Transforming Growth Factor beta1; C498862:Acta2 protein, rat; C076944:salvianolic acid B; D053630:Depsides; C000625843:Tgfbr1 protein, rat