Baicalin and puerarin reverse epithelial-mesenchymal transition via the TGF-β1/Smad3 pathway in vitro

Epithelial-mesenchymal transition (EMT) occurs in the development of fibrosis and carcinogenesis. EMT is associated with chronic liver injury. Evidence shows that hepatocytes undergo EMT in the adult liver. The Qinggan Huoxue Recipe (QGHXR), a Traditional Chinese Medicinal formula, shows a range of pharmacological effects in treating alcoholic liver disease. The present study aimed to investigate the effect of four major components of QGHXR, baicalin, salvianic acid, puerarin and saikosaponin, on EMT in vitro, and to elucidate the potential mechanism of QGHXR against EMT via the transforming growth factor-β1 (TGF-β1)/Smads signaling pathway. EMT models were established using LO2 hepatocytes and HepG2 cells treated with acetaldehyde in vitro. Acetaldehyde presented a mesenchymal cell characteristic in hepatocytes, accompanied by an increased expression of mesenchymal markers, including vimentin and fibronectin, and decreased E-cadherin. Baicalin and puerarin abrogated the increased expression of vimentin and fibronectin, and rescued E-cadherin expression in acetaldehyde-treated hepatocytes. It was further demonstrated that baicalin and puerarin reduced the gene expression of snail, TGF-β1 and Smad3. A decreased expression of tight function markers, including ZO-1, occludin and claudin, were also found in the acetaldehyde-treated hepatocytes. Barcacin regulated the mRNA level of TGF-βl and snail, and then suppressed the EMT process. This was accompanied by an increased mRNA level of E-cadherin and decreased levels of vimentin and fibronectin, but no significant differences in of Smad3, occludin, ZO-1 and claudin were observed. Puerarin regulated the mRNA level of TGF-βl, Smad3 and snail, suppresing the EMT process, which was accompanied by an increased mRNA level of E-cadherin and decreased levels of vimentin and fibronectin, along with increased levels of occludin, ZO-1 and claudin. When the snail gene was silent, barcacin and puerarin did not show significant effects in the acetaldehyde-treated cells. The results presented a novel mechanism through which baicalin and puerarin modulated hepatocyte EMT to improve liver fibrosis.