Honokiol inhibits epithelial-mesenchymal transition and hepatic fibrosis via activation of Ecadherin/GSK3ß/JNK and inhibition of AKT/ERK/p38/ß-catenin/TMPRSS4 signaling axis.

Though Honokiol was known to have anti-inflammatory, antioxidant, anticancer, antithrombotic, anti-viral, metabolic, antithrombotic, and neurotrophic activities, the underlying mechanisms of Honokiol on epithelial-mesenchymal transition (EMT) mediated liver fibrosis still remain elusive so far. Anti-EMT and antifibrotic effects of Honokiol were explored in murine AML-12 hepatocyte cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, wound healing assay, Western blotting and also in CCl4-induced liver injury mouse model by immunohistochemistry. Honokiol significantly suppressed transforming growth factor ß1 (TGF-ß1)-induced EMT and migration of AML-12 cells along with decreased EMT phenotypes such as loss of cell adhesion and formation of fibroblast like mesenchymal cells in TGF-ß1-treated AML-12 cells. Consistently, Honokiol suppressed the expression of Snail and transmembrane protease serine 4 (TMPRSS4), but not p-Smad3, and activated E-cadherin in TGF-ß1-treated AML-12 cells. Additionally, Honokiol reduced the expression of ß-catenin, p-AKT, p-ERK, p-p38 and increased phosphorylation of glycogen synthase kinase 3 beta (GSK3ß) and JNK in TGF-ß1-treated AML-12 cells via TGF-ß1/nonSmad pathway. Conversely, GSK3ß inhibitor SB216763 reversed the ability of Honokiol to reduce Snail, ß-catenin and migration and activate E-cadherin in TGF-ß1-treated AML-12 cells. Also, Honokiol suppressed hepatic steatosis and necrosis by reducing the expression of TGF-ß1 and α-SMA in liver tissues of CCl4 treated mice. These findings provide scientific evidence that Honokiol suppresses EMT and hepatic fibrosis via activation of E-cadherin/GSK3ß/JNK and inhibition of AKT/ERK/p38/ß-catenin/TMPRSS4 signaling axis.

Inhibition of TMPRSS4 mediated epithelial-mesenchymal transition is critically involved in antimetastatic effect of melatonin in colorectal cancers.

In the current study, the underlying anti-metastatic mechanism of melatonin contained in some edible plants was explored in association with transmembrane protease serine 4 (TMPRSS4) mediated metastasis and epithelial-mesenchymal transition (EMT) signaling in human HCT15 and SW620 colorectal cancer cells. Here, TMPRSS4 was highly expressed in HCT15, but was weakly expressed in SW620 cells. Melatonin exerted weak cytotoxicity, decreased invasion, adhesion, and migration, and attenuated the expression of TMPRSS4, cyclin E, pro-urokinase-type plasminogen activator (pro-uPA), p-signal transducer and activator of transcription 3 (p-STAT3), p-focal adhesion kinase (p-FAK), Snail and increased the expression of E-cadherin, p27, pp38 and p-Jun N-terminal kinases (p-JNK) in HCT15 cells. Conversely, overexpression of TMPRSS4 reduced the ability of melatonin to activate E-cadherin and reduce Snail. Furthermore, even in SW620 cells transfected with TMPRSS4-overexpression plasmid, melatonin effectively suppressed invasion and migration along with decreased expression of Snail, cyclin A, cyclin E, pro-uPA and p-FAK and increased expression of E-cadherin and p27. Overall, these findings provide evidence that melatonin suppresses metastasis in colon cancer cells via inhibition of TMPRSS4 mediated EMT.