Extracts of Celastrus Orbiculatus Inhibit Cancer Metastasis by Down-regulating Epithelial-Mesenchymal Transition in Hypoxia-Induced Human Hepatocellular Carcinoma Cells.

OBJECTIVE: To evaluate the effects of Celastrus Orbiculatus extracts (COE) on metastasis in hypoxia-induced hepatocellular carcinoma cells (HepG2) and to explore the underlying molecular mechanisms.

METHODS: The effect of COE (160, 200 and 240 μg/mL) on cell viability, scratch-wound, invasion and migration were studied by 3-4,5-dimethyl-2-thiazolyl-2,5-diphenyl-2-H-tetrazolium bromide (MTT), scratch-wound and transwell assays, respectively. CoCl2 was used to establish a hypoxia model in vitro. Effects of COE on the expressions of E-cadherin, vimentin and N-cadherin were investigated with Western blot and immunofluorescence analysis, respectively.

RESULTS: COE inhibited proliferation and metastasis of hypoxia-induced hepatocellular carcinoma cells in a dose-dependent manner (P<0.01). Furthermore, the expression of epithelial-mesenchymal transition (EMT) related markers were also remarkably suppressed in a dose-dependent manner (P<0.01). In addition, the upstream signaling pathways, including the hypoxia-inducible factor 1α (Hif-1α) and Twist1 were suppressed by COE. Additionally, the Hif-1α inhibitor 3-5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1), potently suppressed cell invasion and migration as well as expression of EMT in hypoxia-induced HepG2 cells. Similarly, the combined treatment with COE and YC-1 showed a synergistic effect (P<0.01) compared with the treatment with COE or YC-1 alone in hypoxia-induced HepG2 cells.

CONCLUSIONS: COE significantly inhibited the tumor metastasis and EMT by suppressing Hif-1α/Twist1 signaling pathway in hypoxia-induced HepG2 cell. Thus, COE might have potential effect to inhibit the progression of HepG2 in the context of tumor hypoxia.