Dihydromyricetin inhibits migration and invasion of hepatoma cells through regulation of MMP-9 expression

AIM: To investigate the effects of dihydromyricetin (DHM) on the migration and invasion of human hepatic cancer cells. METHODS: The hepatoma cell lines SK-Hep-1 and MHCC97L were used in this study. The cells were cultured in RPIM-1640 medium supplemented with 10% fetal bovine serum at 37 degrees C. in a humidified 5% CO2 incubator. DHM was dissolved in dimethyl sulfoxide and diluted to various concentrations in medium before applying to cells. MTT assays were performed to measure the viability of the cells after DHM treatment. Wound healing and Boyden transwell assays were used to assess cancer cell motility. The invasive capacity of cancer cells was measured using Matrigel-coated transwell chambers. Matrix metalloproteinase (MMP)-2/9 activity was examined by fluorescence analysis. Western blot was carried out to analyze the expression of MMP-2, MMP-9, p-38, JNK, ERK1/2 and PKC-delta proteins. All data were analyzed by Student's t tests in GraphPad prism 5.0 software and are presented as mean +/- SD. RESULTS: DHM was found to strongly inhibit the migration of the hepatoma cell lines SK-Hep-1 (without DHM, 24 h: 120 +/- 8 mu mol/L vs 100 mu mol/L DHM, 24 h: 65 +/- 10 mol/L, P < 0.001) and MHCC97L (without DHM, 24 h: 126 +/- 7 mu mol/L vs 100 mu mol/L DHM, 24 h: 74 +/- 6 mu mol/L, P < 0.001). The invasive capacity of the cells was reduced by DHM treatment (SK-Hep-1 cells without DHM, 24 h: 67 +/- 4 mu mol/L vs 100 mu mol/L DHM, 24 h: 9 +/- 3 mu mol/L, P < 0.001; MHCC97L cells without DHM, 24 h: 117 +/- 8 mu mol/L vs 100 mu mol/L DHM, 24 h: 45 +/- 2 mu mol/L, P < 0.001). MMP2/9 activity was also inhibited by DHM exposure (SK-Hep-1 cells without DHM, 24 h: 600 +/- 26 mu mol/L vs 100 mu mol/L DHM, 24 h: 100 +/- 6 mu mol/L, P < 0.001; MHCC97L cells without DHM, 24 h: 504 +/- 32 mu mol/L vs 100 mu mol/L DHM 24 h: 156 +/- 10 mu mol/L, P < 0.001). Western blot analysis showed that DHM decreased the expression level of MMP-9 but had little effect on MMP-2. Further investigation indicated that DHM markedly reduced the phosphorylation levels of p38, ERK1/2 and JNK in a concentration-dependent manner but had no impact on the total protein levels. In addition, PKC-delta protein, a key protein in the regulation of MMP family protein expression, was up-regulated with DHM treatment. CONCLUSION: These findings demonstrate that DHM inhibits the migration and invasion of hepatoma cells and may serve as a potential candidate agent for the prevention of HCC metastasis. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.