ABSTRACT
AIM: Gut microbiota are involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Silybin (Sil), a naturally occurring hepatoprotective agent, is widely used for treating NAFLD. Whether Sil affects gut microbiota during its actions in treating NAFLD is unknown. We aimed to examine the effect of Sil on intestinal flora dysbiosis induced by a high-fat diet (HFD). METHODS: After 10 weeks of feeding normal chow diet or HFD, mice were given a daily gavage for 8 weeks. Cecal contents were harvested for study of short-chain fatty acids, bile acids, and gut microbiota alteration. RESULTS: Sil showed protective effects against dietary-induced obesity and liver steatosis; accordingly, gut microbiota composition changed. At the phylum level, compared with the HFD group, mice in the Sil-treated group had significantly lower levels of Firmicutes, and the ratio of Firmicutes-to-Bacteroidetes was lower (P < 0.05). At the genus level, the Sil-treated group have significantly lower levels of Lachnoclostridium, Lachnospiraceae_UCG-006, and Mollicutes_RF9, which were reported to be potentially related to diet-induced obesity, and increased levels of Blautia (P < 0.05), Akkermansia (P < 0.05), and Bacteroides (P < 0.05), which are known to have a beneficial effect on improving NAFLD. Sil also showed an inhibitory effect on well-known beneficial bacteria, such as Alloprevotella and Lactobacillus. Furthermore, the production of acetate, propionate, and butyrate increased, whereas the generation of formate and conversion of cytotoxic secondary metabolites (lithocholic acid and deoxy-cholic acid) decreased in mice treated with Sil. CONCLUSIONS: Sil might have beneficial effects on ameliorating NAFLD and mediating HFD-induced change of gut microbiota composition, followed by major changes in secondary metabolites, such as short-chain fatty acids and bile acids.
ABSTRACT
BACKGROUND: Cell migration is a basis for invasion and metastasis of malignant tumors. Receptor tyrosine kinases are recognized as important therapeutic targets in antineoplastic strategies. C-met is a receptor tyrosine kinase highly expressed in human hepatocellular carcinoma (HCC) cell line MHCC97-H. Higher expression of c-met in tumor tissue can lead to scattering, angiogenesis, proliferation, enhanced cell motility, invasion, and eventually, metastasis. To explore the roles of c-met in modulating the motility of cell, we silenced c-met expression in the HCC line MHCC97-H by RNA interference (RNAi). MATERIALS AND METHODS: For transient expression, c-met-siRNA 1,2 recombinant plasmids were transfected into phoenix A cells. The MHCC97-H cells were cultured in Dulbecco's modified Eagles's medium (DMEM) with 10% fetal bovine serum (FBS) to establish MHCC97-H HCC cells stably expressing c-met-siRNA. MHCC97-H cells were treated with the recombinant virus for assay of c-met mRNA and protein, evaluation of growth and invasion of MHCC97-H cells, and identification of hepatitis B virus X (HBX) protein correlation with c-met. RESULTS: After transfection of c-met-siRNA for 48 h, the expression of c-met decreased markedly in MHCC97-H cells; the most effective site of the siRNA target sequence is at the 537 upstream, far from the transcription start. In addition, the proliferation, motility, and invasive ability of MHCC97-H cells were significantly inhibited. Furthermore, we showed that hepatitis B virus (HBV) X protein (HBX) potentiated the activities of the extracellular signal-regulated kinase 1/2 (ERK1/2) in MHCC97-H cells. Treatment with extracellular signal-regulated kinase (ERK) inhibitor (U0126), but not P38 MAPK inhibitor (SB203580) or phosphatidylinositol 3-kinase (PI3K) inhibitor (wortmannin), markedly suppressed the expression of c-met protein in MHCC97-H cells. CONCLUSION: These results indicate that the over-expression of c-met protein plays an important role in the cell invasion of MHCC97-H, and HBX protein may promote the expression of c-met by ERKs pathway.
