Epigenetic changes are associated with the regulation of transcription of key cell regulatory genes micro RNAs (miRNAs) during different types of liver injury. This study evaluated the role of ...methylation-associated miRNA, miR-34a, in alcoholic liver diseases. We identified that ethanol feeding for 4 weeks significantly up-regulated 0.8% of known miRNA compared with controls, including miR-34a. Treatment of normal human hepatocytes (N-Heps) and cholangiocytes human intrahepatic biliary epithelial cells (HiBECs) with ethanol and lipopolysaccharide induced a significant increase of miR-34a expression. Overexpression of miR-34a decreased ethanol-induced apoptosis in both N-Heps and HiBECs. In support of the concept that the 5′-promoter region of miR-34a was noted to be embedded within a CpG island, the expression level of miR-34a was significantly increased after demethylation treatment in N-Heps and HiBECs. By methylation-specific PCR, we confirmed that miR-34a activation is associated with ethanol-linked hypomethylation of the miR-34a promoter. A combination of bioinformatics, dual-luciferase reporter assay, mass spectrometry, and Western blot analysis revealed that caspase-2 and sirtuin 1 are the direct targets of miR-34a. Furthermore, modulation of miR-34a also altered expression of matrix metalloproteases 1 and 2, the mediators involved in hepatic remodeling during alcoholic liver fibrosis. These findings provide the basis for an exciting field in which the epigenomic microRNAs of hepatic cells may be manipulated with potential therapeutic benefits in human alcoholic liver diseases.
IL-6/Stat3 is associated with the regulation of transcription of key cellular regulatory genes (microRNAs) during different types of liver injury. This study evaluated the role of IL-6/Stat3 in ...regulating miRNA and miR-21 in alcoholic liver disease. By microarray, we identified that ethanol feeding significantly up-regulated 0.8% of known microRNAs in mouse liver compared with controls, including miR-21. Similarly, the treatment of normal human hepatocytes (N-Heps) and hepatic stellate cells (HSCs) with ethanol and IL-6 significantly increased miR-21 expression. Overexpression of miR-21 decreased ethanol-induced apoptosis in both N-Heps and HSCs. The expression level of miR-21 was significantly increased after Stat3 activation in N-Heps and HSCs, in support of the concept that the 5′-promoter region of miR-21 is regulated by Stat3. Using real time PCR, we confirmed that miR-21 activation is associated with ethanol-linked Stat3 binding of the miR-21 promoter. A combination of bioinformatics, PCR array, dual-luciferase reporter assay, and Western blot analysis revealed that Fas ligand (TNF superfamily, member 6) (FASLG) and death receptor 5 (DR5) are the direct targets of miR-21. Furthermore, inhibition of miR-21 by specific Vivo-Morpholino and knock-out of IL-6 in ethanol-treated mice also increased the expression of DR5 and FASLG in vivo during alcoholic liver injury. The identification of miR-21 as an important regulator of hepatic cell survival, transformation, and remodeling in vitro, as well as its upstream modulators and downstream targets, will provide insight into the involvement of altered miRNA expression in contributing to alcoholic liver disease progression and testing novel therapeutic approaches for human alcoholic liver diseases.
In recent years, the relationship between interleukin-6 (IL-6), hepatobiliary inflammation, and cancer has been studied. It is becoming clear that this cytokine plays an important role in the ...pathogenesis of both cholangiocarcinoma (CCA, cancer of the bile ducts) and hepatocellular carcinoma (HCC, cancer arising from the liver parenchyma). Inflammation due to various chronic hepatobiliary diseases including hepatitis B, hepatitis C, alcoholic liver injury, and primary sclerosing cholangitis (PSC) has been associated with increased levels of IL-6 and with increased rates of malignancy. In this review, we will summarize the current knowledge linking inflammation to hepatobiliary cancer, and discuss the key role of IL-6 and its signaling pathways in mediating this link. We will first review the major signaling pathways that are triggered when IL-6 engages its receptor. These include PI3 kinase, JAK/STAT, p38 MAP kinase and others that ultimately lead to cell proliferation, protection from apoptosis and increased metastatic potential. We will then discuss data linking IL-6 and hepatobiliary cancer, namely HCC and CCA.
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