Effect of miR-183-5p on Cholestatic Liver Fibrosis by Regulating Fork Head Box Protein O1 Expression

Liver fibrosis is a common pathological feature of end-stage liver disease and has no effective treatment. MicroRNAs (miRNAs) have been found to modulate gene expression in liver disease. But the potential role of miRNA in hepatic fibrosis is still unclear. The objective of this research is to study the potential mechanism and biological function of miR-183-5p in liver fibrosis. In this study, we used high-throughput sequencing to find that miR-183-5p is upregulated in human fibrotic liver tissues. In addition, miR-183-5p was upregulated both in rat liver fibrosis tissue induced by bile-duct ligation (BDL) and activated LX-2 cells (human hepatic stellate cell line) according to the result of quantitative real-time PCR (RT-qPCR). Moreover, the inhibition of miR-183-5p alleviated liver fibrosis, decreased the fibrotic biomarker levels in vitro and in vivo, and led toLX-2 cell proliferation inhibition and, apoptosis induction. The result of dual-luciferase assay revealed that miR-183-5p suppressed fork head box protein O1 (FOXO1) expression by binding to its 3′UTR directly. Next, we used lentivirus to overexpress FOXO1 in LX-2 cells, and we found that overexpression of FOXO1 reversed the promotion of miR-183-5p on liver fibrosis, reducing the fibrotic biomarker levels inLX-2 cells, inhibitingLX-2 cell proliferation, and promoting apoptosis. Furthermore, overexpression of FOXO1 prevented the activation of the transforming growth factor (TGF)-β signaling pathway in TGF-β1-induced LX-2 cells according to the result of western blotting. In conclusion, the findings showed thatmiR-183-5p might act as a key regulator of liver fibrosis, and miR-183-5p could promote cholestatic liver fibrosis by inhibiting FOXO1 expression through the TGF-β signaling pathway. Thus, inhibition of miR-183-5pmay be a new way to prevent and improve liver fibrosis.

Opposing Roles of the Fork-head box genes FoxM1 and FoxA2 in Hepatocellular Carcinoma

ABSTRACTThe fork-head box transcription factor FoxMl is essential for hepatocellular carcinoma (HCC) development and its overexpression coincides with poor prognosis. Here, we show that the mechanisms by which FoxM1 drives HCC progression involve overcoming the inhibitory effects of the liver differentiation gene FoxA2. First, the expression patterns of FoxM1 and FoxA2 in human HCC are opposite. We show that FoxM1 represses expression of FoxA2 in G1 phase, a phase in the cell cycle in which cells can undergo differentiation. Repression of FoxA2 in G1 phase is important, as it is capable of inhibiting expression of the pluripotency genes that are expressed mainly in S/G2 phases. Using a transgenic mouse model for oncogenic Ras-driven HCC, we provide genetic evidence for a repression of FoxA2 by FoxM1. Conversely, FoxA2 inhibits expression of FoxM1, and inhibits FoxM1-induced tumorigenicity of HCC cells. Moreover, expression of FoxA2 in mouse liver expressing activated Ras inhibits FoxM1 expression and inhibits HCC progression. The observations provide strong genetic evidence for an opposing role of FoxM1 and FoxA2 in HCC progression.AUTHOR SUMMARYLiver cancer remains untreatable because it is diagnosed at a stage when the cancer is aggressive and resistant to therapeutics. The mechanism that drives aggressive liver cancer is poorly understood. These cancers are made up of poorly differentiated cancer cells. Interestingly, the FoxM1 gene is overexpressed in the aggressive liver cancers. Although FoxM1 is important for expression of the proliferation genes, it does not explain why it is overexpressed mainly in the undifferentiated cancers. The current study addresses this puzzle. Our previous studies demonstrated that FoxM1 increases expression of the pluripotency genes that are expressed mainly in the stem-like cells. In the current manuscript we show that, in addition to activating the pluripotency genes, FoxM1 inhibits expression of the liver differentiation gene FoxA2. Overexpression of FoxM1 is important for this inhibition function, as it involves the retinoblastoma family of proteins, which are often inactivated in cancer cells, and thus, are of low-abundance. Moreover, the inhibition of FoxA2 is significant because FoxA2 could inhibit expression of the pluripotency genes as well as FoxM1. The observations provide new insights into how FoxM1 drives progression of aggressive liver cancer.