FoxC1 may promote HCC metastasis through the induction of EMT and the up-regulation of NEDD9 expression. Thus, FoxC1 may be a candidate prognostic biomarker and a target for new therapies.
The proliferation-specific transcription factor Forkhead box M1 (FoxM1) acts as a master regulator of cancer cell growth and survival and plays an important role in the development of hepatocellular carcinoma. However, the molecular mechanisms that regulate FoxM1 expression remain largely unknown. In the current study, we demonstrated that tumor necrosis factor (TNF)-αα induced FoxM1 expression and transactivated its promoter activity in hepatoma cells. Serial 5" deletion and site-directed mutagenesis revealed that the induction of FoxM1 expression by TNF-α was dependent upon the hypoxia-inducible factor 1 (HIF1)-1 and HIF1-3/4 binding sites within the FoxM1 promoter. Furthermore, at the transcriptional level, the stabilization of HIF-1α via reactive oxygen species generation led to the binding of HIF-1α to the FoxM1 promoter and resulted in increased FoxM1 expression. The inhibition of both HIF-1α expression and reactive oxygen species generation significantly decreased TNF-α-induced FoxM1 overexpression. Consequently, the upregulation of FoxM1 promoted the proliferation of hepatoma cells and enhanced their resistance to TNF-α-induced apoptosis. Consistently, there was a positive correlation between HIF-1α and FoxM1 expression in 406 human hepatocellular carcinoma tissues, and the combination of these two parameters was a powerful predictor of poor prognosis in hepatocellular carcinoma patients after curative resection. Here, we report a new molecular mechanism by which FoxM1 expression is regulated by the TNF-α/reactive oxygen species/HIF-1 pathway, and this mechanism results in the proliferation of hepatoma cells and their resistance to apoptosis.
IL-23 is a newly discovered proinflammatory cytokine that contributes to the maintenance and expansion of Th17 cells. IL-23 has recently been identified as playing a critical role in a number of chronic inflammatory diseases. However, the regulatory mechanism of IL-23 in chronic hepatitis B (CHB) remains largely unknown. The aims of this study were to detect the expression of IL-23 in CHB patients and to explore the molecular mechanism of hepatitis B virus (HBV)-induced IL-23 expression. Serum levels and hepatic expression of IL-23 were significantly upregulated in CHB patients. A positive correlation was found between IL-23 expression and the histological activity index score, HBV DNA load, and serum alanine aminotransferase and aspartate aminotransferase levels. HBx protein increased IL-23 expression in a dose-dependent manner. It also aided in the nuclear translocation of NF-κB, which directly bound to the promoters of IL-23 subunits p19 and p40 to facilitate their transcription. NF-κB inhibitors blocked the effect of HBx on IL-23 induction, and NF-κB subunits p65 and p50 increased the augmented IL-23 expression. Inhibition of ERK1/2 activation and transfection with ERK dominant-negative plasmid significantly blocked the HBx-induced IL-23 expression. Furthermore, PI3K and Ras–MEK–MAPK inhibitors significantly decreased the ERK1/2 activation and IL-23 expression. Thus, we report a new molecular mechanism for HBV-induced IL-23 expression, which involves the activation of the ERK/NF-κB pathway by HBx, leading to the transactivation of the IL-23 p19 and p40 promoters.
These results suggest that DBC1 is over-expressed in colorectal cancer and that it might serve as a predictor for selecting patients at high risk of poor prognosis.
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