Hepatitis B Virus Infection Upregulats Cthrc1Expression And Promotes Progression Of Hepatocellular Carcinoma

Hepatitis B virus (HBV) infection is a major risk factor for human health, especially in Eest Asia and Southern Africa. China is one of the most high-risk regions. HBV infection can influence the expression of lots of genes and gruadually causes chronic hepatitis, cirrhosis and even hepatocellular carcinoma (HCC). HCC is the sixth most common cancer worldwide and the third most common cause of cancer mortality.Collagen triple helix repeat containing1(CTHRC1) is a novel gene with biochemical activities. Rencently, it has been shown to inhibit collagen matrix deposition, promote cell migration and regulate vascular repair. CTHRC1is widely up-regulated in a variety of tumors, such as gastrointestinal cancer, lung cancer, breast cancer, thyroid cancer, ovarian cancer, cervical cancer and pancreatic cancer. However, its contribution to hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) is unknown.Clinical data presented here showed that both CTHRC1mRNA and protein levels were significantly increased in tissues of HBV-related HCC. We hypothesized that CTHRC1may play a role in mediating the development of HBV-related HCC. To investigate this, we analyzed16normal liver tissues,24chronic hepatitis tissues,32cirrhosis tissues and32hepatocellular carcinoma tissues by immunohistochemistry. Positivity of CTHRC1protein gradually increased as the HBV-related HCC progressed. Compared with other pathogenic factors, HBV parallels significantly higher expression levels of CTHRC1. Furthermore, serum CTHRC1levels were significantly higher in patients with HBV infection than in healthy individuals. These clinical data suggest that HBV infection can promote CTHRC1expression.We determined the different expression levels of CTHRC1in hepatic cell lines. HepG2.2.15cells that constitutively express HBV exhibited much higher CTHRC1expression levels than L02normal liver and HepG2hepatoma cells did at both mRNA and protein levels. HBV infection mediated by transfection of pBlueks-HBV in both L02and HepG2cells induced CTHRC1expression in a time-and concentration-dependent manner. Subsequent analysis using reporter gene and chromatin immunoprecipitation assays demonstrated that NFkB and CREB were responsible for this induction.To explore how does CTHRC1contributes to the development of HBV-related HCC, we evaluated the impact of CTHRC1on the expression of HIF-1a and VEGF. We demonstrated that CTHRC1stimulated HIF-1a and VEGF expression in a dose dependent manner, possibly due to the activation of the classic signaling pathways ERK1/2and PI3K. CTHRC1suppressed p53expression, which in turn enhanced transformed phenotypes including colony-forming ability. Moreover, CTHRC1induced the expression of the metalloprotease MMP9, resulting in enhanced cell migration and invasion. All these functions play critical role in the progression of HBV-induced HCC.Finally, we carried out the xenograft studies. HepG2.2.15cells with suppressed expression of CTHRC1by CTHRCl-RNAi-AD significantly attenuated tumorigenic potential in athymic nude mice. In contrast to nonsense RNAi group and blank group, the tumor appearance delayed and the rate of tumor growth was much lower. Tumor volume and weight were significantly less than the control and blank group, P<0.05.In summary, these results indicate that CTHRC1may act as a master regulator in the progression of HBV-related HCC and suggest a potential therapeutic target for the treatment of patients with HCC.