Hepatitis C Virus Infection and Cholangiocarcinoma: An Insight into Epidemiologic Evidences and Hypothetical Mechanisms of Oncogenesis

Hepatitis C virus (HCV) infection is a global public health problem because it is a main cause of liver cirrhosis and hepatocellular carcinoma. This human oncogenic virus is also associated with the development of non-Hodgkin lymphoma and cholangiocarcinoma (CCA). The association between HCV infection and CCA has been examined in a number of epidemiologic studies. However, in vivo and in vitro results demonstrating the oncogenic mechanisms of HCV in CCA development and progression are insufficient. Here, we review the epidemiologic association of HCV and CCA and recent publications of studies of HCV infection of cholangiocytes and CCA cell lines as well as studies of viral infection performed with liver samples obtained from patients. In addition, we also discuss the preliminary results of in vitro assays of HCV protein expression in CCA cell lines. Finally, we discuss the hypothetical role of HCV infection in CCA development by induction of epithelial-mesenchymal transition and up-regulation of hedgehog signaling, and consequently biliary tree inflammation and liver fibrosis. Further studies are required to demonstrate these hypotheses and therefore to elucidate the mechanisms of HCV as a risk factor for CCA.