The NS5A protein of hepatitis C virus transcriptionally upregulates the AGR3 gene expression.

The non-structural protein 5A (NS5A) of hepatitis C virus (HCV) is a multifunctional protein involved in the HCV lifecycle and pathogenesis. The precise molecular mechanisms of NS5A-mediated pathogenesis still remain to be clarified. In this study, we performed cDNA microarray analysis on NS5A-expressing HEK293 cells and the non-expressing control to screen the possible cellular genes dysregulated by NS5A. Subsequent quantitative real time PCR (qRT-PCR) analysis on NS5A-expressing cells and the control confirmed that NS5A upregulated the anterior gradient homolog 3 (AGR3) mRNA expression. The domain III of NS5A was responsible for the activation of AGR3 gene expression. AGR3 mRNA expression levels were upregulated also in Huh7.5 cells harboring a full-genome HCV-1b RNA replicon (FGR) and in those infected with HCV-2a. Moreover, AGR3 promoter activity was activated in NS5A-expressing cells, FGR-harboring cells and HCV-infected cells. Taken together, our present results suggest that HCV NS5A transcriptionally activates the cancer-associated AGR3 gene. This may be a novel mechanism of HCV-mediated pathogenesis, especially hepatocarcinogenesis.