Differences in miR-122 and miR-191 Expression in HBV- versus HCV-associated Hepatocellular Carcinoma
Prior studies have suggested that the expression of miR-122 and miR-191 is decreased and increased, respectively, in hepatocellular carcinoma. However, other evidence suggests miR-122 may be preserved in HCV-associated hepatocellular carcinoma (HCC). The goal of this thesis is to assess miR-122 and miR-191 expression levels in HBV- and HCV-associated HCC, the related non-tumor tissue, and normal liver tissue. Relative quantification of miR-122 and miR-191 in 16 HCV-associated HCC, 10 HBV-associated HCC, the respective neighboring non-tumor tissue, and 9 normal liver tissue samples was performed using RT-PCR. This thesis shows that miR-122 expression levels are maintained in HCV-associated HCC and HBV-non-tumor tissues, but down-regulated in HBV-associated HCC and HCV-non-tumor tissues compared to normal liver tissue. miR-191 was found only to be up-regulated in HBV-associated HCC compared to normal liver expression levels. Furthermore, the miR-122 expression level in HCV-non-tumor tissue was found to have a relationship with rs8099917, a SNP known to predict HCV treatment outcome. miR-122 expression levels were decreased in patients with the TG genotype, unfavorable to HCV treatment, compared to those with the TT genotype, favorable to HCV treatment. A negative correlation of interferon-stimulated gene expression and miR-122 expression was found using Spearman correlation tests. The differences in miR-122 and miR-191 expression levels in HBV- and HCV-associated HCC hint that there are virus-specific mechanisms that influence liver carcinogenesis during chronic infection.