| Summary: | 碩士 === 長庚大學 === 生物醫學研究所 === 100 === Hepatitis B virus (HBV) is one of the most important human pathogens in chronic infectious diseases. Chronic hepatitis B virus infection can lead to chronic active hepatitis and liver cirrhosis, which further results in emergence of hepatocellular carcinoma. Naturally occurring mutations in HBV have been found in patients with acute or chronic HBV infection, wherein some mutants develop in certain stages of chronic HBV infection. Of these HBV mutations, core-gene-defective mutants have been found in some special patient groups. Our present study aims to investigate the prevalence of core-gene-defective HBV mutants in different patient groups as well as the possible pathological effect of the mutants in chronic HBV infection. Firstly, we collected serum samples from patients with chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. To understand the prevalence of core-gene-defective HBV mutants in these three groups of patients, HBV DNA was extracted for PCR amplification of the core genes followed by nucleotide sequencing. We have found a core-gene-defective mutant which causes polymerase overexpression. This type of mutants was presence in patients with hepatocellular carcinoma, but not in patients with chronic hepatitis or liver cirrhosis. Cell growth assay revealed enhanced cell proliferation in hepatoma cells expressing the mutant protein. A lower percentage of apoptotic cells was found in hepatoma cells carrying the mutant HBV, compared to the wild type. Tumorigenecity experiments showed that hepatoma cells carrying the mutant HBV more easily developed xenograft tumors in nude mice. Further studied revealed that the mutant protein physically interacted with miR-10b and miR-183, the miRNAs targeting at many growth enhancing genes.
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