Background: Hepatitis B is a liver infection disease caused by the Hepatitis B Virus
(HBV) that can become chronic and develop into hepatocellular carcinoma. HBV was classified as a
double-stranded DNA virus. Currently, there is a report showing that HBV virus-encoded miRNA
called HBV-miR-3 controls the replication of HBV. However, the regulation of HBV-miR-3 in host
cells remains unclear.
Objective: This study aimed to investigate the regulation of HBV-miR-3 in host gene target which is
related to chronic HBV infection and HCC process.
Methods: In this study, we analyzed the read count of HBV-miR-3 from next-generation sequencing
of chronic hepatitis patients in Pegylated interferon alpha-2a (PEG-IFN-α-2a) treatment. To understand
the regulation of HBV-miR-3 in host cells, the HBV-miR-3 recognition sites were predicted in
host target genes using miRDB. The effect of HBV-miR-3 in host cells was examined using qPCR
and 3′ UTR dual luciferase assay.
Results: The read count of HBV-miR-3 was found in chronic hepatitis patients before treatment.
Moreover, the decrease of HBV-miR-3 was correlated with response group of chronic hepatitis patients
after treatment. On the other hand, the abundance of HBV-miR-3 showed no difference in nonresponse
group of chronic patients after PEG-IFN-α-2a treatment. To study the role of HBV-miR-3
in patients, four HBV-miR-3 target regions from Protein phosphatase 1A (PPM1A) and DIX domain
containing 1 (DIXDC1) were identified in the human genome using miRDB. Interestingly, we found
that HBV-miR-3 hybridized with PPM1A mRNA. The mRNA expression from RT-qPCR showed no
difference between HepG2 transfected with pSilencer_scramble or pSilencer_HBV-miR-3. However,
the reporter assay showed that PPM1A mRNA was suppressed by HBV-miR-3. The protein expression
of PPM1A showed a decrease in cells overexpressing HBV-miR-3. Finally, the HBV-miR-3 can
promote cell proliferation in cells overexpressing HBV-miR-3.
Conclusion: This study is the first report showed the HBV encoded miRNA can regulate host gene
expression. HBV-miR-3 silenced PPM1A by inhibiting the translation process of PPM1A. The
downregulation of PPM1A promotes cell proliferation related to HCC development.