HBV-miR-3 induces hepatic cholesterol accumulation by targeting ABCA1: evidence for potential benefits of statin usage.

The cellular targets of hepatitis B virus (HBV)-encoded miRNAs remain poorly understood. The evolutionary conservation of HBV-miR-3 across HBV genotypes suggests its potential functional importance. Transcriptome profiling of HBV-miR-3 expressing hepatocytes demonstrates differential expression of several genes associated with lipid metabolic processes. The cholesterol efflux regulator gene ABCA1 was found to be down-regulated in our microarray data and in GEO datasets from HBV infected liver. We validated ABCA1 as a bonafide target of HBV-miR-3. HBV-miR-3-mediated suppression of ABCA1 led to increased cholesterol and lipid droplet accumulation in addition to increased proliferation and colony formation in hepatocyte cell lines. Interestingly, widely prescribed cholesterol-lowering drugs (simvastatin, atorvastatin and fluvastatin) could inhibit pro-oncogenic effects of HBV-miR-3. HBV-miR-3 expression was detectable in all liver biopsies (n=20) from chronic HBV (CHBV) patients. Patients with high intrahepatic HBV loads had higher levels of HBV-miR-3, suggesting that the virus-encoded miRNA levels correlate with virus replication. Patients with high HBV-miR-3 expression had significantly lower ABCA1 transcript levels in the liver. Hepatic steatosis was more frequently observed in biopsies of patients with high intrahepatic HBV-miR-3 levels compared to those with low HBV-miR-3 levels (71% vs 53%), although this was not statistically significant. Taken together, our findings support the notion that HBV-miR-3-mediated suppression of ABCA1 contributes to dysregulation of lipid metabolism in CHBV infection. In sum, HBV-miR-3 may represent the 'missing link' between CHBV and altered lipid metabolism in hepatocytes. Statin-mediated inhibition of HBV-miR-3-induced intrahepatic lipid accumulation and cell proliferation has potential clinical utility and merits further investigation.