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 downregulated in our microarray data and GEO datasets from HBV-infected liver. We validated ABCA1 as a bona fide 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 the pro-oncogenic effects of HBV-miR-3. HBV-miR-3 expression was detectable in all liver biopsies (n = 20) from patients with chronic HBV (CHBV). 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.