Hepatic miR-126 is a potential plasma biomarker for detection of hepatitis B virus infected hepatocellular carcinoma

Controversies about the origin of circulating miRNAs have encouraged us to identify organ specific circulating miRNAs as disease biomarkers. To identify liver-specific miRNAs for hepatocellular carcinoma (HCC), global expression profiling of miRNAs in liver tissue of HBV-HCC and HBV-control with no or mild fibrosis was evaluated. A total of 40 differentially expressed miRNAs were identified in HCC. Among ten highly altered miRNAs, six miRNAs were successfully validated in tissues, whereas only two miRNAs, miR-126 and miR-142-3p showed increased expression in plasma of HBV-HCC compared to HBV-non-HCC patients. Subsequently, ROC curve analysis revealed that neither miR-126 nor miR-142-3p performed better than AFP in discriminating HCC from non-HCC while combination of each with AFP showed significantly higher efficiency rather than AFP alone (AUC: 0.922, 0.908 vs. 0.88; sensitivity: 0.84, 0.86 vs. 0.82 and specificity: 0.92, 0.94 vs. 0.86 respectively). Interestingly, triple combination of markers (miR-126 +/- miR-142-3p +/- AFP) showed no additive effect on efficiency (AUC: 0.925) over the dual combination. Again, the expression of only miR-126 was noticed significantly higher in HBV-HCC patients with low-AFP [< 250 ng/ml] compared to either non-HCC or liver cirrhosis (AUC: 0.77, 0.64, respectively). Furthermore, no alteration in expression of mir-126 in HCV-HCC or non-viral-HCC revealed that miR-126 + AFP might be specific to HBV-HCC. To understand the physiological role of these two miRNAs in hepato-carcinogenesis, target genes related to cancer pathways (APAF1, APC2, CDKN2A, IRS1, CRKL, LIFR, EGR2) were verified. Thus, combination of circulating miR-126 +/- AFP is a promising noninvasive diagnostic biomarker for HBV-HCC and may be useful in the management of HCC patients.