Serum exosomal miR-125b is a novel prognostic marker for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide with high mortality. Circulating miRNA has been demonstrated as a novel noninvasive biomarker for many tumors. This study aimed to investigate the potential of circulating miR-125b as a prognostic marker of HCC. Exosomes were extracted from serum samples collected from two independent cohorts: cohort 1: HCC (n=30), chronic hepatitis B (CHB, n=30), liver cirrhosis (LC, n=30); cohort 2: HCC (n=128). We found that miR-125b levels were remarkably increased in exosomes compared to those in serum from patients with CHB, LC, and HCC (P<0.01, respectively). However, miR-125b levels in exosomes and the serum from HCC patients were inferior to that of CHB (P<0.01 and P=0.06) and LC patients (P<0.01 for all). Additionally, miR-125b levels in exosomes were associated with tumor number (P=0.02), encapsulation (P<0.01), and TNM stage (P<0.01). Kaplan-Meier analysis indicated that HCC patients with lower exosomal miR-125b levels showed reduced time to recurrence (TTR) (P<0.01) and overall survival (OS) (P<0.01). Furthermore, multivariate analysis revealed that miR-125b level in exosomes, but not in serum, was an independent predictive factor for TTR (P<0.001) and OS (P=0.011). Exosomal miR-125b levels predicted the recurrence and survival of HCC patients with an area under the ROC curve of 0.739 (83.0% sensitivity and 67.9% specificity) and 0.702 (82.5% sensitivity and 53.4% specificity). In conclusion, exosomal miR-125b could serve as a promising prognostic marker for HCC.