The clinical significance of microRNA-122 in predicting the prognosis of patients with hepatocellular carcinoma: A meta-analysis validated by the Cancer Genome Atlas dataset

BACKGROUND: Although the prognostic value of microRNA-122 (miR-122) for hepatocellular carcinoma (HCC) patients have been evaluated by numerous studies, the results of them were not completely consistent. The present study aims to comprehensively evaluate the predicting value of miR-122 on the prognosis of patients with HCC based on all eligible literatures. METHODS: Numerous electronic databases (MEDLINE, Embase, Pubmed, Google Scholar, and China Biology Medicine disc) were applied to retrieve relevant studies. Overall survival (OS) and progression-free survival (PFS) were used as primary endpoints. All statistical analyses were performed by RevMan software version 5.3.5 and STATA software version 14.1. In addition, the results of this meta-analysis were validated by an independent dataset from the Cancer Genome Atlas (TCGA). RESULTS: A total of 11 studies containing 1124 patients were included in this meta-analysis. The pooled results showed that low miR-122 expression in HCC tissues significantly associated with unfavorable OS (hazard ratio [HR] = 1.48, 95% confidence interval [CI] 1.22–1.80, P < .001) and PFS (HR = 1.54, 95% CI 1.28–1.85, P < .001) in patients with HCC. However, the expression level of miR-122 in blood did not have the ability in predicting OS (HR = 0.75, 95% CI 0.44–1.28, P = .29) and PFS (HR = 0.84, 95% CI 0.58–1.20, P = .33) of HCC. Subgroup analysis further indicated that low expression of miR-122 in tumor tissues predicted poor OS in HCC patients who received curative liver resection (HR = 2.00, 95% CI 1.08–3.70, P = .03). Analysis using TCGA dataset suggested that low miR-122 expression in HCC tissues was significantly associated with OS (HR = 1.61, 95% CI 1.13–2.27, P = .008) other than PFS (HR = 1.30, 95% CI 0.96–1.75, P = .09). CONCLUSION: Low miR-122 expression in HCC tissues was a reliable indicator for predicting the OS of HCC patients who underwent curative resection. Owing to the disagreement between this meta-analysis and the TCGA dataset, the predictive value of miR-122 in tissues for PFS needs to be verified by future well-designed studies with large sample size.