Prognostic and Clinicopathological Significance of MiR-155 in Hematologic Malignancies: A Systematic Review and Meta-analysis.

Background: Aberrant miR-155 expression has been reported in various types of hematologic malignancies. However, the prognostic and clinicopathological value of miR-155 remains unclear. Here, we performed this systemic review and meta-analysis to comprehensively evaluate the prognostic and clinicopathological significance of miR-155 expression in hematologic malignancies. Methods: We systematically searched the PubMed, EMBASE, ISI Web of Science, Cochrane library databases and OVID to identify eligible studies published from Jan 1, 2008 to Aug 1, 2018. The pooled hazard ratios (HRs) and odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to detect the prognostic and clinicopathological role of miR-155 in hematologic malignancies. Results: A total of 18 studies including 2316 patients were enrolled in the present meta-analysis, indicating significant association between elevated miR-155 expression and poor overall survival (OS) in 2114 patients (pooled HR = 1.72, 95%CI [1.50-1.97], p<0.001). Elevated miR-155 expression level was related to shorter event free survival (EFS, pooled HR = 1.55, 95%CI [0.94-2.57], P=0.002), disease free survival (DFS, pooled HR = 1.38, 95%CI [1.13-1.68], P=0.001), progress free survival (PFS, pooled HR = 1.58, 95%CI [1.06-2.35], p<0.001) and treatment free survival (TFS, pooled HR = 1.67, 95%CI [1.16-2.39], P=0.006). Additionally, overexpression of miR-155 was found to be significantly related to FLT3/ITD presence (OR=4.751, 95%CI [3.229-6.990], P<0.001), more WT1 mutation (OR=2.090, 95%CI [1.240-3.522], P=0.006) and less CEBPA mutation (OR=0.477, 95%CI [0.286-0.794], P=0.004) in 552 AML patients. Conclusion: MiR-155 expression was found to be associated with several leukemia-related phenotype and poor prognosis in hematologic malignancies. Therefore, miR-155 overexpression might be a convinced unfavorable prognostic indicator that helps the clinical decision-making process.