The correlation between microRNA-221/222 cluster overexpression and malignancy: an updated meta-analysis including 2693 patients

BACKGROUND: Although miR-221/222 cluster plays an important role in many human malignancies, the correlation between miR-221/222 cluster overexpression and tumor prognosis remains controversial. Therefore, an updated meta-analysis was conducted to clarify its prognostic value in malignancy. METHODS: We conducted a search of literature in English electronic databases of PubMed, Embase, and Cochrane Library, and Chinese electronic databases of China Biology Medicine disc and China National Knowledge Infrastructure to obtain appropriate studies. Besides, we extracted hazard ratios (HRs) and 95% CIs to evaluate the strength of the correlations. In addition, the results of different subgroups analyses and publication bias test were also shown in this article. RESULTS: 32 publications, including 15 tumor types and 2,693 patients were embraced in this meta-analysis. The results of univariate (HR =1.69, 95% CI: 1.18–2.44, P<0.01) and multivariate (HR =2.10, 95% CI: 1.63–2.69, P<0.01) analyses revealed that miR-221/222 cluster high expression in various tumors was significantly associated with adverse overall survival (OS). Correspondingly, we also found subgroups analyses consisted of country, miR-221/222 cluster component, sample size, and test method have similar results. CONCLUSION: miR-221/222 cluster overexpression was closely related to adverse OS in human carcinoma, while overexpression of miRNA-221/222 cluster could be viewed as a protection factor in prostate cancer. Blood-derived miR-221/222 cluster was not proper to assess OS.