The predictive value of MiR-221 in cancer chemoresistance: a systematic review and meta-analysis

Many studies have reported that microRNA-221 (miR-221) is abnormally expressed in various cancers, and there has not been a study to systematically analyze the association between miR-221 and chemoresistance in different cancers. We systematically searched PubMed, Web of Science, Ovid, and Cochrane for relevant studies. The pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate. A total of 30 studies with 1670 patients were enrolled in our study. Thirteen cancer types have been studied, and traditional chemotherapy, targeted drugs, endocrine therapy, chemoradiotherapy, and other treatments were used. High miR-221 expression was associated with poor chemotherapy response in most studies, and the meta-analysis confirmed this result (OR = 3.64, 95%CI: 1.73–7.62, p = 0.001). Besides, the higher level of miR-221 was related to shorter overall survival (OS) (HR = 2.16, 95%CI: 1.47–3.16, p < 0.001) and progression-free survival (PFS) (HR = 1.81, 95%CI: 1.51–2.16, p < 0.001) in patients after chemotherapy. Our results highlight that high miR-221 expression has possible associations with chemoresistance and poor prognosis in multiple cancers. Further studies are needed to discover the molecular mechanisms underlying these associations to provide a solid evidence base for it being used as biomarkers of response to chemotherapeutic interventions in cancer.