miR-21 predicts poor prognosis in patients with osteosarcoma

Background and aims: miR-21 has been demonstrated to play an important role in tumour progression. The aim of the present study was to analyse the correlation betweenmiR-21 expression level and clinicopathologic features, as well as to assess the prognostic significance of miR-21 in osteosarcoma.Methods: Eighty-four pairs ofosteosarcomaand corresponding non-cancerous bone tissues were obtained, and miR-21 expression levels were detected using quantitative real-time PCR (qRT-PCR). A (2) test was used to assess the relationship between miR-21 expression and clinicopathological features. Overall survival (OS) and disease-free survival (DFS) rates were determined by the Kaplan-Meier method and analysed by the log-rank test. The Cox proportional hazards model was used for multivariate analysis.Results: qRT-PCR indicated thatmiR-21 expression in tumour tissues was strongly elevated compared with the adjacent corresponding non-cancerous bone tissue (7.881.04 vs. 1.12 +/- 0.37, respectively; P<0.001). High miR-21 expression levels were linked to advancedclinicalstage (P=0.001), distant metastasis (P=0.001), high tumour grade (P=0.032) and large-sized tumours (P=0.013). A higher miR-21 expression was significantly linked to shorter OS and DFS (both P<0.001). Furthermore, a multivariate analysis confirmed that miR-21 was an independent and significant prognostic factor to predict poor OS and DFS (both P<0.001).Conclusions: Upregulation ofmiR-21 was associated with poor clinicopathological characteristics. It is used as a marker ofpoorprognosisin patients with osteosarcoma.