Effects Of MicroRNA-21 On Osteosarcoma Biological Behaviors

Background and Objective:Osteosarcoma is a primary bone tumor and easily metastas- izes to lung. The lung metastasis of patients is the main reason for treatment failure. To explore the expression of miR-21 in osteosarcoma and the correlation between miR-21 and clinicopathological characteristics.Method:We analyzed the level of miR-21 expression in osteosarcoma tissues and matched normal bone tissues from 42 patients (with 8 sets of matched primary and metastatic tumor samples from the same patients) by real-time RT-PCR and evaluated the clinical relevance of miR-21. The mRNA and protein levels of RECK in 8 primary tumors and matched normal bone tissues were detected by qRT-PCR and Western blot assays. The correlation between RECK protein and miR-21 in these tumor tissues were analyzed by using the Pearson’s method.Result:We found that 38 of 42 (90.5%) showed a higher expression level of miR-21 in tumor tissues than in matched normal tissues(P=0.013). Moreover, analysis of paired primary and metastatic osteosarcoma samples from 12 patients showed an increase in miR-21 expression levels in metastases (P=0.002). However, the expression of miR-21 has nothing to do with the ages, gender, tumor size, tumor site, stage and histological type (P< 0.05). We confirmed the expression of RECK in all tissues and lower level of RECK protein was found in tumor tissues. Accordingly, higher level of miR-21 expression was detected in all tumor tissues. However, the expression level of RECK mRNA in eight pairs of matched osteosarcoma specimens was not different. Statistical analysis indicates that there is an obvious inverse correlation between RECK protein and miR-21 in these tumor tissue specimens by using the Pearson’s methodConclusion:Our results suggest that the expression of miR-21 in tumor tissues is higher than that in matched normal bone tissues and miR-21 can acts as one of diagnosis indicators. The expression of miR-21 in metastatic tumor specimens is higher than that in primary tumor tissues and it means that high expression of miR-21 potentially contributes to human osteosarcoma metastasis and acts as one of prognostic factors. The obvious inverse correlation between RECK protein and miR-21 in these tumor tissue specimens suggests that RECK is a target of miR-21 and miR-21 lead to tumor metastasis by regulating the expression of RECK. Background and purpose:MicroRNAs are small non-coding endogenous RNA molecules that can inhibit protein translation partly through binding with target mRNAs. MiR-21, as an oncomiR, is over expressed in 9 kinds of human tumor cells. The aim of this study was to investigate the regulative effects of miR-21 ASO on the proliferation, invasion, apoptosis and migration of MG-63 cells.Methods:The miR-21 expression in MG-63 cells was measured using real-time PCR after transfection with miR-21 ASO and EmGFP-miR-21. The expression of RECK in MG-63 cells was measured using real-time PCR and Western blot assays after transfection with miR-21 ASO and EmGFP-miR-21. Cell proliferation after transfection with miR-21 ASO and EmGFP-miR-21 was analyzed using the colony formation experiment in vitro. Cell apoptosis was analyzed by Annexin V. Invasion assays were performed using Transwell invasion chambers. Cell migration ability was analyzed by scratch migration assay. Results:After transfection with miR-21 ASO, miR-21 expression in MG-63 cells was decreased significantly. While after transfection with EmGFP-miR-21 miR-21 expression in MG-63 cells was increased. Colony formation was significantly decreased after transfection with miR-21 ASO.While after transfection with EmGFP-miR-21 Colony formation was significantly increased. Cell migration ability was decreases after transfection with miR-21 ASO. While after transfection with EmGFP-miR-21 the number of migrating cells increased. Annexin V assay also indicated that transfection with miR-21 ASO promoted apoptosis greatly. While after transfection with EmGFP-miR-21 the apoptotic rates were decreased. In vivo tumors derived from MG-63 cells transfected with miR-21 ASO grew substantially slow in comparison to the negative control during the whole tumor growth period. Moreover, the expression of RECK protein in MG-63 cells was negatively correlated with the expression of miR-21.Conclusion:Overexpression of miR-21 can promote MG-63 cell proliferation, invasion, migration and inhibit cell apoptosis. While miR-21 ASO reduce the expression of miR-21 and inhibit cell proliferation, invasion, migration and induce cell apoptosis. RECK is a target of miR-21 and miR-21 affect cell functions by regulating the expression of RECK. MiR-21 is an oncogene and miR-21 ASO can now be considered a new option in the treatment of miR-21 overexpressing cancers such as osteosarcoma in future.