Objective:To study the mechanism of effect of miR-21 via Wnt/ β-catenin signaling pathway in human A549 lung cancer cells and Lewis lung carcinoma in mice.Methods:The effect of miR-21 on A549 cells were detected by MTT method.MiR-21 expression levels were overexpressed or inhibited in A549 cells by transfecting with miR-21 mimics or inhibitors.Correlation among key molecules(Wnt1,β-catenin.CyclinD1 and miR-21) of mRNA and protein levels in Wnt/β-catenin signaling pathway were studied by Real-time PCR and Western blot hybridization assay.Invasive ability of A549 cells was determined via Transwell chamber cell invasion assay;the role of miR-21 in A549 cells was explored via the Wnt/β-catenin signaling pathway.A Lewis lung carcinoma animal model was established to detect miR-21 expressions in tumor animals and controlled animal tissues,and verify expression changes of the above moleculesin the Wnt / β-catenin signaling pathway was determined in the animal level.Results:MTT assay results showed that miR-21 overexpression could markedly enhance cell absorbance value;that is,miR-21 could increase the ability proliferation of A549 cells.β-catenin and CyclinD1 expression levels were significantly higher in miR-21 mimic transfected cells(P<0.05),and Wnt 1 gene had no significant change.Wnt 1,β-catenin and CyclinD1 gene expression showed no significant change when miR-21 expression was suppressed,compared with controls.After cells were transfected with miR-21 mimics,cell invasion assay revealed that the perforated cells was significantly higher than the perforated cells in the control group(P<0.01).Lewis lung assay revealed that miR-21 expression levels in the Lewis lung carcinoma were significantly higher;and at the same time.Wnt1,β-catenin and CyclinD1 gene expression levels were significantly increased,compared to controls.Conclusions:In A549 human lung cancer cells and Lewis lung carcinoma in mice,key molecules β-catenin and CyclinD1 of miR-21 expressions and the Wnt/ β-catenin signaling pathway are positively correlated. Objective: To study the mechanism of effect of miR-21 via Wnt / β-catenin signaling pathway in human A549 lung cancer cells and Lewis lung carcinoma in mice. Methods: The effect of miR-21 on A549 cells were detected by MTT method. MiR-21 expression levels were overexpressed or inhibited in A549 cells by transfecting with miR-21 mimics or inhibitors. Correlation among key molecules (Wntl, beta-catenin.CyclinDl and miR-21) of mRNA and protein levels in Wnt / beta-catenin signaling pathway were studied by Real-time PCR and Western blot hybridization assay. Invasive ability of A549 cells was determined via Transwell chamber cell invasion assay; the role of miR-21 in A549 cells was explored via the Wnt / β-catenin signaling pathway. A Lewis lung carcinoma animal model was established to detect miR-21 expressions in tumor animals and controlled animal tissues, and verify expression changes of the molecules in the Wnt / β-catenin signaling pathway was determined in the animal level. Results: MTT assay resu lts showed that miR-21 overexpression could markedly enhance cell absorbance value; that is, miR-21 could increase the ability proliferation of A549 cells. β-catenin and Cyclin D1 expression levels were significantly higher in miR-21 mimic transfected cells (P <0.05 ), and Wnt 1 gene had no significant change. Wnt 1, β-catenin and CyclinD1 gene expression showed no significant change when miR-21 expression was suppressed, compared with controls. After cells were transfected with miR-21 mimics, cell invasion assay revealed that the perforated cells were significantly higher than the perforated cells in the control group (P <0.01). Lewis lung assay revealed that miR-21 expression levels in the Lewis lung carcinoma were significantly higher; and at the same time. Wnt1, β -catenin and CyclinD1 gene expression levels were significantly increased, compared to controls. Conclusions: In A549 human lung cancer cells and Lewis lung carcinoma in mice, key molecules β-catenin and Cyclin D1 of miR-21 expressions and the Wnt / β-catenin signaling pathway are positively correlated.