MicroRNA-221 promotes cell proliferation and inhibit apoptosis in osteosarcoma cells via directly targeting FBXW11 and regulating the Wnt signaling

<p><strong>Figure 1.</strong> miR-221 expression is significantly high in human clinical tissues and cell lines of OS. The expression levels of miR-221 in 30 pairs of OS tissues and their adjacent, non-cancerous normal bone tissues (Normal) (A) and the human osteoblastic cell line hFOB 1.19 and OS cell lines (B) are detected by qRT-PCR. U6 is used as the internal control. **<em>P</em> &lt; 0.01 and ***<em>P</em> &lt; 0.001.</p> <p><strong>Figure 2. </strong>Attenuating miR-221 expression inhibits OS cell proliferation and increase apoptosis. MiR-221 inhibitor is transfected into MG-63-A16 (A) or U2OS cells (B) and induces an obviously lower proliferation rate compared with that in control groups. Further, miR-221 inhibitor is transfected into MG-63-A16 (C) and U2OS cells (D) and triggers a significantly higher apoptosis than controls. And that, the significantly down-regulated Ki67 expression in MG-63-A16 (E) and U2OS cells (F) were observed compared with that in the controls. **<em>P</em> &lt; 0.01 and ***<em>P</em> &lt; 0.001.</p> <p><strong>Figure 3. </strong>FBXW11 can directly target to miR-221. (A) An potential target of miR-221, called as FBXW11 has been predicted by bioinformatics-based target prediction analysis, and the binding site is on the 3&rsquo;UTR of FBXW11. (B) RT-PCR analysis of FBXW11 expression in the OS tumor tissues and noncancerous counterparts. (C) The obviously down-regulated expression levels of FBXW11 mRNA are observed in OS cell lines compared with those in hFOB 1.19 cells. (D) A negative Spearman&rsquo;s correlation between miR-221 and FBXW11 mRNA levels was observed in 30 OS tumor tissues. (E) The significantly decreased luciferase activity driven by 3&rsquo;UTR of FBXW11 is observed in the miR-211 mimic group and the 3&rsquo;UTR-MUT group and negative control are as control. (F) The down-regulation of miR-221 induces a dramatic overexpression of FBXW11 protein. (G) A distinctly lower cell proliferation rate is observed in the group of pcDNA-FBXW11 compared with control. (H) An obviously higher apoptosis is observed in the group of pcDNA-FBXW11 than control. (I) The significantly decreased Ki67 expression is detected in the pcDNA-FBXW11 group than control. **<em>P</em> &lt; 0.01 and ***<em>P</em> &lt; 0.001.</p> <p><strong>Figure 4.</strong> miR-221 and FBXW11 regulate cell proliferation and apoptosis in OS through inhibiting Wnt signaling. (A) The markedly down-regulated expression levels of &beta;-catenin, cyclin D1 and c-myc were detected in the group of miR-221 inhibitor compared with controls. (B) The obviously decreased expression levels of &beta;-catenin, cyclin D1 and c-myc were determined in the pcDNA-FBXW11 group compared with controls. **<em>P</em> &lt; 0.01 and ***<em>P</em> &lt; 0.001.</p> <p><strong>Figure 5. </strong>The effect of Wnt signaling on the cell proliferation and apoptosis of OS cell lines. A distinctly lower cell proliferation rate (A and B) and an obviously higher apoptosis rate (C and D) were detected in the Wnt1 siRNA groups (siRNA1, siRNA2) than si-control, and similar results were observed in the CGP049090 group. (E and F) The obviously decreased Ki67 expression were detected in the Wnt1 siRNA groups compared with si-control, and similar results were observed in the CGP049090 group. **<em>P</em> &lt; 0.01 and ***<em>P</em> &lt; 0.001.</p>