ABSTRACT
BACKGROUND: miR-15b plays an important role in the initiation and development of tumors, based on which, we speculate that miR-15b may be involved in the migration and invasion of glioma stem cells (GSCs). However, there is no relevant report and the mechanism of action is also unclear. OBJECTIVE: To identify the effects of miR-15b on the migration and invasion of GSCs and the mechanisms involved in this process. METHODS: Quantitative PCR was performed to evaluate the expression of miR-15b in the gliomas tissues, normal brain tissues, GSCs and non-GSCs. After knockdown of ATP-binding cassette superfamily G member 2 (ABCG2) by ABCG2 specific siRNA, Transwell assay was performed to determine the effect of ABCG2 on GSCs migration and invasion. Additionally, the GSCs were transfected with miR-15b mimics or inhibitor to up-regulate or down-regulate the expression of miR-15b. At 48 hours after transfection, Transwell assay was used to detect the effect of miR-15b on GSCs migration and invasion; ELISA and gelatin zymography assays were performed to determine the matrix metalloproteinase-2/-9 (MMP-2/-9) expression and activity after treatment with miR-15b. CD133-positive or non-CD133-positive cells were directly injected subcutaneously into nude mice. Tumor formation was observed within 30 days after injection. RESULTS AND CONCLUSION: miR-15b was significantly down-regulated in gliomas tissues compared with normal brain tissues, which was negatively correlated with the stage of gliomas. In addition, miR-15b was significantly down-regulated in GSCs compared with non-GSCs. Up-regulation of miR-15b significantly reduced the migration and invasion ability of GSCs (P < 0.01), and down-regulation of miR-15b significantly enhanced the cell migration and invasion of GSCs (P < 0.01). By target prediction analysis, we obtained that ABCG2 was a potential target gene of miR-15b. Luciferase assay confirmed that miR-15b targeted ABCG2 directly, and migration and invasion of GSCs were dramatically reduced by ABCG2 siRNA (P < 0.01). ELISA results showed that up-regulation miR-15b significantly inhibited MMP-2/-9 expression. ELISA and gelatin zymography assay results showed that ABCG2 siRNA did not affect MMP-2/-9 expression, but significantly inhibited the activity of MMP-2/-9. In the in vivo tumor model, GSCs were more tumorigenic as compared with non-GSCs from the same tumor in vivo. To conclude, miR-15b regulates the migration and invasion of GSCs by targeting the ABCG2 signaling pathway, and up-regulation of miR-15b can suppress the migration and invasion of GSCs.
ABSTRACT
@#Objective To establish normal reference range of surface electromyography (sEMG) in related myoelectric activity when maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors in healthy middle to old people. Methods From Septem-ber to December, 2015, a total of 110 healthy people aged 41 to 75 years were divided into 41 to 50 years group, 51 to 60 years group and>60 years group according to age. The integral electrical values were measured in each subject by sEMG technique and analysis system under maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors. Results and Conclusion Under ankle dorsiflexion and plantar flexion movement modes, no significant difference was found in the integral electrical values of tibialis anterior muscle, long perone-al muscle, short tibial muscle and gastrocnemius among different groups (F<4.545, P>0.05). No significant difference was found in the inte-gral electrical values of different sides and different genders (F<7.028, P>0.05). Normal reference range for integral electrical values was es-tablished under maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors in healthy people.
ABSTRACT
@#Objective To establish normal reference range of surface electromyography (sEMG) in related myoelectric activity when maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors in healthy middle to old people. Methods From Septem-ber to December, 2015, a total of 110 healthy people aged 41 to 75 years were divided into 41 to 50 years group, 51 to 60 years group and>60 years group according to age. The integral electrical values were measured in each subject by sEMG technique and analysis system under maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors. Results and Conclusion Under ankle dorsiflexion and plantar flexion movement modes, no significant difference was found in the integral electrical values of tibialis anterior muscle, long perone-al muscle, short tibial muscle and gastrocnemius among different groups (F<4.545, P>0.05). No significant difference was found in the inte-gral electrical values of different sides and different genders (F<7.028, P>0.05). Normal reference range for integral electrical values was es-tablished under maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors in healthy people.