MicroRNAs are important gene regulators that play a profound role in tumorigenesis.MicroRNA-145 (miR-145),an important member in the family of microRNAs,is under-expressed in several types of tumors and acts as a tumor suppressor.The role and probable pathway of miR-145 in osteosarcoma carcinogenesis is still unknown.In this study,we found that miR-145 was significantly under-expressed in osteosarcoma tissues,and the overexpression of miR-145 could inhibit invasion and angiopoiesis of osteosarcoma cells.Furthermore,the results showed vascular endothelial growth factor (VEGF) expression was down-regulated in osteosarcoma cells after miR-145 transfection.Based on these results,we performed the luciferase assay and verified that miR-145 could down-regulate VEGF at the translational level by partially binding to VEGF 3UTR.Therefore,it can be concluded that miR-145 can inhibit invasion and metastasis of osteosarcoma ceils.One of the mechanisms is miR-145 down-regulates VEGF expression by binding to the 3UTR of VEGF mRNA specifically.These novel findings may have extensive implications for an effective gene therapy of osteosarcoma.