Study On The Effects And Mechanisms Of MiR-129-5p In The Proliferation And Apoptosis Of Osteosarcoma

BACKGROUNDOsteosarcoma is the most common primary malignant bone tumor with highly invasive characteristic in children and adolescents.Although the combination of surgery and chemotherapy has increased the five-year survival rate of osteosarcoma from 20% to 60% ~ 70%,patients were prone to develop drug resistance to chemotherapy,leading to recurrence or metastasis,and ultimately leading to treatment failure.It is urgent to explore the mechanism involved in the development of osteosarcoma,and to find new molecular markers and therapeutic targets to further improve the therapeutic effect and prognosis of osteosarcoma.MicroRNA(miRNA)is a kind of non-coding small RNA molecules and it is about 21 nucleotides.MiRNAs are identified as post-transcriptional regulators which have been found to involve in lots of cell biological activities and dysregulate in various types of cancers.Studies have revealed that miR-129-5p has tumor suppressive function in most tumors.MiR-129-5p is related to diverse biological properties including cell proliferation,epithelial mesenchymal transformation,apoptosis,metastasis and autophagy.The role of miR-129-5p in osteosarcoma and its molecular mechanism remain to be further studied.OBJECTIVETo explore the effects of miR-129-5p on proliferation and apoptosis of OS cells and the underlying mechanisms.METHODS(1)qRT-PCR was employed to detect the expression of miR-129-5p in MG63,Saos2 cells and hFOB1.19 cells respectively.(2)CCK8 assay,colony formation assay and flowcytometry were used to explore the effects of miR-129-5p on the proliferation and apoptosis of osteosarcoma cells.(3)Double luciferase reporting assay,qRT-PCR and western blot were used to verifiy the relationship between miR-129-5p and PAK5.(4)The underlying molecular mechanisms of miR-129-5p was explored by cancer cell sphere formations experiment,qRT-PCR,western blot and drug sensitivity experiment.RESULTS(1)MiR-129-5p was downregulated in MG63 and Saos-2 cells.(2)After overexpression of miR-129-5p,the proliferation ability and clone formation ability of MG63 and Saos2 cells were decreased and apoptosis level was increased.(3)Luciferase activity assay revealed that PAK5 was a direct target of miR-192-5p.(4)Upregulation of miR-129-5p or downregulation of PAK5 attenuated the stem cell-like phenotype in OS cells.(5)Further molecular assays revealed miR-129-5p downregulated the expression of p-Glycogen Synthase Kinase(GSK)3? and ?-catenin.The rescue assays with the ?-catenin inhibitor and PAK5 overexpressed plasmids showed PAK5 regulated stem cell-like phenotype and drug resistance to DOX in OS cells through p-GSK3?/?-catenin signaling pathway.CONCLUSIONBy targeting PAK5,miR-129-5p down-regulated the stem cell-like phenotype of osteosarcoma and inhibited the proliferation ability of osteosarcoma and promoted apoptosis through GSK3?/?-catenin pathway.MiR-129-5p could be a promising marker for prognosis of osteosarcoma patients,and PAK5 could be an effective molecular target for clinical treatment of osteosarcoma.