MicroRNA-199a-5p Promotes Cell Proliferation And Tumor Growth By Targeting PIAS3 In Human Osteosarcoma

Osteosarcoma(OS)remains a leading cause of cancer death in adolescents.Further study of the pathogenesis for OS has an important guiding significance to the clinical treatment.As 21-25 nucleotides non-coding RNA,microRNA have demonstrated important transcriptional regulation on the development of various cancers.Previous studies in our lab have found miR-199a-5p was statistically higher in OS clinical specimens compared with their counterparts.In this thesis,we carried out research on the regulation mechanism of miR-199a-5p involved in the OS development.We predicted PIAS3 may be an important target gene of miR-199a-5p and further confirm the negative correlations between them in OS tissues.Q-PCR,luciferase assay and western blot were adopted for the target evaluation.The functional effects of miR-199a-5p in OS cells were assessed by its forced or inhibited expression.We found that overexpression of miR-199a-5p could lower PIAS3 protein level significantly and increase STAT3 phosphorylation level in vitro.The upregulation of miR-199a-5p significantly enhanced proliferation and inhibited apoptosis in OS cell lines,whereas the knockdown of miR-199a-5p exhibited an inverse effect.Moreover,the over-expressing of miR-199a-5p stably in osteosarcoma cells could promote tumor growth in xenograft model.In addition,tumor sizes were significantly reduced by inhibition of miR-199a-5p through intratumoral injection of anti-miR-199a-5p oligonucleotide in xenograft model.Our findings first indicate that as an oncogene,miR-199a-5p plays an important regulation role in OS.It can suppress the expression of PIAS3 in post-transcriptional level and promote Stat3-mediated tumorigenesis in osteosarcoma.Thus,miR-199a-5p-targeted inhibitors may be a promising approach for clinical therapy for OS.