The Molecular Mechanisms Study Of LncRNA OIP5-AS1 Up-regulating PTN Expression To Promote The Drug Resistance In Osteosarcoma

BACKGROUNDOsteosarcoma is a common and primary bone malignant tumor,mainly occurring in children and adolescents,with a high grade malignancy and pulmonary metastasis.In osteosarcoma,the occurrence of drug resistance has caused poor prognosis of patients.Until now,the mechanisms of the occurrence of drug resistance in osteosarcoma have not been clearly elucidated.Therefore,it is of great clinical significance to search for molecular targets related to the drug resistance of osteosarcoma so as to reverse it and improve the survival of patients.LncRNAs is a cluster of RNA with over 200 nucleotides and lack protein-coding ability.LncRNA can regulate gene expression at the levels of transcription and posttranscription,thus participating in a range of biological activities.LncRNA OIP5-AS1 serves as the oncogene role in a great variety of tumors,and is involved in the malignant phenotypes of tumor such as proliferation,apoptosis,invasion,migration and drug resistance.The role of LncRNA OIP5-AS1 in drug resistance of osteosarcoma and its molecular mechanisms have not been well understood.OBJECTIVETo investigate the role and molecular mechanisms of LncRNA OIP5-AS1 in drug resistance of osteosarcoma.METHODS(1)qRT-PCR assay was used to detect the expression level of LncRNA OIP5-AS1 in osteosarcoma parent cell MG63 and drug-resistant cell MG63/ADR.(2)CCK8 assay,EDU assay,clone formation assay and flow cytometry were used to detect the effect of LncRNA OIP5-AS1、mi R-137-3p and PTN on the drug resistance of osteosarcoma cell.(3)Xenograft assay were employed to examine the effect of LncRNA OIP5-AS1 on the drug resistance of osteosarcoma in vivo.(4)Dual luciferase reporter gene assay、qRTPCR and western blot verified the regulatory relationship between LncRNA OIP5-AS1 and mi R-137-3p、mi R-137-3p and PTN.RESULTS(1)LncRNA OIP5-AS1 was upregulated in drug-resistant cell MG63/ADR than in parental cell MG63.(2)When LncRNA OIP5-AS1 was knocked down,the chemoresistance to adriamycin of MG63/ADR was decreased and the apoptosis level was increased,together with reduced tumor weight and volume.(3)The overexpression of mi R-137-3p or the inhibition of PTN decreased the chemoresistance to adriamycin and clonal formation ability in MG63/ADR,while the inhibition of mi R-137-3p or the overexpression of PTN exhibited the opposite effects in MG63.(4)Dual luciferase reporter gene assay、qRT-PCR and western blot confirmed that mi R-137-3p was the target of LncRNA OIP5-AS1 and PTN was the target of mi R-137-3p.CONCLUSIONLncRNA OIP5-AS1 upregulated the expression of PTN by negatively regulating mi R-137-3p expression thus promoting the drug resistance of osteosarcoma.LncRNA OIP5-AS1 may serve as a potential target for reversing drug resistance of osteosarcoma.