MALAT1 promotes proliferation, migration, and invasion of MG63 cells by upregulation of TGIF2 via negatively regulating miR-129

PURPOSE: This article aimed to investigate the mechanism by which MALAT1 and miR-129 affected the development of osteosarcoma. METHODS: Tumor tissues and adjacent tissues of 23 osteosarcoma patients were collected. Normal osteoblasts hFOB1.19 and osteosarcoma cells MG63 were cultured. MG63 cells were transfected and grouped: si-negative control (NC) group, si-MALAT1 group, miR-129 NC group, miR-129 mimics group, p-Empty vector group, p-MALAT1 group, p-MALAT1+ miR-129 mimics group, and p-MALAT1+ si-TGIF2 group. Luciferase reporter assay, Cell Counting Kit-8 assay, Transwell assay, quantitative reverse transcription PCR, Western blot, and Pearson correlation analysis were performed. RESULTS: MALAT1 expression in tumor tissues and MG63 cells was increased (P<0.01). High MALAT1 expression predicted poor prognosis of osteosarcoma patients. MG63 cells of si-MALAT1 group exhibited much lower cell viability, migration, and invasive cell numbers when compared with si-NC group (P<0.01). For MG63 cells of miR-129 mimics group, they had markedly lower cell viability, migration, and invasive cell numbers than miR-129 NC group (P<0.01). miR-129 was targetedly and negatively regulated by MALAT1. TGIF2, which was targetedly and negatively regulated by miR-129, was overexpressed in tumor tissues and MG63 cells (P<0.01). miR-129 overexpresison and TGIF2 downregulation significantly reversed the enhanced cell viability, migration, and invasion induced by MALAT1 (P<0.01). CONCLUSION: MALAT1 promotes TGIF2 expression through negative regulation of miR-129, which further promotes the proliferation, migration, and invasion of MG63 cells.