SP1-mediated upregulation of lncRNA ILF3-AS1 functions a ceRNA for miR-212 to contribute to osteosarcoma progression via modulation of SOX5.

Long noncoding RNA ILF3-AS1 (ILF3-AS1) has been reported to be abnormally expressed in several tumors. However, its expression pattern and function in osteosarcoma have not been investigated. In this study, we showed that ILF3-AS1 expression was significantly up-regulated in both osteosarcoma tissues and cell lines. We first reported that ILF3-AS1 upregulation was induced by nuclear transcription factor SP1. Clinical assays revealed that higher expression of ILF3-AS1 was associated with advanced clinical stage, distant metastasis and shorter overall survival. in multivariate analysis, ILF3-AS1 expression level was found to be an independent prognostic factor for osteosarcoma patients. Functional investigations showed that knockdown of ILF3-AS1 suppressed the proliferation, migration and invasion of osteosarcoma cells, and promoted apoptosis. Bioinformatic software predicted that miR-212 both targeted the 3'-UTR of ILF3-AS1 and SOX5, which was confirmed using luciferase reporter assay, RT-PCR and Western blot. Taken together, ILF3-AS1 displayed its tumor-promotive roles in the progression of osteosarcoma through miR-212/SOX5 axis. Our findings help to elucidate the tumorigenesis of osteosarcoma, and future study will provide a novel therapeutic target for osteosarcoma.