Long Noncoding RNA CCDC144NL-AS1 Promotes the Oncogenicity of Osteosarcoma by Acting as a Molecular Sponge for microRNA-490-3p and Thereby Increasing HMGA2 Expression

PURPOSE: The long noncoding RNA CCDC144NL antisense RNA 1 (CCDC144NL-AS1) exhibits important functions in gastric cancer. In this study, we aimed to investigate the roles of CCDC144NL-AS1 in modulating the phenotype of osteosarcoma (OS) cells in vitro and in vivo and elucidate its underlying mechanisms. METHODS: Reverse transcription quantitative polymerase chain reaction (PCR) was performed to determine the expression level of CCDC144NL-AS1 in OS tissues and cell lines. The proliferation, apoptosis, migration, and invasion in vitro as well as tumor growth in vivo were determined in OS cells using the Cell Counting Kit 8 assay, flow cytometric analysis, transwell migration and invasion assays, and xenograft experiments, respectively. Bioinformatics analysis was performed to identify the potential microRNA targets of CCDC144NL-AS1, which were subsequently confirmed using the luciferase reporter assay, RNA immunoprecipitation assay, reverse transcription quantitative PCR, Western blotting, and rescue experiments. RESULTS: CCDC144NL-AS1 expression was upregulated in OS tissues and cell lines. Patients with OS who exhibited high CCDC144NL-AS1 expression had shorter overall survival than those who exhibited low CCDC144NL-AS1 expression. Functionally, interference in CCDC144NL-AS1 expression led to a notable decrease in the proliferation, migration, and invasion of OS cells and an increase in cell apoptosis in vitro. Furthermore, CCDC144NL-AS1 knockdown impaired OS tumor growth in vivo. Mechanistically, CCDC144NL-AS1 directly bound to miR-490-3p in OS cells, where it functioned as a molecular sponge and subsequently increased the expression of high-mobility group AT-hook 2 (HMGA2). Rescue experiments further demonstrated that miR-490-3p suppression or HMGA2 restoration abated CCDC144NL-AS1 deficiency-induced cancer-inhibitory actions in OS cells. CONCLUSION: CCDC144NL-AS1 exhibits pro-oncogenic roles in OS by functioning as a sponge for miR-490-3p and increasing HMGA2 expression. Our findings suggest that greater understanding of the CCDC144NL-AS1/miR-490-3p/HMGA2 pathway can provide useful information for OS diagnosis, prognosis, and therapy.