Long non‑coding RNA‑DUXAP8 regulates TOP2A in the growth and metastasis of osteosarcoma via microRNA‑635.

Osteosarcoma (OS) is a malignant disease with high morbidity and mortality rates in children and adolescents. Evidence has indicated that long non‑coding RNAs (lncRNAs) may serve important roles in human cancer progression, including OS. In the present study, the role of lnc‑double homeobox A pseudogene 8 (DUXAP8) in the development of OS was identified. The expression of lncRNA‑DUXAP8 was determined by reverse transcription‑quantitative polymerase chain reaction in OS tissues. Cell proliferation was evaluated using Cell Counting kit‑8 and colony formation assays, and Transwell assays were conducted to measure cell invasion. Cell migration was evaluated using a wound healing assay. The binding site between lnc‑DUXAP8 and miR‑635 RNAs was investigated using a luciferase reporter assay. The expression of lnc‑DUXAP8 was significantly upregulated in OS samples and OS cell lines compared with normal tissues. High expression of lncRNA DUXAP8 was associated with shorter overall survival times. Knockdown of lncRNA DUXAP8 inhibited proliferation, migration and invasion in OS cells. Notably, mechanistic investigation revealed that lncRNA DUXAP8 predominantly acted as a competing endogenous RNA in OS by regulating the miR‑635/topoisomerase alpha 2 (TOP2A) axis. lncRNA DUXAP8 is upregulated in OS, and lncRNA DUXAP8‑knockdown serves a vital antitumor role in OS cell progression through the miR‑635/TOP2A axis. The results of the present study suggested that lncRNA DUXAP8 may be a novel, promising biomarker for the diagnosis and prognosis of OS.