lncRNA DANCR promotes tumor progression and cancer stemness features in osteosarcoma by upregulating AXL via miR-33a-5p inhibition.

lncRNAs regulate the initiation and progression of osteosarcoma, although the mechanism by which this occurs remains unknown. The present study shows that over-expression of the lncRNA DANCR increased osteosarcoma cell proliferation, migration, and invasion in vitro, as well as promoted xenograft tumor growth and lung metastasis in vivo. Mechanistically, DANCR promoted osteosarcoma progression by mediating cancer stem cells (CSCs) features. Moreover, pull-down assays and luciferase reporter assays indicated that DANCR upregulated expression of the receptor tyrosine kinase AXL by competitively binding to miR-33a-5p. Furthermore, DANCR enhanced the expression of proteins downstream of the AXL-Akt pathway. DANCR was consistently significantly increased in osteosarcoma tissues, and its expression was positively correlated with tumor size and metastasis as an independent poor prognostic factor. Furthermore, both in patient tumors and xenograft tumors, DANCR expression was positively related to AXL and negatively related to miR-33a-5p. Taken together, our results suggest that DANCR is a crucial upregulator of osteosarcoma and an independent predictor of prognosis. DANCR increases CSCs function by upregulating AXL via competitively binding to miR-33a-5p, and this function is sequentially performed through the PI3K-Akt signaling pathway.