LncRNA TMPO-AS1 serves as a ceRNA to promote osteosarcoma tumorigenesis by regulating miR-199a-5p/WNT7B axis

Osteosarcoma (OS) is a common kind of aggressive tumor in bone which was mostly identified in children and adolescents with extremely high risk of death. Accumulating research works have displayed that long noncoding RNAs (lncRNAs) exert an essential role in the development of multiple cancers. It has been reported that TMPO-AS1 is an oncogene in cancers; nonetheless, its molecular mechanism in OS is totally unclear. Our present study elucidated that a remarkable overexpression of TMPO-AS1 was found in OS tissues and cells. Moreover, TMPO-AS1 depletion restrained Wnt/β-catenin pathway and cell proliferation as well as facilitated cell apoptosis. Further molecular mechanism investigations showed that TMPO-AS1 can sponge to miR-199a-5p. Moreover, miR-199a-5p was at a low level at OS cells. Importantly, miR-199a-5p's overexpression was associated with the OS cells' decreased proliferation and increased apoptosis. In addition, WNT7B was confirmed as a downstream gene of miR-199a-5p. Also the WNT7B expression was reversely modulated by miR-199a-5p and positively modulated by TMPO-AS1. Rescue experiments suggested that downregulated WNT7B rescued miR-199a-5p inhibitor-mediated repression on OS progression, but the treatment of LiCl counteracted the effect of WNT7B downregulation. In a word, TMPO-AS1 serves as a competing endogenous RNA to boost osteosarcoma tumorigenesis by regulating miR-199a-5p/WNT7B axis, which provided an underlying therapeutic target for patients with OS.