Long Noncoding RNA GAS5 Suppresses Cell Growth and Epithelial-Mesenchymal Transition in Osteosarcoma by Regulating the miR-221/ARHI Pathway.

Dysregulated long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play key roles in the development of human cancers. The lncRNA growth arrest-specific 5 (GAS5) is reported to be a tumor suppressor in multiple cancers. However, the roles of GAS5 and its related miRNAs in osteosarcoma are poorly understood. This study explored the potential functions and mechanisms of GAS5 in the tumorigenesis of osteosarcoma. Here, the expression of GAS5, miR-221 and aplasia Ras homologue member I (ARHI) was determined in osteosarcoma tissues and cells by Real-time PCR (RT-qPCR). The underlying mechanism of GAS5 in osteosarcoma growth was analyzed via MTT, Transwell, RT-qPCR, Western blot, dual-luciferase reporter assay, RNA immunoprecipitation, and xenograft models after GAS5 overexpression. GAS5 and ARHI levels were significantly reduced, while miR-221 increased, both in osteosarcoma tissues and cells. Overexpression of GAS5 suppressed the proliferation, migration, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. GAS5 could directly bind to miR-221 to decrease miR-221 expression and enhance ARHI expression. The effect of GAS5 overexpression on the proliferation, migration and EMT was reversed by miR-221 mimics or ARHI siRNA in osteosarcoma cells. Additionally, GAS5 suppressed tumor volume, Ki-67 and PCNA staining, and EMT process in the development of osteosarcoma in vivo. Taken together, lncRNA GAS5 functions as a competing endogenous RNA for miR-221 to suppress cell growth and EMT in osteosarcoma by regulating the miR-221/ARHI pathway. J. Cell. Biochem. 118: 4772-4781, 2017.