Long-non-coding RNA RUSC1-AS1 accelerates osteosarcoma development by miR-101-3p-mediated Notch1 signalling pathway

BACKGROUND: Long non-coding RNA (lncRNA) RUSC1-AS1 has been found to modulate several cancers development. In this study, we explored the role of RUSC1-AS1 on osteosarcoma (OS) progression. METHODS: Quantitative Real-time PCR (qRT-PCR) was conducted to test the relative expression of RUSC1-AS1, Notch1 mRNA and miR-101-3p in OS tissues and adjacent normal tissues. Gain- or loss- of functional assays were carried out to determine the roles of RUSC1-AS1 and miR-101-3p in OS progression both in vitro and in vivo. The expression of E-cadherin, N-cadherin, Vimentin, Snail, Notch1, Ras and ERK was determined by Western blot. Furthermore, the relationships between RUSC1-AS1 and miR-101-3p, Notch1 and miR-101-3p were confirmed through RNA immunoprecipitation (RIP) and dual luciferase reporter gene assay. RESULTS: RUSC1-AS1 and Notch1 were up-regulated in OS cells and tissues. Down-regulating RUSC1-AS1 significantly attenuated the proliferative, epithelial-mesenchymal transition (EMT), growth, lung metastasis, migrative and invasive abilities of MG-63 and Saos-2 cells, and aggravated apoptosis, accompanied with down-regulated Notch1-Ras-ERK1/2 in those cells both in vitro and in vivo, while overexpression of RUSC1-AS1 exerted opposite effects. Overexpressing miR-101-3p in OS cells had similar effects as RUSC1-AS1 inhibition. In addition, RUSC1-AS1 functioned as a competing endogenous RNA (ceRNA) to competitively sponge miR-101-3p, thus upregulating Notch1 expression and mediating the malignant behaviors of OS cells. CONCLUSION: RUSC1-AS1 is a novel oncogenic lncRNA in OS through the miR-101-3p-Notch1-Ras-ERK pathway, which might be a potential therapeutic target for OS.