Long non-coding RNA UASR1 promotes proliferation and migration of breast cancer cells through the AKT/mTOR pathway

Long non-coding RNAs (lncRNAs) are non-coding RNAs longer than 200 nucleotides that function as regulatory factors in many human diseases, including cancer. However, majority of lncRNAs remain to be characterized. In this study, we characterized a novel lncRNA transcript, named UNC5B antisense RNAI (UASRI ). UASRI is 647bp in length consisting of two exons. This lncRNA is an antisense of intron 1 of unc-5 netrin receptor B (UNC5B) gene. In breast cancer tissues, UASRI was upregulated. Ectopic expression of UASRI promoted proliferation and clonogenic growth of breast cancer cells MCF7 and MDA-MB-231. The migration of these cells also increased as demonstrated by wound healing and transwel I assays. In contrast, silencing of UASRI suppressed cell proliferation and migration. Further studies showed that UASRI activated AKT and AKT-mediated mTOR signaling pathway to stimulate cell proliferation and growth. In these cells, active pAKT, pTSC2, p4EBP1 and pp70S6K were increased. Taken together, our data suggest that UASRI plays an oncogenic role in breast cancer cells through activation of the AKT/mTOR signaling pathway, being a novel RNA oncogene.