LncRNA TMPO-AS1 up-regulates the expression of HIF-1α and promotes the malignant phenotypes of retinoblastoma cells via sponging miR-199a-5p

Abstract

BackgroundLong non-coding RNA (lncRNA) TMPO antisense RNA 1 (TMPO-AS1) is reported to be oncogenic in prostate cancer and lung cancer. This study aims to investigate the expression and biological function of it in retinoblastoma (RB), and explore its regulatory role for miR-199a-5p and hypoxia-inducible factor-1α (HIF-1α). MethodsPaired RB samples were collected, and the expression levels of TMPO-AS1, miR-199a-5p and HIF-1α were examined by quantitative real-time polymerase chain reaction (qRT-PCR); TMPO-AS1 overexpressing plasmids and TMPO-AS1 shRNA were transfected into HXO-RB44 and SO-Rb50 cell lines respectively, and then proliferation, migration and invasion of RB cells were detected by CCK-8 assay and Transwell method. qRT-PCR and western blot were used to analyze the regulatory function of TMPO-AS1 on miR-199a-5p and HIF-1α; luciferase reporter gene assay was used to determine the regulatory relationship between miR-199a-5p and TMPO-AS1. ResultsTMPO-AS1 was significantly up-regulated in cancerous tissues of RB samples (relatively expression: 2.97 vs 3.93, p < 0.001), negatively correlated with miR-199a-5p (r=-0.4813, p < 0.01). There was one binding site on TMPO-AS1 for miR-199a-5p. After transfection of TMPO-AS1 shRNAs into RB cells, the proliferation, migration and invasion of cancer cells was significantly inhibited, while TMPO-AS1 had opposite effects; TMPO-AS1 was also demonstrated to regulate the expression of HIF-1α on both mRNA and protein levels via negatively regulating miR-199a-5p. ConclusionTMPO-AS1 is abnormally up-regulated in RB tissues, and it can modulate the proliferation and migration of RB cells. It has the potential to be the “ceRNA” to regulate HIF-1α expression by sponging miR-199a-5p.