NONHSAT028579 lncRNA Acts as a Tumor Suppressor gene by Titrating MicroRNA-133

In recent decade, several studies have shown that long noncoding RNAs (lncRNAs) are involved in numerous physiological and pathological processes through regulating gene expression at the transcriptional, post-transcriptional, and epigenetic levels, especially in the development and progression of different carcinomas. Thus, the investigation of the role of lncRNAs could help in the understanding of oncogenesis and identify novel potential treatment targets. Recently, a role of competing endogenous RNAs, or natural miRNA sponges, has been proposed. In this model, lncRNA can post-transcriptionally regulate other genes expression by competitively binding to a miRNA. The aim of this study was to investigate NONHSAT028579 gene role as a competing RNA.Methods and Materials  Bioinformatics To find the lncRNAs that may play important role in gastric cancer, TCGA RNA-seq data was analyzed. Assuming that the selected lncRNA may act by sponging mechanism, the whole length of NONHSAT028579 gene was scanned in searching the microRNAs that have predicted MREs on the lncRNA (RNA Hybrid, Target scan and miRWalk online tools were used for this purpose).  Experimental Procedures To investigate possible direct interaction of the lncRNA with miR-133, NONHSAT028579 transcript was PCR-amplified and cloned into Psi-check2 dual luciferase vector in downstream of Renila luciferase gene. Then, psi-check2-NONHSAT028579 and PEGFPC1-Mir-133 vectors were co-transfected to Hek293 cell line and after 48 hours cell lysates were extracted and emission is measured in a counting Luminometer. A fragment with no MRE for miR-133 was used as a negative control. Normalization was performed and data is presented as Mean +/- SEM.Results and Discussion The result of TCGA RNA-seq data analysis introduced NONHSAT028579 as differentially expressed lncRNA in gastric cancer compared with adjacent normal tissues that may have a crucial role in the cancer. To investigate possible molecular mechanism of function of this lncRNA, the whole transcript was scanned in order to find domains that by means of them; NONHSAT028579 may exert its function. The online tools predicted miR-133 to interact with NONHSAT028579. Hence, direct interaction of miR-133 and NONHSAT028579 was surveyed by Dual luciferase assay. The normalized data showed that NONHSAT028579 directly interacts with miR-133 and therefor by titrating miR-133 off the target genes, may attenuate oncogenic function of the microRNA. But more experiments are needed to elucidate NONHSAT028579 function and other partners (microRNAs, lncRNAs and proteins) that may cooperate with this lncRNA.