Differential MiRNA Expression and Their Target Genes Between NGX6-positive and Negative Colon Cancer Cells

Nasopharyngeal carcinoma-associated gene 6 (NGX6) was shown to be a novel putative tumor suppressor gene in colon cancer. The purpose of this study is to investigate its role in regulation of miRNA expression for in the hopes of translating this data into a novel strategy in control of colon cancer. In this study colon cancer HT-29 cells were stably transfected with NGX6 or vector-only plasmid and then subjected to miRNA array analysis, and Q-RT-PCR was then used to verify miRNA array data. Then bioinformatic analyses using Sanger, Target Scan, and MicroRNA software were performed to obtain data on the target genes of each miRNA and define their function. Our results showed that 14 miRNAs were found to be differentially expressed in NGX6-transfected cells compared to the control cells. In particular, miR-126, miR-142-3p, miR-155, miR-552, and miR-630 were all upregulated, whereas miR-146a, miR-152, miR-205, miR-365, miR-449, miR-518c, miR-584, miR-615, and miR-622 were downregulated after NGX6 transfection. Q-RT-PCR confirmed all of these miRNAs, and invalidated miR-552 and miR-630. Furthermore, bioinformatic analyses of these 12 miRNAs, among these miRNAs, target genes of miR-615 are unclear, another 11 miRNAs produced a total of 254 potential target genes and further study showed that these genes together formed a regulatory network that contributes to apoptosis, mobility/migration, hydrolysis activity, and molecular signaling through targeting JNK and Notch pathways. Taken together, these results have suggested that NGX6 plays an important role in regulation of apoptosis, mobility/migration, and hydrolase as well as activity of JNK and Notch pathways through NGX6-mediated miRNA expression. Further investigation will reveal the function of these differentially expressed miRNAs and verify expression of the miRNA-targeted genes for development of novel strategies for better control of colon cancer.