| Summary: | 碩士 === 國立陽明大學 === 解剖學及細胞生物學研究所 === 98 === The modulation of gene expression by small non-coding RNAs has been recently discovered in animals and plants. Among the small non-coding RNAs, microRNAs (miRNAs) are the most well-developed and have been proved to be involved in almost all physiological regulation including cell proliferation, differentiation, and apoptosis. In addition, recent studies have shown that miRNAs exert both oncogenic and tumor suppressive effects in tumorigenesis. MBP-1 (c-myc promoter binding protein) is produced by the alternative translation initiation of mRNA of ??enolase, a glycolytic enzyme most distributed in cytoplasm. In contrast, MBP-1 does not retain the glycolytic enzyme activity and is predominantly distributed in nuclei as a transcriptional suppressor. MBP-1 acts as a tumor suppressor gene in regulation of c-myc proto-oncogene and COX-2 expressions and inhibits cancer progression.
Although miRNAs have been implicated in gastric cancer progression, the regulatory mechanisms remain to be elucidated. In this study, the relationship between MBP-1 and miRNAs during gastric cancer progression were investigated using reporter gene analysis, miRNA microarray, and miRNA real-time PCR. Here, it was demonstrated that luciferase activity after transfection with the reporter plasmid containing ENO1-3’UTR was inhibited in gastric cancer cells. Based on the prediction from miRNA databases and the results of miRNA microarray, it was suggested that some miRNAs (miR-22, miR-363, miR-151-3p, and miR-425-5p) may target ENO1-3’UTR. Expression level of miR-363 was negatively correlated with that of MBP-1, and luciferase activity after transfection with reporter plasmid containing ENO1-3’UTR was suppressed in the gastric cancer cell line which expresses higher level of miR-363.
According to the results of miRNA microarray and real-time PCR, there was six miRNAs down-regulated in the MBP-1-overexpressed gastric cancer cells. By using reporter gene analysis, it was shown that MBP-1 inhibited expression of miR-23b-27b-24-1 cluster through regulating the promoter of its host gene. Thus, the relationship between MBP-1 and miRNAs in gastric cancer cells and their roles in gastric cancer progression are worth further studying.
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