| Summary: | 博士 === 國立中興大學 === 生命科學系所 === 104 === Gastric carcinoma (GC) remains one of the most common cancers and the third leading cause of cancer deaths worldwide. Despite a steady decline in GC incidence, GC still represents a major health problem, but the molecular mechanisms underlying the development of GC are still poorly understood. GC is a multi-factorial disease that involves both genetic and epigenetic modification. The process of carcinogenesis was always followed with the genetic variations that are not changes in nucleotide sequence but changes in the phenotype to affect gene regulation. It is called epigenetic modification. These modifications are including DNA methylation, histone modifications and microRNA expression mechanisms. Therefore, we would like to use the concept of biochip, high-throughput and automated analysis, to characterize and realize the GC genome wide profile. Here, we were using differential methylation hybridization (DMH) to profile methylation alterations of CGIs on patients with GC. According to preliminary microarry data analysis, Regulator of chromosome condensation 1 (RCC1) was selected to verify the methylation and gene expression status by methylation analysis and other biotechnological methods. Our data indicate that RCC1 expression is frequently lost in poorly differentiated gastric cell lines and gastric carcinoma tissues. Loss of RCC1 expression is correlated with tumor differentiation and depth of invasion. These findings suggest that RCC1 may play a tumor suppressor role in GC. On the other hand, most GC often diagnosed with advanced stage, but the prognosis and overall 5-year survival rate of GC patients remains approximately 20%. Thus, early detection of GC is a key measure to reduce the mortality and improve the prognosis of GC. Previous studies indicated that miRNAs circulate in highly, stable, cell-free forms in blood. Serum and plasma miRNAs are relatively easy to access, circulating miRNAs have great potential to serve as non-invasive biomarkers. To investigate the potential of serum miRNAs as noninvasive biomarkers for detection of GC, miRNA array was used to identify and validate the differential serum miRNAs in GC patients. The miR-4728-3p, miR-6716-3p, miR-3184-3p and miR-4290 were selected as a candidate for a further analysis. These miRNAs were validated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and droplet digital PCR (ddPCR). The results showed miR-4728-3p, miR-6716-3p and miR-3184-3p had significantly higher copy number in serum of GC patients compared with cancer-free controls. These results suggest that miR-4728-3p, miR-6716-3p and miR-3184-3p have potential as novel non-invasive biomarkers for detection of GC, but need to analyzed more GC samples.
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