Plasma MiRNAs As Potential Biomarkers For Detecting Gastric Cancer

Objective: Gastric cancer is one of the highest mortality of malignant tumor in the world, East Asia is a major high‐incidence areas. A large number of studies have confirmed that specific miRNA molecules can be detected in the plasma of patients of different types of cancer. The plasma miRNA molecules is expected to become molecular markers for tumor detection. Long non‐coding RNA （lncRNA） has recently been extensive attention, an important role of lncRNA in the process of tumor development has been widely recognized. Therefore, the purpose of this study is to screening and identification the candidate plasma miRNAs for detecting of gastric cancer, and to evaluate the feasibility as a biomarker for gastric cancer detection. The research also includes screening and identification of differentially expression of lncRNA for gastric cancer detection, and establishing a new method for detection of miRNA molecules. Methods:1)24patients plasma samples with gastric adenocarcinoma and24cases plasma samples of non‐tumor samples were mixed respectively,135candidate miRNA molecules were detected by real‐time quantitative PCR in order to obtain the candidate miRNAs for detection of gastric cancer.15and7obtained candiate miRNAs were assessed with188cases independent of plasma samples （99cases of gastric cancer,89cases of control）. In the47patients tissue samples with gastric adenocarcinoma and six gastric cancer cell lines, real‐time quantitative PCR analysis of the expression levels of selected differences lncRNA.3) Total RNA was polyuronidesed in miRNA3’end by poly（U） polymerase, and then cDNA was synthesized and reverse transcriptase using the poly（U）‐tailed total RNA as templates. The miRNAs were detected by PCR. Results:1) Of the135miRNAs were detected in the mixed plasma,15candidate miRNAs were obtained. The further experimental results showed the expression levels of miR‐378, miR‐379, miR‐485‐3p, miR‐885‐5p, let‐7a, let‐7f in gastric cancer patients plasma compared with the control group the difference was statistically significant. Combined with the analysis of the clinical data, these6m i R N A s a r e a u x i l i a r y v a l u e I n d e t e c t i o n o f g a s t r i c c a n c e r. 2) Arraystar Human LncRNA microarray results suggested that lncRNA expression profiles of gastric carcinoma and adjacent tissues is differences. Quantitative real‐time PCR analysis results showed that the expression of AK001058, AL359062, NR₀15379, uc002.the and AK025209in47cases of gastric cancer tissues and adjacent tissues is different, as well as in6gastric cancer cell lines.3) The poly（U）‐tailed RT‐PCR is a convenient and effective method to detect the expression of miRNAs. Conclusions: We obtained6candidate miRNAs for detection of gastric cancer. A preliminary understanding of the relationship between expression of lncRNAs with gastric cancer, and lncRNA expression vectors of AK001058and AL359062were constructed. The poly（U）‐tailed RT‐PCR is a new method for detecting miRNAs and studing functional mechanisms of miRNAs.