Dysregulated Expression Of Mirnas In Gastric Cancer And Its Clinical Significance

Chapter â…  MiRNA expression profiles in intestinal-type gastric cancersObjectives:Screening dysregulated expression of miRNAs in intestinal-type gastric cancer.Method:We used miRCURYTM Array LNA microRNA chip to evaluate miRNA expression levels between intestinal-type gastric cancer tissues and adjacent non-tumours tissues. All6paired gastric cancers were pathological classified in TNM category of â…¢ stage or â…£stage. and average change more than2fold and p value less than0.01are set as a cutoff level.Results:We found that24genes have been reported in the gastric cancers among40up-regulated genes. New upregulated genes include recently named genes such as:miR-886-5p, miR-1259and miR-1308.19genes have been reported in the gastric cancers among36downregulated genes;17new miRNAs were found in intestinal-type gastric cancers, and especially a number of hsa-miRPlus genes. To compare the relative miRNA expression levels between RT-qPCR and chip analysis,10miRNAs were selected and they are among the top differentially expressed miRNAs by chip analysis. We analyzed expression level of these miRNAs in29-paired samples of intestinal-type gastric cancer, and results showed that miRNA expression in the paired benign and tumor tissue was consistently increased or decreased in all cases. We found all5up-regulated miRNAs in chip analysis increase expression level in gastric cancers tissues, and6down-regulated miRNAs also decrease expression in adjacent normal tissues. The correlation of relative miRNAs expression levels was analyzed by cDNA array (Array Fold) versus RT-qPCR (qPCR Fold). Pearson correlation of down-regulated miRNAs was0.98(p<0.01) and Pearson correlation of up-regulated miRNAs was0.90(p<0.01). Pearson correlation of both down-and up-regulated miRNAs was0.96(p<0.01). For clustering analysis, we set p value less than0.01as a cutoff level, Expression level of40up-regulated genes and36down-regulated genes are analyzed by unsupervised hierarchical clustering. Our data showed that all76miRNAs express very resemble pattern. The heatmap demonstrates that all those genes changed resemble in the different pair of gastric cancer tissues, and the same pathological stage samples group to the same subclusters.Conclusion:â‘ Reported here are the results of the first detailed miRNA expression profiling study in intestinal-type gastric cancers. Expression profiling identified a large number of miRNAs and never reported them before. â‘¡We identified more dysregulated expression miRNAs than any other previous reports, and it is easier to detect new aberrant miRNAs using subtype and the same or resemble stages cancers.â‘¢10aberrantly expressed miRNAs were confirmed by RT-qPCR and suggested our data are reliable.Chapter II Different expression pattern of miRNAs between subtypes of gastric cancersObjectives:To test if it exist different expression pattern of miRNAs between intestinal-type and diffuse-type gastric cancers.Methods:We selected4aberrant miRNAs of gastric cancers and detected the expression levels from29-paired intestinal-type and21-paried diffuse-type gastric cancers.Results:miR-27a expression level increase5.54fold of adjacent non cancer tissues in diffuse-type gastric cancers and higher upregulated3.22fold in intestinal-type gastric cancers. Although miR-494decrease expression both in intestinal-type and diffuse-type gastric cancers and p value less than0.01by t-test analysis, but miR-494decrease0.23fold of adjacent non cancer tissues in diffuse-type gastric cancers and only0.43fold in intestinal-type cancers, and it exist significant difference between two subtype cancers (p<0.01). miR-145decrease0.34fold of adjacent non cancer tissues in intestinal-type gastric cancers (p<0.01), but it does not change in diffuse-type gastric cancers (p>0.05), and it exist some difference between both subtype cancers (p<0.01). Of course, most of miRNAs expression levels are resembled in both subtype gastric cancers such as miR-886-5p (p>0.05).Conclusion:4miRNAs expression levels are different in two subtype cancers and miRNAs expression pattern exist significant difference. miRNAs expressing different pattern of subtype cancers will be increase our understand of pathogenesis of intestinal-type gastric cancer.Chapter â…¢ miRNA expression levels are related with pathological staging of intestinal-type gastric cancersObjectives:Some miRNAs may target invasion and metastasis-related genes and are involved in progress of cancers. In this study, we investigate the relationship between miRNA expression levels and pathological staging of intestinal-type gastric cancers.Methods:4dysregulated expression miRNAs are detected in different pathological stages of gastric cancers;Results:Comparing with adjacent non cancer tissues, miR-32expression level of I stage is significantly decrease in the intestinal-type gastric cancers, it is lower than that of â…¢ stage of intestinal-type gastric cancers and that of â…£ stage, p values are0.0046and0.004respectively. Although we did not find it exist significant difference between â…  stage and â…¡ stage (p value>0.05), it exists statically difference between â…¡ stage and IVstage. miR-182expression levels also increase in the different stages of intestinal-type gastric cancers, it does not exist significantly difference between â…  stage and â…¡ stage and between â…¢ stage and IV stage, but it shows significantly difference between â… &â…¡ stage and â…¢&â…£stage (p<0.05). Expression level of miR-143, significantly decreases in â…£stage. Comparing with â…  and â…¡ stages, p values are0.04and0.03respectively (p<0.05). miR-886-5p also decrease in the intestinal-type gastric cancers, but it does not exist difference between â…  stage and â…¢ stage (p>0.05) and between â…  stage and â…£ stage (p>0.05).Conclusion:Expression levels of miR-32, miR-182and miR-143exist significant difference in the various pathological stages of intestinal-type gastric cancer, and they may be involved in the malignant progression of intestinal-type gastric cancer. SummaryWe identified a series of aberrant expressed miRNAs in the intestinal-type gastric cancer by gene chips; we also showed the difference expression level of some miRNAs between intestinal-type and diffuse-type gastric cancers; we approved the abereant expressed levels of miR-32, miR-182and miR-128are related with the progression of intestinal-type gastric cancers. Our data may provide diagnostic biomarkers for intestinal-type gastric cancers and offer new clues to study the molecular mechanism of carcinogenesis of gastric cancer.