| Objective The diagnostic value of circulating non-coding RNA（miRNA and lncRNA）in gastric cancer was evaluated by meta-analysis.Meanwhile,miRNA expression profile chip in early gastric cancer tissues and serum in the GEO database was used to analyze circulating differentially expressed miRNAs.In order to evaluate the feasibility of noninvasive diagnosis of circulating miRNAs in early gastric cancer,ROC curve was constructed to develop the diagnosis model of circulating miRNAs.Further,miR-18b-5p was selected to study its correlation with gastric cancer immunity,to analyze the correlation between miR-18b-5p and the clinicopathology of gastric cancer patients,and to illustrate the application value of miR-18b-5p in the diagnosis and prognosis of gastric cancer.Methods 1.the diagnostic value of circulating non-coding RNA（miRNA and lncRNA）for gastric cancer,a systematic review and meta-analysis The four databases of Pub Med,Embase,Cochrane library and Web of Science were searched through the search terms.According to the inclusion and exclusion criteria,two researchers independently carried out literature screening,data extraction and quality evaluation.The Meta-Disc software（version 1.4）conducts statistical analysis.2.diagnostic value of serum miRNAs for early gastric cancer High throughput analysis of miRNAs in early gastric cancer tissues and adjacent tissues was performed by miRNA expression profile microarray.Then,the GEO database was retrieved to screen the serum miRNA microarray dataset GSE164174 of early gastric cancer.The miRNA expression profiles in the two sets of data were analyzed,and the eligible miRNAs were screened out according to preset conditions.At the same time,binary logistic regression was used to construct the ROC curve to evaluate the diagnostic value of a single miRNA and the combination of different miRNAs as molecular markers for gastric cancer.3.the correlation between miR-18b-5p and immune infiltrating cells of gastric cancer,verification of miR-18b-5p expression level and its relationship with clinicopathological features of gastric cancer Predict the target genes of miR-18b-5p through miRDB,miRWalk,star Base,and calculate the correlation between miRNA and mRNA;using star Base database to predict upstream lncRNA and its correlation;using TCGA,TIMER,Imm Lnc databases to detect the correlation among miR-18b-5p,lncRNA,mRNA and immune infiltrating cells.Finally,the expression level of miR-18b-5p in gastric cancer cell lines and tissues was tested by real-time fluorescence quantitative PCR,and the correlation with clinicopathological of gastric cancer patients was analyzed.Results 1.the diagnostic value of circulating non-coding RNA（miRNA and lncRNA）for gastric cancer,a systematic review and meta-analysis 88 articles（46 related to miRNA and 42 related to lncRNA）were screened,including a total of 83 miRNAs and 50 lncRNAs.（1）miRNA: the overall sensitivity for diagnosing gastric cancer was 0.82（95%CI: 0.81-0.83）,the specificity was 0.77（95%CI: 0.76-0.78）,and the AUC was 0.89;the results of subgroup analysis indicated that the diagnostic values of those derived from serum samples,combination and up-regulation were better than plasma samples,single and down-regulated miRNAs.Regression analysis illustrated that the main source of heterogeneity was the sample source.（2）lncRNA: the overall sensitivity for diagnosing gastric cancer was 0.80（95%CI: 0.79-0.81）,the specificity was 0.70（95%CI: 0.69-0.71）,and the AUC was 0.86.The subgroup analysis results showed that lncRNAs derived from plasma samples,combination and up-regulated lncRNAs had better diagnostic value than serum,single and down-regulated lncRNAs.Regression analysis indicated the expression level of lncRNA was the main source of heterogeneity.2.diagnostic value of serum miRNAs for early gastric cancer（1）High throughput detection of miRNA in early gastric cancer tissue and para cancer tissue samples was carried out by miRNA expression profile chip technology.Meanwhile,GEO2 R was used to analyze serum miRNA microarray dataset GSE164174 of early gastric cancer.A total of 45 up-regulated miRNAs in early gastric cancer were screened by the intersection of the two groups（log2FC>1,P<0.05）.TCGA database was used to analyze the expression and survival of 45 miRNAs,finally,14 miRNAs were obtained for subsequent analysis.（2）In GSE164174,1417 serum early gastric cancer samples and 1417 healthy controls were randomly assigned to the training set and validation set according to 1:1.By constructing the ROC curve,it was found that the AUC of 14 miRNAs combination could reach 0.976（95%CI: 0.969-0.984）both in the training set and validation set.In addition,the diagnostic performance of 14 miRNAs was not affected by gender,age and degree of gastric cancer differentiation.3.the correlation between miR-18b-5p and immune infiltrating cells of gastric cancer,verification of miR-18b-5p expression level and its relationship with clinicopathological features of gastric cancer（1）Predicted the target genes of miR-18b-5p through miRDB,miRWalk,and star Base.Took the intersection to get a total of 236 mRNAs.Using TCGA to calculate the expression level,and 21 down-regulated mRNAs with significant expression differences were screened,12 of which were negatively correlated with miR-18b-5p.（2）Determined the 79 upstream regulatory lncRNAs of miR-18b-5p through the star Base.The expression of TCGA showed that 49 lncRNAs had significant differences in expression,11 of which were significantly negatively correlated with miR-18b-5p.（3）TCGA immunoassay results showed that miR-18b-5p was significantly related to CD8+ T cells,B cells,dendritic cells and other immune cells in gastric cancer.Meanwhile,the expression status of miR-18b-5p in gastric cancer also affected the infiltration of immune cells.（4）miR-18b-5p,FENDRR,and 12 mRNA were significantly correlated with Th2 cells,and were correlated with immune checkpoint CD200 and BTLA.（5）miR-18b-5p was significantly overexpressed in gastric cancer cell lines and tissues,and the expression level of miR-18b-5p was correlated with the differentiation of gastric cancer.Conclusion 1.Circulating miRNA can be a reliable marker for the diagnosis of gastric cancer.2.Novel diagnostic markers based on 14 serum miRNAs may be a potential strategy for large-scale early gastric cancer screening.3.miR-18b-5p is highly expressed in gastric cancer and may be involved in the regulation of immune cell infiltration in gastric cancer,which is expected to be a potential marker for predicting the efficacy and prognosis of immune checkpoint inhibitors. |
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