Analysis of expression profile of miRNA in stomach adenocarcinoma

Stomach adenocarcinoma (STAD) has become the second main cause of cancer death around the world, and accumulated evidence has suggested that micro-RNAs (miRNAs) are likely to be served as indicator for diagnosis and prognosis in a variety of tumors. The purpose of this study was to discover the miRNAs acting as independent prognostic factors of STAD and to provide reference for the STAD diagnosis and prognosis.

In this study, we analyzed the clinical data collected from 393 STAD cases of the Cancer Genome Atlas (TCGA;USA) and the expression data of 1881 miRNAs to screen miRNAs that were associated with STAD via Cox regression univariate analysis and those miRNAs with independent effect on the prognosis of STAD via Cox regression multivariate analysis.

We found differential expressions of 218 miRNAs in STAD tumors and normal tissues, and a key role of miR- 7 in STAD. In Cox regression multivariate analysis, miR- 378i (p=0.0010), miR-7-3 (p=0.01), miR-137 (p=0.03) and miR-372 (p=0.04) were independent prognostic factors, for which we performed Kaplan-Meier analysis, and the results showed that there was a statistically significant difference in comparison of the survival duration between the highexpression and low-expression of miR-7-3 groups, but no differences were identified between the groups of miR-378i (p=0.7), miR-137 (p=0.11) and miR-372 (p=0.13).

miR-7-3 is proved to be an independent prognostic indicator for STAD and this study confirmed that tumor-specific miRNA can predict the progression and prognosis of STAD.