Identification of the key miRNAs associated with survival time in stomach adenocarcinoma

Stomach adenocarcinoma (STAD) is one of the leading causes of cancer morbidity and mortality worldwide. The present study aimed to identify the microRNAs associated with STAD survival time. The clinical information and microarray miRNA and mRNA expression profiles of STAD patients were downloaded from The Cancer Genome Atlas. Differential expression (DE) analysis was performed to identify DEmiRNAs and DEmRNAs in STAD. The DEmiRNAs associated with the survival time of patients with STAD were identified through DE analysis, negative correlation pair analysis, miRNA target gene prediction, univariate Cox regression analysis and Kaplan-Meier analysis. The functions of the target genes of the DEmiRNAs were predicted with Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. A total of 355 DEmiRNAs and 1,722 DEmRNAs were identified between STAD and normal tissues. A total of 5 DEmiRNAs were identified to be associated with STAD survival, including 4 risk-associated DEmiRNAs (miR-30a, -143, -145 and -133b) and 1 protective DEmiRNA (miR-135b). The target DEmRNAs were significantly enriched for DNA metabolic process in the biological process GO category, and in KEGG cell cycle signaling pathways. Kaplan-Meier curves indicated that the overall survival time in the miR-30a, -143, -145 and -133b high expression groups was significantly shorter than that in the low expression groups, whereas the survival time was prolonged in the miR-135b high expression group compared with that in the low expression group. Therefore, miR-30a, -143, -145, -133b and -135b may be involved in the tumorigenesis and development of STAD, and may be potential biomarkers for its early diagnosis and prognosis.