The clinical significance of downregulation of mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p in gastric cancer tumorigenesis

Dysregulated miRNAs in gastric cancer are usually screened by miRNA microarray from clinical samples, however, reports have indicated that results of each miRNA microarray screening are considerably different, and dysregulated miRNAs, especially downregulated miRNAs were contradictory. In view of this, the Human Cancer Pathway Finder miRNA PCR array was applied to compare 7 gastric cancer cell lines AGS, SGC-7901, MKN-45, MKN-28, MGC-803, BCG-823, and HGC-27 with an immortalized normal gastric cell line, GES-1 in cancer pathway-related miRNA expression profile, followed by qPCR verification, the clinical significance of downregulated miRNAs and the Enriched KEGG pathways and GO terms of their target genes were analyzed. Thirty-eight miRNAs were upregulated, and four miRNAs were downregulated in gastric cancer cell lines. Clinical significance of 4 miRNAs including mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p in gastric cancer tissue compared with adjacent non-tumor tissues of 58 patients indicated that the low-expression group of mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p showed more extensive lymph node metastasis, lymphatic invasion, venous invasion, high-stage Borrmann type, lymphatic invasion and poor differentiation than that of the high-expression groups, respectively (P<0.05; chi(2) test). Enriched KEGG pathway analyses showed that most of the targeted genes of the 4 miRNAs concentrated on 37 signaling pathways, and were involved in the same pathways related to cancer. Enriched GO terms showed that targeted genes of the 4 miRNAs concentrated on 339 terms, 24 of 339 terms are associated with cancer tumorigenesis. The Human Cancer Pathway Finder miRNA PCR array could be used to screen dysregulated miRNAs effectively, and 4 screened miRNAs, mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p were found to be downregulated in gastric cancer. Clinical significance and bioinformatic analysis on the target genes of these 4 miRNAs indicated that they were deeply involved in tumorigenesis, suggesting roles such as miRNA tumor suppressors in gastric cancer tumorigenesis which could be applied in gastric cancer diagnosis and prognosis.