BACKGROUND/AIMS: This study was conducted to identify microRNAs (miRNAs) that are differentially expressed in Helicobacter pylori-infected patients with an intestinal type of gastric cancer using miRNA microarray and to confirm the candidate miRNA expression levels.

METHODS

Total RNA was extracted from the cancerous and noncancerous regions of formalin-fixed, paraffin-embedded tissues of H. pylori-positive (n=8) or H. pylori-negative (n=8) patients with an intestinal type of gastric cancer. RNA expression was analyzed using a 3,523 miRNA profiling microarray based on the Sanger miRBase. Validation analysis was performed using TaqMan miRNA assays.

RESULTS

A total of 219 miRNAs in the aber-rant miRNA profiles across the miRNA microarray showed at least a 2-fold change differential expression in H. pylori-positive and H. pylori-negative cancer tissues. After candi-date miRNAs were selected using online miRNA databases, TaqMan miRNA assays confirmed that three miRNAs (miR-99b-3p, miR-564, and miR-638) were significantly increased in three H. pylori-positive cancer tissues compared to the H. pylori-negative cancer tissues. Additionally, four miRNAs (miR-204-5p, miR-338-5p, miR-375, and miR-548c-3p) were significantly increased in H. pylori-negative cancer tissues compared to H. pylori-positive cancer tissues.

CONCLUSIONS

miRNA expression in the intestinal type of H. pylori infection-dependent gastric cancer suggests that different gastric can-cer pathogenesis mechanisms could exist between H. pylori-positive and H. pylori-negative gastric cancer. Additional functional studies are required. (Gut Liver, 2015;9188-196).