Helicobacter pylori-miRNA interaction in gastric cancer tissues: First prospective study from Turkey

Helicobacter pylori (H. pylori) is involved in the etiology of gastric cancer (GC). miRNAs are short RNAs that regulate gene expression by marking mRNAs for degradation. miRNAs are involved in tumorigenesis, metastasis, and cell proliferation. We aimed to investigate the miRNA expression profiles of tissues from H. pylori (+) and (-) GC patients. Forty GC patients, 20 H. pylori (+) and 20 H. pylori (-), and a healthy control group were included. The miRNA expression levels were investigated by microarrays and quantitative RT-PCR. We detected 9 upregulated and 4 downregulated miRNAs by microarray. We selected 5 upregulated and 5 downregulated miRNAs for the quantitative RT-PCR assay. The relative fold changes of miRNAs in the cancerous tissue and non-tumor mucosa specimens of H. pylori (+) GC patients for hsa-miR-194 were 4.24- and 3.83-fold higher, respectively, whereas the hsa-miR-145 expression levels were downregulated 0.33-fold and 0.43-fold, respectively, in the same group. The presence of H. pylori significantly upregulated hsa-miR-194 and downregulated hsa-miR-145 expression levels in H. pylori (+) GC cases, compared to H. pylori (-) GC cases. Regional differences in the virulence of H. pylori strains may also be involved in the up- or downregulation of miRNA expression levels.