Expression analysis of miR-98 and miR-16-5P miRNA in polymorphic Helicobacter pylori genotypes in gastric cancer

Gastric cancer is the fourth most common cancer in the world; and second in terms of cancer-related deaths. Besides the high rates of incidence, stomach cancer cause deaths within a few years because of its late diagnosis. The most well known risk factors are the use of tobacco products, diet and Helicobacter pylori infection. It is known that bacterial infection, when combined with genetic predisposition, significantly increases gastric cancer risk. Helicobacter pylori carries two important genes which play a role in cancer formation and show polymorphic characteristics, called CagA and VacA. MicroRNAs are small, non-coding RNA molecules. These molecules are about 20-25 nucleotides and regulate gene expression in the negative direction in the post-transcriptional stage. It is known that they have important roles in cancer mechanisms. They can both trigger and suppress tumor. In this study, VacA and CagA polymorphisms of Helicobacter pylori genes were studied in Turkish population and the relationship between these polymorphisms and gastric cancer was investigated. Also, miR-98 and miR-16-5p miRNAs have been examined for changes in expression levels in tumor tissues. CagA and VacA polymorphisms have been found to be associated with disease, while tumor suppressor and pro-apoptotic miRNAs have been found to be reduced in expression levels relative to AGS control cell line.