Expression of let-7a, miR-106b and miR-29b is changed in human gastric cancer

MicroRNA (miRNA) are small, noncoding RNA sequences that post-transcriptionally regulate the proliferation, activity and apoptosis of human gastric cancer cells by controlling various signaling cascades. Processes that involve miRNA molecules can create a specific network of interactions in a cell, and disruption of its functioning may contribute to the transformation of normal cells into cancerous cells. Aims of our survey were: 1) study the relationship between the expression of selected miRNA types (let-7a, miR-106b, miR-29b, miR-21, miR-155, miR-222) in the gastric mucosa and pathomorphological changes determined by classical histopathological methods, 2) perform in silico analysis to select target genes for selected miRNAs and to perform functional analysis of these genes. Eighty-three subjects (45 women, 38 men; mean age 39±14 years, range: 21-80 years, were examined). Among them were 18 (21.5%) patients with chronic active gastritis, 42 (50.6%) people with chronic inactive gastritis, 9 (10.8%) patients with gastric cancer and 14 (16.9%) patients without histopathological changes. The study demonstrated that mainly the expression of 3 (miR-29b, let-7a miR-106b) out of 6 selected miRNAs are significantly different depending on the site of biopsy (body of the stomach or antrum) and the group of patients. Expression of miR-106b in the antrum and body was the highest in the group of cancer patients and the lowest in patients with chronic active gastritis. The expression of let-7a differed depending on group of patients and location. The highest expression was in the body in the group with inactive gastritis and the lowest in gastric cancer. Patients with cancer had the lowest expression of miR-29b in stomach body and it was the highest in the patients with inactive gastritis in this location. Expression of miR-21 and miR-155 determinations were not statistically significant in comparison to groups or locations, and of miR-222 was not different between the groups, but only in the control group was higher in the antrum than in the body. We conclude that identification of miRNAs may represent a promising modern complementary method in the diagnosis of gastric diseases, especially cancer.