Determination of mirna expression levels in tissues with colorectal cancer

Colorectal cancer is among the most common cancer types in the world and is a heterogeneous disease with different molecular pathways that lead to different phenotypes. For this reason, many studies are carried out for the early diagnosis of the disease. MicroRNAs (miRNA) show tumor suppressor and oncogenic properties according to the molecular pathway of the target mRNA. In recent years, by determining the functions of miRNAs and their role in cancer development, it has supported both the understanding of the molecular pathology of cancers and the development of new treatment approaches for molecular targets. The aim of this thesis is to determine the expression levels of miR-639, miR-641, miR-1915-3p and miR-3613-3p in patients with colorectal cancer and the potential of these miRNAs in the diagnosis of the disease. For this purpose, tumor and healthy adjacent tissue samples were collected from 59 patients with colorectal cancer. Expression levels of miR-639, miR-641, miR-1915-3p and miR-3613-3p were determined by quantitative Real Time-PCR method. As a result of the study, the expression of miR-639 (p = 0.000), miR-641 (p = 0.000) and miR-3613-3p (p = 0.000) was statistically significantly decreased in tumor tissues compared to normal tissues, it was determined that miR-1915-3p (p = 0.032) increased significantly. However, a significant correlation was found between low expression of miR-639 and advanced stage of the disease (p<0.05). In conclusion, it is thought that miR-639, miR-641 and miR-3613-3p play a tumor suppressor role in the pathogenesis of colorectal cancer, while miR-1915-3p plays an oncogenic role and may be new biomarkers that can be used in the diagnosis.