Comparison of OGG1 gene expression level in gastric adenocarcinoma and adjacent normal tissue

Background and aims: Gastric cancer is a major public health issue as the fourth leading cause of cancer-related death in the world. Reactive oxygen species (ROS) induce DNA damage and this process plays an important role in gastric cancer development and progression. OGG1 is an essential component of the base excision repair pathway  that is required for the removal of oxidized guanine nucleotides from DNA exposed to ROS. This study aimed to compare the expression of the OGG1 gene in cancerous and healthy tissues of gastric cancer. Methods: Fifty pairs of tumors and adjacent normal tissues were collected from gastric cancer patients. Total RNA was extracted and complementary DNA (cDNA) was synthesized. The relative gene expression of OGG1 was determined using quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR). A data mining study was also performed to determine the prognostic role of OGG1 expression in the overall survival of gastric cancer patients. Results: OGG1 gene expression was significantly increased in patients' tumor samples compared to normal adjacent tissue samples. In addition, the expression of OGG1 in patients with early stages of gastric cancer was significantly higher than those with advanced stages. Also, a negative correlation was observed between the high expression of OGG1 and the overall survival rate. Conclusion: It can be concluded that the expression of OGG1 increases in the early stages of gastric cancer, which could be related to the increase in oxidative damage to DNA.