Analysis of the Correlation Between Altered Expression of NT5E and PLCXD3 Genes in Gastric Cancer Tumor Samples Versus Adjacent Normal Tissue as diagnostic biomarker

Abstract

Gastric cancer ranks fourth in terms of mortality rate. According to the World Health Organization's report in 2020, gastric cancer, with 1,089,103 cases, is among the five most common cancers worldwide. Epidemiological studies indicate that the prevalence of this disease has globally increased in recent years, affecting a wide range of people, with men being twice as likely to be affected as women. The high statistics are due to the rapid progression of malignancy, late onset of clinical symptoms, and insufficient knowledge of the involved molecular mechanisms. Methods: In this study, we initially identified genes with altered expression in gastric cancer tissue samples compared to normal tissue samples using informatics analyses and the TCGA database. Subsequently, from the candidate genes, those associated with the survival of gastric cancer patients were selected using the GEPIA database. The impact of these genes on the survival of gastric cancer patients was further assessed using the Kaplan-Meier plotter database. Next, from the candidate genes, those with higher predictive value were examined for expression changes in laboratory samples. A total of 25 gastric cancer tissue samples and 25 adjacent healthy tissue samples were obtained from the Iranian Tumor Bank located at Imam Khomeini Hospital in Tehran. RNA extraction and cDNA synthesis were performed using commercial kits. The expression of target genes was then evaluated in the samples by real-time PCR. Findings and Conclusion: This study aimed to identify genes involved in the survival of gastric cancer patients. Through bioinformatics analyses, several genes associated with the prognosis of gastric cancer patients were identified. These genes included NT5E, PLCXD3, and several others that showed altered expression in gastric cancer tissues and were related to patient survival. The impact of these genes on patient survival was confirmed using the OncoDB database. Laboratory experimental results also indicated that the expression of NT5E and PLCXD3 was significantly increased and decreased, respectively, in gastric cancer samples. Additionally, the DNA methylation patterns of these genes differed in cancerous samples compared to normal samples.