Detection of Mutations in Exons 5, 6, and 7 of the TP53 Gene in the Tumor Tissue and Stool Samples of Patients with Colorectal Cancer from Northwest Iran

Abstract

Background: Colorectal cancer (CRC) is the third most prevalent cancer with approximately 9,000 annual deaths worldwide. However, early detection can provide a high survival rate. The fecal DNA, as a non-invasive method for detecting the genetic markers, such as the TP53 gene, can be conducive to disease diagnosis. In this study, we aimed to investigate the presence of the TP53 mutations in the stool samples and their relationship with somatic mutations in the tissue samples of CRC patients from northwestern Iran. Method: In the present cohort study, tumor and stool samples were obtained from 64 CRC patients (mean age of 60), who were undergoing surgery. Total genomic DNA was extracted from the tissue and stool samples, and TP53 mutations were detected using the PCR-SSCP method, followed by direct sequencing. Differences between mutations were observed in the tumors, and the stools were examined using the McNemar method. Results: Of 64 CRC patients, 19 individuals (30%) demonstrated 27 point mutations in exons 5-7 of the TP53 in the tumor samples. Furthermore, analysis of the stool specimens revealed that the 22 mutations (81.5%) identified in the tumor specimens were also present in the stool of 12 patients (P = 0.063). Conclusion: Based on the results, the DNA from the tissue could be replaced with fecal DNA in the mutation detections for CRC. Given the non-invasive nature of fecal sampling, it can be desirable and acceptable for patients in molecular screening tests as it increases the screening rates and improves timely CRC diagnosis.

Keywords

• colorectal cancer (crc)
• tp53 gene
• mutation
• tumor
• stool