Abnormal DNA Methylation in Colorectal Cancer Patients of Different Ethnicities

Colorectal cancer ranks as the third most common cancer worldwide. In Taiwan, both the incidence and mortality of colorectal cancer have shown a rapid increasing trend. The incidence rate has risen from 22.9 to 42.9 individuals per 100,000 population from 1995 to 2019. The mortality rate has also increased from 13.3 to 14.6 individuals per 100,000 population. According to statistics, early detection and proper treatment of colorectal cancer can result in a 5-year survival rate of over 90%. This study aimed to detect early occurrence of colorectal cancer through DNA methylation analysis, which could help identify microenvironmental changes during cancer formation processes. By comparing DNA methylation data from 314 colorectal cancer patients and 38 normal tissue samples from the TCGA dataset, as well as the clinical colorectal cancer samples clustered into three different ethnic groups, we performed cross-comparison analyses to identify common methylated genes with significant abnormal methylation patterns among different ethnicities, while excluding ethnicity-specific methylation biomarkers. We obtained a set of 79 associated genes exhibiting significant abnormal methylation among different ethnic groups. Lastly, gene functional annotation analysis was conducted to select representative genes involved within multiple biological processes, cellular components, and molecular functions. The methylation biomarkers of TWIST1, GPC6, NR5A2, FLI1, and IRF4 were identified as biomarkers due to associating with various genetic functions. Through a thorough review of existing literature, we gained a deeper understanding of the relationship between these genes and the development of colorectal cancer. The findings of this study contribute to the identification of methylation biomarkers that can be detected for colorectal cancer for different ethnic groups, providing valuable insights for future development of methylation- based screening toolkits for colorectal cancers in different racial groups.