Systematic analysis of functional genetic and epigenetic variants in colorectal cancer

Abstract

Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide, yet the functional impact of noncoding variants on enhancer activity remains largely unexplored. In this study, we adapted and applied two high-throughput techniques, SNP-STARR-seq and Methyl-STARR-seq, to systematically evaluate the influence of 30,790 noncoding SNPs and more than 134,000 CpG sites on enhancer activity in primary and metastatic CRC cells. We identified 922 SNPs and 487 CpG-containing elements modulating enhancer activity in primary cells and found 3136 SNPs and 3008 methylation-sensitive elements with metastasis-specific regulatory effects. Multi-omics integration linked these variants to target genes, and CRISPR editing validated their roles in driving tumorigenic and metastatic phenotypes. Furthermore, we identified two CRC-specific hypermethylated loci, cg08640619 and cg25982657, as exceptional tissue-based early detection biomarkers (AUC?> 0.96). Mechanistically, hypermethylation at cg08640619 disrupts RUNX2 binding, leading to inhibition of KIRREL1 and ETV3. Our study provides a comprehensive platform for understanding how genetic and epigenetic variants disrupt transcriptional programs in CRC, offering insights into disease susceptibility and identifying potential diagnostic and therapeutic targets.