Hypermethylated GRIA4 , a potential biomarker for an early non-invasive detection of metastasis of clinically known colorectal cancer

Colorectal cancer (CRC) can develop through several dysregulated molecular pathways, including the serrated pathway, characterized by CpG island methylator (CIMP) phenotype. Although the tumor tissue is a commonly tested material, sample types such as stool or plasma, bring a new, non-invasive approach. Several cancer-related methylated genes have been identified in CRC patients, including gene , showing promising diagnostic potential. The aim of our study was to develop a sensitive droplet digital PCR (ddPCR) assay to examine hypermethylation status in CRC patients and evaluate its diagnostic potential in tissue and liquid biopsy samples. In total, 23 patients participated in this study, 7 patients with primary CRC and 16 patients with liver metastasis of clinically known CRC. We obtained tumor and non-tumor tissues (N=17), blood samples pre- and post-surgery (N=22), and blood of five volunteers without a personal cancer history. We have developed and optimized a ddPCR assay for hypermethylation detection, from tissue and plasma samples. We detected significantly increased methylation in tumor tissues compared to their adjacent non-tumor tissue, p