Objectives: Patients with ulcerative colitis (UC) are at increased risk for developing colorectal cancer (CRC). Surveillance in this at-risk population remains challenging. We assessed the methylation status of genes in the non-neoplastic mucosa of UC-CRC patients and controls to identify potential biomarkers of CRC.
Methods: We evaluated the methylation status of 10 genes (p16, p14, runt-related transcript factor-3 (RUNX3), cyclooxygenase-2 (COX-2), E-cadherin, methylated-in-tumor-1 (MINT1), MINT31, HPP1, estrogen receptor, SLC5A8) in UC-CRC tumors and non-neoplastic sections from both UC-CRC cases and UC controls (n=114 for each) using methylation-specific PCR.
Results: Amplification was successful for 96 UC controls, 83 tumors, and 66 non-adjacent, non-neoplastic samples. The prevalence of methylation was significantly greater in UC-CRC tumors for p16, RUNX3, MINT1, MINT31, and HPP1. Methylation of COX-2 and E-cadherin was greater in UC controls than in tumors. Univariate testing of these genes using non-adjacent, non-neoplastic sections from UC-CRC cases indicated that associations between p16, RUNX3, MINT1, MINT31, E-cadherin, and COX-2 and UC-CRC remained significant. In multivariable analysis of the six genes, only RUNX3, MINT1, and COX-2 remained significantly associated with the UC-CRC cases (odds ratio=12.6, 9.0, and 0.2, respectively). The results remained unaffected by the presence of PSC or severity of inflammation. Logistic regression modeling with the three genes showed interactions that increased the odds ratio for each gene.
Conclusions: RUNX3, MINT1, and COX-2 are potential biomarkers for detecting the presence of CRC in patients with UC. These genes should be evaluated as biomarkers for colorectal dysplasia.