DNA methylation of SFRP1, SFRP2, and WIF1 and prognosis of postoperative colorectal cancer patients

Background As biomarkers, DNA methylation is used to detect colorectal cancer (CRC) and make assessment of CRC prognosis. The published findings showed the association between the methylation of SFRP1, SFRP2, and WIF1, located in the Wnt signaling pathway, and the prognosis of CRC were not consistent. Our study aimed to explore the potential possibility of SFRP1, SFRP2, and WIF1 concomitant promoter methylation as prognostic biomarkers of postoperative CRC patients. Methods As a total of 307 sporadic postoperative CRC patients were followed up, we detected SFRP1, SFRP2, and WIF1 methylation obtained from tumor tissues and adjacent non-tumor tissues respectively on the basis of methylation-sensitive high resolution melting analysis. Univariate and multivariate Cox regressions were carried out so as to assess the potential possibility of SFRP1, SFRP2, and WIF1 promoter methylation as predictors of prognosis. Confounders in our study were controlled by Propensity Score (PS) analysis. Results The SFRP1, SFRP2, and WIF1 methylation levels in tumor tissues were significantly higher than that in adjacent non-tumor tissues (P < 0.001). SFRP2 hypermethylation was significantly associated with a favorable clinical outcome at the hazard ratio (HR) of 0.343 [95% confidence intervals (CI): 0.164-0.718, P = 0.005] and 0.410 (95% CI: 0.200-0.842, P = 0.015) in multivariate Cox regression and PS analysis, respectively. Co-hypermethylation of SFRP1 and SFRP2 was significantly associated with a favorable clinical outcome at the HR of 0.333 (95% CI: 0.159-0.694, P = 0.003) and 0.398 (95% CI: 0.192-0.821, P = 0.013) in multivariate Cox regression and PS analysis, respectively. Co-hypermethylation of SFRP1, SFRP2 and WIF1 was significantly associated with a favorable clinical outcome at the HR of 0.326 (95% CI: 0.117-0.908, P = 0.032) and 0.401 (95% CI: 0.146-1.106, P = 0.077) in multivariate Cox regression and PS analysis, respectively. Conclusions SFRP1, SFRP2, and WIF1 were frequently hypermethylated in CRC tumor tissues. It was apparent that the promoter hypermethylation of SFRP2 and co-hypermethylation of SFRP1 and SFRP2 might be considered as independent prognostic predictors for survival advantage of postoperative CRC patients.