Exon 1 methylation status of CDH13 is associated with decreased overall survival and distant metastasis in patients with postoperative colorectal cancer.

Background: Cadherin 13 (CDH13) is a member of the cadherin superfamily that exerts tumor-suppressive effects on cancers derived from epithelial cells. Although hypermethylation of CDH13 promoter has been reported in various cancers, its prognostic value for colorectal cancer (CRC) is still controversial. The methylation alterations of CDH13 within exon 1 have not yet been investigated.

Methods: A total of 49 CRC patients were recruited for the prospective study. The methylation status of CpG sites was quantified by Bisulfite Amplicon Sequencing (BSAS) in malignant tissues and adjacent normal tissues. The primary endpoint of the study was overall survival (OS) after surgery. The relationship between methylation level with pathological stage and OS was also evaluated.

Results: Compared with adjacent normal tissues, the overall average methylation level within exon 1 was significantly increased in tumor tissues (p < 0.001). The association study showed that the hypermethylation status of the CpG1 site was non-significantly associated with the presence of distant metastasis (p = 0.032). Moreover, the hypermethylation of two CpG sites, including CpG1 (p = 0.003) and CpG5 (p = 0.032), was associated with worse OS in CRC. Co-hypermethylation of CpG1 and CpG5 sites was significantly associated with a worse clinical outcome (HR: 4.43 [95% CI 1.27-15.46]; p = 0.019) in multivariate Cox regression analysis.

Conclusion: The methylation level of CDH13 exon 1 in CRC tissue was significantly higher than in adjacent normal tissues. Hypermethylation at the CpG1 site suggests a risk of distant metastasis in CRC. The hypermethylation of the CpG1 site and CpG5 site, including the co-hypermethylation of these two sites, may serve as a valuable prognostic biomarker.