Abstract
AIM: To detect CDX2 gene methylation status and CDX2 protein expression in serrated lesions to explore their clinical significance and role in carcinogenesis.
METHODS: Taqman probe qPCR (MethyLight) was used to detect CDX2 gene CpG island methylation status in 225 cases of serrated lesions (including 96 cases of hyperplastic polyps, 61 cases of sessile serrated adenomas/polyps, and 68 cases of traditional serrated adenomas), 54 cases of tubular adenomas, 69 cases of colorectal cancer, and 42 cases of normal colorectal mucosa tissue. The amplified sequences were verified by direct sequencing. Immunohistochemistry was used to detect CDX2 protein expression in 116 cases of serrated lesions (including 52 cases of hyperplastic polyps, 41 cases of sessile serrated adenomas/polyps, and 23 cases of traditional serrated adenomas), 20 cases of tubular adenomas, 24 cases of colorectal cancer, and 24 cases of normal colorectal mucosa tissue.
RESULTS: The rates of CDX2 promoter methylation differed significantly between normal colorectal mucosa tissue and hyperplastic polyps (P = 0.019), sessile serrated adenomas/polyps (P = 0.015), and traditional serrated adenomas (P = 0.002), between colorectal cancer and hyperplastic polyps (P = 0.000), sessile serrated adenomas/polyps (P = 0.000) and traditional serrated adenomas (P = 0.000), and between tubular adenomas and traditional serrated adenomas (P = 0.027). The positive rates of CDX2 protein differed significantly between colorectal cancer and hyperplastic polyps (P = 0.001), between tubular adenomas and hyperplastic polyps (P = 0.005), and between hyperplastic polyps and traditional serrated adenomas (P = 0.038). The rate of CDX2 promoter methylation and CDX2 protein expression had weak negative correlations among hyperplastic polyps (P = 0.652, r = -0.064), sessile serrated adenomas/polyps (P = 0.238, r = -0.182) and traditional serrated adenomas (P = 0.519, r = -0.142). The rate of CDX2 gene promoter methylation was positively correlated with age in hyperplastic polyps (P = 0.002, r = 0.312), sessile serrated adenomas/polyps (P = 0.000, r = 0.473), traditional serrated adenomas (P = 0.001, r = 0.392), and tubular adenoma (P = 0.001, r = 0.440).
CONCLUSION: CDX2 upstream promoter methylation status is complicated, and CDX2 protein expression is little affected by CDX2 upstream promoter methylation in serrated lesions. The rate of CDX2 upstream promoter methylation in serrated lesions gradually increases as the age increases.
Collapse