Hypermethylation of the promoter region of the E-cadherin gene (CDH1) in sporadic and ulcerative colitis associated colorectal cancer

Background-Ulcerative colitis associated colorectal cancer (UCACRC) has sev eral distinctive clinicopathological and genetic features which differ from sporadic colorectal cancer (SCRC). Hypermethylation of the E-cadherin gene (CDH1) has not been described previously in colorectal cancer, Aims-A panel of SCRC and UCACRC were investigated for mutations in CDH1, an d for hypermethylation of the promoter region of CDH1. Subjects and Methods-DNA was available from 14 patients with UCACRC and fro m 14 with SCRC. All exons of CDH1 were amplified with the polymerase chain reaction (PCR) and screened using single strand conformational polymorphism and direct sequencing. Hypermethylation of the CDH1 promoter region was de termined by methylation specific PCR following bisulphite modification, and compared with E-cadherin protein expression from a previous immunohistoche mistry study. Results-Thirteen of 28 cancers (46%) were hypermethylated in the CDH1 promo ter region-eight cancers (57%) in the UCACRC group and five cancers (36%) i n the SCRC group (NS)-and this correlated with reduced E-cadherin expressio n (p<0.05). There was a trend for methylation to be associated with a more advanced stage of cancer although this did not reach statistical significan ce. There were no mutations in CDH1 in either group although there were sev eral polymorphisms. Conclusion-We have demonstrated hypermethylation of the promoter region in CDH1 in 46% of colorectal cancers studied. There was no difference between the UCACRC and SCRC groups. Just as there are specific differences in the g enetic changes between UCACRC and SCRC, there is also likely to be a large degree of overlap among the genetic pathways of these cancers.