Contribution of cyclin d1 (CCND1) and E-cadherin (CDH1) polymorphisms to familial and sporadic colorectal cancer.
Porter TR., Richards FM., Houlston RS., Evans DGR., Jankowski JA., Macdonald F., Norbury G., Payne SJ., Fisher SA., Tomlinson I., Maher ER.
The molecular basis for most non-HNPCC familial colorectal cancer cases is unknown, but there is increasing evidence that common genetic variants may play a role. We investigated the contribution of polymorphisms in two genes implicated in the pathogenesis of colorectal cancer, cyclin D1 (CCND1) and E-cadherin (CDH1), to familial and sporadic forms of the disease. The CCND1 870A/G polymorphism is thought to affect the expression of CCND1 through mRNA splicing and has been reported to modify the penetrance of HNPCC. Inactivation of E-cadherin is common in colorectal cancer, and truncating germline mutations have been reported to confer susceptibility to colorectal as well as diffuse gastric cancer. The -160A/C CDH1 polymorphism appears to affect expression of CDH1 and may therefore also confer an increased risk. We found a significantly higher frequency of CCND1 870A allele in 206 familial cases compared to 171 controls (P=0.03). Odds ratios in heterozygotes and homozygotes were 1.7 (95% CI: 1.0-2.66) and 1.8 (95% CI: 1.0-3.3) respectively. The difference was accounted for by an over-representation of A allele in non-HNPCC familial cases (P=0.007). Over-representation of the CCND1 A allele was also seen in sporadic colorectal cancer cases compared to controls but this did not attain statistical significance (P=0.08). No significant differences between the frequency of CDH1 -160A/C genotypes in familial, sporadic colorectal cancer cases and controls were seen, although a possible association between the low expressing A allele and right-sided tumours was detected in familial cases.