Association of CDH1 haplotypes with susceptibility to sporadic diffuse gastric cancer Bostjan Humar 1 , Francesco Graziano 2 , Stefano Cascinu 3 , Vincenzo Catalano 4 , Anna M Ruzzo 5 , Mauro Magnani 5 , Tumi Toro 1 , Tudor Burchill 1 , Matthias E Futschik 6 , Tony Merriman 7 and Parry Guilford* ,1 1 Cancer Genetics Laboratory, University of Otago, Dunedin, Aotearoa, New Zealand; 2 Division of Medical Oncology, Hospital of Urbino, 61029 Urbino, Italy; 3 Medical Oncology, Hospital of Parma, 43100 Parma, Italy; 4 Medical Oncology, Hospital of Pesaro, 61100 Pesaro, Italy; 5 G Fornaini Institute of Biochemistry and Molecular Biology, University of Urbino, 61029 Urbino, Italy; 6 Knowledge Engineering Laboratory, University of Otago, Dunedin, Aotearoa, New Zealand; 7 Biochemistry Department, University of Otago, Dunedin, Aotearoa, New Zealand Truncating mutations in the gene for the cell to cell adhesion protein E-cadherin are the most consistent genetic alterations observed in sporadic and hereditary diffuse gastric cancer (DGC). In addition to these inactivating mutations, a CDH1 promoter polymorphism at position 7160 has been reported to lead to transcriptional downregulation of the gene in vitro. We therefore performed a case – control study to investigate whether this variant is associated with an increased susceptibility to DGC. The frequency of the 7160A allele was significantly higher (P50.005) in 53 diffuse gastric cancer cases compared to 70 matched controls. The odds ratio associated with the A-allele was 2.27 for CA-heterozygotes (95%CI 1.16 – 4.44) and 7.84 for AA- homozygotes (95%CI 2.89 – 21.24). Two additional polymorphisms (the 48+6T?C and the 2076C?T variant) were genotyped and shown to be equally distributed among cases and controls. Haplotype analysis with the three polymorphisms confirmed an association with disease (P50.004). However, this analysis suggested the 7160C?A CDH1 promoter polymorph- ism may be in linkage disequilibrium with a distinct aetiological locus or acts in combination with other functional variants in or near the CDH1 region. Oncogene (2002) 21, 8192 – 8195. doi:10.1038/sj.onc. 1205921 Keywords: diffuse gastric cancer; E-cadherin; CDH1; polymorphism; genetics Introduction Over recent decades a steady decline in the incidence of gastric cancer has been observed. Nevertheless, gastric cancer remains a major health concern due to the high mortality and poor prognosis for this disease (Dunbier and Guilford, 2001; Howson et al., 1986). Gastric cancer is usually divided into two predominant histological forms, the intestinal and the diffuse type (Lauren, 1965). Intestinal gastric cancer is strongly associated with older age groups and its incidence appears to parallel the worldwide decrease in gastric cancer. The diffuse form is more prevalent in younger age groups and more likely to show familial clustering. Limited data suggests the incidence of diffuse gastric cancer (DGC) to be stable (Borch et al., 2000; Lauren and Nevalainen, 1993). The E-cadherin gene (CDH1, OMIM 192090) encodes a homophilic transmembrane cellular adhesion protein that is expressed in epithelial tissues and found to be mutated in about 50% of sporadic DGCs (Berx et al., 1998). Significant familial clustering of the malignancy is attributable to truncating germline mutations in CDH1 (Guilford et al., 1998) and underscores the central role of the gene as a tumour suppressor in DGC. Several polymorphic variants of CDH1 exist in the population (Berx et al., 1998), albeit without any apparent biological consequences. Recently, Li et al. (2000) characterized a C to A polymorphism located 160 bp upstream from the CDH1 transcription start site and found the A-allele to have reduced transcriptional factor binding strength and only 32% of the transcriptional activity of the C- allele in vitro. The 7160C?A CDH1 promoter variant may thus reduce CDH1 expression in vivo and be regarded as a candidate low-penetrance cancer suscept- ibility polymorphism. However, recent epidemiological studies failed to demonstrate a correlation between the promoter CDH1 variant and breast (Lei et al., 2002) or colorectal cancer (Porter et al., 2002). Moreover, the A-allele was suggested to be protective against gastric cancer (Wu et al., 2002). The study described here is aimed at clarifying the role of the 7160C?A CDH1 promoter polymorphism in DGC susceptibility. In order to investigate whether the 7160C?A CDH1 promoter polymorphism (Table 1) may confer an increased risk to DGC, its frequency was Received 9 May 2002; revised 30 July 2002; accepted 31 July 2002 *Correspondence: P Guilford, Cancer Genetics Laboratory, Depart- ment of Biochemistry, PO Box 56, Dunedin, Aotearoa, New Zealand; E-mail: parry.guilford@otago.ac.nz Oncogene (2002) 21, 8192 – 8195 ª 2002 Nature Publishing Group All rights reserved 0950 – 9232/02 $25.00 www.nature.com/onc