title: The functional IGFBP7 promoter -418G>A polymorphism and risk of head and neck cancer.
abstract: Insulin-like growth factor binding protein 7 (IGFBP7) functions mostly independent of the IGF signaling pathway and acts as a tumor suppressor in multiple cancers, but roles of IGFBP7 genetic variants in cancer remains unknown. In a hospital-based study of 1065 patients with squamous cell carcinoma of head and neck (SCCHN) and 1112 cancer-free controls of non-Hispanic whites, we investigated associations between two putatively functional IGFBP7 promoter single nucleotide polymorphisms (SNPs) (-702G>C, rs11573014 and -418G>A, rs4075349) and SCCHN risk. A significantly lower SCCHN risk was observed in those subjects carrying -418AG (adjusted OR=0.82, 95% CI=0.67-0.99) and -418AG+AA (adjusted OR=0.82, 95% CI=0.69-0.99) genotypes than those carrying the -418GG genotype, but not for the -702G>C SNP. However, those subjects carrying two common homozygous genotypes of these two SNPs (-418GG and -702GG) had an increased risk (adjusted OR=1.21, 95% CI=1.00-1.46) than did those carrying variant genotypes (-418AG+AA and -702CG+CC). This increased risk was more evident in subgroups of never smokers and subjects with oral cancer. Further functional analysis showed that the IGFBP7 -418A allele had significantly higher promoter and DNA-protein binding activities than did the G allele, suggesting a tumor suppressor role of this allelic change in the SCCHN etiology. We conclude that the functional variant -418G>C in the IGFBP7 promoter is associated with reduced risk of SCCHN, likely by enhancing the IGFBP7 promoter and DNA-protein binding activities. Larger studies are needed to validate our findings.
authors.affiliation: Department of Epidemiology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Yu-Jing
authors.initials: YJ
authors.lastname: Huang
authors.forename: Jiangong
authors.initials: J
authors.lastname: Niu
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Li-E
authors.initials: LE
authors.lastname: Wang
authors.forename: Erich M
authors.initials: EM
authors.lastname: Sturgis
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Wei
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006258:Head and Neck Neoplasms / Q000235:genetics; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D012306:Risk
chemical_list: D018969:Insulin-Like Growth Factor Binding Proteins; C102529:insulin-like growth factor binding protein-related protein 1