Genetic variation in the genome-wide predicted estrogen response element-related sequences is associated with breast cancer development.

Introduction: Estrogen forms a complex with the estrogen receptor (ER) that binds to estrogen response elements (EREs) in the promoter region of estrogen-responsive genes, regulates their transcription, and consequently mediates physiological or tumorigenic effects. Thus, sequence variants in EREs have the potential to affect the estrogen-ER-ERE interaction. In this study, we examined the hypothesis that genetic variations of EREs are associated with breast cancer development.

Methods: This case-control study involved 815 patients of Asian descent with incident breast cancer and 821 healthy female controls. A total of 13,737 ERE sites in the whole genome predicted by a genome-wide computational algorithm were blasted with single-nucleotide polymorphism (SNP) sequences. Twenty-one SNPs located within 2,000 bp upstream or within introns 1 and 2 of putative genes and with a minor allele frequency greater than 5% were identified and genotyped. Frequencies of SNPs were compared between cases and controls to identify SNPs associated with cancer susceptibility.

Results: A significant combined effect of rs12539530, an ERE SNP in intron 2 of NRCAM which codes for a cell adhesion molecule, and SNPs of ESR1, the gene coding for ER, on breast cancer risk was found. Interestingly, this combined effect was more significant in women who had experienced a longer period of lifetime estrogen exposure, supporting a hormonal etiology of this SNP in breast tumorigenesis.

Conclusions: Our findings provide support for a role of genetic variation in ERE-ESR1 in determining susceptibility of breast cancer development.