Functional polymorphism rs7072793 C > T affect individual susceptibility to breast cancer by modulating CD25 transcription activity.

Substantial evidence has demonstrated immune defects in breast cancer patients. They have decreased numbers of peripheral blood lymphocytes, but higher numbers of functionally suppressive CD4(+) CD25(+) Treg in both peripheral blood and tumor microenvironment. Constitutive high expression of CD25 is a pivotal characteristic of natural Treg cells. This study aims at investigating if CD25 variability affects breast carcinogenesis. Two polymorphisms (rs7072793 C > T, rs3118470 C > T) in the promoter of CD25 were selected and analyzed by a multiple independent case-control study to assess the association between CD25 genotypes and breast cancer risk. Genotyping a total of 1110 patients and 1060 healthy controls in Chinese populations showed that rs7072793 CT genotype had an odd ratio of 1.49 (95% confidence interval, 1.23-1.89) for developing breast cancer compared with CC genotype, the rs7072793 TT carriers had a further increased risk of breast cancer (OR = 2.11; 95% CI = 1.66-2.87). Furthermore, our transient transfection which focused on reporter gene expression modulated by CD25 promoter demonstrated that the presence of an rs7072793 T allele led to greater transcriptional activity than the C allele. Similarly, rs13347 T carriers were shown to have larger proportion of CD4(+) CD25(+) Tregs in the PBMCs than C carriers in the flow cytometry analysis. However, no significant differences were found in genotype frequencies at rs3118470 C > T site between cases and controls. Our findings suggest that rs7072793 C > T genetic variation in CD25 genes may be genetic modifier for developing breast cancer.