Figure 5

Functional examination of the two estrogen response element–associated single-nucleotide polymorphisms rs2839494 and rs1078272 in 21q22.3. (A) Activity in MCF-7 cells of the luciferase reporter gene, either alone (denoted as “No promoter”) or linked to the 21q22.3 region (that is, the segment shown in Figure 3B, bottom panel) to which estrogen receptor α (ERα) binds, and which contains the two estrogen response element (ERE)–associated single-nucleotide polymorphisms (SNPs) (denoted as “21q22.3”), in the presence or absence of estradiol (E2). (B) Decreased activity of the luciferase reporter gene in MCF-7 cells when linked to the 21q22.3 region harboring the variant allele (VT) of rs2839494 or rs1078272 compared to that containing both wild-type alleles (WT). The results shown in (A) and (B) are means ± standard deviations (n = 3). The P-values of differences between groups and the P-values for trends within groups were estimated by regression analysis. (C) Hypothetical model explaining the similar, but not identical, effects of the two ERE-associated SNPs at 21q22.3, showing that the variant allele of rs1078272 might block the binding of a coactivator to the 21q22.3 sequence (bottom panel), whereas the variant allele of rs2839494 might directly affect the binding of ERα (center panel), both decreasing reporter gene activity compared to the wild-type 21q22.3 sequence (top panel).