Fig. 3

IGF1R SNP can affect ER binding and result in higher gene expression. a Confirmation of ER binding to IGF1R SNP by ChIP-qPCR in MCF7 cell line. The cells were estrogen deprived for 3 days and subsequently treated by Veh or E2 (1nM) for 45 min. ChIP was performed as describes in the “Methods” section. ER binding is significantly enriched upon treatment by E2. b Allele-specific ChIP result shows a significant enrichment of SNP allele (70%) vs. WT allele (30%) in ER ChIP-binding site. c Luciferase transactivation assay using MCF7 cells transfected with constructs containing the ER ChIP-binding site with WT or SNP. The luciferase assay demonstrates that the binding site with variant allele has higher affinity to ER upon induction by estradiol (1 nM) (**p value < 0.01). d IGF1R gene expression in different breast cancer cell lines treated by Veh or E2 (1 nM). The significant induction of IGF1R expression in MCF7 cell line may contribute to the presence of regulatory SNP compared to the other cell lines with WT allele (*p value < 0.05)