Figure 1.

Ectopic ZEB1 increases DNA methylation of the ER-α promoter. (a) An upstream CpG-rich region was located at position −4138/−3872 of the ER-α promoter, and two canonical E₂-box elements for ZEB1 binding were identified within. (b and c) Percentage of DNA methylation of the ER-α promoter was determined by bisulfite sequencing PCR (BSP) in ZEB1/MCF-7 versus Ctrl/MCF-7 cells (b) and in shZEB1/231 versus shCtrl/231 cells (c). (d and e) Basal methylation levels of the ER-α promoter were determined by methylation-specific PCR (MSP) in ZEB1/MCF-7 versus Ctrl/MCF-7 cells (d) and in ZEB1/ZR-75-1 versus Ctrl/ZR-75-1 cells (e). *P<0.05 versus the respective control in Student's t-test. (f and g) Basal methylation levels of the ER-α promoter were determined by MSP in shZEB1/231 versus shCtrl/231 cells (f) and in shZEB1/SUM-159 versus shCtrl/SUM-159 cells (g). *P<0.05 versus the respective control in Student's t-test