Figure 3. Reciprocal regulation of HIF-2α and ERα.

ERα was knocked down in MCF-7 cells using siERα (A and C) or shERα (B) and then treated with 10 nM E2 under normoxic or hypoxic conditions. mRNA and protein levels were subsequently determined by RT-qPCR (A and B) and immunoblotting (C, upper panel), respectively. Shown are mean mRNA (A and B) and protein (C, lower panel) values ± SEM of three independent experiments. For statistical evaluation, the effects of ERα silencing were compared with siCtrl cells; the effects of E2 treatment were compared with ethanol solvent control (Ctrl) treatment. n.s., not significant; *P<0.05; **P<0.01. D. Microarray data from public databases were compiled using the R2 genomic analysis tool. Significance of the negative correlation between HIF-2α (red dots) and ERα (blue squares) mRNA levels was assessed by one-way ANOVA.