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. 2011 Dec 22;6(12):e29466. doi: 10.1371/journal.pone.0029466

Figure 2. E2-induced Noxa transcription is ERα-dependent and p53-independent.

Figure 2

(A) MCF7 cells were treated with vehicle (veh), 10 nM E2 alone, 10 nM E2 in combination with 1 µM tamoxifen (Tam), or 10 nM E2 in combination with 1 µM ICI 182780 (ICI) for various times. Four, 8, 16 and 24 hr after treatment, cells were harvested, and Noxa mRNA expression levels were analyzed by qPCR. (B, C, & D) MCF7 cells were transfected with non-silencing control (NS), ERα, or p53 siRNA for 24 hr, followed by treatment with vehicle (veh) or E2 (10 nM) for 8 hr, and then harvested for analyses of ERα, p53, and β-actin (internal control) protein expression by western blotting (B), Noxa mRNA expression by qPCR (C), and pS2 mRNA expression by qPCR (D). (E) MCF7 cells were treated with vehicle (veh), E2 (10 nM), doxorubicin (DOX; 1.70 µM), adozelesin (ADO; 4 nM), or left without treatment (NT) for 16 hr. Occupancy of p53 on the proximal region of the NOXA promoter was determined by ChIP assays, using anti-p53 antibody or normal mouse IgG (M IgG; control antibody) for immunoprecipitation. Graphical data points in A, C, and D are means ± S.D. of three independent experiments (*** P<0.001).