Fig. 3.

OP-1074 inhibits proliferation and degrades ERα in breast cells. a, Inhibition of E2-stimulated transcription of an estrogen responsive reporter gene, ERE-tk109-Luc. Luciferase activity was assayed after treating MCF-7 cells with antiestrogens for 22 h in the presence of 100 pM E2. Shown are means + /− s.e.m. from triplicate wells of a representative experiment in which values were normalized to %E2. Dotted line represents basal activity in the absence of E2. b, c, Inhibition of E2-stimulated proliferation in breast cells. Breast cells were treated with antiestrogens in the presence of 100 pM E2 for 7 days (b, MCF-7 cells) or 8 days (c, CAMA-1 cells) and subsequently exposed to a fluorescent DNA-binding dye that approximates cell number. Shown is a representative figure analyzed and presented as above. d, Western blot of destabilization of ERα protein by OP-1074. MCF-7 and CAMA-1 cells were treated with 100 nM ligands for 24 h and lysates immunoblotted with antibody to ERα and β-actin