Figure 3

Cell proliferation assays of human cell lines. A-C). Effect of knockdown of retinoic acid receptor (RAR)γ on proliferation of human MCF-10A immortalized, non-tumorigenic mammary epithelial cells (A), MCF-7 breast cancer cells (B) and MDA-MB-231 breast cancer cells (C) using siRARγ. Cells transfected with scrambled siRNA were used as controls. Treatment of siRARγ-transfected cells with 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carboxamido]benzoic acid (Am580) (100 nM) in DMSO (0.01% final concentration) further reduced proliferation of MCF-10A and MCF-7 cells, which express RARα, but did not reduce that of the RARα-negative MDA-MB-231 cells. D) Relative to c-Myc expression in MCF-10A cells, that in MCF-7 and MDA-MB-231 cells was 38- and 55-fold higher, respectively, according to quantitative PCR. Results shown are representative of two independent experiments.