Figure 4.

Primary mammary epithelial cells in two- and three-dimensions express ERα. (A) Western blot analysis of ERα protein expression in mammary epithelial cells in two-dimensional culture after 3 and 6 days in culture with E₂ or vehicle. MCF7 human breast cancer cells and MCF10A human immortalized mammary epithelial cells were used as positive and negative controls for ERα protein expression, respectively. (B) qRT-PCR analysis of genes regulated by estrogens in two-dimensional culture following a 24 h treatment with E₂ or vehicle. (C) Western blot analysis of ERα protein expression in mammary organoids after 12 days in culture. MCF7 human breast cancer cells and MCF10A human immortalized mammary epithelial cells were used as positive and negative controls for ERα protein expression, respectively. (D) qRT-PCR analysis of genes regulated by estrogens in primary mammary gland organoids following 24 h or 10 d of treatment with E₂ or vehicle. For (B, D), results are shown as mean ± SEM of three independent experiments performed at least in duplicate. (E) Percentage of luminal, opaque, and lobular organoids over time, maintained in culture with and without E₂. Results are shown as the mean ± SEM of one out of three independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001. (F) Number of visible organoids treated with E₂ or vehicle. Results are shown as the mean ± SEM of two independent experiments performed in triplicate.