Endotoxin Triggers Tumor Initiation Events in Nontumorigenic Breast Epithelial Cells and Enhances Invasion-Related Phenotype in Pretumorigenic and Tumorigenic Breast Epithelial Cells

Figure 5

Endotoxin disrupts lumen formation in 3D cultures of human breast epithelial S1 cells. Acini of (a) control untreated S1 cells (0 μg/ml) and (b) S1 cells subjected to long-term ET treatment at 10 μg/ml were stained with Hoechst (blue) on day 11 and scored for lumen formation. White arrows point at acini with normal monolayered lumen, while red arrows point at those with disrupted multilayered lumen. (c) Bar graph shows percentages of acini with undisrupted monolayered lumen in control untreated S1 cells and those subjected to short-term as well as long-term ET treatment at 10 μg/ml. One hundred acini were scored for each condition in every replicate. Each bar represents triplicate analyses of mean ± SD. compared to the untreated control. (d) Representative S1 acini immunostained for β-catenin (red) and counterstained with Hoechst (blue). The upper lane shows a control untreated S1 acinus with undisrupted monolayered lumen and apicolateral β-catenin localization. The middle lane shows an S1 acinus following short-term ET treatment at 10 μg/ml, and the lower lane shows an S1 acinus following long-term ET treatment at 10 μg/ml. Both short-term and long-term treatments reveal higher abundance of multilayered acini devoid of lumen, with relocalization of β-catenin across the entire cell membrane.

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