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

Figure 1

Short-term treatment with endotoxin induces MMP-9 activity in normal mouse (SCp2) and human (S1) mammary epithelial cells. Gelatin zymography of (a) SCp2 and (c) S1 conditioned media collected from untreated control cells (0 µg/ml) and ET-treated cells (0.1, 0.5, and 1 µg/ml for SCp2 cells; 2, 5, 10, 15, and 20 µg/ml for S1 cells) upon reaching 75% confluence after treatment showed dose-dependent upregulation of MMP-9 activity. No differences in the growth profile of ET-treated cells were noted, and all cultures reached 75–80% confluence within the same time frame. The abundant MMP-2 levels noted in the conditioned media of a SCp2 are comparable to basal levels in growth medium (GM). (b, d) Bar graphs represent the quantification of fold increase in peak area of MMP-9 bands shown in the respective zymograms. Each bar represents triplicate analyses of mean ± SD; compared to the untreated control.

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