Figure 1.

Human mammary epithelial cells from different stages in a malignant progression series exhibit unique growth characteristics in normal- and tumor-like microenvironments. Immunofluorescence staining of (A–D) normal and (E,F) invasive breast cancer tissue sections. ECM components; (A,B,E) COL4 (red), COL1 (green), (C,F) pan-laminin (LAM, green) and (D) LAM5 (green) in (A–D) normal mammary gland tissue and (E,F) invasive breast cancer, were stained with (A–F) nuclei marker Hoechst (blue), (C,E,F) epithelial cell marker (EPCAM) or with (D) myoepithelial cell marker (K14, red). (G) Diagram of the 184-progression series derivation. (H) Single cell suspensions of 184, 184A1, and 184AA3 cells were embedded in matrigel- and COL1-3D gels, after 12 days cells were fixed and stained with luminal cell marker (K19, green) and myoepithelial cell marker (K14, red). Images are representative of three individual experiments. (A,C–F,H) Bars represent 50 μm and (B) 5 μm. (I) Gene expression of microenvironment related genes (RT²Profiler™ PCR array, Human Epithelial to mesenchymal transition EMT, Qiagen) in 184A1 and 184AA3 cells cultured on matrigel (control = 1) or on COL1. Data represent mean ± SE, from two (184A1) or three (184AA3) individual experiments, statistical significance was calculated by using student T-test (^*p < 0.05, ^**p < 0.01).