Figure 1

Malignant stroma regulates proliferation of breast cancer cells in vitro . A. MCF-7, BT-474, MDA-MB-231 and BT-20 breast cancer cells growing as monocultures in 2D on plastic, were incubated with control media, or media conditioned (CM) by BJ3Z or NMF stromal-like cells. Proliferation of the breast cancer cells was quantified by immunocytochemistry (ICC) for percent BrdU incorporation (green nuclei) compared to total cells (DAPI; blue), n = 3. Breast cancer cells were counterstained by ICC for Cytokeratin-18 (CK18, red). Bar: 100 μm. B. The same breast cancer cell lines were cultured in 3D on Matrigel and grown as colonies in monoculture or co-culture with BJ3Z or NMF cells. Colonies were stained by immunohistochemistry (IHC). Proliferation was quantified by counting BrdU incorporation (green nuclei) compared to total cells (DAPI, blue). To visualize the breast cancer cells they were counterstained with markers previously determined to be appropriate for each: CK18 (red) for MCF-7 and BT-474; CD44 (red) for MDA-MB-231; CK5 (red) for BT-20, n = 3. Bar: 100 μm *p < 0,05 by ANOVA followed by Tukey’s post-test.