Fig. 5

MMP-8 expression in myoepithelial cells alters tumour cell invasion in 3D organotypics. a 3D organotypic microenvironment of the breast was created by mixing collagen and Matrigel with normal breast fibroblasts. β6-1089 cells transfected with empty vector (EMPTY) wild-type matrix metalloproteinase-8 (MMP-8 WT) or inactive mutant MMP-8 (EA) were plated on top of the gel and allowed to attach, then MDA-MB-231 cells were plated on top of the transfected β6-1089 cells. Organotypics were grown at an air/liquid interface for 10 days then fixed and embedded in paraffin. Section were taken and stained with H&E and images were taken for analysis. b An invasion index was determined for each condition by multiplying; the average depth of invasion (from multiple points in each section), the number of invading aggregates and the size of the aggregates. MDA-MB-231 cells grown with β6-1089 transfected with WT exhibited a significantly reduced invasion index relative to the β6-1089 transfected with EMPTY and EA. c Organotypic sections were stained for Ki67 and the positively staining cells were quantified to determine the level of proliferation in each condition. There was no difference observed between any of the groups. ^*** p = 0.001 (Student’s t test). Error bars = SEM, n = 3 independent experiments