Fig. 4

Overexpression of human epidermal growth factor receptor 2 (HER2) in the luminal compartment of a bilayer model results in destabilisation of the bilayer and luminal filling. a HER2 expression in luminal cells infected with inducible HER2 lentiviral particles and cultured in 0.01, 0.1 or 1 μg/ml doxycycline (DOX) for 48 h. b Representative z-sections of 4′,6-diamidino-2-phenylindole (DAPI)-labelled nuclei (upper panels) and HER2 expression (lower panels) of ductal spheroids following 14 days of culture plus 7 further days with (middle panel) or without (left panel) 1 μg/ml DOX treatment. Alternatively, DOX-treated cultures were also treated with 10 μg/ml trastuzumab for the final 7 days of culture (right panel). Scale bar = 20 μm. c Quantification of spheroids following treatment presented as ratio of total cell volume to total sphere volume. d HER2 and vimentin expression in representative HER2-expressing ductal spheroids and ductal carcinoma in situ breast sections. Cell nuclei are labelled with DAPI (blue). Scale bar = 20 μm. Data are presented as mean ± SD. Images are representative of structures formed from cells derived from at least three donors. ** P < 0.01