Fig. 6: Yap promotes breast cancer invasion in vivo.

a Experimental strategy for injecting MMTV-PyMT organoids harboring dox-inducible Yap shRNA1 or shRNA2 in the 4th mammary fat pad. b Tumor volumes were monitored weekly using digital caliper in the context of doxycycline (dox)-containing or control food with the starting time of dox treatment (week 7 or 9) depending on tumor size. Values represent the average tumor volume with SD. 13 mice (2–13 weeks) per condition. c Representative hematoxylin and eosin (H&E) stainings of primary tumors from control and dox-treated mice. Dashed lines indicate the invasive front contours. e–g quantification of tumor invasion assessed by protrusive index (related to Supplementary Fig. S3a) in response to Yap knockdown (shRNA1 or shRNA2) and expression of YTIP. d, e Each value represents the average of (e, f) at least 2–4 regions of tumor borders (10× objective) per tumor from n = 12 (-Dox) and n = 10 (+Dox) for shRNA1 and n = 8 mice per condition for shRNA2 and g 1–3 regions (20x objective) per tumor from n = 10 mice per condition. P values, two-sided unpaired Mann–Whitney test. h Summary of K14 and nuclear Yap protein expression in IDC samples. i, j K14, and Yap immunostaining of (whole) section from a K14 positive IDC sample (Representative image n = 7 tissue sections). Zoom ins depict multicellular invasive cells with nuclear YAP distribution, particularly in the basal-like cells located at the interface with the breast tissue. j Percentage of cells with SD that have nuclear Yap that are located at the interface with the ECM and that are K14 positive. Data represent average percentage from 7 K14 positive IDC patients. Scale bars: 100 μm (c), 50 μm (d, i). Source data are provided as a Source Data file.