Fig. 1: Basal-like cells form the invasive front in a subset of IDC patients and in MMTV-PyMT model in vitro and in vivo.
From: A YAP-centered mechanotransduction loop drives collective breast cancer cell invasion
a In vitro and in vivo model based on MMTV-PyMT organoids cultured in 3D basement membrane extract (BME). After isolation from BME cultures, organoids were either embedded in 3D Collagen I or injected as cell suspension into the mammary fat pad of mice. b, c Confocal imaging of K8 and K14 in MMTV-PyMT organoids (b) grown in 3D Collagen I for 5 days or (c) in mammary fat pad for 13 weeks. b, c Representative images from three independent experiments. b, c White arrowheads: K14 positive cells located at the tumor-ECM interface and leading edges of the tumors; red arrowheads K14 positive cells lining mammary ducts. d Mean gray values of K14 and K8 in the K14 positive cells lining the mammary ducts (myoepithelial cells) and at the invasive tumor margins (basal-like cells). Red line median from 10 cells per cell type from one confocal slice from 1 experiment. e Summary of K14 expression in IDC. f–h Representative K8/K18 and K14 immunohistochemistry in serial tissue (whole) sections from IDC samples with zoom in on the cancer cell groups collectively invading the surrounding breast tissue. The invasive cancer cell groups showed (f) absence of K14 expression (12/19 IDC patients) (g) K14 expression throughout the invasive patterns (3/7 IDC patients) and (h) exclusive K14 expression in the cells located at the ECM-interface (4/7 IDC patients). Insets, K8/18 positive cells. Black arrowheads: K14 positive cells in the multicellular invasive cancer cell groups. Asterisk: K14 negative cells at the tumor-ECM interface. Scale bars: 250 (f–h), 100 μm (c), 50 μm (b; f–h, Zoom in), 10 μm (f–h, inset). Source data are provided as a Source Data file.
