Effects of lentiviral knockdown of EpCAM on in vivo growth and invasion of EpCAM
breast cancer cell lines. (A) In vivo growth of MCF-7 breast cancer cell xenografts in the chicken chorioallantoic membrane model (CAM). Magnification 1x. (B) Xenografts form tumors (arrow) that can be monitored due to expression of GFP by stereo-fluorescence microscopy. Within six days of observation tumors grew inside the CAM and attracted and co-opted blood vessels. Magnification 20x. (C) Immunohistochemical analysis of tumor xenografts in the host tissue. Brown color indicates a positive reaction. All nuclei were counterstained with hematoxylin (blue). Proliferating tumor cells were stained for the nuclear antigen Ki67, mural cells of blood vessels (myofibroblasts) with alpha smooth muscle cell actin (ASMA) or pericytes (fibroblasts) with desmin. Knockdown of EpCAM (E#2) resulted in tumors with less invasion and proliferation in host tissue and in a reduction of stromal responses to the tumor. Yellow arrows indicate invading tumor cell clusters and yellow lines borders between xenograft and host tissue. (Magnification 200x). In vivo experiments were performed with at least 12 embryos per group and 4 onplants/CAM. Asterisks indicate blood vessels of the underlying CAM.