PDF file - 482K, Supplemental Table 1 displays patients' characteristics of paraffin-embedded tumor tissue sections analyzed in Figure 6D; Supplemental Fig.1 demonstrates tumor-vascularization of CEA-mimotop immunized mice; Supplemental Fig.2 displays Matrigel-invasion as well as CaKi2-xenotransplant in vivo assays; Supplemental Fig.3 gives a description of the purity of CEA used in in vitro assays; Supplemental Fig4 reflects CEA-induced integrin activation and it's independency of VEGF; Supplemental Fig.5 gives a summary of CEAR expression as well as a potential CEA effect in different cell types; Supplemental Fig.6 displays consequences of CEACAM1 downregulation on CEA-induced intracellular signal transduction; a detailed description of the materials and methods used is given in the appendix of the Supplemental Information.
ARTICLE ABSTRACT
Carcinoembryonic antigen (CEA, CD66e, CEACAM-5) is a cell-surface–bound glycoprotein overexpressed and released by many solid tumors that has an autocrine function in cancer cell survival and differentiation. Soluble CEA released by tumors is present in the circulation of patients with cancer, where it is used as a marker for cancer progression, but whether this form of CEA exerts any effects in the tumor microenvironment is unknown. Here, we present evidence that soluble CEA is sufficient to induce proangiogenic endothelial cell behaviors, including adhesion, spreading, proliferation, and migration in vitro and tumor microvascularization in vivo. CEA-induced activation of endothelial cells was dependent on integrin β-3 signals that activate the focal-adhesion kinase and c-Src kinase and their downstream MAP–ERK kinase/extracellular signal regulated kinase and phosphoinositide 3-kinase/Akt effector pathways. Notably, while interference with VEGF signaling had no effect on CEA-induced endothelial cell activation, downregulation with the CEA receptor in endothelial cells attenuated CEA-induced signaling and tumor angiogenesis. Corroborating these results clinically, we found that tumor microvascularization was higher in patients with colorectal cancer exhibiting higher serum levels of soluble CEA. Together, our results elucidate a novel function for soluble CEA in tumor angiogenesis. Cancer Res; 73(22); 6584–96. ©2013 AACR.
