The Chorioallantoic Membrane (CAM) Assay for the Analysis of Starvation-Induced Autophagy

During avian development, the chorioallantoic membrane (CAM) is generated around 4 days after fertilization following the fusion of the allantois and the chorion. The CAM develops rapidly over the next several days and gets heavily vascularized and therefore has been explored widely as a tool for the study of angiogenesis. Additionally, being immunodeficient, the CAM can be used for tumor growth of human origin and its metastasis. Of note, the CAM assay is minimally invasive for the chicken embryo and lacks innervation, which gives this in vivo model a low ethical burden. Here, we describe the protocol for the generation of microtumors from human colorectal cancer cell lines on the CAM, incubated in a nutrient-deficient medium for the activation of autophagy. We show that pre-inoculation markers of autophagy induced through nutrient deficiency are retained in the microtumors generated on the CAM.