Quantifying epithelial-mesenchymal heterogeneity and EMT scoring in tumor samples via tyramide signal amplification...

Tumor heterogeneity presents an ongoing challenge to disease progression and treatment in many solid tumor types. Understanding the roots of intra-tumoral heterogeneity and how it may relate to the high incidence of metastasis is critical in overcoming disease relapse and chemoresistance. The epithelial-to-mesenchymal transition is a dynamic cellular program that is co-opted by cancer cells to enhance, among others, migratory and invasive cell traits. It is a key contributor to heterogeneity, chemo-resistance, and metastasis in many carcinoma-types, with the intermediate or hybrid EMT state playing a critical role due to its increased tumor-initiating potential. A critical component in utilizing this knowledge in patient treatment is to first detect and score the impact of EMT in a patient sample. Here, we provide a detailed protocol to detect EMT states and quantify the resulting epithelial-mesenchymal heterogeneity within tumors using a novel multiplexed immunostaining approach and analysis method. This protocol and concept can easily be adapted using custom panels of markers to explore other sources of tumoral heterogeneity in addition to EMT.