Protein drug target activation homogeneity in the face of intra-tumor heterogeneity: implications for precision medicine

// Erika Maria Parasido 1,2 , Alessandra Silvestri 1 , Vincenzo Canzonieri 3 , Claudio Belluco 4 , Maria Grazia Diodoro 5 , Massimo Milione 6 , Flavia Melotti 6 , Ruggero De Maria 7 , Lance Liotta 1 , Emanuel F. Petricoin 1,* and Mariaelena Pierobon 1,* 1 Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA, USA 2 Department of Experimental Oncology, CRO-National Cancer Institute, Aviano, Italy 3 Department of Pathology, CRO-National Cancer Institute, Aviano, Italy 4 Department of Surgical Oncology, CRO-National Cancer Institute, Aviano, Italy 5 Department of Pathology, Istituto Nazionale Tumori Regina Elena, Roma, Italy 6 Department of Pathology, Fondazione IRCCS Istituto Nazionale Tumori, Milano, Italy 7 Department of Pathology, Sacred Heart Catholic University of Rome, Roma, Italy * These authors have contributed equally to this work Correspondence to: Mariaelena Pierobon, email: // Keywords : intra-tumor heterogeneity, personalized therapy, kinase signaling, laser capture microdissection, reverse phase protein microarray Received : August 16, 2016 Accepted : December 09, 2016 Published : December 15, 2016 Abstract Introduction: Recent studies indicated tumors may be comprised of heterogeneous molecular subtypes and incongruent molecular portraits may emerge if different areas of the tumor are sampled. This study explored the impact of intra-tumoral heterogeneity in terms of activation/phosphorylation of FDA approved drug targets and downstream kinase substrates. Material and methods: Two independent sets of liver metastases from colorectal cancer were used to evaluate protein kinase-driven signaling networks within different areas using laser capture microdissection and reverse phase protein array. Results: Unsupervised hierarchical clustering analysis indicated that the signaling architecture and activation of the MAPK and AKT-mTOR pathways were consistently maintained within different regions of the same biopsy. Intra-patient variability of the MAPK and AKT-mTOR pathway were <1.06 fold change, while inter-patients variability reached fold change values of 5.01. Conclusions: Protein pathway activation mapping of enriched tumor cells obtained from different regions of the same tumor indicated consistency and robustness independent of the region sampled. This suggests a dominant protein pathway network may be activated in a high percentage of the tumor cell population. Given the genomic intra-tumoral variability, our data suggest that protein/phosphoprotein signaling measurements should be integrated with genomic analysis for precision medicine based analysis.