Receptor tyrosine kinases (RTKs) drive development and progression of many types of cancer. The archetypic member of the RTK family, epidermal growth factor receptor (EGFR), is overexpressed or mutated in bladder, brain, intestinal, colon, ovarian, lung and head-and-neck cancer. EGFR has become the major prognostic marker and therapeutic target in cancer. However, despite the success of EGFR targeted therapy in a subset of cancers expressing constitutively-active mutants of EGFR, EGFR inhibitors have not been effective in cancers expressing wild-type EGFR. This is attributable in large part to insufficient mechanistic understanding of the regulation of oncogenic signaling networks involving EGFR in tumors in vivo. The long-term objective of our research is to elucidate regulatory mechanisms of EGFR signaling and subsequently contribute to addressing the important clinical question of how to improve EGFR targeted therapy. We propose to accomplish this goal by defining the mechanisms by which EGFR signaling is regulated by endocytosis focusing on EGFR overexpressing head-and- neck squamous cell carcinoma (HNSCC) as the main experimental model.
Our research aims at testing two broad hypotheses: 1) dysregulation of EGFR endocytosis is critical to cancer cell growth, survival and motility; and 2) endocytic system can be explored to develop new predictive/prognostic markers and identify new cancer therapeutic targets. Our studies in cultured cells during last years established working models of key stages of EGFR endocytic trafficking in vitro. We have also developed approaches to analyze EGFR activities and endocytosis in vivo in mouse tumor xenografts. Our analysis of the EGFR-dependent phosphoproteome using time-resolved multiplexed mass-spectrometry identified new putative signaling pathways initiated by EGFR in endosomes. We are now in a unique position to 1) elucidate the mechanisms of endocytic trafficking of EGFR in vivo in EGFR-dependent tumor models; 2) define the major signaling pathways involved in growth and motility of cancer cells that are triggered by endosomal EGFR; 3) decipher the complex effects of dysregulated EGFR endocytic trafficking on tumorigenic processes in mouse tumor models; and 4) test the hypothesis that slow EGFR endocytosis correlates with the sensitivity of human HNSCC to the therapeutic EGFR antibody, cetuximab. The proposed studies will untangle the multi- faceted regulatory mechanisms underlying the impact of dysregulated EGFR endocytic trafficking on signaling processes in tumor cells in vitro and in vivo, and develop strategies for using the components of the EGFR/RTK endocytic machinery as prognostic markers and therapeutic targets in cancer.

Public Health Relevance

Epidermal growth factor receptor (EGFR) is involved in the development and progression of many types of cancers. Dysregulated endocytosis of EGFR is observed in cancer cells, and the pharmaceutical intervention with the ability of tumor cells to dysregulate EGFR endocytosis may constitute a novel paradigm for cancer therapy.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Molecular Oncogenesis Study Section (MONC)
Program Officer
Salnikow, Konstantin
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pittsburgh
Anatomy/Cell Biology
Schools of Medicine
United States
Zip Code
Martínez-Mármol, Ramón; Styrczewska, Katarzyna; Pérez-Verdaguer, Mireia et al. (2017) Ubiquitination mediates Kv1.3 endocytosis as a mechanism for protein kinase C-dependent modulation. Sci Rep 7:42395
Pinilla-Macua, Itziar; Grassart, Alexandre; Duvvuri, Umamaheswar et al. (2017) EGF receptor signaling, phosphorylation, ubiquitylation and endocytosis in tumors in vivo. Elife 6:
Martínez-Mármol, Ramón; Comes, Núria; Styrczewska, Katarzyna et al. (2016) Unconventional EGF-induced ERK1/2-mediated Kv1.3 endocytosis. Cell Mol Life Sci 73:1515-28
Pinilla-Macua, Itziar; Watkins, Simon C; Sorkin, Alexander (2016) Endocytosis separates EGF receptors from endogenous fluorescently labeled HRas and diminishes receptor signaling to MAP kinases in endosomes. Proc Natl Acad Sci U S A 113:2122-7
Pinilla-Macua, Itziar; Sorkin, Alexander (2015) Methods to study endocytic trafficking of the EGF receptor. Methods Cell Biol 130:347-67
Tomas, Alejandra; Vaughan, Simon O; Burgoyne, Thomas et al. (2015) WASH and Tsg101/ALIX-dependent diversion of stress-internalized EGFR from the canonical endocytic pathway. Nat Commun 6:7324
Nagashima, Takeshi; Inoue, Norihiko; Yumoto, Noriko et al. (2015) Feedforward regulation of mRNA stability by prolonged extracellular signal-regulated kinase activity. FEBS J 282:613-29
Fortian, Arola; Dionne, Lai K; Hong, Sun H et al. (2015) Endocytosis of Ubiquitylation-Deficient EGFR Mutants via Clathrin-Coated Pits is Mediated by Ubiquitylation. Traffic 16:1137-54
Schmid, Sandra L; Sorkin, Alexander; Zerial, Marino (2014) Endocytosis: Past, present, and future. Cold Spring Harb Perspect Biol 6:a022509
Fortian, Arola; Sorkin, Alexander (2014) Live-cell fluorescence imaging reveals high stoichiometry of Grb2 binding to the EGF receptor sustained during endocytosis. J Cell Sci 127:432-44

Showing the most recent 10 out of 30 publications