Development of an Epidermal Growth Factor Derivative with EGFR Blocking Activity

Clara Panosa,Masaharu Seno,Francesc Tebar,Anna Massaguer,Rafael De Llorens,Montserrat Ferrer-Batallé,Raymond M Reilly,Humphrey Fonge,Karl X Chai

doi:10.1371/journal.pone.0069325

Abstract

The members of the epidermal growth factor (EGF)/ErbB family are prime targets for cancer therapy. However, the therapeutic efficiency of the existing anti-ErbB agents is limited. Thus, identifying new molecules that inactivate the ErbB receptors through novel strategies is an important goal on cancer research. In this study we have developed a shorter form of human EGF (EGFt) with a truncated C-terminal as a novel EGFR inhibitor. EGFt was designed based on the superimposition of the three-dimensional structures of EGF and the Potato Carboxypeptidase Inhibitor (PCI), an EGFR blocker previously described by our group. The peptide was produced in E. coli with a high yield of the correctly folded peptide. EGFt showed specificity and high affinity for EGFR but induced poor EGFR homodimerization and phosphorylation. Interestingly, EGFt promoted EGFR internalization and translocation to the cell nucleus although it did not stimulate the cell growth. In addition, EGFt competed with EGFR native ligands, inhibiting the proliferation of cancer cells. These data indicate that EGFt may be a potential EGFR blocker for cancer therapy. In addition, the lack of EGFR-mediated growth-stimulatory activity makes EGFt an excellent delivery agent to target toxins to tumours over-expressing EGFR.

Highlights

The cells of multi-cellular organisms need a constant communication with the environment to maintain their homeostasis, to survive, to differentiate, and to proliferate
Wild type Human EGF (hEGF) was produced in parallel to EGF peptide (EGFt) in order to obtain a positive control for the experiments and for future applications
The encoding sequences of hEGF and EGFt were cloned into a periplasmic secretion system that contains the OmpA (Outer membrane protein A) signal sequence [23] in order to obtain the peptides in the supernatant of the cell culture

Summary

Introduction

The cells of multi-cellular organisms need a constant communication with the environment to maintain their homeostasis, to survive, to differentiate, and to proliferate. One of the most important communication systems is represented by the Polypeptide Growth Factors that include eight families. The Epidermal Polypeptide Growth Factor (EGF)/ErbB family represents a very important – essential – family of growth factors governing a multitude of cellular events. The prominent role of the ErbB family in the development and surviving of cancer cells was described in the 1980’s, when Sporn and Todaro established the theory of the ‘‘autocrine secretion’’ of growth factors by cancer cells to maintain a high rate of proliferation [2]. In many types of cancer the overexpression of ErbB receptors and enhanced ligand production allow an autocrine stimulation of the cell proliferation. We would like to suggest that ‘‘it is time to turn again our attention to the role played by the ligands’’, the receptors, to design new therapeutic strategies against cancer

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