Inhibiting Epidermal Growth Factor Receptor Dimerization and Signaling Through Targeted Delivery of a Juxtamembrane Domain Peptide Mimic

Abstract

Overexpression and deregulation of the epidermal growth factor receptor (EGFR) are implicated in multiple human cancers and therefore are a focus for the development of therapeutics. Current strategies aimed at inhibiting EGFR activity include monoclonal antibodies and tyrosine kinase inhibitors. However, activating mutations severely limit the efficacy of these therapeutics. There is thus a growing need for novel methods to inhibit EGFR. One promising approach involves blocking the association of the cytoplasmic juxtamembrane (JM) domain of EGFR, which has been shown to be essential for receptor dimerization and kinase function. Here, we aim to improve the selectivity and efficacy of an EGFR JM peptide mimic by utilizing the pH(low) insertion peptide (pHLIP), a unique molecule that can selectively target cancer cells solely based on their extracellular acidity. This delivery strategy potentially allows for more selective targeting to tumors than current methods and for anchoring the peptide mimic to the cytoplasmic leaflet of the plasma membrane, increasing its local concentration and thus efficacy. We show that the conjugated construct is capable of inhibiting EGFR phosphorylation and downstream signaling and of inducing concentration- and pH-dependent toxicity in cervical cancer cells. We envision that this approach could be expanded to the modulation of other single-span membrane receptors whose activity is mediated by JM domains.

EJP18 peptide derived from the juxtamembrane domain of epidermal growth factor receptor represents a novel membrane-active cell-penetrating peptide

“…It would be interesting to determine whether this shorter peptide influences the membrane spanning capacity of pHLIP or whether EJP18 could also be active in this way attached to pHLIP to give higher selectivity. While there were no links between EGFR expression and EJP18 induced toxicity, the peptide may be having some effects on receptor dimerisation and/or activation, similar to those seen with TE64562, T654, and pHLIP-JMA [17,41,42]. To interact with the EGFR JM domain, as initially predicted, would require crossing the plasma membrane to reach the target.…”

“…However, uptake was monitored after 16 h and it is very difficult to determine its subcellular localisation. More recently a peptide consisting of a pH-dependent membrane spanning sequence ( pHLIP) in frame with a very short EGFR JM sequence 654-TLRRLLQ-660 was shown to inhibit EGRF dimerisation, inhibit cell migration and induce cytotoxicity and downstream effects [42]. It would be interesting to determine whether this shorter peptide influences the membrane spanning capacity of pHLIP or whether EJP18 could also be active in this way attached to pHLIP to give higher selectivity.…”

The Molecular and Functional Characteristics of HLA-G and the Interaction with Its Receptors: Where to Intervene for Cancer Immunotherapy?

“…Almost all HLA-G isoforms are capable of forming dimers, thereby enhancing its inhibitory capacity. Various studies have shown that preventing dimerization can inhibit the function of proteins [ 109 , 110 , 111 ]. For example, Qi et al demonstrated that inhibiting dimerization of the oncoprotein survivin leads to degradation of the protein and apoptosis in cancer cells [ 111 ].…”

Mechanistic insights into differential requirement of receptor dimerization for oncogenic activation of mutant EGFR and its clinical perspective

“…However, most next generation drugs are also based on ATP-analogs and thus remain highly susceptible to developing inevitable resistance (56). Considering that dimerization of EGFR is a critical biological step required for its enzymatic activation, an ideal approach may be to take advantage of these features in developing novel EGFR-targeted drugs (57). Regarding this point, Mig6 segment 1-based peptides specifically targeting dimers can be considered as a novel potential drug particularly for dimerization-dependent mutant EGFR.…”