Inhibition of protein–protein interaction of HER2–EGFR and HER2–HER3 by a rationally designed peptidomimetic

Abstract

Protein–protein interactions (PPI) play a crucial role in many biological processes and modulation of PPI using small molecules to target hot spots has therapeutic value. As a model system we will use PPI of human epidermal growth factor receptors (EGFRs). Among the four EGFRs, EGFR–HER2 and HER2–HER3 are well known in cancer. We have designed a small molecule that is targeted to modulate HER2-mediated signaling. Our approach is novel because the small molecule designed disrupts dimerization not only of EGFR–HER2, but also of HER2–HER3. In the present study we have shown, using surface plasmon resonance analysis, that a peptidomimetic, compound 5, binds specifically to HER2 protein extracellular domain and disrupts the dimerization of EGFRs. To evaluate the effect of compound 5 on HER2 signaling in vitro, Western blot and PathHunter assays were used. Results indicated that compound 5 inhibits the phosphorylation of HER2 kinase domain and inhibits the heterodimerization in a dose-dependent manner. Molecular modeling methods were used to model the PPI of HER2–HER3 heterodimer.

Keywords:

• EGFR
• HER2
• peptidomimetic
• homology modeling
• surface plasmon resonance
• protein–protein interactions
• PathHunter assay

Acknowledgments

The project described was supported by the National Center for Research Resources (5P20RR016456-11) and the National Institute of General Medical Sciences (8 P20GM103424-11) from the National Institutes of Health. Banappagari was supported by LBRN summer research program to conduct SPR analaysis presented in this manuscript. SPR was performed in the Molecular Interaction Core of the Louisiana Vaccine Center, supported by the LA Board of Regents Post-Katrina Support Fund. Herceptin was purchased at the pharmacy of Children’s Hospital, New Orleans. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health.