Stapled EGFR peptide reduces inflammatory breast cancer and inhibits additional HER-driven models of cancer

Background: The human epidermal growth factor receptor (HER) family of transmembrane tyrosine kinases is overexpressed and correlates with poor prognosis and decreased survival in many cancers. The receptor family has been therapeutically targeted, yet tyrosine kinase inhibitors (TKIs) do not inhibit kinase-independent functions and antibody-based targeting does not affect internalized receptors. We have previously demonstrated that a peptide mimicking the internal juxtamembrane domain of HER1 (EGFR; EJ1) promotes the formation of non-functional HER dimers that inhibit kinase-dependent and kinase-independent functions of HER1 (ERBB1/EGFR), HER2 (ERBB2) and HER3 (ERBB3). Despite inducing rapid HER-dependent cell death in vitro, EJ1 peptides are rapidly cleared in vivo, limiting their efficacy. Method: To stabilize EJ1 activity, hydrocarbon staples (SAH) were added to the active peptide (SAH-EJ1), resulting in a 7.2-fold increase in efficacy and decreased in vivo clearance. Viability assays were performed across HER1 and HER2 expressing cell lines, therapeutic-resistant breast cancer cells, clinically relevant HER1-mutated lung cancer cells, and patient-derived glioblastoma cells, in all cases demonstrating improved efficacy over standard of care pan-HER therapeutics. Tumor burden studies were also performed in lung, glioblastoma, and inflammatory breast cancer mouse models, evaluating tumor growth and overall survival. Results: When injected into mouse models of basal-like and inflammatory breast cancers, EGFRvIII-driven glioblastoma, and lung adenocarcinoma with Erlotinib resistance, tumor growth is inhibited and overall survival is extended. Studies evaluating the toxicity of SAH-EJ1 also demonstrate a broad therapeutic window. Conclusions: Taken together, these data indicate that SAH-EJ1 may be an effective therapeutic for HER-driven cancers with the potential to eliminate triple negative inflammatory breast cancer.Arizona Cancer Therapeutics; Ginny L Clements Breast Cancer Research Fund; NIH [NIH 1R41CA203353]; NCI [P30 CA023074]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Wrong place at the wrong time: how retrograde trafficking drives cancer metastasis through receptor mislocalization

Retrograde trafficking is a well-regulated, multi-component pathway that can result in endosomal trafficking to the trans-Golgi network, the perinuclear space, or the nucleus. Either clathrin or the retromer complex can travel with proteins endocytosed from the plasma membrane, guided by Rabs (including 5, 6, 7, 9, 22A), interacting with a host of sorting nexin proteins, and fusing with Golgi-specific anchors to allow transport of activated receptor tyrosine kinases to a potential end within the nucleus. Amplification in these constituents is common in cancer, leading to increased retrotranslocation and a reduction in degradation of receptor tyrosine kinases, an event highly associated with cancer metastasis. Here, we review the role of retrograde trafficking in altering transmembrane receptor localization and activity and the relationship to metastasis, focusing on all four members of the ErbB family, with comparison to other receptor tyrosine kinases including the insulin receptor and fibroblast growth factor receptor, as well as other transmembrane proteins dysregulated in metastasis. By examining how these receptors are being alternatively trafficked and the cancer-associated events resulting from this process, we hope to identify novel therapeutic targets