Systematic Identification of Oncogenic EGFR Interaction Partners

- A combined screening approach involving an image-based green fluorescent protein-Grb2 translocation assay and a mammalian membrane two-hybrid protein-protein interaction assay identified 11 novel interactors of EGFR.
- Eight of those were further confirmed by co-immunoprecipitation.
- TACC3 was identified as a novel EGFR interactor, which specifically binds to oncogenic EGFR variants.
- TACC3 directly modulates EGFR stability at the cell surface and hence promotes mitogen-activated protein kinase signaling.
- Targeting TACC3 in non-small cell lung cancer cells partially resensitizes TK-resistant cells to TK inhibitors.

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase (TK) that-once activated upon ligand binding-leads to receptor dimerization, recruitment of protein complexes, and activation of multiple signaling cascades. The EGFR is frequently overexpressed or mutated in various cancers leading to aberrant signaling and tumor growth. Hence, identification of interaction partners that bind to mutated EGFR can help identify novel targets for drug discovery.Here, we used a systematic approach to identify novel proteins that are involved in cancerous EGFR signaling. Using a combination of high-content imaging and a mammalian membrane two-hybrid protein-protein interaction method, we identified eight novel interaction partners of EGFR, of which half strongly interacted with oncogenic, hyperactive EGFR variants. One of these, transforming acidic coiled-coil proteins (TACC) 3, stabilizes EGFR on the cell surface, which results in an increase in downstream signaling via the mitogen-activated protein kinase and AKT pathway. Depletion of TACC3 from cells using small hairpin RNA (shRNA) knockdown or small-molecule targeting reduced mitogenic signaling in non-small cell lung cancer cell lines, suggesting that targeting TACC3 has potential as a new therapeutic approach for non-small cell lung cancer.

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