Abstract A033: Nuclear EGFR as a regulator of the tumor microenvironment

Abstract

Abstract Overexpression of the Epidermal Growth Factor Receptor (EGFR) is observed in all subtypes of breast cancer and is associated with large tumor size, poor differentiation, and poor clinical outcomes. However, the role of EGFR in driving the disease remains unclear, as EGFR-targeted antibodies and tyrosine kinase inhibitors fail to work effectively in breast cancer patients with EGFR overexpression. A possible explanation for therapeutic resistance is the role of intracellular EGFR, where retrograde trafficking of EGFR to the nucleus results in EGFR functioning directly as a transcriptional cofactor, regulating the expression of genes that promote tumor growth, metastasis, and an immune suppressive microenvironment. Our goal is to understand how targeting nuclear EGFR impacts this microenvironment. Using a novel therapeutic peptide (cSNX1.3) that targets retrograde trafficking of EGFR, we discovered that inhibiting retro-translocation of EGFR elicited an immune response as demonstrated by the secretion of inflammatory cytokines. Using RNA-Seq analysis, we detected an increase in the expression of cytokine receptors and natural killer (NK) cell ligands, such as RAET1 and AICL. We demonstrated that this active immune microenvironment is not observed when we treat with the EGFR kinase inhibitor Erlotinib, indicating a nuclear EGFR-specific outcome. Studies from tumor-bearing WAP-TGFα transgenic mice (an EGFR-dependent model of breast cancer) found the presence of NK cells and the expression of their activating ligands and receptors, IL-33 and SLAM7, respectively, in the tumor microenvironment. We hypothesize that nuclear EGFR is suppressing the expression of inflammatory cytokines, receptors, and ligands important for activation and recruitment of NK cells, thereby allowing immune evasion and ultimately progression of the disease. Future studies will investigate the potential to combine nuclear EGFR inhibitors with immunotherapies to activate the tumor immune microenvironment and promote optimal therapeutic efficacy. Citation Format: Angelica Escoto. Nuclear EGFR as a regulator of the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A033.