Abstract 1681: DUOX1 expression in lung cancer disrupts pro-oncogenic activation mechanisms and localization of Src and EGFR

Abstract

Abstract Non-small cell lung cancer (NSCLC) remains to be one of the leading causes of cancer-related mortalities worldwide. The NADPH oxidase homolog, Dual Oxidase 1 (DUOX1), is an H2O2 producing enzyme located in the airway epithelium with key roles in mucosal host defense and wound repair mechanisms. Recent studies indicate that DUOX1 is epigenetically silenced in many forms of NSCLC via hypermethylation of its promoter. We previously demonstrated that DUOX1 silencing in lung cancer cells is associated with epithelial-to-mesenchymal transition (EMT), a key feature of tumor invasiveness and metastasis, and that RNAi-mediated DUOX1 suppression can promote EMT, but the mechanism(s) by which DUOX1 silencing promotes these outcomes are not understood. Previous findings indicate that DUOX1-dependent epithelial host defense pathways are mediated by redox-dependent activation of epithelial signaling via the non-receptor tyrosine kinase, Src, and the receptor tyrosine kinase, EGFR. We therefore hypothesized that loss of DUOX1 in lung cancer may be associated with aberrant regulation of Src and/or EGFR, tyrosine kinases that are frequently overexpressed and activated in lung cancer and strongly contribute to tumor growth and survival. Furthermore, nuclear Src/EGFR localization and phosphorylation of EGFR-Y1101 in lung cancers was recently associated with metastatic cell behavior and poor clinical outcome. Preliminary findings in alveolar lung cancer A549 cells, which possesses some EMT-like features, indicate that DUOX1 overexpression redistributes Src localization to the plasma membrane and decreases its nuclear accumulation. Moreover, DUOX1 overexpression in A549 cells also suppressed EGF-stimulated EGFR internalization and nuclear translocation, in association with reduced EGFR phosphorylation on its Src target, Y1101. Conversely, RNAi-mediated silencing of DUOX1 in the epithelial cancer cell line H292 (which has retained DUOX1 expression) promoted EGF-mediated EGFR nuclear translocation and Y1101 phosphorylation. Further mechanistic studies will be performed to elucidate the molecular mechanisms by which DUOX1 is able to alter these events. Collectively, our findings indicate that DUOX1 silencing in lung cancer may contribute to EMT and/or tumor invasiveness by altering Src/EGFR localization and activation mechanisms. Citation Format: Andrew C. Little, Karamatullah Danyal, Robert A. Bauer, David E. Heppner, Milena Hristova, Christopher Dustin, Aida Habibovic, Albert van der Vliet. DUOX1 expression in lung cancer disrupts pro-oncogenic activation mechanisms and localization of Src and EGFR. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1681.