Abstract C15: Neutrophil elastase (NE) induces epithelial-mesenchymal transition (EMT) via upregulation of inhibitor of DNA binding 1 (ID1)

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Abstract Neutrophil elastase is a neutrophil-derived serine protease with broad substrate specificity. We have previously shown that NE promotes lung tumor growth in vitro and in vivo and that NE is capable of entering tumor cell endosomes in a clathrin-dependent fashion. Epithelial-mesenchymal transition (EMT) is a fundamental event for primary tumors to metastasize to distant sites. Altered gene and protein expression causes changes in cell morphology and behavior resulting in the loss of attachment to neighboring cells, intravasation, and migration into distant tissue. However, the entities residing within the tumor microenvironment that drive EMT are poorly understood. We identified NE, expressed and released by tumor-associated neutrophils, as such an entity. We found that NE induces EMT-like morphology and behavior in several cancer cell lines as well as upregulates genes (Snail and Twist) and proteins (N-cadherin, α-SMA, Fibronectin and Vimentin) associated with EMT. Furthermore, NE provokes tumor cell migration and invasion in vitro and is required for metastasis formation in vivo. Besides known EMT markers we identified significant upregulation of inhibitor of DNA binding 1 (ID1) in tumor cells in the presence of NE. Increased ID1 expression was previously shown to correlate with tumor progression and metastasis. Clathrin-dependent NE internalization is required for both ID1 expression and the EMT-like phenotype. We localized NE in different compartments of tumor cells and found it predominantly in the nuclear fraction; more specifically, NE is located in the chromatin-bound fraction, indicating a potential role in chromatin remodeling and transcriptional regulation. Additionally, the proteolytic activity of NE was measured in the nuclear and chromatin-bound fractions and is required for induction of ID1 expression and EMT-like behavior. Taken together, these data suggest the importance of NE-induced ID1 expression in metastasis formation. Citation Format: Julia Kargl, Alyssa Gregory, Hye Youn Yang, Stephanie Busch, Heather Metz, A. McGarry Houghton. Neutrophil elastase (NE) induces epithelial-mesenchymal transition (EMT) via upregulation of inhibitor of DNA binding 1 (ID1). [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr C15.