Abstract 2049: HNSCC-derived exosomes promote angiogenesis and tumor progression through reprogramming of the tumor microenvironment in vitro and in vivo

Abstract

Abstract Head and neck squamous cell carcinoma (HNSCC) is the seventh most common malignant disease. For solid tumors, such as HNSCC, an adequate blood supply is of critical importance for tumor development, growth and metastasis. Tumor-derived exosomes (TEX) accumulate in the tumor microenvironment (TME) and serve as a communication system between the tumor and normal stromal cells. TEX may be one of the mechanisms responsible for induction of tumor angiogenesis. This study evaluates in vitro and in vivo effects mediated by TEX that result in promotion of tumor angiogenesis. Biologically-active exosomes produced by SCC47 and PCI-13 tumor cell lines were isolated by mini size exclusion chromatography (mini-SEC). Exosomes were also isolated from plasma specimens of HNSCC patients or healthy donors. Exosome morphology, size and numbers were characterized using TEM and q-Nano. Molecular profiles were evaluated by western blots with the exosome-specific marker TSG101 blotted as control. The angiogenesis-inducing potential of TEX was measured in arrays with human endothelial cells (HUVEC). Uptake of labeled TEX by HUVEC cells was demonstrated by confocal microscopy. Proliferation, migration, chemotaxis and the tube formation by HUVECs in response to TEX were investigated. The matrigel plug model and the 4-nitroquinoline-1-oxide (4-NQO) oral carcinogenesis were used to confirm that exosomes induce the same results in vivo. In vitro and in vivo experiments were repeated with plasma-derived exosomes obtained from HNSCC patients and healthy donors. TEX were found to be potent inducers of angiogenesis in vitro and in vivo through functional re-programming and phenotypic modulation of endothelial cells. HNSCC-derived exosomes carried angiogenesis markers (coagulation factor III, IGFBP-3, thrombospondin 1 and uPA) and were internalized by HUVECs within 4 h. Cell line derived exosomes stimulated proliferation (PCI-13 p < 0.05; SCC47 p < 0.01), migration (p < 0.05) and tube formation (p < 0.001) by endothelial cells and promoted formation of defined vascular structures in vivo. Proliferation, migration and tube formation of plasma-derived exosomes obtained from HNSCC patients were significantly enhanced compared to healthy donors' exosomes (p < 0.05). Our data suggest that HNSCC-derived exosomes promoting angiogenesis, are an adverse factor in carcinogenesis and a potential biomarker of angiogenesis. Moreover, future efforts should focus on eliminating or silencing TEX and thereby adding new options for improving existing anti-angiogenic therapies. Citation Format: Nils Ludwig, Saigopalakrishna S. Yerneni, Beatrice M. Razzo, Theresa L. Whiteside. HNSCC-derived exosomes promote angiogenesis and tumor progression through reprogramming of the tumor microenvironment in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2049.