Alternatively Spliced Tissue Factor and Pathobiology of Pancreatic Cancer

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DESCRIPTION (provided by applicant): We propose to evaluate whether a recently discovered protein termed alternatively spliced Tissue Factor (asTF) can lead to the development of new strategies to fight pancreatic cancer, specifically pancreatic ductal adenocarcinoma (PDAC), a highly lethal form of cancer and a major therapeutic challenge. asTF expression is increased in PDAC and it enhances monocyte recruitment, PDAC cell proliferation and migration, resistance to hypoxia, metastatic spread, and vessel growth. We posit that asTF enhances PDAC growth and spread as it accrues in tumor stroma, acting as a non-proteolytic cell agonist. To study asTF's mode(s) of action in PDAC and evaluate its potential utility as a target, we propose the following three Aims: 1. To identify the domain(s) of human asTF required for binding to, and signaling via beta1 integrins. asTF binds beta1 integrins in a non-canonical region, acting as an integrin ligand/activator. We will map asTF domain(s) required to signal via beta1 integrins by generating recombinant asTF mutants, assessing the resultant phenotype(s) in vitro, and then expressing them in PDAC cells to confirm our findings in vivo. 2. To determine the contribution of tumor-derived versus host- derived asTF to PDAC progression. Rationale for this Aim is grounded in the hypothesis that asTF expressed by tumor cells as well as stromal monocytes fuels PDAC cell proliferation, monocyte recruitment, and aggressive growth of established metastases. We will use a unique set of tools (cell lines, genetically modified mice, and innovative imaging technologies) to assess the relative contribution of tumor cell-derived asTF, and host cell-derived asTF to PDAC progression. 3. To investigate the potential utility of the inhibitory anti-asTF monoclonal antibod Rb1 to treat PDAC. We established the procedure for growing human PDAC tumor specimens in nude mice, and developed an inhibitory anti-human asTF monoclonal antibody Rb1 that reduces migration of PDAC cells in vitro, and suppresses PDAC cell growth in vivo. We will assess the ability of systemically administered Rb1 to reduce the growth of human PDAC cells and patient-derived PDAC tumor xenografts, and Rb1's potential to induce immune cell- and complement-mediated cytotoxicity. Upon completion, our studies are highly likely to i) yield new insights into the role of asTF in PDAC progression, which may open new avenues to treat PDAC, ii) elucidate the significance of beta1 integrin signaling in PDAC pathogenesis, and iii) improve understanding of the role(s) played by monocytes/macrophages in PDAC pathobiology.