Abstract 4169: Tumor endothelium regulates microenvironment-mediated migration via the proteolysis of extracellular TFPI-2 by trypsinogen 4

Abstract

Abstract Proteases secreted from endothelial cells (EC) play an important part in angiogenesis, tumor metastasis and blood coagulation processes. In particular, perivascular proteases influence tumor vascularization in many different ways: regulating migration and invasion of endothelial and mural cells, activating chemokines, growth factors, growth factor receptors, break down extracellular matrix and modifying cellular adhesion molecules. Understanding the complexity of protease activities and their regulation by endothelium in response to different microenvironment stimuli might help identify new targets for the inhibition of vascularization in cancer and angiogenesis related diseases. The expression of serine protease 3 (PRSS3) a member of the trypsinogen family, in vivo is associated to the tumors vasculature and in vitro characterizes EC isolated from cancer specimens [Ghilardi, BMC Genomics 2008]. Herein, we used EC isolated from cancer specimens (tumor-derived EC) to elucidate a mechanism linking micro-environment cues to endothelium migration. We show that trypsinogen 4 isoform of PRSS3 is the trypsin family member expressed by human endothelium, and its expression is up-regulated by a tumor pro-angiogenic milieu (i.e. the combined action of VEGF, FGF-2 and EGF; particularly rich in the cancer environment). Trypsinogen 4 depletion profoundly impaired the migratory capability of tumor-derived EC initiated and driven by the tumor pro-angiogenic milieu. We identified Tissue Factor Pathway Inhibitor-2 (TFPI-2) as the functional proteolitic target. TFPI-2 negatively regulated the migration of tumor-derived EC; trypsinogen 4 was capable to cleave TFPI-2 and also to displace it from the extracellular matrix (ECM) deposited by tumor-derived EC. Accordingly, we observed an increased accumulation of TFPI-2 in the extracellular matrix of tumor-derived EC silenced for trypsinogen IV. Altogether, the results indicate that the tumor microenvironment triggers and sustains the expression of trypsinogen 4 to impair TFPI-2 function and permits the migration of endothelium; essential for angiogenesis and blood vessel remodeling. Our findings contribute to advance the understanding of tumor vascular biology, and the comprehension of an active role for trypsinogen 4 and TFPI-2 in microenvironment-mediated tumor neo-vascularization. The identification of the specific protease and its functional target may be of aid for the design of inhibitor(s) exploitable as anti-cancer therapeutics. Supported by the Italian Association for Cancer Research (AIRC) and the CARIPLO foundation. Citation Format: Carmen Ghilardi, Figini Sara, Monica Lupi, Alessia Anastasia, Raffaella Giavazzi, Mariarosa Bani. Tumor endothelium regulates microenvironment-mediated migration via the proteolysis of extracellular TFPI-2 by trypsinogen 4. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4169. doi:10.1158/1538-7445.AM2015-4169