Coagulation factors as modifiers of the colon cancer microenvironment

 描述(由申请人提供)：本研究计划的目标是确定止血因素促进结直肠癌(CRC)发病的机制。越来越多的证据表明，结直肠癌的病理生物学独特地依赖于中枢止血蛋白酶--凝血酶。PIS实验室最近发表的研究表明，凝血酶和纤维蛋白原推动结肠炎相关性结肠癌的肿瘤发生，这表明凝血酶在结直肠癌发病机制中具有独特的重要性。这些研究代表了凝血酶/纤维蛋白原轴在肿瘤发生和肿瘤生长中发挥主要作用的唯一确凿例子。拟议的研究建立在这些结果的基础上，以及强有力的初步数据显示，凝血酶介导的蛋白分解在癌前和恶性肿瘤微环境中是CRC发病的一个广泛重要的决定因素，而不仅仅是与炎症性结肠炎相关的环境。凝血酶似乎通过与纤维蛋白原和凝血酶激活受体-1(PAR-1)偶联的独特机制促进结直肠癌的发生和肿瘤生长。拟议的研究将直接确定凝血酶与结直肠癌发病机制的偶联，并首次探索最近批准的针对凝血酶原/凝血酶原/凝血酶的下一代药物的治疗潜力，以阻止结直肠癌的发生和发展。这项建议中的研究将使用专门针对这一提议开发的新的基因靶向小鼠品系、尖端药理学药物和创新的体外互补分析来检验以下特定假设：1)凝血酶/纤维蛋白原轴在将局部免疫微环境转变为能够支持肠道肿瘤发生的致病、炎症状态方面具有广泛的重要性；2)血管外纤维蛋白沉积，特别是纤维蛋白介导的整合素M2的参与，推动肠道肿瘤的发生；b)推动肠道单核细胞向促肿瘤表型转变；3)纤维蛋白介导的巨噬细胞相关的M2结合触发依赖于核因子-κB的促肿瘤细胞因子、趋化因子、促肿瘤因子的产生。凝血酶还通过激活不同的组织特异性PAR-1信号机制参与结直肠癌的发生和发展，包括癌前病变和肿瘤微环境中的巨噬细胞以及转化的肠上皮细胞，5)凝血酶原的表达或凝血酶的生成可以通过多种不同的药理学手段在小鼠的结直肠癌发病机制中加以限制。这项拟议的研究将为了解止血因素在结直肠癌病理生物学中的确切作用提供迫切需要的见解，将阐明凝血酶介导的蛋白分解与结直肠癌进展的关键机制途径，并将在实验动物中提供关于高级抗凝剂作为预防或治疗结直肠癌辅助治疗的可译性的必要的原则证明数据。

 DESCRIPTION (provided by applicant): The objective of this research program is to define the mechanisms by which hemostatic factors promote colorectal cancer (CRC) pathogenesis. Growing evidence suggests that CRC pathobiology is uniquely dependent on the central hemostatic protease, thrombin. The unique importance of thrombin in CRC pathogenesis is evinced by recently published studies from the PIs laboratory revealing that thrombin and fibrinogen drive tumorigenesis in colitis-associated colon cancer. These studies represent the only definitive example of a context where the thrombin/fibrinogen axis plays a major role in tumorigenesis and tumor growth. The proposed studies build on these results, as well as powerful preliminary data revealing that thrombin-mediated proteolysis in the premalignant and malignant tumor microenvironments is a broadly important determinant of CRC pathogenesis, not just settings associated with inflammatory colitis. Thrombin appears to promote CRC tumorigenesis and tumor growth through unique mechanisms coupled to fibrinogen and the thrombin-activatable receptor, protease activated receptor-1 (PAR-1). The proposed studies will directly define the mechanisms coupling thrombin to CRC pathogenesis, and explore, for the first time, the therapeutic potential of recently approved and next-generation pharmacological agents targeting pro/thrombin to impede the development and progression of CRC. The studies in this proposal will use novel gene-targeted mouse lines developed specifically for this proposal, cutting-edge pharmacological agents, and innovative complementary in vitro analyses to test the following specific hypotheses: 1) the thrombin/fibrinogen axis is broadly important in shifting the local immunological microenvironment towards a pathogenic, inflammatory state capable of supporting intestinal tumorigenesis, 2) extravascular fibrin deposition, and specifically fibrin-mediated engagement of the integrin M2, drives intestinal tumorigenesis b pushing intestinal monocytes toward a pro-tumorigenic phenotype, 3) fibrin-mediated binding of macrophage-associated M2 triggers NF-κB-dependent production of pro-tumorigenic cytokines, chemokines, and growth factors, thereby supporting the proliferation/survival of transformed intestinal epithelial cells, 4) thrombin is also coupled to the development and progression of CRC through activation of distinct, tissue-specific PAR-1 signaling mechanisms involving macrophages in the premalignant and tumor microenvironments, as well as transformed intestinal epithelial cells, and 5) CRC pathogenesis can be limited in mice by multiple distinct pharmacological approaches at the level of prothrombin expression or thrombin generation. The proposed studies will provide much needed insights into the precise contribution of hemostatic factors in CRC pathobiology, will illuminate key mechanistic pathways coupling thrombin-mediated proteolysis to CRC progression, and will provide essential proof-of-principle data in experimental animals regarding the translatability of advanced anticoagulants as adjuvant therapy for the prevention or treatment of CRC.