Dissecting the Function of Cysteine Cathepsins in the Tumor Microenvironment

描述(申请人提供)：发生癌症的组织微环境在抑制肿瘤发展方面起着关键作用，但反过来也可能被癌细胞挪用来提供支持恶性生长的因素。我们的长期目标是了解肿瘤和宿主细胞之间的分子串扰，并确定宿主组织促进癌症进展的机制。这项建议侧重于半胱氨酸组织蛋白降解酶家族在肿瘤-宿主分子相互作用中的贡献。半胱氨酸组织蛋白在许多人类和小鼠癌症中表达上调，它们的表达增加与恶性进展和患者预后不良有关。一些组织蛋白酶家族成员在肿瘤细胞中表达上调，而其他成员则由宿主细胞(包括内皮细胞和天然免疫细胞)额外或排他性地提供。在RIP1-Tag2胰腺癌小鼠模型中，使用广谱组织蛋白酶抑制剂，我们已经证明组织蛋白酶家族在肿瘤发展的所有阶段都是重要的。该抑制物治疗减少了血管生成转换，阻断了肿瘤生长，并显著损害了肿瘤血管形成、细胞增殖和肿瘤侵袭。尽管组织蛋白酶在癌症进展中起着重要作用，但它们促进肿瘤发生的分子机制在很大程度上仍不清楚。我们的假设是，组织蛋白酶家族中的个别成员对于获得癌症每一种不同的“标志性能力”的不同步骤至关重要。我们将确定在癌症中上调的6个组织蛋白酶家族成员中，哪些对肿瘤的发展是重要的。我们将验证这一假说，即组织蛋白酶促进肿瘤侵袭的分子机制需要细胞外裂解E-钙粘蛋白，并通过降解和释放血管基膜蛋白来促进血管生成。我们还将确定组织蛋白酶在癌症微环境中的细胞来源是否对其促肿瘤功能是必要的。为了实现这些目标，我们将结合细胞共培养、生化和药理学实验来分析6个组织蛋白酶家族成员的小鼠基因敲除。这些研究将为组织蛋白在癌症中的生物学、微环境在肿瘤进展中的作用提供重要的见解，并使在这一临床前小鼠模型研究的基础上开发和应用治疗癌症的策略成为可能。

DESCRIPTION (provided by applicant): The tissue microenvironment in which a cancer arises plays a critical role in inhibiting tumor development, but conversely can also be misappropriated by cancerous cells into providing factors that support malignant growth. Our long-term objective is to understand the molecular crosstalk between tumor and host cells, and to determine the mechanisms by which host tissues are co-opted to facilitate cancer progression. This proposal focuses on the contribution of the Cysteine Cathepsin family of degradative enzymes to tumor-host molecular interactions. Cysteine cathepsins are up-regulated in many human and mouse cancers and their increased expression is associated with malignant progression and a poor patient prognosis. Some cathepsin family members are upregulated in tumor cells, however others are additionally or exclusively provided by host cells including endothelial and innate immune cells. Using a broad-spectrum cathepsin inhibitor, we have shown that the cathepsin family is important for all stages of tumor development in the RIP1-Tag2 pancreatic cancer mouse model. Treatment with this inhibitor decreased angiogenic switching, blocked tumor growth, and significantly impaired tumor vascularization, cell proliferation and tumor invasion. Despite the important role for cathepsins in cancer progression, the molecular mechanisms by which they facilitate tumorigenesis are still largely unknown. Our hypothesis is that individual members of the cathepsin family are crucial for distinct steps in acquiring each distinct 'hallmark capability' of cancer. We will identify which of the 6 cathepsin family members upregulated in cancers are important for tumor development. We will test the hypothesis that cathepsins promote tumor invasion by a molecular mechanism requiring the extracellular cleavage of E-cadherin, and facilitate angiogenesis through the degradation and release of vascular basement membrane proteins. We will also determine if the cellular source of cathepsin expression in the cancer microenvironment is necessary for its pro-tumorigenic functions. To achieve these aims, we will analyze 6 mouse gene knockouts of cathepsin family members with a combination of cell co-culture, biochemical and pharmacological experiments. These studies will provide vital insights into the biology of cathepsins in cancer, the role of the microenvironment in tumor progression, and enable the development and application of therapeutic cancer strategies based on studies in this pre-clinical mouse model.