Dissecting the Function of Cysteine Cathepsins in the Tumor Microenvironment

描述（由申请人提供）：癌症发生的组织微环境在抑制肿瘤发展中起着关键作用，但反过来也可能被癌细胞滥用，成为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，并确定宿主组织被增选以促进癌症进展的机制。本研究的重点是半胱氨酸组织蛋白酶家族降解酶在肿瘤-宿主分子相互作用中的作用。半胱氨酸组织蛋白酶在许多人类和小鼠癌症中上调，其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上调，但其他成员则由宿主细胞（包括内皮细胞和先天免疫细胞）额外或专门提供。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RIP1-Tag2胰腺癌小鼠模型中对肿瘤发展的所有阶段都很重要。用这种抑制剂治疗可减少血管生成转换，阻断肿瘤生长，并显著损害肿瘤血管化、细胞增殖和肿瘤侵袭。尽管组织蛋白酶在癌症进展中发挥着重要作用，但它们促进肿瘤发生的分子机制仍在很大程度上是未知的。我们的假设是，组织蛋白酶家族的单个成员在获得癌症的每个独特的“标志能力”的不同步骤中至关重要。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一个对肿瘤的发展是重要的。我们将验证组织蛋白酶通过细胞外分裂E-cadherin的分子机制促进肿瘤侵袭，并通过血管基底膜蛋白的降解和释放促进血管生成的假设。我们还将确定在癌症微环境中组织蛋白酶表达的细胞来源是否是其促肿瘤功能所必需的。为了达到这些目的，我们将采用细胞共培养、生化和药理实验相结合的方法分析6个小鼠组织蛋白酶家族成员基因敲除。这些研究将为组织蛋白酶在癌症中的生物学作用、微环境在肿瘤进展中的作用提供重要的见解，并使基于临床前小鼠模型的癌症治疗策略的开发和应用成为可能。

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.