Targeting Cathepsin L: A Novel Strategy to Impede Prostate and Breast Cancer Meta

描述(申请人提供)：在接受手术或放射治疗的乳腺癌和前列腺癌患者中，转移仍然是治疗失败、预后差和死亡率高的主要原因。显然，需要新的方法来减少癌症患者的转移发生率，提高患者的总体存活率。目前的建议集中于针对转移级联中的关键角色-半胱氨酸蛋白酶L组织蛋白(CTSL)的治疗。CTSL在多种癌症类型的原发肿瘤和转移性病变中过度表达和过度激活，包括乳腺癌和前列腺癌。它的过度激活与肿瘤侵袭性和肿瘤分级相关，导致患者预后不良。CTSL通过直接降解E-钙粘附素、细胞外基质和基底膜成分，启动迁移和侵袭过程。组织蛋白还在骨骼中转移的肿瘤细胞刺激破骨细胞介导的骨吸收的过程中起关键作用；这是前列腺癌和乳腺癌患者显著发病率的来源。因此，CTSL可能在转移过程中提供一个独特的靶点。本研究的目的是利用小分子靶向方法，在人(MBA-MB-231，PC-3ML)和啮齿动物(TRAMP)乳腺癌和前列腺癌模型中探索CTSL抑制的抗转移潜能。目的1将评估选择性小分子CTSL抑制剂对与肿瘤细胞扩散相关的关键功能步骤的影响，包括ECM降解、细胞运动和细胞侵袭。在目标2中，将评估实体肿瘤中常见的低氧和酸性肿瘤微环境对CTSL的释放、活性和对小分子抑制的反应的影响。目标3将研究组织蛋白酶靶向是否可以抑制骨吸收；骨吸收是导致癌症患者骨骼发病率的关键过程。AIM 4将评估 CTSL分子抑制和选择性治疗联合靶向治疗CTSL的体内抗转移潜能。首先，将通过心内途径注射已知数量的MDA-MB-231或PC-3ML细胞，CTSL抑制剂(KGP94或KGP207)的有效性将通过(I)使用体内成像系统对转移负荷进行非侵入性监测，以及(Ii)量化骨转移的数量来确定。其次，部分研究将评估CTSL干扰在(I)接受原位移植乳腺肿瘤手术切除的小鼠和(Ii)自发前列腺癌转移TRAMP模型小鼠中癌细胞从原发肿瘤向次级部位扩散的效果。最后，目标5将阐述CTSL的作用及其对肿瘤诱导的血管生成和血管生成的抑制，这是肿瘤转移的关键因素。拟议研究的成功完成将为CTSL成为新型抗转移药物的潜在治疗靶点提供证据。 癌症疗法。针对癌细胞扩散的方法的临床前研究可能最终提供临床益处，因为它能够开发出未来的治疗方案，旨在提高晚期乳腺癌和前列腺癌患者现有手术干预和放射治疗的结果。

DESCRIPTION (provided by applicant): Metastasis remains the major cause of therapeutic failure, poor prognosis and high mortality in breast and prostate cancer patients treated with surgery or radiotherapy. Novel approaches to reduce metastatic incidences and improve overall survival of cancer patients clearly are needed. The current proposal is focused on therapeutically targeting a key player in the metastatic cascade; the cysteine protease cathepsin L (CTSL). CTSL is over-expressed and hyper-activated in primary tumors and metastatic lesions in many cancer types, including breast and prostate cancer. Its over-activation correlates with tumor invasiveness and tumor grade, yielding a poor patient prognosis. CTSL initiates migratory and invasive processes through direct degradation of E-Cadherin, extracellular matrix, and basement membrane components. Cathepsins also critically contribute to the process by which metastatic tumor cells in the skeleton stimulate osteoclast-mediated bone resorption; a source of significant morbidity in prostate and breast cancer patients. CTSL may therefore provide a unique target in the metastatic process. The goal of the present proposal is to explore the anti-metastatic potential of CTSL inhibition using a small molecule targeting approach in human (MBA-MB-231, PC-3ML) and rodent (TRAMP) breast and prostate cancer models. Aim 1 will assess the impact of selective small molecule CTSL inhibitors on key functional steps associated with tumor cell dissemination including ECM degradation, cell motility, and cell invasion. In Aim 2 the effect of hypoxic and acidic tumor microenvironments, as commonly occur in solid tumors, on CTSL release, activity, and response to small molecule inhibition will be assessed. Aim 3 will examine whether cathepsin targeting can inhibit bone resorption; a key process leading to skeletal morbidity in cancer patients. Aim 4 will evaluate the in vivo anti-metastatic potential of CTSL targeting using both molecular suppression and selective therapeutic inhibition of CTSL. First, a known number of MDA-MB- 231 or PC-3ML cells will be injected via the intracardiac route and the efficacy of CTSL inhibitors (KGP94 or KGP207) will be determined by (i) non-invasive monitoring of the metastatic burden using an in vivo imaging system, and (ii) quantifying the number of bone metastases. Second, select studies will evaluate the effect of CTSL interference on the spread of cancer cells from primary tumors to secondary sites in (i) mice undergoing surgical removal of orthotopically transplanted breast tumors and (ii) the spontaneous prostate cancer metastasis TRAMP model. Finally, Aim 5 will address the role of CTSL and its inhibition to tumor induced angiogenesis and vasculogenesis, key contributors to metastasis. The successful completion of the proposed studies will provide evidence that CTSL is a potential therapeutic target for novel anti-metastatic cancer therapies. Preclinical investigations of approaches targeting the spread of cancer cells may ultimately provide clinical benefit by enabling the development of future treatment regimes designed to enhance outcomes of existing surgical interventions and radiotherapy treatments for advanced breast and prostate cancer patients.