Cyclic Peptide Protease Inhibitors for the Treatment of Prostate Cancer

虽然新的治疗方法已经产生了影响，延长了患有糖尿病的男性的生活质量和数量， 前列腺癌（PCa），迫切需要新的治疗方法来对抗该疾病的侵袭性形式。 最近，我们在靶向膜的治疗性肽的开发中取得了几个关键发现 结合金属蛋白酶氨肽酶N（APN）在前列腺癌的侵袭性亚型。能够准确且可靠地 为了研究APN在前列腺癌组织中的表达，我们通过噬菌体展示鉴定了一种新的抗体， 在福尔马林固定的石蜡包埋组织中识别APN。这种抗体使我们能够筛选前列腺癌组织 微阵列（TMA）的保真度前所未有。患者活检组织的免疫组织化学分析， TMAs发现APN在非雄激素受体（AR）驱动的PCa中优先过表达， AR驱动的前列腺腺癌。我们还记录了种族差异TMA和患者活检， APN在非裔美国人的前列腺癌中表达，而在白人患者中不表达。两个非洲人- 美国男性和患有非AR驱动的PCa的男性代表了表现出侵袭性疾病的患者群体。 总体生存率很低使用基于APN的底物特异性的合理设计方法，我们 鉴定了一种环肽（Leu-His-Ser-Pro-Trp = cLHSPW），它是APN酶的微摩尔抑制剂， 活动发现该肽在高剂量下在表达APN的PCa异种移植物中具有中度治疗性。 通过接头将两个cLHSPW肽系在一起产生了在体外和体内具有增强效力的二聚体。 vivo.二聚体是APN的纳摩尔抑制剂，并迅速被癌细胞内化。当 当以与单体相同的高剂量施用时，二聚体导致体内完全肿瘤消耗。这些 这些发现提示更高级的多价cLHSPW肽可能是有效的APN靶向治疗剂。在 在这个提议中，我们将使用大环框架合成二聚体、三聚体和四聚体cLHSPW肽。 除了易于合成外，大环框架还可以螯合放射性金属以发射正电子 断层扫描（PET）。为了开发一类新的前列腺癌治疗剂，研究了肽的体外治疗功效， 将进行表征，并在体内进行PET成像，以监测生物分布（目标1）， 将检查消除皮下异种移植物中的肿瘤负荷的肽（Aim 2）和X射线 将对与肽复合的APN进行晶体学和冷冻电子显微镜检查，以获得 机制的见解，并最终导致优化抑制剂的发展（目标3）。我们的初步数据 这强烈表明，我们已经开发出有效的治疗方法，有可能导致戏剧性的转变， 如何治疗侵袭性前列腺癌

Although new therapies have had an impact prolonging the quality and quantity of life of men suffering from prostate cancer (PCa), novel treatments are urgently needed to combat aggressive forms of the disease. Recently, we made several key discoveries in the development of therapeutic peptides targeting the membrane bound metalloprotease aminopeptidase N (APN) in aggressive subtypes of PCa. To accurately and reliably interrogate the expression of APN in PCa tissues, we identified a novel antibody by phage display that specifically recognized APN in formalin-fixed paraffin embedded tissues. This antibody allowed us to screen PCa tissue microarrays (TMAs) with a fidelity never before seen. Immunohistochemistry analysis of patient biopsies and TMAs found that APN was preferentially overexpressed in non-androgen receptor (AR) driven PCa compared to AR-driven prostate adenocarcinoma. We also documented in a race disparity TMA and patient biopsies that APN was expressed in the PCa of African-American men while absent in Caucasian patients. Both African- American men and men with non-AR driven PCa represent patient populations who exhibit aggressive disease with poor overall survival. Using a rational design approach based off of the substrate specificity of APN, we identified a cyclic peptide (Leu-His-Ser-Pro-Trp = cLHSPW) that was a micromolar inhibitor of APN’s enzymatic activity. This peptide was found to be moderately therapeutic in APN-expressing PCa xenografts at high doses. Tethering of two cLHSPW peptides together by a linker created a dimer with enhanced potency in vitro and in vivo. The dimer was a nanomolar inhibitor of APN and was rapidly internalized by the cancer cell. When administered at the same high dose as the monomer, the dimer led to complete tumor attrition in vivo. These findings suggest that higher order multivalent cLHSPW peptides may be effective APN-targeted therapeutics. In this proposal, we will synthesize dimeric, trimeric, and tetrameric cLHSPW peptides using macrocyclic frames. In addition to ease of synthesis, the macrocyclic frames can also chelate radiometals for positron-emission tomography (PET). To develop a new class of PCa therapeutics, the in vitro therapeutic efficacy of the peptides will be characterized and PET imaging will be performed in vivo to monitor biodistribution (Aim 1), the ability of the peptides to eliminate tumor burden in subcutaneous xenografts will be examined (Aim 2) and X-ray crystallography and cryo-electron microscopy will be performed on APN complexed with the peptides to obtain mechanistic insights and ultimately lead to the development of optimized inhibitors (Aim 3). Our preliminary data strongly suggest that we have developed potent therapeutics that have the potential to result in a dramatic shift in how aggressive PCa is treated.