SIGMA-2/PEPTIDOMIMETIC CONJUGATES TARGET APOPTOSIS IN PANCREATIC CANCER

描述（由申请人提供）：胰腺癌是一种毁灭性疾病，2010年美国估计有43，140例新发病例，在所有癌症中死亡率排名第四。我们研究工作的目标是开发治疗胰腺癌的新疗法。 Sigma-2（S2）配体是作为成像剂在临床研究中的小分子，因为它们的受体在胰腺癌中过表达，这是它们选择性地定位于这些肿瘤的原因。此外，S2配体被用作治疗剂，因为它们具有引起癌症选择性细胞死亡的内在能力。快速和癌症选择性摄取机制与其内在的杀伤能力相结合，使σ-2配体成为药物开发评估的战略地位。XIAP是通过阻断caspase-3/7和caspase-9的活化来抑制细胞凋亡的关键分子。因此，XIAP通过外在和内在凋亡途径控制凋亡的诱导。最近的X射线晶体学和NMR研究已经确定了XIAP和其天然抑制剂SMAC之间的结构相互作用。值得注意的是，使用与SMAC模拟物缀合的σ-2配体的初步数据显示了对胰腺癌细胞的稳健杀伤。在这里，我们提出了几种新的SMAC模拟物共轭sigma-2配体的合成和功能分析，最终目标是选择最好的候选药物用于胰腺癌患者的I期临床试验。我们假设，通过化学连接至σ-2配体的SMAC模拟物的肿瘤选择性靶向将证明在胰腺癌的治疗中是有效的。 在目标1中，我们提出了一系列新的S2/Smac共轭物的合成和体外表征，主要集中在它们诱导肿瘤细胞凋亡的能力。在目标2中，我们将评估我们目前的S2/Smac缀合物和几种新化合物在体内选择性靶向和杀死胰腺癌的能力。 总之，我们在这里提出了一种新的概念，癌症选择性，σ-2介导的共同交付的肿瘤诱导货物。一旦进入细胞内，这些药物缀合物通过两个部分的组合活性介导增强的杀伤（双结构域治疗剂）。因此，递送剂的细胞毒性活性在其货物的信号传导途径之后增强。这一新概念为开发未来的小分子药物提供了一个创新的机会，这些药物在单一试剂中具有双重功能。

DESCRIPTION (provided by applicant): Pancreatic cancer is a devastating disease, with an estimated 43,140 new cases in the United States in 2010, and represents the fourth highest mortality overall amongst all cancers. The objective of our research efforts is to develop novel therapeutics for the treatment of pancreatic cancer. Sigma-2 (S2) ligands are small molecules that are under clinical investigation as imaging agents because their receptors are overexpressed in pancreatic cancer, which is the reason why they selectively localize to these tumors. In addition, S2 ligands are pursued as therapeutics because they have an intrinsic ability to cause cancer-selective cell death. The rapid and cancer-selective uptake mechanism in combination with their intrinsic killing capacity puts sigma-2 ligands into a strategic position for drug development evaluations. XIAP is a key molecule for the inhibition of apoptosis by blocking the activation of caspases-3/7 and caspase-9. As such, XIAP controls induction of apoptosis through the extrinsic as well as the intrinsic apoptosis pathway. Recent X-ray crystallography and NMR studies have identified the structural interactions between XIAP and its natural inhibitor, SMAC. Of note, preliminary data using a sigma-2 ligand conjugated to a SMAC mimetic showed robust killing of pancreatic cancer cells. Here, we propose the synthesis and functional analysis of several novel SMAC mimetics conjugated to sigma-2 ligands with the ultimate goal of selecting the best drug candidate(s) for a phase I clinical trial in patients with pancreatic adenocarcinoma. We hypothesize that tumor-selective targeting of SMAC mimetics through chemical linkage to sigma-2 ligands will prove efficacious in the treatment of pancreatic adenocarcinoma. In Aim 1, we propose the synthesis and in vitro characterization of a series of novel S2/Smac conjugates focusing primarily on their ability to induce tumor cell apoptosis. In Aim 2, we will assess our current S2/Smac conjugate and the top few new compounds for their ability to selectively target and kill pancreatic cancers in vivo. In summary, we present here a novel concept for the cancer-selective, sigma-2- mediated co-delivery of apoptosis-inducing cargo. Once inside the cell, these drug conjugates mediate enhanced killing via the combined activities of both moieties (dual-domain therapeutics). As a result, the cytotoxic activity of the delivery agent is augmented following the signaling pathway of its cargo. This new concept represents an innovative opportunity for the development of future small molecule drugs with dual functionality combined in a single reagent.