Elucidation and therapeutic exploitation of PAK mediated radioresistance

项目摘要/摘要 肿瘤对放射治疗的抵抗仍然是改善确诊患者预后的关键障碍 局部晚期、不能切除的癌症。细胞对电离辐射(IR)的敏感性由细胞内决定 和细胞外因子。为了克服肿瘤的放射抗性，使肿瘤细胞对电离敏感的药物 使用辐射(IR)。在放射治疗的同时给予非靶向细胞毒化疗 证明癌症患者的肿瘤控制和总体存活率得到了改善。然而，由于这个范例 方法的转变发生在20世纪80年代，S在发展分子方面的进展令人震惊地缺乏 定向放射增敏方法。系统结合提高胰岛素抵抗的治愈率 给药一般有两种方法：1)使用阻断DNA损伤修复的药物 反应2)选择性地向肿瘤输送放射增敏药物。这两种方法是正交的。 达到在减少正常组织的同时增加IR诱导的肿瘤杀伤的相同最终目标的技术 毒物。为了解决这两个基本的癌症治疗问题，我们将重点放在靶向上。 发现和肿瘤选择性药物输送载体。关于目标发现，我们最近对 CRAF的非规范功能导致我们发现了PAK在DNA损伤修复和修复中的意外作用 对红外线的敏感性。PAK由一个由6个激酶组成的家族组成，分为I组和II组。 参与肿瘤发生、肿瘤侵袭性和患者生存的中心过程。攻克肿瘤 选择性给药，我们正在开发药物结合可激活细胞穿透肽(ACPP)以 根据细胞外肿瘤蛋白酶活性，选择性地向肿瘤输送有效的放射增敏剂。ACPP 由药物偶联聚阳离子细胞穿透肽和自抑制聚阴离子多肽组成 通过柔韧的多肽连接物彼此分开。这种多肽连接物被蛋白酶特异性地切割。 富含在细胞外肿瘤微环境中。在ACPP完好的情况下，药物结合细胞 穿透性多肽被多阴离子多肽中和(即，处于药物前状态)，从而使药物 无法访问其细胞内目标。肿瘤微环境蛋白裂解ACPP释放 药物结合的细胞穿透肽，然后被肿瘤细胞摄取。我们建议的目标是 为了深入了解PAK如何管理辐射抵抗，然后通过靶向PAK治疗来利用这一点 抑制剂。在目标1中，我们将从基因上确定第一组和第二组PAK治理的机制 红外线抵抗。在目标2中，我们将对小分子肿瘤的放射增敏能力进行药理学测试。 PAK抑制剂。在目标3中，我们将测试肿瘤靶向ACPP是否增加结合的PAK的治疗率 抑制剂。我们的方法在DNA损伤靶点发现和肿瘤方面都有互补的创新 选择性给药。将这些方法结合在一起，将为摆脱无针对性奠定基础 生物标记物驱动的分子导向放射增敏的细胞毒性放射增敏。

PROJECT SUMMARY/ABSTRACT Tumor resistance to radiotherapy remains a critical barrier to improving outcomes for patients diagnosed with locally advanced, unresectable cancers. Cellular sensitivity to ionizing radiation (IR) is governed by intracellular and extracellular factors. To overcome tumor radioresistance, drugs that sensitize tumor cells to ionizing radiation (IR) are used. Non-targeted cytotoxic chemotherapies given concurrently with radiotherapy have demonstrated improved tumor control and overall survival in cancer patients. However, since this paradigm shifting approach occurred in the 1980's there has been a shocking lack of progress in developing molecularly targeted radiosensitization approaches. Improving the therapeutic ratio of IR in combination with systemically delivered drugs can be achieved by two general approaches, 1) using drugs that block DNA damage repair responses 2) delivering radiosensitizing drugs selectively to tumors. These two methods are orthogonal techniques to achieve the same end goal of increasing IR induced tumor kill while reducing normal tissue toxicities. To address both of these fundamental cancer therapy problems, we have focused on target discovery and tumor selective drug delivery vehicles. With regards to target discovery, our recent studies on non-canonical CRAF functions led to our discovery of an unexpected role for PAK in DNA damage repair and sensitivity to IR. PAK is comprised of a family of six kinases subdivided in Group I and II. Importantly, PAK are involved in process central to oncogenesis, tumor aggressiveness and patient survival. To tackle tumor selective drug delivery, we are developing drug conjugated activatable cell penetrating peptides (ACPP) to selectively deliver potent radiosensitizers to tumors based on extracellular tumor protease activity. ACPP consist of a drug conjugated polycationic cell penetrating peptide and an autoinhibitory polyanionic peptide separated from each other by a flexible peptide linker. This peptide linker is specifically cleaved by proteases enriched in the extracellular tumor microenvironment. While ACPP is intact, the drug conjugated cell penetrating peptide is neutralized (i.e. held in a “pro-drug” state) by the polyanionic peptide so that the drug cannot gain access to its intracellular target. Tumor microenvironment proteases cleave ACPP and release the drug conjugated cell penetrating peptide, which is then taken up by tumor cells. The goals of our proposal are to gain insight into how PAK governs radioresistance and then therapeutically exploit this with targeted PAK inhibitors. In Aim 1, we will genetically determine the mechanisms through which Group I and II PAKs govern IR resistance. In Aim 2, we will pharmacologically test the ability to radiosensitize tumors with small molecule PAK inhibitors. In Aim 3, we will test if tumor targeted ACPP increase the therapeutic ratio of conjugated PAK inhibitors. Our approach has complementary innovations in both DNA damage target discovery and tumor selective drug delivery. Combining these approaches will lay a foundation for moving away from non-targeted cytotoxic radiosensitization to biomarker driven molecularly guided radiosensitization.