Efficacy of PDI inhibitors in glioblastoma

 描述(由申请人提供)：蛋白质二硫键异构酶(PDI)通过介导氧化蛋白质折叠，在维持细胞内稳中起关键作用。它催化内质网中二硫键的形成、断裂和重排，并具有伴侣蛋白活性。越来越多的证据表明，PDI支持几种癌症的生存和进展，最重要的是脑癌。癌细胞需要更高水平的PDI来应对显著的内质网压力，并需要全球蛋白质合成的增加来维持快速增殖。蛋白质合成增加导致内质网中存在大量错误折叠的蛋白质，需要通过PDI进行重折叠。因此，癌细胞比正常细胞更容易受到PDI的抑制，这使得PDI成为治疗脑癌的新的令人兴奋的靶点。虽然PDI仍然是一个非常有希望的肿瘤学靶点，但目前还没有PDI抑制剂在临床开发中。迫切需要开发针对脑癌基本途径的药物。以前对胶质瘤进行靶向治疗的尝试都没有产生治愈效果。由于PDI是协调快速扩散所必需的整个过程的中枢，选择性地阻断其功能将导致内质网压力增加，从而导致 癌细胞的死亡。这种方法与以前的尝试截然不同，以前的尝试是以单一蛋白质为靶点，导致容易逃脱和肿瘤复发。此前，我们发现了一类新型的、不可逆的PDI抑制剂，它们可以选择性地与PDI结合，并显示出显著的体内疗效，没有明显的全身毒性。最近，我们进行了高通量筛选，并确定了几种PDI的NM抑制剂，代表了迄今为止发现的最有效的PDI抑制剂。我们建议优化和表征这些化合物，以选择治疗多形性胶质母细胞瘤(GBM)的临床线索。为了确定PDI信号在肿瘤进展中的意义及其对肿瘤生长的抑制作用，我们提出了以下目标。目的1：验证PDI作为靶点，确定PDI在GBM细胞系中的表达水平，筛选内质网应激基因。目标2：进行基于结构和配位导向的先导优化活动，以选出具有期望的效力、选择性和PK性质的前5个化合物。目的3：利用Bru-Seq技术在一组GBM细胞系中研究Aim 2作为单一药物以及与替莫唑胺和放射治疗(TMZ/IR)联合使用的前5种化合物的作用机制。目的：研究PDI抑制剂单独及与TMZ/IR合用对患者来源异种移植(PDX)模型的体内疗效。

 DESCRIPTION (provided by applicant): Protein disulfide isomerase (PDI) has a key role in maintaining cellular homeostasis by mediating oxidative protein folding. It catalyzes disulfide bond formation, breakage and rearrangement in the endoplasmic reticulum (ER), and possesses chaperone protein activity. Increasing evidence suggests that PDI supports the survival and progression of several cancers and most significantly brain cancer. Cancer cells require higher levels of PDI to cope with significant ER stress and global increase in protein synthesis to sustain rapid proliferation. Increased protein synthesis leads to an abundant presence of misfolded proteins in the ER that need to be refolded by PDI. As such, cancer cells are more vulnerable to PDI inhibition than normal cells making PDI a new and exciting target to treat brain cancer. Although PDI remains a very promising oncology target, currently there are no PDI inhibitors under clinical development. There is an urgent need to develop drugs targeting essential pathways in brain cancer. Previous attempts at targeted therapy for glioma did not produced cures. Since PDI is a hub for orchestrating an entire process essential for rapid proliferation, selective blockade of its function will result in increased ER stress leading to the death of cancer cells. This approach is drastically different from previous attempts that target a single protein leading to facile escape and tumor recurrence. Previously, we discovered a class of novel and irreversible PDI inhibitors that selectively bind to PDI and demonstrated significant in vivo efficacy with no apparent systemic toxicity. More recently, we performed a high throughput screen and have identified several nM inhibitors of PDI representing the most potent PDI inhibitors discovered to date. We propose to optimize and characterize these compounds to select clinical leads for the treatment of glioblastoma multiforme (GBM). To determine the significance of PDI signaling in cancer progression and the effect of its inhibition on tumor growth, we propose the following aims. Aim 1: To validate PDI as a target and to determine the expression levels of PDI and select ER stress genes in GBM cell lines. Aim 2: To perform a structure-based and ADMET-guided lead optimization campaign to select the top 5 compounds with desirable potency, selectivity, and PK properties. Aim 3: To perform mechanistic studies of top 5 compounds from Aim 2 as single agents and in combination with temozolomide and radiation (TMZ/IR) using Bru-Seq technology in a panel of GBM cell lines. Aim 4: To determine in vivo efficacy of PDI inhibitors, as a single agent and in combination with TMZ/IR in patient-derived xenograft (PDX) models.