Translating Novel Antitumor Targets of Vitamin E into New Chemopreventive Agents

将维生素 E 的新型抗肿瘤靶点转化为新型化学预防剂

• 批准号: 8698025
• 负责人: CHING-SHIH CHEN
• 金额: $ 31.93万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8698025
• 关键词: Adenocarcinoma; Affinity; Androgen Receptor; Androgens; Animal Model; Binding; Biological Markers; Boxing; CWR22Rv1; Cancer Etiology; Cell Proliferation; Cells; Cessation of life; Chemopreventive Agent; Chromans; Clinic; Clinical Management; Data; Defect; Development; Disease; Evaluation; Exhibits; Generations; Glycogen Synthase Kinase 3; Goals; Growth; Head; Hydrogen Bonding; Knock-out; LNCaP; Lead; Leucine-Rich Repeat; Ligands; Light; Malignant neoplasm of prostate; Mediating; Membrane; Modeling; Molecular; Molecular Models; Mus; Nude Mice; Oxidation-Reduction; PH Domain; PTEN gene; Peptides; Pharmaceutical Preparations; Phosphoric Monoester Hydrolases; Play; Prevention strategy; Prostate; Prostatic Neoplasms; Protein Dephosphorylation; Protein phosphatase; Receptor Inhibition; Receptor Signaling; Regulation; Relative (related person); Research; Role; Second Primary Cancers; Side; Signal Transduction; Structure; Tocopherols; Toxic effect; Transgenic Animals; Transgenic Organisms; Translating; Tumor Suppressor Proteins; Vertebral column; Vitamin E; analog; base; cancer cell; cancer diagnosis; improved; in vivo; inhibitor/antagonist; men; molecular modeling; mutant; novel; phosphatidylinositol 3,4,5-triphosphate; pre-clinical; prostate cancer cell; prostate carcinogenesis; public health relevance; research study; scaffold; tool; transcription factor; tumor; tumor growth; tumor progression; tumor xenograft

DESCRIPTION (provided by applicant): This project is based on the PI's novel finding that -tocopherol and, to a greater extent, -tocopherol facilitate the selective dephosphorylation of Akt at Ser-473 through PH domain-mediated membrane co- localization of Akt and PHLPP1 (PH domain leucine-rich repeat phosphatase 1). PHLPP1, a Ser-473 Akt phosphatase, acts as a tumor suppressor by negatively regulating Akt. From a mechanistic perspective, these findings provide the first evidence that -/ -tocopherol mediates redox-independent antitumor effects, at least in part, by counteracting the effect of phosphatidylinositol 3,4,5-trisphosphate on Akt activation. This unique mechanism provides a paradigm shift with respect to the regulation of Akt activity through membrane recruitment of PHLPP1, sheds light onto the enigma of how vitamin E mediates its chemopreventive effect and of why -tocopherol is more potent relative to the counterpart in suppressing cancer cell proliferation. In light of the tumor suppressor role of PHLPP in blocking PTEN mutant prostate carcinogenesis, this finding provides a molecular rationale for the use of -tocopherol as a scaffold to develop a novel class of PHLPP1-targeted Akt inhibitors, which have a distinct mode of action from other types of Akt inhibitors. The proof-of-concept of this lead optimization is provided by -VE5, a side chain-truncated -tocopherol derivative, which exhibited at least 20-fold higher potency relative to -tocopherol in mediating Akt dephosphorylation and growth inhibition of prostate cancer cells. Equally important, -VE5 exhibited in vivo efficacy in suppressing the growth of PTEN- deficient PC-3 and LNCaP-abl xenograft tumors in nude mice. Thus, this proposal consists of three specific aims with the goal of translating this novel mechanistic finding into a novel class of PHLPP1-targeted Akt inhibitors to block or delay the onset of prostate tumorigenesis. Aim 1 is to conduct structure-based lead optimization of -VE5 to develop more potent PHLPP1-targeted Akt inhibitors. Based on modeling and mutational analyses, we hypothesize that increasing polar interactions of the ligand with the hydrophilic residues in the binding pocket will enhance binding affinity for the PH domain. Proof-of-concept of this premise has been established by analysis of lead -VE5 derivatives. Continued optimization of these leads to generate 2nd generation compounds via isosteric replacement of metabolically labile moieties is proposed. Aim 2 is to investigate the mechanisms by which optimized -VE5 derivatives inhibit cell proliferation of PTEN-deficient prostate cancer cells. The top 3 optimal -VE5 derivatives from Aim 1 will be mechanistically validated by examining their effects on the activation status of Akt and various Akt downstream targets relevant to prostate carcinogenesis and tumor progression, especially glycogen synthase kinase (GSK)3¿, the forkhead box transcription factor Foxo3a, NF-¿B, and AR signaling. As PHLPP1 plays a pivotal role in mediating the effect of AR inhibition on Akt activation in PTEN- deficient prostate cancer cells, the effects of these compounds on crosstalk of AR signaling with PHLPP1- mediated regulation of Akt activation will also be explored. In vivo efficacy of three optimal -VE5 derivatives will be evaluated in both PTEN-deficient (LNCaP-abl and PC-3) and PTEN-functional (22RV1) xenograft tumor models, which will be correlated with changes in the aforementioned biomarkers in tumors. Aim 3 is to assess the in vivo chemopreventive efficacy of a structurally optimized -VE5 derivative to block prostate tumorigenesis in the PTEN-knockout and TRAMP models. In light of the role of aberrant Akt signaling in prostate carcinogenesis, these two transgenic animal models represent therapeutically relevant models to evaluate the chemopreventive activities of these -VE5-derived PHLPP1-targeted Akt inhibitors.

描述(申请人提供)：这个项目是基于PI的新发现，-生育酚，在更大程度上，-生育酚通过PH域介导膜共定位Akt和PHLPP1(PH域富含亮氨酸的重复磷酸酶1)促进Akt在Ser-473选择性去磷酸化。PHLPP1是一种Ser-473Akt磷酸酶，通过负性调节Akt发挥肿瘤抑制作用。从机制的角度来看，这些发现提供了第一个证据，表明-/-生育酚至少部分地通过抵消磷脂酰肌醇3，4，5-三磷酸对Akt激活的影响来介导氧化还原非依赖性的抗肿瘤作用。这一独特的机制提供了一种通过膜上招募PHLPP1来调节Akt活性的范式转变，揭示了维生素E如何介导其化学预防作用以及为什么-生育酚在抑制癌细胞增殖方面比对应物更有效的谜团。鉴于PHLPP在阻断PTEN突变的前列腺癌发生中的肿瘤抑制作用，这一发现为以生育酚为支架开发一类新型的PHLPP1靶向Akt抑制剂提供了分子基础，该抑制剂具有不同于其他类型Akt抑制剂的作用模式。这种先导优化的概念验证是由-VE5提供的，它是一种侧链截断的生育酚衍生物，在介导前列腺癌细胞Akt去磷酸化和生长抑制方面表现出比-生育酚至少20倍的效力。同样重要的是，-VE5在体内显示了抑制PTEN缺陷的PC-3和LNCaP-ABL裸鼠移植瘤的生长的效果。因此，这项建议包括三个具体目标，目的是将这一新的机制发现转化为一类新的PHLPP1靶向Akt抑制剂，以阻断或延迟前列腺癌的发生。目标1是对-VE5进行基于结构的先导优化，以开发更有效的PHLPP1靶向Akt抑制剂。基于模型和突变分析，我们假设增加配体与结合口袋中亲水残基的极性相互作用将增强与PH的结合亲和力 域。通过对铅-VE5衍生物的分析，建立了对这一前提的概念验证。建议通过对代谢不稳定的部分进行等位取代来继续优化这些化合物以生成第二代化合物。目的2研究优化的VE5衍生物抑制PTEN缺陷性前列腺癌细胞增殖的机制。来自AIM 1的前3个最佳VE5衍生物将通过检测它们对Akt和与前列腺癌发生和肿瘤进展相关的各种Akt下游靶点的激活状态的影响进行机械验证，特别是糖原合成酶激酶(GSK)3？、叉头盒转录因子Foxo3a、核因子-B和AR信号。由于PHLPP1在介导AR抑制PTEN基因缺失的前列腺癌细胞Akt活化中起关键作用，这些化合物对AR信号与PHLPP1介导的Akt激活调节的串扰的影响也将被探讨。在PTEN缺乏(LNCaP-ABL和PC-3)和PTEN功能(22Rv1)异种移植瘤模型中，将评估三种最佳VE5衍生物的体内疗效，这将与上述肿瘤生物标志物的变化相关。目的3评估结构优化的VE5衍生物在PTEN基因敲除和TRAMP模型中阻断前列腺癌发生的体内化学预防效果。鉴于异常的Akt信号在前列腺癌发生中的作用，这两个转基因动物模型代表了评估这些VE5衍生的PHLPP1靶向Akt抑制剂的化学预防活性的治疗相关模型。