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（由申请人提供）：本项目基于PI的新发现，即-生育酚和更大程度上的-生育酚通过Akt和PHLPP 1（PH结构域富亮氨酸重复磷酸酶1）的PH结构域介导的膜共定位促进Akt在Ser-473处的选择性去磷酸化。PHLPP 1是一种Ser-473 Akt磷酸酶，通过负调控Akt发挥肿瘤抑制作用。从机理的角度来看，这些发现提供了第一个证据，即-/ -生育酚介导氧化还原非依赖性抗肿瘤作用，至少部分地，通过抵消磷脂酰肌醇3，4，5-三磷酸对Akt激活的作用。这种独特的机制提供了一个范式转变，通过膜募集PHLPP 1调节Akt活性，揭示了维生素E如何介导其化学预防作用的谜团，以及为什么生育酚在抑制癌细胞增殖方面相对于对应物更有效。鉴于PHLPP在阻断PTEN突变型前列腺癌发生中的肿瘤抑制作用，这一发现为使用-生育酚作为支架开发一类新的PHLPP 1靶向Akt抑制剂提供了分子基础，该抑制剂具有与其他类型Akt抑制剂不同的作用模式。这种先导优化的概念验证由-VE 5提供，-VE 5是一种侧链截短的-生育酚衍生物，其在介导Akt去磷酸化和前列腺癌细胞生长抑制方面表现出相对于-生育酚至少高20倍的效力。同样重要的是，-VE 5在抑制裸鼠中PTEN缺陷型PC-3和LNCaP-abl异种移植肿瘤的生长方面表现出体内功效。 因此，该提案包括三个具体目标，目的是将这种新的机制发现转化为一类新的PHLPP 1靶向Akt抑制剂，以阻断或延迟前列腺肿瘤发生。目的1是对-VE 5进行基于结构的先导优化，以开发更有效的PHLPP 1靶向Akt抑制剂。基于建模和突变分析，我们假设配体与结合口袋中亲水残基的极性相互作用的增加将增强PH的结合亲和力。 域这一前提的概念验证已通过分析铅-VE 5衍生物建立。建议继续优化这些导致通过代谢不稳定部分的电子等排置换产生第二代化合物。目的二是研究优化的-VE 5衍生物抑制PTEN缺陷型前列腺癌细胞增殖的机制。来自Aim 1的前3个最佳-VE 5衍生物将通过检查它们对Akt和与前列腺癌发生和肿瘤进展相关的各种Akt下游靶标（特别是糖原合成酶激酶（GSK）3、叉头框转录因子Foxo 3a、NF-B和AR信号传导）的活化状态的作用来进行机械验证。由于PHLPP 1在介导AR抑制对PTEN缺陷型前列腺癌细胞中Akt活化的影响中起关键作用，因此还将探索这些化合物对AR信号传导与PHLPP 1介导的Akt活化调节的串扰的影响。将在PTEN缺陷型（LNCaP-abl和PC-3）和PTEN功能性（22 RV 1）异种移植肿瘤模型中评估三种最佳-VE 5衍生物的体内功效，这将与肿瘤中上述生物标志物的变化相关。目的3是评估结构优化的-VE 5衍生物在PTEN敲除和TRAMP模型中阻断前列腺肿瘤发生的体内化学预防功效。鉴于异常Akt信号传导在前列腺癌发生中的作用，这两种转基因动物模型代表了评估这些-VE 5-衍生的PHLPP 1-靶向Akt抑制剂的化学预防活性的治疗相关模型。