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（由适用提供）：该项目基于PI的新颖发现，即生育酚和更大程度地说， - 生育酚在Ser-473上通过pH结构域介导的膜膜的膜共定位AKT和PHLPP1（PHLPP1和PHLPP1）（PHLPP1）（pH Domain-PHLPP1）（pH Domain-PHLPP1）（PHLPEN liucine-rich-rich-Rich-Rich-Rich-Rich-Rich Phosphospase 1）促进了AKT的选择性去磷酸化。 PHLPP1是SER-473 AKT磷酸酶，通过负面控制AKT充当肿瘤抑制器。从机械的角度来看，这些发现提供了第一个证据，即 - /托酚介导了氧化还原依赖性的抗肿瘤作用，至少部分是通过抵消磷脂酰肌醇3,4,5-三磷酸对Akt激活的影响。这种独特的机制通过膜募集PHLPP1提供了对AKT活性的调节的范式转移，使启示了维生素E如何介导其化学预防效应的谜团以及抑制抑制癌细胞扩散的相对于对应物的潜在潜力。鉴于PHLPP在阻断PTEN突变体癌变中的肿瘤抑制作用，这一发现为使用-topherol作为脚手架提供了一种分子理由，以开发出一种新型的PHLPP1 -TargeTAgentArget Akt Akt抑制剂，这些抑制剂具有其他类型的AKT抑制剂的独特作用模式。该铅优化的概念概念由-VE5（一种侧链截断的 - 生育酚衍生物）提供，在介导Akt脱磷酸化和前列腺癌细胞的生长抑制时，相对于 - 托酚酚的效力至少高20倍。同样重要的是，-VE5在抑制裸鼠中缺乏PTEN缺陷型PC-3和LNCAP-ABL XENOGRACH肿瘤的生长方面暴露了体内效率。这是由三个特定目标组成的，目的是将这种新型的机械性发现转化为新型的PHLPP1靶向Akt抑制剂，以阻止或延迟前列腺肿瘤发生的发作。 AIM 1是进行-VE5的基于结构的铅优化，以开发出更多的潜在PHLPP1靶向Akt抑制剂。根据建模和突变分析，我们假设配体与结合口袋中亲水性保留的极性相互作用增加将增强对pH的结合亲和力 领域。通过分析铅-VE5衍生物的分析，已经确定了此前提的概念概念。提出了这些导管的持续优化，从而提出了代谢标记部分的等质替代品生成第二代化合物。目的2是研究优化-VE5衍生物抑制PTEN缺陷前列腺癌细胞的细胞增殖的机制。来自AIM 1的前3个最佳-VE5衍生物将通过检查其对AKT的激活状态的影响以及与前列腺癌发生和肿瘤进展相关的各种AKT的激活状态的影响，尤其是糖原合成酶激酶（GSK）3€，forkhead box Transcription fix fix foxo3aa，nf -nf -b and Ar n anf and Ar and Ar and ard anfight。由于PHLPP1在介导AR抑制对PTEN缺乏的前列腺癌细胞中AKT激活的影响中起关键作用，因此这些化合物对与PHLPP1介导的AKT激活调节的AR信号传导的作用也将得到探索。将在PTEN缺陷率（LNCAP-ABL和PC-3）和PTEN功能（22RV1）异种移植肿瘤模型中评估三种最佳-VE5衍生物的体内效率，这将与肿瘤中Priore生物标志物的变化相关。 AIM 3是评估体内化学预防的有效性-DE5衍生物以阻断PTEN敲除和流浪汉模型中前列腺肿瘤的发生。鉴于异常AKT信号传导在前列腺癌发生中的作用，这两个转基因动物模型代表了与治疗相关的模型，以评估这些衍生的pHLPP1-PHLPP1靶向的AKT抑制剂的化学预防活性。