Loss of Filamin A Nuclear Localization in Prostate Cancer Progression

丝蛋白的丢失是前列腺癌进展中的核定位

• 批准号: 8394615
• 负责人: PARAMITA M. GHOSH
• 金额: --
• 依托单位: VA NORTHERN CALIFORNIA HEALTH CARE SYS
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8394615
• 关键词: Affect; Androgen Receptor; Androgens; Apoptosis; Benign; Biopsy; California; Cancer Patient; Castration; Cell Nucleus; Cell Survival; Cells; Clinical Trials; Cyclic AMP-Dependent Protein Kinases; Cytoplasm; Data; Deposition; Development; Diagnosis; Funding; Genetic Transcription; Goals; Growth; Hormonal; Human; In Vitro; Individual; Induction of Apoptosis; Laboratories; Malignant neoplasm of prostate; Mediating; Metastatic Prostate Cancer; Morbidity - disease rate; NCOA2 gene; NF-kappa B; Neoplasm Metastasis; Normal tissue morphology; Nuclear; PC3 cell line; Patients; Pharmaceutical Preparations; Phosphorylation; Play; Prostate; Proteins; Publications; Radical Prostatectomy; Recurrence; Resistance; Role; Signal Pathway; Steroid Receptors; System; Testing; Time; Tissues; Toxic effect; Treatment Failure; United States; Withdrawal; abstracting; castration resistant prostate cancer; cell behavior; cell motility; filamin; hormone therapy; inhibitor/antagonist; innovation; male; mortality; mouse model; prevent; prostate cancer cell; therapeutic target; tumor; tumor progression

DESCRIPTION (provided by applicant): Project Summary/Abstract Prostate cancer is listed as a primary diagnosis for approximately 16% of older male VHA users, and contributes significantly to morbidity and mortality rates in these individuals. The majority of VA patients with metastatic prostate cancer, similar to most non-VA patients in the United States, receives hormonal treatment which is initially effective, but frequently fail indicative of the development of castration resistant prostate cancer (CRPC). The treatment options for patients who fail hormonal therapy are limited, despite numerous clinical trials testing multiple drugs. Hence, our laboratory has undertaken the innovative overall strategy of identifying therapeutic targets that can prevent prostate cancer progression to castration resistance, rather than trying to cure it after it has already developed. Studies performed during the previous funding period, which resulted in 14 publications in related topics, contributed to understanding the importance of the cell survival regulator Akt in prostate cancer development and progression. While a number of Akt inhibitors have been developed commercially, their utility has been compromised by high levels of toxicity when used in human patients, caused by the induction of apoptosis in normal tissue including non-tumor prostate regions. As a result, a goal of the project was to identify natural antagonists of Akt that selectively counteract the effects of the increase in Akt phosphorylation in the tumor without affecting basal levels of Akt activation in other cells. Two of our recent publications demonstrate that Filamin A (FlnA) may be one such protein. In vitro studies showed that FlnA localization to the nucleus resulted in castration sensitive growth of prostate cancer cells which was mediated by antagonism of Akt phosphorylation and its downstream effectors. FlnA nuclear localization is regulated by its phosphorylation, which in turn is regulated by PKA activity. The effects of FlnA nuclear localization are likely caused by its interaction with the androgen receptor (AR), a nuclear steroid receptor mediating the effects of the androgens on cell mechanisms. Therefore, in the current application, we will investigate the role nuclear FlnA plays in regulating castration sensitive cell behavior. We hypothesize that FlnA counters the effects of Akt phosphorylation and its downstream effectors, and that its localization is in turn regulated by its phosphorylation. The following aims will test this hypothesis. Specific Aim 1: To test the hypothesis that FlnA 16-24 nuclear localization sensitizes prostate cancer cells to androgen withdrawal by preventing the effects of Akt on AR activity and cell survival. We will determine whether FlnA16-24 induces sensitivity to androgen blockade in CRPC cells by antagonizing an Akt- dependent signaling pathway and preventing AR/TIF2 interactions. We will also investigate whether nuclear localization of FlnA 16-24 induces apoptosis by repressing NF-kB activation and stimulating AR-dependent p21Cip1 transcription. Specific Aim 2: To test the hypothesis that FlnA phosphorylation is a key factor responsible for preventing FlnA nuclear localization in castrate resistant prostate cancer. We will examine whether FlnA phosphorylation prevents FlnA nuclear localization and causes castration resistance in prostate cancer cell lines expressing a functional AR. We will also determine whether inhibition of FlnA phosphorylation prevent the development of castration resistance in a mouse model of recurrent prostate cancer. Specific Aim 3: To test the hypothesis that increased FlnA phosphorylation and decreased FlnA nuclear localization predict time to treatment failure in VA patients with metastatic prostate cancer on androgen withdrawal therapy who did not undergo radical prostatectomy. We have identified patients within the VA Northern California System who presented with metastatic prostate cancer. We will determine in biopsies of the prostates of these patients the localization of Filamin A, FlnA phosphorylation, AR levels and Akt phosphorylation and determine whether they respond to androgen withdrawal therapy.

描述（由申请人提供）： 项目摘要/摘要前列腺癌被列为大约16％的男性VHA使用者的主要诊断，并为这些人的发病率和死亡率做出了重大贡献。大多数VA转移性前列腺癌患者（类似于美国大多数非VA患者）接受荷尔蒙治疗，这最初是有效的，但经常失败表明耐法的前列腺癌（CRPC）的发展。尽管许多临床试验测试了多种药物，但针对荷尔蒙治疗失败的患者的治疗选择仍有限。因此，我们的实验室已经采取了创新的总体策略，以鉴定可以防止前列腺癌向cast割耐药性进展的治疗靶标，而不是在已经开发出来后试图治愈它。在上一个资金期间进行的研究导致了14个相关主题出版物，这有助于了解细胞存活调节剂AKT在前列腺癌发展和进展中的重要性。尽管已商业开发了许多AKT抑制剂，但在人类患者中使用时，它们的效用受到高水平的毒性的损害，这是由于包括非肿瘤前列腺区域的正常组织诱导凋亡引起的。结果，该项目的目标是确定AKT的自然拮抗剂，这些拮抗剂有选择地抵消肿瘤中Akt磷酸化增加的影响，而不会影响其他细胞中Akt的基础水平。我们最近的两个出版物表明，丝蛋白A（FLNA）可能是一种蛋白质。体外研究表明，FLNA定位到核中导致前列腺癌细胞的cast依敏感生长，这是由Akt磷酸化及其下游效应子的拮抗作用介导的。 FLNA核定位受其磷酸化的调节，而PKA活性则受到调节。 FLNA核定位的影响可能是由于其与雄激素受体（AR）的相互作用引起的，雄激素受体（AR）是一种介导雄激素对细胞机制的影响的核类固醇受体。因此，在当前的应用中，我们将研究核FLNA在调节cast割敏感细胞行为中的作用。我们假设FLNA可以抵消Akt磷酸化及其下游效应子的作用，并且其定位又受其磷酸化的调节。以下目标将检验这一假设。具体目的1：测试FLNA 16-24核定位化的假设通过防止AKT对AR活性和细胞存活的影响，使前列腺癌细胞降低了前列腺癌细胞的敏感性。我们将通过拮抗依赖AKT的信号通路并防止AR/TIF2相互作用来确定FLNA16-24是否会诱导CRPC细胞中雄激素阻断的敏感性。我们还将研究FLNA的核定位16-24是否通过抑制NF-KB激活和刺激AR依赖性的P21CIP1转录来诱导凋亡。具体目的2：检验FLNA磷酸化是负责防止Castrate抗性前列腺癌中FLNA核定位的关键因素的假设。我们将检查FLNA磷酸化是否阻止FLNA核定位，并在表达功能性AR的前列腺癌细胞系中引起cast割耐药性。我们还将确定在复发前列腺癌的小鼠模型中，FLNA磷酸化的抑制是否阻止了cast割抵抗的发展。特定目的3：测试以下假设：增加FLNA磷酸化并降低FLNA核定位的假设可以预测在不接受前列腺切除术的雄激素戒断疗法上的VA转移性前列腺癌患者治疗失败的时间。我们已经确定了北加州系统中的患者，他们出现了转移性前列腺癌。我们将在这些患者的前列腺活检中确定丝蛋白A，FLNA磷酸化，AR水平和AKT磷酸化的定位，并确定它们是否对雄激素戒断疗法反应。