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 前列腺癌被列为约 16% 的老年男性 VHA 用户的主要诊断，并且对这些个体的发病率和死亡率有显着影响。与美国大多数非 VA 患者类似，大多数患有转移性前列腺癌的 VA 患者接受激素治疗，该治疗最初有效，但经常失败，表明发生去势抵抗性前列腺癌 (CRPC)。尽管有大量临床试验测试了多种药物，但激素治疗失败的患者的治疗选择仍然有限。因此，我们的实验室采取了创新的总体策略，确定可以预防前列腺癌进展为去势抵抗的治疗靶点，而不是在它已经发展后试图治愈它。上一资助期间进行的研究产生了 14 篇相关主题的出版物，有助于了解细胞存活调节剂 Akt 在前列腺癌发生和进展中的重要性。虽然许多 Akt 抑制剂已经商业化开发，但当用于人类患者时，它们的效用受到高水平毒性的影响，这是由诱导包括非肿瘤前列腺区域在内的正常组织细胞凋亡引起的。因此，该项目的目标是鉴定 Akt 的天然拮抗剂，选择性抵消肿瘤中 Akt 磷酸化增加的影响，而不影响其他细胞中 Akt 激活的基础水平。我们最近发表的两篇文章表明，Filamin A (FlnA) 可能就是这样的一种蛋白质。体外研究表明，FlnA 定位于细胞核导致前列腺癌细胞的去势敏感生长，这是由 Akt 磷酸化及其下游效应子的拮抗作用介导的。 FlnA 核定位受其磷酸化调节，而磷酸化又受 PKA 活性调节。 FlnA 核定位的影响可能是由其与雄激素受体 (AR) 的相互作用引起的，雄激素受体是一种核类固醇受体，介导雄激素对细胞机制的影响。因此，在当前的应用中，我们将研究核FlnA在调节去势敏感细胞行为中的作用。我们假设 FlnA 对抗 Akt 磷酸化及其下游效应子的影响，并且其定位反过来又受到其磷酸化的调节。以下目标将检验这一假设。具体目标 1：检验 FlnA 16-24 核定位通过阻止 Akt 对 AR 活性和细胞存活的影响而使前列腺癌细胞对雄激素撤退敏感的假设。我们将确定 FlnA16-24 是否通过拮抗 Akt 依赖性信号通路并阻止 AR/TIF2 相互作用来诱导 CRPC 细胞对雄激素阻断的敏感性。我们还将研究 FlnA 16-24 的核定位是否通过抑制 NF-kB 激活和刺激 AR 依赖性 p21Cip1 转录来诱导细胞凋亡。具体目标 2：检验以下假设：FlnA 磷酸化是阻止去势抵抗性前列腺癌中 FlnA 核定位的关键因素。我们将检查 FlnA 磷酸化是否会阻止 FlnA 核定位并导致表达功能性 AR 的前列腺癌细胞系的去势抵抗。我们还将确定抑制 FlnA 磷酸化是否可以防止复发性前列腺癌小鼠模型中去势抵抗的发展。具体目标 3：检验以下假设：FlnA 磷酸化增加和 FlnA 核定位减少可预测未接受根治性前列腺切除术的转移性前列腺癌 VA 患者接受雄激素戒断治疗后治疗失败的时间。我们已经在 VA 北加州系统内发现了患有转移性前列腺癌的患者。我们将在这些患者的前列腺活检中确定 Filamin A、FlnA 磷酸化、AR 水平和 Akt 磷酸化的定位，并确定他们是否对雄激素戒断治疗有反应。