Therapeutic Efficacy of Riluzole in Prostate Cancer

描述(申请人提供)：有氧糖酵解和谷氨酰胺分解是癌细胞的主要特征。在糖酵解和谷氨酰胺分解过程中，葡萄糖分别转化为乳酸，谷氨酰胺转化为谷氨酸。除了作为重要的生物合成前体的作用外，谷氨酸代谢还与脂肪生成和雄激素生物合成途径密切相关。抑制AR及其信号通路仍然是雄激素刺激(AS)和去势耐药前列腺癌(CRPCa)的关键治疗靶点。PCa细胞在功能和代谢上与谷氨酸和糖酵解途径有关，其特征之一是由于关键酶脂肪酸合成酶(Fas)的过度表达而增加从头合成脂肪酸。为了评估谷氨酸的临床相关性，我们测定了正常男性(n=60)、原发性PCa患者(n=197)和转移性PCa患者(n=109)的血清谷氨酸水平。我们最近报道Gleason评分e8的血清谷氨酸水平明显高于Gleason评分d7，这与PCa的临床侵袭性有关。我们还发现谷氨酸受体GRM1在原发和转移性前列腺癌组织中过表达。雄激素非依赖性或CRPCa细胞系(如PC-3、DU-145、VCaP)的GRM1受体表达也高于AS-LNCaP或原代PCa细胞系E006AA。利鲁唑是FDA批准的一种耐受性良好的口服药物，用于治疗肌萎缩侧索硬化症(ALS)，并在几个活跃的临床试验中治疗抑郁症、癫痫和其他良性神经疾病，已被证明是GRM1的有效药理抑制剂。利鲁唑抑制AS和CRPCa细胞系的增殖、迁移和侵袭，并诱导细胞凋亡。我们的最新数据显示，利鲁唑降低了Pca细胞中Fas的表达。根据利鲁唑的抗肿瘤活性，我们推测利鲁唑可能是一种治疗前列腺癌的新型药物。为了验证我们的假设，我们将研究：(1)利鲁唑对(I)皮下抗去势(CR)进展模型中的肿瘤生长和(Ii)原位异种移植模型中的自发转移能力的影响。(目的2)探讨利鲁唑对原发和转移性肿瘤Fas表达和细胞凋亡标志物的影响。为了达到这个目的，我们将能够通过检查利鲁唑治疗与肿瘤移植瘤中Fas表达和脂肪酸含量之间的关系来验证我们的体外数据。此外，我们还将探讨利鲁唑下调PCa细胞Fas表达的潜在机制。这些临床前探索性研究应该验证我们的体外数据，并验证利鲁唑和抗GRM1靶向治疗的疗效，从而开发出在PCa患者中使用GRM1阻滞剂的临床试验。

DESCRIPTION (provided by applicant): Aerobic glycolysis and glutaminolysis are the major hallmarks of cancer cells. During glycolysis and glutaminolysis, glucose is converted to lactate and glutamine to glutamate, respectively. Other than its role as a significant biosynthetic precursor, glutamate metabolism is intimately linked to lipogenesis and androgen biosynthetic pathways. Inhibition of the AR and its signaling pathways remain a key therapeutic target for both androgen-stimulated (AS) and castrate-resistant prostate cancer (CRPCa). One of the hallmarks of PCa cells which are functionally and metabolically linked to glutamate and glycolytic pathways is an increased de novo fatty acid synthesis due to overexpression of the key enzyme, fatty acid synthase (FAS). To assess the clinical relevance of glutamate, we measured serum glutamate levels in normal men (n=60) and patients with primary PCa (n=197) or metastatic-CRPCa (n=109). We recently reported significantly higher serum glutamate levels in Gleason score e 8 compared to Gleason score d 7 which is associated with clinical aggressiveness of PCa. We also found that glutamate receptor GRM1 is overexpressed in primary and metastatic PCa tissues. GRM1 receptor expression in androgen-independent or CRPCa cell lines (e.g., PC-3, DU-145, VCaP) was also higher than in the AS-LNCaP or primary PCa cell line, E006AA. Riluzole, a well-tolerated FDA-approved oral medicine for the treatment amyotropic lateral sclerosis (ALS) and in several active clinical trials for depression, epilepsy, and other benign neurological diseases, has been shown to be a potent pharmacological inhibitor of GRM1. Riluzole decreased proliferation, migration, and invasion and induced apoptosis in both AS and CRPCa cell lines. Our most recent data demonstrated that Riluzole decreases FAS expression in PCa cells. Based on antitumor activities of Riluzole, we hypothesize that Riluzole serves as a novel therapeutic agent for PCa. To test our hypothesis, we will investigate: (Aim 1) The effect of Riluzole on (i) tumor growth in a subcutaneous castrate-resistant (CR) progression model and (ii) spontaneous metastatic ability of an orthotopic xenograft model. (Aim 2) Determine the effect of Riluzole on FAS expression and apoptotic markers in primary and metastatic tumors. In this Aim, we will be able to verify our in vitro data by examining the association between Riluzole treatment and FAS expression and fatty acid content in tumor xenografts. In addition, we will investigate the underlying mechanisms by which Riluzole downregulates FAS expression in PCa cells. These preclinical exploratory studies should verify our in vitro data and validate therapeutic efficacy of Riluzole and anti-GRM1 targeted therapy leading to the development of clinical trials using GRM1-blocking agents in PCa patients.