Inhibition of Na-H Exchanger Selectively Kills Gliomas

抑制 Na-H 交换剂选择性杀死神经胶质瘤

• 批准号: 6639691
• 负责人: FREDRIC A GORIN
• 金额: $ 24.28万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6639691
• 关键词: amiloride; astrocytoma; cell death; cerebrospinal fluid; clinical research; confocal scanning microscopy; cysteine endopeptidases; disease /disorder model; drug resistance; flow cytometry; free radical oxygen; glioma; glutathione; human tissue; hydrogen; inhibitor /antagonist; laboratory rat; membrane potentials; membrane transport proteins; mitochondrial membrane; neurons; neuropharmacology; pharmacokinetics; sodium; sodium hydrogen exchanger; terminal nick end labeling; tissue /cell culture

DESCRIPTION: High grade astrocytomas (, malignant gliomas) are the most commonly occurring type of lethal adult brain-tumor with an individual's average life expectancy being less than 2 years from the time of diagnosis. Neither radiation therapy nor chemotherapy has significantly improved quality or length of survival. Since Warburg's initial observation, it has been recognized that most transformed tumor cells have high rates of glycolytic metabolism and consequent H+ production. Given the optimal alkaline pH dependence of key glycolytic enzymes, such as phosphofructokinase and hexokinase, it is essential that tumor cells employ an effective means of removing free cytosolic H+ to maintain metabolism. We have determined that intracellular pH in rat and human gliomas are significantly above that of normal astrocytes (0.2-0.6 pH units) despite the tumor's high rates of metabolic H+ production. This intracellular alkalosis appears to result from persistent activation of the type 1 isoform of the Na+-H+ exchanger (NHE 1). Our preliminary investigations have determined that this altered regulation of NHE 1 is most probably posttranslational and does not result from alterations of the NHE1 gene or proteins expressed in these highly malignant astrocytomas. Unexpectedly, we found that inhibition of NHE I in rat and human glioma cell lines with the diuretic drug, amiloride, or with its derivatives, HOE 694 and EIPA, cause a 70-100 percent cell death within 48-72 hours. By, contrast, primary astrocyte cultures were unaffected by NIHE 1 inhibition. Cell culture and in vivo analyses indicate that glioma death following NHE 1 inhibition appears to be predominantly non-apoptotic and independent of preceding caspase activation. Rat C6 gliomas were implanted into rat brains and allowed to establish for 4 days. Amiloride infusion into the cerebrospinal fluid for 8 days produced a 73 percent reduction in tumor volume. Amiloride is an oral diuretic that is approved for human use. Preliminarily, this novel intrathecal administration of amiloride in rats does not appear to cause behavioral or neuropathological alterations. Amiloride produced a dose-dependent decrease in intracellular pH in malignant gliomas, but not astrocytes. We have pilot data indicating that this ApHi initiates the selective tumor death. We propose to (1) identify the intracellular mechanisms mediating glioma death; (2) use brain implanted tumor models to more thoroughly delineate selective glioma death by NIlE I inhibitors; and (3) study the pharmacological and H+ regulatory properties of surviving gliomas. NHE I inhibitors may represent a new class of pharmacological agents that are useful for treatment of these highly aggressive and lethal brain tumors.

描述：高级星形胶质细胞瘤（恶性神经胶质瘤）是最大的 通常发生致命的成人脑肿瘤类型 自诊断之日起，平均预期寿命不到2年。 放射疗法和化学疗法都没有显着提高质量 或生存时间。自沃堡（Warburg）的最初观察以来， 认识到大多数转化的肿瘤细胞具有较高的糖酵解速率 代谢和随之而来的H+产生。考虑到最佳碱性pH 关键糖酵解酶的依赖性，例如磷酸果糖激酶和 己糖酶，肿瘤细胞采用有效手段至关重要 去除自由的胞质H+以保持代谢。我们已经确定 大鼠和人神经胶质瘤的细胞内pH值显着高于 尽管肿瘤的速率很高，但正常星形胶质细胞（0.2-0.6 pH单位） 代谢H+产生。这种细胞内碱中毒似乎是由 Na+ -H+交换器的类型1同工型的持续激活（NHE 1）。 我们的初步调查确定了这种调节 NHE 1很可能是翻译后的，并且不是由于更改而造成的 在这些高度恶性星形胶质细胞瘤中表达的NHE1基因或蛋白质的。 出乎意料的是，我们发现在大鼠和人神经胶质瘤细胞中对NHE I的抑制作用 使用利尿剂，氨氧化胺或其衍生物HOE 694和 EIPA在48-72小时内导致70-100％的细胞死亡。对比， 原发性星形胶质细胞培养不受NIHE 1抑制的影响。细胞培养 体内分析表明，NHE 1抑制后神经胶质瘤死亡 似乎主要是非凋亡的，并且与先前的caspase无关 激活。将大鼠C6神经胶质瘤植入大鼠大脑中，并允许 建立4天。阿米洛德输注脑脊液8 天的肿瘤体积减少了73％。 Amiloride是口头 批准用于人类的利尿剂。初步的，这是这个新颖的鞘内 在大鼠中给予阿米洛德似乎并不引起行为或 神经病理学改变。阿米洛德（Amiloride）导致剂量依赖性降低 恶性神经胶质瘤中的细胞内pH，而不是星形胶质细胞。我们有飞行员数据 表明该APHI启动了选择性肿瘤死亡。我们建议 （1）确定介导神经胶质瘤死亡的细胞内机制； （2）使用大脑 植入肿瘤模型以更彻底地描绘出选择性神经胶质瘤死亡 尼罗I抑制剂； （3）研究药理和H+调节 存活的神经胶质瘤的特性。 nhe i抑制剂可能代表一个新的类 可用于治疗这些高度侵略性的药理剂 和致命的脑肿瘤。