Na-K-Cl cotransporter in Glioblastoma Multiforme

多形性胶质母细胞瘤中的 Na-K-Cl 协同转运蛋白

• 批准号: 8309081
• 负责人: Dandan Sun
• 金额: $ 32.73万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8309081
• 关键词: Apoptosis; Apoptotic; Bumetanide; Caspase; Categories; Cell Death; Cell Survival; Cell Volumes; Cells; Cessation of life; Characteristics; DNA; DNA Damage; DNA Repair; Data; Enzymes; Family; Glioblastoma; Glioma; Homeostasis; In Vitro; Infiltration; Ion Transport; Ionic Strengths; Ions; Isotonic Exercise; Lesion; Light; Lysine; Malignant - descriptor; Malignant Neoplasms; Mediating; Methyltransferase; Patients; Phosphotransferases; Play; Primary Brain Neoplasms; Process; Protein Isoforms; Protein-Serine-Threonine Kinases; Proteins; Regulation; Resected; Resistance; Role; Signal Pathway; Small Interfering RNA; Stimulus; Survival Rate; Testing; Time; Water; World Health Organization; Xenograft Model; base; cancer cell; cancer stem cell; chemotherapy; chloride-cotransporter potassium; genetic regulatory protein; improved; inhibitor/antagonist; novel; novel therapeutics; response; solute; symporter; temozolomide; tumor growth; tumor xenograft

DESCRIPTION (provided by applicant): Glioblastoma multiforme (GBM) is a World Health Organization Grade IV cancer, the most malignant category of glial tumors with median survival time less than one year. The combined temozolomide (TMZ)-mediated chemoradiotherapy only modestly improves survival of GBM patients [2-yr survival rate of 27%] and 80% of totally resected GBM recur. The key challenge in the treatment is an increase of a subpopulation of GBM cancer cells which are resistant to apoptosis. Therefore, new strategies are needed to improve the efficiency of the current therapies for GBM. TMZ causes a DNA O6-methylguanine lesion which triggers DNA repair, depletes the enzyme O6-methylguanine methyltransferase, and leads to apoptotic cell death. The hallmark of apoptosis is a drastic reduction in cell volume resulting from loss of K+i and Cl-i, termed apoptotic volume decrease "AVD". AVD is an ubiquitous characteristic of apoptosis which is independent of the death stimuli. Loss of cell volume and reduction of total intracellular ionic strength (via loss of K+ and Cl-) occur before any other detectable characteristics of apoptosis. The reduction of intracellular ionic strength has been suggested to play a permissive role in activation of caspases and triggering the entire caspase cascade and apoptotic machinery. Normally, cells respond to volume perturbations by activating volume regulatory mechanisms. The process by which shrunken cells return to normal volume is termed regulatory volume increase (RVI). RVI can only be regulated by the gain of osmotically active solutes such as Na+, K+ and Cl-. Na+-K+-2Cl- co-transporter isoform 1 (NKCC1), which transports 1 Na+, 1 K+ and 2 Cl- ions into the cell, is the primary cell volume regulatory protein in RVI in response to either hypertonic or isotonic cell shrinkage. Therefore, NKCC1-mediated RVI will promote cell survival. However, it remains unexplored whether NKCC1-mediated K+, Cl- accumulation can counteract AVD, restore intracellular ionic strength, reduce caspase-mediated apoptosis, and promote cell survival in response to TMZ-mediated DNA damage. Our preliminary data illustrate that NKCC1 is the most important ion transport mechanism in regulating Cl-i and RVI in GBM cancer cells. Interestingly, pharmacological blockade of NKCC1 activity with its potent inhibitor bumetanide enhanced TMZ- mediated apoptosis. This led us to hypothesize that NKCC1 activity is stimulated in the TMZ-treated cells and its inhibition can sensitize glioma to TMZ-mediated apoptosis. Completion of this study will shed light on whether a combined TMZ-based therapy with NKCC1 inhibition presents a novel therapeutic strategy, which may increase the efficiency of the current chemotherapy.

描述（由申请人提供）：多形性胶质母细胞瘤（GBM）是世界卫生组织IV级癌症，是胶质瘤中最恶性的一类，中位生存时间不到一年。联合替莫唑胺 (TMZ) 介导的放化疗只能适度改善 GBM 患者的生存率 [2 年生存率为 27%]，并且完全切除的 GBM 患者中有 80% 会复发。治疗中的关键挑战是抵抗细胞凋亡的 GBM 癌细胞亚群的增加。因此，需要新的策略来提高当前 GBM 疗法的效率。 TMZ 会引起 DNA O6-甲基鸟嘌呤损伤，从而触发 DNA 修复，耗尽 O6-甲基鸟嘌呤甲基转移酶，并导致细胞凋亡。细胞凋亡的标志是由于K+i和Cl-i的损失导致细胞体积急剧减少，称为细胞凋亡体积减少“AVD”。 AVD是细胞凋亡的普遍特征，与死亡刺激无关。细胞体积的损失和细胞内总离子强度的降低（通过 K+ 和 Cl- 的损失）发生在任何其他可检测到的细胞凋亡特征之前。细胞内离子强度的降低被认为在半胱天冬酶的激活和触发整个半胱天冬酶级联和细胞凋亡机制中发挥许可作用。通常，细胞通过激活体积调节机制来响应体积扰动。缩小的细胞恢复正常体积的过程称为调节体积增加（RVI）。 RVI 只能通过渗透活性溶质（例如 Na+、K+ 和 Cl-）的增加来调节。 Na+-K+-2Cl- 协同转运蛋白亚型 1 (NKCC1) 将 1 个 Na+、1 个 K+ 和 2 个 Cl- 离子转运到细胞中，是 RVI 中响应高渗或等渗细胞收缩的主要细胞体积调节蛋白。因此，NKCC1介导的RVI将促进细胞存活。然而，NKCC1 介导的 K+、Cl- 积累是否可以抵消 AVD、恢复细胞内离子强度、减少 caspase 介导的细胞凋亡并促进细胞对 TMZ 介导的 DNA 损伤的存活仍有待探索。我们的初步数据表明，NKCC1 是 GBM 癌细胞中调节 Cl-i 和 RVI 的最重要的离子转运机制。有趣的是，用强效抑制剂布美他尼药理学阻断 NKCC1 活性可增强 TMZ 介导的细胞凋亡。这使我们推测 TMZ 处理的细胞中 NKCC1 活性受到刺激，并且其抑制作用可以使神经胶质瘤对 TMZ 介导的细胞凋亡敏感。这项研究的完成将揭示基于 TMZ 的联合疗法与 NKCC1 抑制是否能提供一种新的治疗策略，从而可能提高当前化疗的效率。