Cancer cell adaptation to glutamine deprivation

癌细胞对谷氨酰胺剥夺的适应

• 批准号: 8811793
• 负责人: MEI KONG
• 金额: $ 35.24万
• 依托单位: BECKMAN RESEARCH INSTITUTE/CITY OF HOPE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8811793
• 关键词: Affect; Alanine; Aspartic Acid; Bioenergetics; Cancer cell line; Catabolism; Cell Line; Cell Proliferation; Cell Survival; Cells; Co-Immunoprecipitations; Complex; Data; Embryo; Face; Family; Fibroblasts; Glutamine; Goals; Growth; Human; Knockout Mice; Laboratories; Maps; Mass Spectrum Analysis; Mediating; Metabolic; Metabolic stress; Metabolism; Molecular; Mutate; Mutation; NF-kappa B; Normal tissue morphology; Nutrient; Oncogenic; Pathway interactions; Phosphorylation; Phosphorylation Site; Process; Protein Dephosphorylation; Protein Phosphatase 2A Regulatory Subunit PR53; Reagent; Relative (related person); Reporting; Resistance; Role; Signal Pathway; Signal Transduction; Starvation; Testing; Therapeutic; Toxic effect; Transcriptional Activation; cancer cell; cancer therapy; chromatin immunoprecipitation; deprivation; falls; in vivo; inhibitor/antagonist; insight; killings; knock-down; meetings; neoplastic cell; novel; novel therapeutic intervention; novel therapeutics; p65; promoter; protein phosphatase 2A regulatory subunit 65 kDa; public health relevance; response; scaffold; sensor; small hairpin RNA; transcription factor; tumor; tumor growth; tumor xenograft; tumorigenesis

DESCRIPTION (provided by applicant): Glutamine is an essential nutrient to support the survival and proliferation of cancer cells, and increased use of glutamine to fuel anabolic processes has been observed in a wide variety of tumors. However, as tumors grow, increased glutamine catabolism often depletes the local supply, leading tumor cells to face periods of glutamine deprivation. How tumor cells sense glutamine levels and survive these temporary periods of glutamine deprivation is unclear, but such survival is necessary for tumors to persist. Our goal is to define the molecular pathways that regulate cell survival under low glutamine conditions and evaluate the potential of simultaneously blocking both glutamine metabolism and the adaptive survival response as a novel therapeutic approach for cancer treatment. We have recently shown that glutamine deprivation leads to induction of the protein phosphatase 2A regulatory subunit B55a, thereby triggering the formation of an active PP2A complex consisting of catalytic C and scaffolding A subunits and the specifically-induced B55a subunit. This B55a- containing PP2A complex is required for tumor cell survival upon glutamine depletion. We further found that induction of B55a activates p53, an important sensor of metabolic stress. Our preliminary data suggest that B55a activates p53 through a mechanism that involves dephosphorylation of EDD, a previously unidentified substrate of B55a that is a known negative regulator of p53. In addition, we have preliminary data indicating that IKK?, the master regulator of NF-kB transcription factors, is phosphorylated upon glutamine deprivation and required for B55a induction. We therefore hypothesize that B55a is induced by the IKK? pathway to dephosphorylate EDD, thereby leading to p53 activation and cancer cell survival under low glutamine conditions. Thus, targeting both glutamine metabolism and the IKK? B55a-EDD-p53 survival pathway could be an effective therapeutic approach to kill tumor cells. To test this hypothesis, we propose three specific aims: 1) Determine the role of IKK? in B55a-mediated activation of p53 and cell survival upon glutamine deprivation; 2) Examine if B55a activates p53 upon glutamine deprivation by dephosphorylating EDD; 3) Determine the combined effect of IKK? and glutamine metabolism inhibition on growth of tumors with different p53 status. The results of the proposed studies will define the molecular mechanisms and functional impact of the IKK? B55a- p53 pathway in the metabolic adaptive response to glutamine deprivation. A wide variety of human cancer cell lines are sensitive to glutamine starvation, and reagents that impair cells' ability to use glutamine are currently being studied as novel cancer therapies. The proposed studies will provide deeper understanding of the survival pathway used by cancer cells when glutamine metabolism is blocked, and thus will reveal novel therapeutic directions for targeting both glutamine metabolism and the survival pathway in order to efficiently kill tumor cells.

描述（由申请人提供）：谷氨酰胺是支持癌细胞存活和增殖的必需营养素，并且在多种肿瘤中观察到谷氨酰胺用于促进合成代谢过程的使用增加。然而，随着肿瘤的生长，谷氨酰胺催化剂的增加往往会耗尽局部供应，导致肿瘤细胞面临谷氨酰胺缺乏的时期。肿瘤细胞如何感知谷氨酰胺水平并在这些短暂的谷氨酰胺缺乏期存活尚不清楚，但这种存活是肿瘤持续存在所必需的。我们的目标是确定在低谷氨酰胺条件下调节细胞存活的分子途径，并评估同时阻断谷氨酰胺代谢和适应性生存反应作为癌症治疗的新治疗方法的潜力。我们最近已经表明，谷氨酰胺剥夺导致蛋白磷酸酶2A调节亚基B55 a的诱导，从而触发由催化C和支架A亚基和特异性诱导的B55 a亚基组成的活性PP 2A复合物的形成。这种含有B55 a的PP 2A复合物是谷氨酰胺耗尽后肿瘤细胞存活所必需的。我们进一步发现，B55 a的诱导激活了p53，这是代谢应激的重要传感器。我们的初步数据表明，B55 a激活p53通过一种机制，涉及EDD，一个以前未确定的B55 a的底物，是一个已知的负调节p53的去磷酸化。此外，我们有初步数据表明IKK？，NF-kB转录因子的主要调节因子，在谷氨酰胺缺乏时被磷酸化，并且是B55 a诱导所需的。因此，我们假设B55 a是诱导IKK？这是一种使EDD去磷酸化的途径，从而导致p53活化和癌细胞在低谷氨酰胺条件下存活。因此，针对谷氨酰胺代谢和IKK？B55 a-EDD-p53生存通路可能是一种有效的治疗肿瘤的途径。为了验证这一假设，我们提出了三个具体目标：1）确定IKK的作用？在B55 a介导的p53激活和谷氨酰胺剥夺后细胞存活; 2）检查B55 a是否通过去磷酸化EDD激活谷氨酰胺剥夺后的p53; 3）确定IKK？以及谷氨酰胺代谢抑制对不同p53状态肿瘤生长的影响。拟议的研究结果将定义IKK的分子机制和功能影响？B55 a-p53通路在谷氨酰胺剥夺代谢适应性反应中的作用多种人类癌细胞系对谷氨酰胺饥饿敏感，并且目前正在研究损害细胞利用谷氨酰胺的能力的试剂作为新型癌症疗法。拟议的研究将提供对谷氨酰胺代谢被阻断时癌细胞所使用的生存途径的更深入了解，从而揭示靶向谷氨酰胺代谢和生存途径的新治疗方向，以有效杀死肿瘤细胞。