BAK Autoactivation in Hematological Malignancies

血液系统恶性肿瘤中的 BAK 自动激活

基本信息

批准号：
10684892
负责人：
SCOTT H KAUFMANN
金额：
$ 35.64万
依托单位：
MAYO CLINIC ROCHESTER
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2025-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10684892
关键词：
Acute Myelocytic Leukemia American Androgen Antagonists Antineoplastic Agents Apoptosis Apoptotic BAX gene BCL-2 Protein BCL2 gene BCL2L1 gene BCL2L11 gene Binding Binding Proteins Binding Sites Biochemical Biology C-terminal Cardiolipins Cell Death Cell Line Cell Membrane Permeability Cells Cellular Stress Cessation of life Clinic Clinical Cytoplasm Data Development Disease Enzyme Inhibitor Drugs Epithelium Exposure to FDA approved Family Family member Funding Glucocorticoids Hematologic Neoplasms Hematopoietic Hematopoietic Neoplasms Higher Order Chromatin Structure Hormonal Human In Vitro Induction of Apoptosis Lead Leukemic Cell Leukocytes Life Lipid Binding Lymphoid Cell Lymphoma cell MCL1 gene MEKs Malignant Neoplasms Mediating Membrane Lipids Mitochondria Molecular Morphology Mus Myeloid Cells Nature Outer Mitochondrial Membrane PIK3CG gene PMAIP1 gene Pathway interactions Pattern Peptides Permeability Phase Play Positioning Attribute Preclinical Testing Process Protein Family Proteins Proto-Oncogene Proteins c-akt Regimen Regulation Role Sampling Seminal Specimen Stimulus Structure Testing Therapeutic Tissues antagonist anticancer treatment base biophysical analysis cancer cell cancer therapy cell type cytotoxicity design dimer drug sensitivity effective therapy experimental study improved in vivo inhibitor insight interest leukemia leukemia treatment mTOR Inhibitor member mimetics monomer novel paralogous gene postnatal research clinical testing resistance mechanism response restraint small molecule structural determinants targeted agent targeted treatment truncated BID protein tumor

项目摘要

ABSTRACT The mitochondrial apoptotic pathway plays a critical role in the response to various cellular stresses, including targeted anticancer therapies. This pathway is regulated by interactions between various members of the BCL2 family of proteins. In particular, BAX and BAK play an indispensible role in this pathway by permeabilizing the mitochondrial outer membrane (MOM). While BAX plays a predominant role in epithelial tissues, especially in postnatal life, BAK is particularly abundant in normal white blood cells, leukemia cell lines, and clinical leukemia specimens. Our previous studies have demonstrated that BAK activation is initiated by two distinct processes: i) Transient binding of BH3-only members of the BCL2 family in response to certain stimuli (e.g., transient binding of NOXA, which is upregulated in response to the NEDD8 activating enzyme inhibitor pevonedistat), and ii) concentration-dependent BAK autoactivation, a process we initially described. Once activated, BAK forms multimers that permeabilize the MOM. Our recent studies indicate that this MOM permeabilization involves the action of a C-terminal lipid binding domain that is externalized upon BAK activation and interacts with the MOM lipid cardiolipin. Counterbalancing this pro-apoptotic effect, however, BAK can be bound and neutralized by anti- apoptotic BCL2 paralogs in lymphohematopoietic cell lines and primary acute myeloid leukemia (AML) specimens. Importantly, the response of these cells to BH3 mimetics, proapoptotic small molecules that selectively bind and neutralize BCL2, BCLXL and/or MCL1, reflects which of the anti-apoptotic BCL2 family member(s) constitutively bind BAK. Collectively, these observations lead to the hypothesis that AMLs with higher BAK levels will harbor more constitutively activated BAK and will be particularly sensitive to BH3 mimetics as well as targeted therapies that activate BH3-only proteins. We now propose three aims that will test this hypothesis and provide additional insight into the action of BAK in AML during anti-leukemic therapy. First, we will assess the mechanisms responsible for high BAK expression in some AMLs but not others because high BAK expression contributes to BAK autoactivation. Second, we will determine the biochemical basis for BAK autoactivation and subsequent restraint by anti-apoptotic BCL2 family members because this partially- activated-and-then-restrained BAK is the species poised to kill leukemia cells upon exposure to BH3 mimetics and targeted therapies that upregulate BH3-only proteins. Third, we will assess the relationship between high BAK expression, BAK restraint by various anti-apoptotic BCL2 family members, and response of clinical AML to a novel pevonedistat-containing combination undergoing early phase clinical testing, thereby assessing the potential importance of constitutive BAK activation in the clinical setting. These studies, which build on our recent advances in understanding the action of BAK at the molecular level, are collectively designed to enhance current understanding of BCL2 family biology and simultaneously provide new insight into a potentially important determinant of AML sensitivity in the clinic.

抽象的线粒体凋亡途径在对各种细胞应激的反应中发挥着关键作用，包括靶向抗癌治疗。该通路受 BCL2 各成员之间相互作用的调节蛋白质家族。特别是，BAX 和 BAK 通过透化该途径在该途径中发挥着不可或缺的作用。线粒体外膜（MOM）。虽然 BAX 在上皮组织中发挥着主导作用，尤其是在出生后，BAK 在正常白细胞、白血病细胞系和临床白血病中特别丰富标本。我们之前的研究表明 BAK 激活是由两个不同的过程启动的： i) BCL2家族中仅有BH3的成员响应某些刺激的瞬时结合（例如，瞬时结合 NOXA，其响应 NEDD8 激活酶抑制剂 pevonedistat 而上调），以及 ii) 浓度依赖性 BAK 自动激活，这是我们最初描述的过程。一旦激活，BAK 就会形成使 MOM 通透的多聚体。我们最近的研究表明，这种 MOM 透化作用涉及 C 端脂质结合结构域的作用，该结构域在 BAK 激活后外化并与 MOM 相互作用脂质心磷脂。然而，为了平衡这种促凋亡作用，BAK 可以被抗凋亡因子结合并中和。淋巴造血细胞系和原发性急性髓系白血病 (AML) 中的凋亡 BCL2 旁系同源物标本。重要的是，这些细胞对 BH3 模拟物（促凋亡小分子）的反应选择性结合并中和 BCL2、BCLXL 和/或 MCL1，反映了抗凋亡 BCL2 家族的哪一个成员组成型结合BAK。总的来说，这些观察结果得出这样的假设：AML 较高的 BAK 水平将包含更多的组成型激活 BAK，并且对 BH3 特别敏感模拟物以及激活 BH3-only 蛋白的靶向疗法。我们现在提出三个目标将测试这一假设，并为抗白血病治疗期间 BAK 在 AML 中的作用提供更多见解。首先，我们将评估在某些 AML 中导致 BAK 高表达的机制，但在其他 AML 中则不然，因为 BAK 高表达有助于 BAK 自动激活。其次，我们将确定其生化基础。 BAK 自动激活和随后被抗凋亡 BCL2 家族成员抑制，因为这部分- 激活后抑制的 BAK 是一种在接触 BH3 模拟物后能够杀死白血病细胞的物种以及上调 BH3-only 蛋白的靶向疗法。第三，我们将评估高水平之间的关系。 BAK 表达、各种抗凋亡 BCL2 家族成员对 BAK 的抑制以及临床 AML 的反应一种新型的含有 pevonedistat 的组合正在进行早期临床测试，从而评估组成型 BAK 激活在临床环境中的潜在重要性。这些研究建立在我们最近的在理解 BAK 在分子水平上的作用方面取得的进展，共同旨在增强当前的了解 BCL2 家族生物学，同时提供对潜在重要的新见解临床中 AML 敏感性的决定因素。