Role of branched-chain amino catabolism in lymphopoiesis and lymphomagenesis

支链氨基分解代谢在淋巴细胞生成和淋巴瘤发生中的作用

• 批准号: 9461496
• 负责人: Mario R Fernandez
• 金额: $ 6.52万
• 依托单位: H. LEE MOFFITT CANCER CTR & RES INST
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9461496
• 关键词: Acetates; Acetoacetates; Acetyl Coenzyme A; Acute; Affect; Apoptosis; B Cell Proliferation; B-Cell Development; B-Cell Lymphomas; B-Lymphocytes; Branched-Chain Amino Acids; Burkitt Lymphoma; CD19 gene; Carbon; Catabolism; Cell Line; Cell Maturation; Cell Survival; Cells; Chronic; Citric Acid Cycle; Definity; Dependence; Development; Disease; Doxycycline; Elements; Engraftment; Enterobacteria phage P1 Cre recombinase; Enzymes; FADH2; Fetal Liver; Flow Cytometry; Generations; Genes; Genetic Transcription; Genetic study; Glucose; Glucose Transporter; Glutamates; Glutamine; Glycolysis; Goals; Growth; Hematopoietic stem cells; Homeostasis; Human; Image; Impairment; Isoleucine; Knock-out; Leucine; Lymphoma; Lymphomagenesis; Lymphopoiesis; MYCN gene; Maintenance; Malignant - descriptor; Malignant Neoplasms; Messenger RNA; Metabolic; Metabolic Pathway; Mitochondria; Modeling; Molecular; Mus; NADH; Nutrient; Oncoproteins; Pathway interactions; Pharmacology Study; Play; Precancerous Conditions; Premalignant; Proteins; Reporter; Respiration; Retroviridae; Role; Supplementation; Testing; Tetanus Helper Peptide; Tetracyclines; Therapeutic; Tissues; Trans-Activators; Transgenic Mice; Transplantation; Ursidae Family; Valine; alpha ketoglutarate; cancer cell; cancer prevention; cancer therapy; cell growth; congenic; fatty acid biosynthesis; feeding; fetal stem cell; gabapentin; human model; inhibitor/antagonist; knock-down; malignant lymphocyte; malignant state; mouse model; nanoluciferase; neoplastic; neoplastic cell; novel; novel therapeutics; overexpression; propionyl-coenzyme A; public health relevance; senescence; succinyl-coenzyme A; transcription factor; transport inhibitor; tumor; uptake

 DESCRIPTION (provided by applicant) Cancer cells rewire metabolic pathways to drive the uptake and/or catabolism of nutrients that sustain the high energetic demands needed for their growth (mass) and rapid rates of proliferation. Myc oncoproteins function as transcription factors and are activated in over half of all human cancers. Myc induces the transcription of several genes involved in glycolysis and glutaminolysis, including those encoding transporters of glucose, glutamine, lactate and branched-chain amino acids (BCAA: valine, leucine and isoleucine, via LAT1/SLC7A5). Tumors driven by Myc are addicted to and utilize L-glutamine to feed carbon intermediates into the Krebs cycle. We reasoned that Myc would also control the catabolism of BCAAs, which also provides key metabolic intermediates, specifically acetoacetate, acetyl-CoA, propionyl-CoA/succinyl-CoA, NADH and FADH2. In support of this notion, our new studies of Eμ-Myc transgenic mice, a validated model of human B cell Burkitt lymphoma (BL) that bear MYC/Ig translocations, and of BL cells, demonstrate that: (i) premalignant and neoplastic Myc-expressing B cells express elevated mRNA and protein levels of Bcat1, which is a bona fide Myc transcription target and the first enzyme in BCAA catabolism; (ii) elevated levels of several other enzymes that direct BCAA catabolism are evident in Eμ-Myc B cells and BL; (iii) BCAT1 knockdown impairs the growth, survival and clonogenicity of BL cells; (iv) treatment with Gabapentin, a known BCAT1 inhibitor, impairs the growth and survival of Eμ-Myc lymphoma and of BL, but not of normal B cells. These findings support the hypothesis that BCAT1 is necessary for the development and maintenance of Myc-driven lymphoma. In Specific Aim 1, we will use mouse models to test if Bcat1 plays essential, intrinsic roles in B lymphopoiesis and homeostasis, and if Bcat1 loss affects B cell proliferation and survival. In Specific Aim 2, we will test if Bcat1 is necessary for the development and maintenance of Myc-driven lymphomagenesis. Here we will assess the effects of Bcat1 loss: (i) on the proliferation and survival of pre-malignant Eμ-Myc B cells; (ii) on lymphoma onset and overall survival; and (iii) on maintenance of the malignant state. In Specific Aim 3, we will defin the metabolic perturbations that ensue following chronic versus acute Bcat1 loss or depletion in normal B cells, Eμ-Myc lymphomas and BL cell lines. Here we will assess changes in the steady-state levels and flux of metabolites derived from BCAAs, and possible alterations in mitochondrial respiration, glycolysis and nutrient uptake. In addition, the effects of Bcat1 loss o depletion on the sensitivity of mouse and human lymphomas to glycolytic, OXPHOS and lactate transport inhibitors will be determined. We submit that these studies will establish BCAA catabolism as a novel therapeutic vulnerability for human tumors with MYC/MYCN involvement and that they will offer new avenues for cancer prevention and treatment.

 描述（由申请人提供） 癌细胞重新连接代谢途径以驱动营养物质的摄取和/或分解代谢，以维持其生长（质量）和快速增殖所需的高能量需求。超过一半的人类癌症会诱导参与糖酵解和谷氨酰胺分解的多种基因的转录，包括编码葡萄糖、谷氨酰胺、乳酸和支链氨基酸转运蛋白的基因。 （支链氨基酸：缬氨酸、亮氨酸和异亮氨酸，由 Myc 驱动）提供关键的代谢中间体，特别是乙酰乙酸、乙酰辅酶A、丙酰辅酶A/琥珀酰辅酶A、NADH为了支持这一观点，我们对 Eμ-Myc 转基因小鼠（具有 MYC/Ig 易位的人类 B 细胞伯基特淋巴瘤 (BL) 模型）和 BL 细胞的新研究表明：(i) 癌前病变。表达 Myc 的肿瘤 B 细胞表达 Bcat1 的 mRNA 和蛋白水平升高，Bcat1 是真正的 Myc 转录靶点，也是 BCAA 分解代谢中的第一个酶 (ii) 水平升高；指导 BCAA 分解代谢的其他几种酶在 Eμ-Myc B 细胞和 BL 中很明显；(iii) BCAT1 敲低会损害 BL 细胞的生长、存活和克隆形成；(iv) 加巴喷丁（一种已知的 BCAT1 抑制剂）治疗会损害生长。和 Eμ-Myc 淋巴瘤和 BL 的存活，但不包括正常 B 细胞的存活。这些发现支持这样的假设：BCAT1 对于 Myc 驱动的发育和维持是必需的。在特定目标 1 中，我们将使用小鼠模型来测试 Bcat1 是否在 B 淋巴细胞生成和稳态中发挥重要的内在作用，并且在特定目标 2 中，我们将测试 Bcat1 是否是必要的。在这里，我们将评估 Bcat1 缺失的影响：(i) 对恶性前 Eμ-Myc B 细胞的增殖和存活；(ii) (iii) 恶性状态的维持 在具体目标 3 中，我们将定义正常 B 细胞、Eμ-Myc 淋巴瘤和 BL 中慢性与急性 Bcat1 丢失或耗竭后发生的代谢扰动。在这里，我们将评估 BCAA 代谢物的稳态水平和通量的变化，以及线粒体呼吸、糖酵解和营养吸收的可能变化。我们将确定 Bcat1 缺失或缺失对小鼠和人类淋巴瘤对糖酵解、OXPHOS 和乳酸转运抑制剂敏感性的影响，我们认为这些研究将确定 BCAA 分解代谢作为涉及 MYC/MYCN 的人类肿瘤的一种新的治疗脆弱性。它们将为癌症预防和治疗提供新途径。