Role of intrinsic apoptotic pathway in therapy-related myelodysplastic syndrome

内在凋亡途径在治疗相关骨髓增生异常综合征中的作用

基本信息

批准号：
8316565
负责人：
ELISE Peterson LU
金额：
$ 2.85万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-05-01 至 2015-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8316565
关键词：
Adult Affect Aftercare Alkylating Agents Anemia Apoptosis Apoptotic Biological Assay Blast Cell Blood Bone Marrow Bone Marrow Transplantation Cells Characteristics DNA Damage Data Defect Disease Drug Exposure Dysmyelopoietic Syndromes Dysplasia Erythroid Ethylnitrosourea Exposure to Fetal Liver Gene Expression Genes Genetic Genetic Models Genotoxic Stress Growth Hematopoietic Hepatocyte Heritability Human In Vitro Inbred Strain Incidence Lead Malignant - descriptor Malignant Neoplasms Marrow Mass Spectrum Analysis Measures Methylcellulose Modeling Molecular Profiling Mouse Strains Mus Mutation Myelogenous Myeloid Cells Nitrosourea Compounds Nucleosides Pathogenesis Pathway interactions Patients Pharmaceutical Preparations Physicians Population Populations at Risk Predisposition Radiation Relative (related person)Research Project Grants Resistance Risk Role Sampling Spleen Splenomegaly Staging Stem cells Stratification Syndrome Testing Time Transplantation White Blood Cell Count procedure cancer therapy caspase-9 cell growth chemotherapy cytopenia disorder prevention genetic risk factor genetic variant high risk in vitro Assay in vivo leukemia mutant overexpression peripheral blood prevent resistant strain response stem therapy development trait

项目摘要

DESCRIPTION (provided by applicant): Therapy-related myelodysplastic syndrome (tMDS) is a severe form of MDS caused by exposure to chemotherapeutics, particularly alkylators, used as treatment for other malignancies. tMDS makes up 10 to 20% of new MDS cases and the incidence is rising. Only a small percentage of patients exposed to alkylators develop tMDS and little is known about what predisposes patients to disease. Current evidence suggests a genetic component to predisposition. Mutations in genes associated with the DNA damage response and apoptosis have been implicated in predisposition to some therapy-related malignancies. However, aside from mutations in a few well known cancer predisposition syndromes, genetic alterations predisposing to tMDS are unknown. Identification of genetic variants that predispose to tMDS could allow stratification of patients at risk to better prevent or manage the disease. Our lab has found that susceptibility to tMDS is a heritable trait in mice, with some inbred strains being susceptible and others resistant. Preliminary data shows that altered expression of genes of the intrinsic apoptotic cascade correlates with susceptibility in this model. Furthermore, hematopoietic stem/progenitor cells (HSPCs) from susceptible strains underwent apoptosis at a lower rate than their resistant counterparts after treatment with alkylators. Thus, we hypothesize that reduced function of the intrinsic apoptotic cascade predisposes to tMDS. To test our hypothesis, we will analyze three genetic models of apoptotic deficiency in mice: loss of Caspase-9 (Casp9) or Apaf1 or overexpression of Bcl2. In Aim 1 we will take an in vitro approach to determine the functional consequences of defective apoptosis after genotoxic stress. Defective apoptosis could allow cells to survive with excessive DNA damage, giving rise to a cell population at risk for dysplasia. To test this idea, we will expose cells to N-ethyl-N-nitrosourea (ENU), an alkylator, and measure apoptosis and DNA damage. We will study fetal liver cells (FLCs) from Casp9 and Apaf1 deficient mice and adult hematopoietic cells from mice overexpressing Bcl2 (Vav-Bcl2 strain). In Aim 2, we will examine the effects of defective apoptosis on the clonogenic potential of HSPCs in vitro and in vivo. MDS is a clonal disease even in its early stages and HSPCs are the cells most likely to give rise to these dysplastic clones. We believe that defective apoptosis will affect the colony forming potential of HSPCs after alkylator treatment, resulting in the growth of a clonal population of cells that could cause disease. To determine how alterations in apoptosis impact HSPC clonogenic potential, we will perform colony forming assays in vitro and competitive repopulation assays in vivo on wild type and mutant cells. In Aim 3, we will examine the effect of defective apoptosis on the rate of MDS in mice. To determine if defects in apoptosis confer susceptibility to tMDS, we will transplant irradiated mice with bone marrow or FLCs with one of our mutations, with or without ENU treatment, and examine at three and nine months post-transplant for signs of MDS, including cytopenias and dysplastic erythroid and/or myeloid cells in the bone marrow. PUBLIC HEALTH RELEVANCE: Therapy-related myelodysplastic syndrome (tMDS) is a severe form of MDS that makes up 10-20% of new MDS cases and, as the population surviving primary cancer treatment increases, the incidence of this disease will only rise. This research project will examine the role of the intrinsic apoptotic cascade in susceptibility to tMDS in mice, to determine if genetic alterations in this cascade could predispose to tMDS in humans. Ultimately, this could lead to the identification of specific genetic risk factors for tMDS that wil give physicians a better sense of the pathogenesis of this disease and allow them to take steps to prevent it.

描述（由申请人提供）：治疗相关骨髓增生异常综合征（tMDS）是一种严重的骨髓增生异常综合征，由接触化疗药物（尤其是用于治疗其他恶性肿瘤的烷化剂）引起。 tMDS 占新发 MDS 病例的 10% 至 20%，且发病率正在上升。只有一小部分接触烷化剂的患者会患上 tMDS，而且对于患者患病的原因知之甚少。目前的证据表明遗传因素是易感性的一部分。与 DNA 损伤反应和细胞凋亡相关的基因突变与某些治疗相关恶性肿瘤的易感性有关。然而，除了一些众所周知的癌症易感综合症的突变之外，易患 tMDS 的基因改变尚不清楚。识别易患 tMDS 的基因变异可以对有风险的患者进行分层，以更好地预防或控制该疾病。我们的实验室发现，对 tMDS 的易感性是小鼠的一种遗传特征，一些近交系易感，而另一些则具有耐药性。初步数据表明，内在凋亡级联基因表达的改变与该模型的易感性相关。此外，用烷化剂处理后，敏感菌株的造血干/祖细胞（HSPC）的凋亡率低于耐药菌株。因此，我们假设内在凋亡级联功能的降低易患 tMDS。为了检验我们的假设，我们将分析小鼠细胞凋亡缺陷的三种遗传模型：Caspase-9 (Casp9) 或 Apaf1 的缺失或 Bcl2 的过度表达。在目标 1 中，我们将采用体外方法来确定基因毒性应激后细胞凋亡缺陷的功能后果。有缺陷的细胞凋亡可能使细胞在过度 DNA 损伤的情况下存活，从而导致细胞群面临发育不良的风险。为了测试这个想法，我们将细胞暴露于 N-乙基-N-亚硝基脲 (ENU)（一种烷化剂），并测量细胞凋亡和 DNA 损伤。我们将研究来自 Casp9 和 Apaf1 缺陷小鼠的胎儿肝细胞 (FLC) 以及来自过度表达 Bcl2 的小鼠（Vav-Bcl2 品系）的成年造血细胞。在目标 2 中，我们将检查细胞凋亡缺陷对体外和体内 HSPC 克隆形成潜力的影响。即使处于早期阶段，MDS 也是一种克隆性疾病，而 HSPC 是最有可能产生这些发育不良克隆的细胞。我们认为，有缺陷的细胞凋亡将影响烷化剂处理后 HSPC 的集落形成潜力，导致细胞克隆群的生长，从而导致疾病。为了确定细胞凋亡的改变如何影响 HSPC 克隆形成潜力，我们将对野生型和突变细胞进行体外集落形成测定和体内竞争性再增殖测定。在目标 3 中，我们将研究细胞凋亡缺陷对小鼠 MDS 发生率的影响。为了确定细胞凋亡缺陷是否会导致对 tMDS 的易感性，我们将用骨髓或带有我们的一种突变的 FLC 移植受辐射的小鼠，无论是否接受 ENU 治疗，并在移植后 3 个月和 9 个月检查 MDS 的迹象，包括血细胞减少症以及骨髓中发育不良的红细胞和/或骨髓细胞。公共卫生相关性：治疗相关骨髓增生异常综合征 (tMDS) 是一种严重的 MDS 形式，占新发 MDS 病例的 10-20%，并且随着初次癌症治疗后存活的人口增加，这种疾病的发病率只会上升。该研究项目将研究内在细胞凋亡级联在小鼠 tMDS 易感性中的作用，以确定该级联中的基因改变是否会导致人类罹患 tMDS。最终，这可能会导致 tMDS 特定遗传风险因素的识别，从而使医生更好地了解这种疾病的发病机制，并允许他们采取措施预防它。