Exploring the oncogenic potential of human APOBEC3 cytosine deaminases

探索人 APOBEC3 胞嘧啶脱氨酶的致癌潜力

• 批准号: 8876242
• 负责人: Matthew D. Weitzman
• 金额: $ 18.27万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8876242
• 关键词: Antibody Diversity; Antiviral Agents; B-Lymphocytes; Bone Marrow; Cancer cell line; Cell Lineage; Cell Nucleus; Cell Proliferation; Cell Survival; Cell physiology; Cells; Chronic Myeloid Leukemia; Cytosine; Cytosine deaminase; DNA; DNA Damage; DNA Double Strand Break; DNA Repair Inhibition; DNA Sequence; DNA Sequence Alteration; DNA Sequence Rearrangement; DNA lesion; Deaminase; Deamination; Development; Drosophila pros protein; Drug resistance; Environment; Enzymes; Etiology; Family; Flow Cytometry; Frequencies; Gene Rearrangement; Genome; Genome Stability; Goals; Hematopoietic; Homeostasis; Homologous Gene; Human; Human Genome; Imatinib; Immunoglobulin Class Switching; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; Individual; Induced Mutation; Interferons; Ki-1 Large-Cell Lymphoma; Knowledge; Lead; Lesion; Malignant - descriptor; Malignant Childhood Neoplasm; Malignant Neoplasms; Modeling; Monitor; Mus; Mutate; Mutation; Neuroblastoma; Non-Small-Cell Lung Carcinoma; Normal Cell; Nucleotides; Oncogenic; Outcome; Pediatric Hospitals; Pharmaceutical Preparations; Phenotype; Philadelphia; Point Mutation; Population; Process; Proteins; Research; Research Personnel; Research Project Grants; Research Proposals; Resistance; Retroviridae; Role; Single-Stranded DNA; Somatic Mutation; Spectral Karyotyping; System; Testing; Uracil; Viral Genome; Virus Diseases; activation-induced cytidine deaminase; aged; anaplastic lymphoma kinase; anticancer research; bcr-abl Fusion Proteins; cancer cell; cancer therapy; chemotherapeutic agent; drug sensitivity; genome integrity; insight; mouse model; neoplastic cell; novel; novel therapeutic intervention; pathogen; public health relevance; response; targeted cancer therapy; targeted treatment; therapy resistant; treatment strategy; tumor; tumor initiation; tumor progression; tumorigenesis; tumorigenic; virus host interaction

 DESCRIPTION (provided by applicant): Cancer is driven by somatically acquired point mutations resulting from DNA nucleotide damage, and genomic rearrangements arising from DNA double strand breaks (DSBs). The etiology of these DNA lesions remains unclear, but it is known that cellular processes that increase rates of DNA damage and frequencies of DSBs can induce lesions that initiate transformation. Mutations and genomic rearrangements that develop in a malignancy may also result in clonal populations that are either resistant or sensitive to particular chemotherapeutic agents. Identifying cellular enzymes capable of generating DNA lesions that drive malignant progression will suggest targets for development of novel drugs to treat therapy-resistant cancers. The human genome encodes seven APOBEC3 (hA3) enzymes that normally induce mutations and DSBs. These hA3 enzymes, and the related AID protein, constitute a family of deaminases that convert cytosines to uracils in single-stranded DNA substrates. The APOBEC3 proteins (hA3A through hA3H) mutate viral genomes and thereby confer antiviral functions. AID induces mutations and DSBs in immunoglobulin loci in B lymphocytes to generate antibody diversity and thereby protect humans from pathogens. Accumulating evidence suggests that "off-target" APOBEC3/AID activities induce mutations and genomic rearrangements that drive initiation, progression, and drug-resistance of tumors, but may also present opportunities for new cancer treatment strategies. The objectives of this proposal are to assess the impact of hA3 expression on (i) proliferation, genome integrity, and malignant transformation in mouse models and (ii) acquisition of drug resistance and sensitivity in human cancer cells. We focus on hA3A and hA3B since these active cytosine deaminases have been shown to cause mutations and DSBs in the genome when over-expressed in human cells. The hA3A protein is expressed in hematopoietic cells and can be induced to high levels by virus infection and interferon, while hA3B is broadly expressed but is upregulated in a number of human cancers. Our hypothesis is that sustained expression of hA3A or hA3B results in deamination of the host cellular genome, inducing a cancer- promoting mutator phenotype and/or development of drug-resistant cancers. We will test our hypothesis by assessing the impact of hA3A and hA3B expression on mouse hematopoietic cells (Aim 1) and the ability of hA3A and hA3B to cause drug-resistant cancer cells, yet also render cancer cells sensitive to inhibition of DNA repair factors (Aim 2). The rationale for the proposed studies is that individual expression of hA3A or hA3B in cells that lack endogenous protein will reveal insights into how hA3 proteins contribute to initiation and drug- resistance of human cancers. The outcomes of these Aims will reveal the extent to which hA3A and hA3B confer pro-oncogenic activities in tumor initiation, progression, or acquisition of therapy resistance, and will suggest that inhibitig hA3 protein activities may limit acquisition of tumorigenic mutations and drug resistance.

 描述（由申请人提供）：癌症是由DNA核苷酸损伤引起的体细胞获得性点突变和DNA双链断裂（DSB）引起的基因组重排驱动的。这些DNA损伤的病因尚不清楚，但已知增加DNA损伤速率和DSB频率的细胞过程可诱导引发转化的损伤。在恶性肿瘤中发生的突变和基因组重排也可能导致对特定化疗剂耐药或敏感的克隆群体。鉴定能够产生DNA损伤的细胞酶，这些DNA损伤驱动恶性进展，这将为开发治疗耐药癌症的新药提供靶点。人类基因组编码七种APOBEC 3（hA 3）酶，通常诱导突变和DSB。这些hA 3酶和相关的AID蛋白构成了一个脱氨酶家族，该家族在单链DNA底物中将胞嘧啶转化为尿嘧啶。APOBEC 3蛋白（hA 3A至hA 3 H）使病毒基因组突变，从而赋予抗病毒功能。AID诱导B淋巴细胞中免疫球蛋白基因座的突变和DSB，以产生抗体多样性，从而保护人类免受病原体的侵害。越来越多的证据表明，“脱靶”APOBEC 3/AID活性诱导突变和基因组重排，从而驱动肿瘤的发生、进展和耐药性，但也可能为新的癌症治疗策略提供机会。本提案的目的是评估hA 3表达对（i）小鼠模型中的增殖、基因组完整性和恶性转化以及（ii）人类癌细胞获得耐药性和敏感性的影响。我们专注于hA 3A和hA 3B，因为这些活性胞嘧啶脱氨酶已被证明在人类细胞中过度表达时会导致基因组中的突变和DSB。hA 3A蛋白在造血细胞中表达，并且可以通过病毒感染和干扰素诱导至高水平，而hA 3B广泛表达，但在许多人类癌症中上调。我们的假设是hA 3A或hA 3B的持续表达导致宿主细胞基因组的脱氨基，诱导癌症促进突变子表型和/或耐药性癌症的发展。我们将通过评估hA 3A和hA 3B表达对小鼠造血细胞的影响（Aim 1）以及hA 3A和hA 3B导致耐药癌细胞的能力来测试我们的假设，同时也使癌细胞对DNA修复因子的抑制敏感（Aim 2）。拟议研究的理由是， hA 3A或hA 3B在缺乏内源性蛋白的细胞中的表达将揭示hA 3蛋白如何有助于人类癌症的起始和耐药性。这些目的的结果将揭示hA 3A和hA 3B在肿瘤起始、进展或获得治疗抗性中赋予原癌活性的程度，并将表明抑制hA 3蛋白活性可能限制肿瘤发生突变和药物抗性的获得。