Role of DNA Double Strand Break Response in Suppression of Thymic Lymphoma

DNA 双链断裂反应在抑制胸腺淋巴瘤中的作用

• 批准号: 7780950
• 负责人: Frederick W. Alt
• 金额: $ 44.71万
• 依托单位: DANA-FARBER CANCER INST
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7780950
• 关键词: ATM deficient; ATM gene; Address; Affect; Alleles; Am 80; Cell Culture Techniques; Chromosomal translocation; Chromosomes; Chromosomes, Human, Pair 12; Chromosomes, Human, Pair 14; Collaborations; DNA; DNA Double Strand Break; DNA Repair Pathway; DNA Sequence Rearrangement; Development; Double Strand Break Repair; Enhancers; Frequencies; Gene Targeting; Generations; Genes; Genetic Recombination; Genomics; Goals; Human; LMO2 gene; Lead; Location; Lymphomagenesis; Malignant Neoplasms; Malignant lymphoid neoplasm; Measures; Mediating; Modeling; Molecular; Monitor; Mus; Mutant Strains Mice; Mutate; Nature; Nonhomologous DNA End Joining; Oncogenes; Oncogenic; Pathway interactions; Pattern; Population; Process; Protein p53; Proto-Oncogenes; Recurrence; Relative (related person); Research Personnel; Residual state; Role; T-Cell Development; T-Cell Lymphoma; T-Cell Receptor; T-Lymphocyte; Testing; Thymic Lymphoma; Tumor Suppressor Genes; V(D)J Recombination; Work; base; c-myc Genes; comparative genomic hybridization; fusion gene; mouse model; novel; prevent; programs; repaired; response; thymocyte; tumor

Immature T cell lymphomas comprise a significant portion of human lymphoid malignancies. Many of these tumors harbor recurrent chromosomal translocations and related aberrations that either activate proto-oncogenes, inactivate tumor suppressor genes, or create novel oncogenic fusion genes. Most oncogenic translocations of human immature T cell lymphomas are thought to occur via errors in the repair of DNA double strand breaks (DSBs) introduced at T cell receptor (TCR) loci during V(D)J recombination and/or general DSBs at other genomic locations. We propose to elucidate functions of the DSB response in suppression of translocations associated with T cell lymphomas and to generate novel mouse models for human T cell lymphoma. We also propose to elucidate molecular mechanisms that underlie recurrent translocations in T cell lymphomas, including how spatial proximity, DSB frequency and DNA repair pathway availability affect translocation patterns. Recurrent chromosome 14 translocations in the vicinity of the TCRa/d locus are found frequently in ATM-deficient mouse thymic lymphomas and similar translocations are found in human T cell lymphomas that have mutated ATM genes. In this regard, we find that a region 10 Mb upstream of the TCRa/d locus is highly amplified on chromosome 14 in most ATM-deficient mouse thymic lymphomas. We propose to fully investigate this recurrent translocation/amplification in ATM-deficient T cell lymphomas i) to elucidate mechanistic aspects, including potential roles of TCRa/d locus V(D)J recombination and TCRa/d enhancers (with Project 2, Harald von Boehmer), ii) to identify target oncogene(s) (with Project 5, Rick Young), and iii) to determine relevance to human T cell lymphomas (with Project 1 Tom Look). For translocations, participating loci on different chromosomes must be broken and must be in close proximity for joining. Thus we propose to test the hypothesis that frequent activation of certain proto-oncogenes via translocation to TCR loci in human, but not mouse, T cell lymphomas may reflect the relative frequency of DNA DSBs and the spatial proximity of target loci. To address this question, we will employ various approaches including 3D FISH and the generation of novel cell culture and mouse models in which DNA breaks are introduced into target T-cell oncogenes during T-cell development. We will also employ these models to test our hypothesis that ATM and its substrates (e.g., H2AX) prevent translocations resulting from aberrant V(D)J recombination by stabilizing TCR locus DSBs introduced during V(D)J recombination. Together, these studies should allow us to address long-standing questions regarding the mechanisms underlying chromosomal translocation targeting in T-ALL and other cancers.

未成熟T细胞淋巴瘤是人类淋巴系统恶性肿瘤的重要组成部分。其中许多肿瘤存在反复的染色体易位和相关的异常，这些异常要么激活原癌基因，要么失活肿瘤抑制基因，要么产生新的癌基因融合基因。大多数人未成熟T细胞淋巴瘤的致癌易位被认为是由于V(D)J重组过程中T细胞受体(TCR)基因座引入的DNA双链断裂(DSB)修复错误和/或其他基因组位置的一般DSB所致。我们建议阐明DSB响应在 抑制与T细胞淋巴瘤相关的易位，并建立新的人类T细胞淋巴瘤小鼠模型。我们还建议阐明T细胞淋巴瘤复发易位的分子机制，包括空间邻近、DSB频率和DNA修复途径的可用性如何影响易位模式。在ATM缺陷的小鼠胸腺淋巴瘤中，TCRA/d基因附近的14号染色体反复易位是常见的，在ATM基因突变的人类T细胞淋巴瘤中也发现了类似的易位。在这方面，我们发现在大多数ATM缺陷的小鼠胸腺淋巴瘤中，TCRA/d基因上游10Mb的区域在14号染色体上高度扩增。我们建议全面研究ATM缺陷性T细胞淋巴瘤的这种反复易位/扩增，以阐明机制方面，包括TCRA/d位点V(D)J重组和TCRA/d增强子的潜在作用(与项目2，Harald von Boehmer)，II)识别目标癌基因(S)(与项目5，Rick Young)，以及iii)以确定与人类T细胞淋巴瘤的相关性(与项目1 Tom Look)。对于易位，不同染色体上的参与位点必须被打断，并且必须非常接近才能连接。因此，我们建议检验这样一种假设，即某些原癌基因通过易位到TCR位点的频繁激活可能反映了DNADSB的相对频率和靶点的空间接近。为了解决这个问题，我们将采用各种方法，包括3D FISH和产生新的细胞培养和小鼠模型，在这些模型中，DNA断裂被引入到T细胞发育过程中的目标T细胞癌基因中。我们还将利用这些模型来检验我们的假设，即ATM及其底物(例如，H_2AX)通过稳定V(D)J重组过程中引入的TCR基因座DSB来防止V(D)J重组异常引起的易位。总之，这些研究应该使我们能够解决长期存在的问题，即T-ALL和其他癌症中染色体易位靶向的潜在机制。