Pax5:Hematopoietic Transcription Factor Involved in ALL

描述（由申请人提供）：PAX 5是介导B淋巴细胞分化的关键转录因子之一。它在转录上激活和抑制大量基因，这些基因允许B淋巴细胞的发育并阻止分化为T淋巴细胞或骨髓细胞。我们通过SNP芯片检查了633例急性淋巴细胞白血病（ALL）样本的PAX 5改变（469例儿科病例，70例儿科复发病例，74例成人病例和50例作为异种移植物生长的ALL样本）。PAX 5基因组异常发生在H 27%的样品中，包括26个PAX 5融合到5个其他基因中的一个。该基金的总体目标是了解PAX 5改变在ALL中的临床和病理意义。特异性目标1将确定ALL中PAX 5基因组异常的频率并确定其临床影响。具体目标2将定义和理解PAX 5融合蛋白和突变蛋白在ALL中的异常功能（离体研究）。研究将包括凝胶阻滞和报告基因分析，以及测试这些蛋白质转录激活选定的靶基因的能力。将使用两种PAX 5融合蛋白[PAX 5-ETV 6; PAX 5-C20 orf 112（C20）]进行详细研究，包括使用cDNA微阵列分析和高通量ChIP测序研究对ALL中PAX 5融合蛋白的靶基因进行全基因组鉴定。结果的全面验证将使用各种技术。此外，将确定PAX 5融合蛋白对造血细胞分化的影响。具体目标3将使用体内模型来检查PAX 5融合和缺失的异常功能。首先，我们将确定PAX 5融合蛋白的表达是否通过损害分化、促进特定隔室的存活和/或增殖来破坏正常稳态淋巴细胞生成或造血？其次，我们将鉴定与PAX 5融合蛋白协同诱导ALL的继发事件。第三，我们将确定PAX 5缺失是否影响人Ph 1 + ALL异种移植物的病程。总之，我们将首次将PAX 5改变与患者的临床和病理特征相关联，并充分定义这些改变的功能意义。这些研究将对ALL的分类、提供新的治疗靶点和加深对ALL发病机制的认识具有重要意义。公共卫生相关性：PAX 5淋巴转录因子在634例ALL样本中约27%存在结构异常。我们的研究将首次深入了解PAX 5改变在急性淋巴细胞白血病（ALL）中的临床意义，并了解PAX 5改变在ALL中的功能影响。我们的研究将为急性白血病提供新的治疗靶点，并提供对ALL生物学的更深入了解。

DESCRIPTION (provided by applicant): PAX5 is one of the key transcription factors mediating differentiation of B-lymphocytes. It transcriptionally activates and represses a very large number of genes that permits the development of B-lymphocytes and prevents differentiation to T-lymphocytes or myeloid cells. We examined by SNP chip 633 acute lymphocytic leukemia (ALL) samples for PAX5 alterations (469 pediatric cases, 70 pediatric relapse cases, 74 adult cases and 50 ALL samples growing as xenografts). PAX5 genomic abnormalities occurred in H 27% of the samples including 26 PAX5 fusions to one of 5 other genes. Overall goal of the grant is to understand the clinical and pathologic significance of PAX5 alterations in ALL. Specific Aim 1 will determine frequency of genomic abnormalities of PAX5 in ALL and determine their clinical impact. Specific Aim 2 will define and understand the aberrant functions of PAX5 fusion and mutant proteins in ALL (Ex Vivo Studies). Studies will include gel retardation and reporter gene analysis as well as testing the ability of these proteins transcriptionally to activate selected target genes. Detailed studies will be done using two of the PAX5 fusions [PAX5-ETV6; PAX5- C20orf112 (C20)] including genome-wide identification of target genes of PAX5 fusion proteins in ALL using cDNA microarray analysis and high through-put ChIP sequencing studies. Comprehensive validation of the results will use a variety of techniques. Also, effect of PAX5 fusion proteins on hematopoietic cell differentiation will be determined. Specific Aim 3 will use in vivo models to examine the aberrant function of PAX5 fusions and deletions. First, we will determine if expression of PAX5 fusion proteins disrupts normal steady-state lymphopoiesis or hematopoiesis by impairing differentiation, promoting survival and/or proliferation of specific compartments? Second, we will identify secondary events that synergize with PAX5 fusion proteins to induce ALL. Third, we will determine if PAX5 deletions affect the course of human Ph1+ ALL xenografts. In summary, we will for the first time, correlate PAX5 alterations with clinical and pathological characteristics of the patients and define fully the functional significance of these alterations. These studies will have importance for classification of the disease, offer new therapeutic targets and foster our understanding of the pathogenesis of ALL. PUBLIC HEALTH RELEVANCE: PAX5 lymphoid transcription factor is structurally abnormal in approximately 27% of 634 ALL samples. Our studies will for the first time provide insights into the clinical significance of PAX5 alterations in acute lymphocyte leukemia (ALL), as well as provide an understanding of the functional ramifications of PAX5 alterations in ALL. Our studies should lead to new therapeutic targets for acute leukemias, as well as provide a greater understanding of the biology of ALL.