The Role of MMSET in the Pathogenesis and Progression of Lymphoid Malignancy

 描述（由申请人提供）：我们研究了MMSET（也称为WHSC 1或NSD 2）蛋白，一种组蛋白赖氨酸甲基转移酶，通过其在多发性骨髓瘤（MM）中与免疫球蛋白基因座异常过表达的重排鉴定。MMSET的过表达导致染色质修饰和基因表达的显著变化，并刺激细胞生长。MMSET过表达还与前列腺癌、肺癌和神经母细胞瘤中的异常细胞生长和侵袭特性有关。最近，我们和其他人描述了急性淋巴细胞白血病（ALL）中MMSET的SET结构域中的复发性点突变（E1099 K）。这种突变的重要性正在增长，因为基因组测序显示，这种突变存在于约10%的套细胞淋巴瘤（MCL）病例中，并且在约10-20%的复发性儿科ALL病例中发现。总的来说，这些数据表明，MMSET及其调节的途径代表了MM和其他恶性肿瘤的治疗靶点。我们的总体假设是MMSET的过度表达或功能突变的获得改变了基因调控，导致MM的发病机制和ALL的进展。虽然一些靶基因可能在这些肿瘤中共同激活，但我们的初步数据表明，MMSET突变使ALL中的一组独特基因失调。通过构建E1099 K突变的基因工程细胞系和小鼠模型，我们将确定MMSETE 1099 K影响基因表达的详细分子机制，确定关键靶基因和途径，并发现癌症治疗的新治疗机会。我们的具体目标将是：目标1：评估多发性骨髓瘤中多发性骨髓瘤样病变的复发性点突变的生物学活性。我们将确定这种蛋白质的作用机制以及它如何改变组蛋白甲基化水平。使用新制备的CRISPR/CAS9编辑的细胞系，我们将确定突变的MMSET如何调节细胞生长和对治疗的反应。目的2：明确MMSET致癌突变影响的遗传靶点和途径。初步数据表明，与MM中受影响的基因相比，突变MMSET激活ALL中不同的一组基因。使用基因编辑的细胞系，我们将确定突变如何改变整个基因组的染色质构型，并确定其致癌作用的关键基因和途径。目的3：评价突变MMSET与已知MM和ALL癌基因协同作用的能力。我们将一个新创建的敲入小鼠表达MMSETE 1099 K与建立的小鼠模型的ALL和MM，以确定这种疾病的等位基因如何驱动发病机制和疾病的进展。

 DESCRIPTION (provided by applicant): We have studied the MMSET (also known as WHSC1 or NSD2) protein a histone lysine methyltransferase identified by its rearrangement with the immunoglobulin locus aberrant overexpression in multiple myeloma (MM). Overexpression of MMSET leads to dramatic shifts in chromatin modification and gene expression and stimulates cell growth. MMSET overexpression has also been linked to aberrant cell growth and invasive properties in prostate, lung cancer and neuroblastoma. More recently we and others described a recurrent point mutation (E1099K) in the SET domain of MMSET in acute lymphoblastic leukemia (ALL). The importance of this mutation is growing as genome sequencing showed that this mutation in present in ~10% of cases of mantle cell lymphoma (MCL) and is found in ~10-20% of cases of relapsed pediatric ALL. Collectively these data indicate that MMSET and the pathways it regulates represent therapeutic targets in MM and other malignancies. Our overarching hypothesis is that overexpression or gain of function mutations of MMSET alter gene regulation leading to the pathogenesis of MM and to the progression of ALL. While some target genes may be activated in common across these tumors, our preliminary data suggests that MMSET mutation dysregulates a unique set of genes in ALL. By constructing genetically engineered cell line and mouse models of models of the action of the E1099K mutation we will ascertain the detailed molecular mechanisms, by which MMSETE1099K affects gene expression, identify critical target genes and pathways and uncover new therapeutic opportunities for cancer treatment. Our specific aims will be: Aim 1: Evaluate the Biological Activity of a Recurrent Point Mutation of MMSET in Malignancy. We will determine the mechanism of action of this protein and how it alters histone methylation levels. Using newly prepared CRISPR/CAS9 edited cell lines we will determine how mutant MMSET modulates cell growth and response to therapy. Aim 2: Define the Genetic Targets and Pathways Affected by Oncogenic Mutations of MMSET. Preliminary data suggest that mutant MMSET activates a different set of genes in ALL compared to those affected in MM. Using genetically edited cell lines, we will determine how the mutation alters chromatin configuration across the genome and identify critical genes and pathways of its oncogenic action. Aim 3: Evaluate the Ability of Mutant MMSET to Collaborate with Known MM and ALL Oncogenes. We will cross a newly created knockin mouse expressing MMSETE1099K with established mouse models of ALL and MM to determine how this disease allele may drive pathogenesis and progression of disease.