MOLECULAR TARGETS OF TRANSLOCATION T(4;14) IN MULTIPLE MYELOMA PATHOGENESIS

多发性骨髓瘤（MM）是美国第二常见的血液恶性肿瘤， 每年约有14，500名美国人，占所有癌症死亡人数的2% （SEER.cancer.gov）中找到。MM是一种分泌抗体的浆B细胞的不可治愈的恶性肿瘤，其病因是 不太了解。染色体易位t（4;14）（p16.3;q32.33）与总生存期缩短相关 在15%的MM患者中发现。4p16.3处的候选癌基因WHSC 1（MMSET）编码组蛋白 甲基转移酶作为t（4;14）在MM细胞中过度表达的结果。令人惊讶的是，过度表达 WHSC 1 cDNA在小鼠中表达时不能转化细胞系或诱导任何表型。我们 鉴定了ACA 11，一种孤儿盒H/ACA小核仁RNA（snoRNA），编码于WHSC 1中， 4p16.3，在携带t（4;14）的细胞系和MM患者样本中上调。ACA 11调节氧化 应激，有助于MM细胞生长并赋予对化疗的抗性。ACA 11是一种新的致癌基因， 非编码RNA，也在其他癌症类型中表达。 与t（4;14）共同参与骨髓瘤发生的突变尚不清楚，但13号染色体缺失 在MM中，Del（13）与t（4;14）高度相关。在85-94%的t（4;14）患者中发现Del（13）， 与预后不良有关。我们将MM患者样本中的最小缺失区域映射到 视网膜母细胞瘤（RB 1）基因位于13 q14。我们的模型是ACA 11表达与RB 1缺失协同作用， 我们建议描述ACA 11在多发性骨髓瘤中的作用。具体目标1： ACA 11与组蛋白甲基转移酶WHSC 1之间的合作。我们假设ACA 11 在骨髓瘤发病机制中与MMSET蛋白表达协同作用，WHSC 1组蛋白 甲基转移酶活性是合作所必需的。我们将共表达野生型WHSC 1或HMT-死亡 在细胞系和小鼠中单独或与ACA 11一起的WHSC 1。具体目标2：目标2：ACA 11如何影响水平 ROS和化疗敏感性的关系这些需要什么样的ACA 11域和合作伙伴 影响？我们的数据表明，ACA 11调节活性氧和化疗耐药性， 骨髓瘤我们将确定ACA 11的哪些残基是该功能所需的。我们假设 ACA 11的RNA结合残基将对ACA 11的氧化应激功能起作用，但ACA 11的RNA结合残基将对ACA 11的氧化应激功能起作用。 蛋白质结合域将是关键的。具体目标3：ACA 11介导的恶性转化 Rb 1缺失的背景。所有MM患者中50%的13号染色体长臂缺失，所有MM患者中90%的13号染色体长臂缺失。 t（4;14）的患者。我们假设RB 1缺失与t（4;14）在骨髓瘤发病机制中协同作用。 我们将测试ACA 11和WHSC 1表达对B细胞发育、氧化应激和免疫应答的影响。 在Rb 1缺乏的背景下转化。最后，我们将[通过RNA鉴定t（4;14）的靶基因- 对患者样品进行测序。对t（4;14）如何促进骨髓瘤的理解， 对癌症生物学的广泛影响，并将促进新的治疗方法的发展， 预后不良的MM患者。

Multiple Myeloma (MM) is the second most common hematologic malignancy in the United States, diagnosed in approximately 14,500 Americans each year, and is responsible for 2% of all cancer deaths (SEER.cancer.gov). MM is an incurable malignancy of antibody-secreting plasma B-cells whose etiology is poorly understood. Chromosomal translocation t(4;14)(p16.3;q32.33) is associated with shorter overall survival and is found in 15% of MM patients. The candidate oncogene WHSC1 (MMSET) at 4p16.3 encodes a histone methyltransferase over-expressed as a result of the t(4;14) in MM cells. Surprisingly, over-expression of WHSC1 cDNA's failed to transform cell lines or to induce any phenotype when expressed in mice. We identified ACA11, an orphan box H/ACA small nucleolar RNA (snoRNA) encoded hosted within WHSC1 at 4p16.3, to be up-regulated in cell lines and MM patient samples harboring t(4;14). ACA11 modulates oxidative stress, contributes to MM cell growth and confers resistance to chemotherapy. ACA11 is a novel oncogenic non-coding RNA and is also expressed in other cancer types. Mutations that cooperate with t(4;14) in myeloma initiation are unknown, but chromosome 13 deletions (Del(13)) are highly correlated with the t(4;14) in MM. Del(13) is found in 85-94% of patients with t(4;14) and associated with poor prognosis. We mapped a minimally deleted region in MM patient samples to the retinoblastoma (RB1) gene at 13q14. Our model is that ACA11 expression cooperates with RB1 loss to cause poor-prognosis MM. We propose to characterize the role of ACA11 in multiple myeloma. Specific Aim 1: Cooperation between ACA11 and the histone methyltransferase WHSC1. We hypothesize that ACA11 cooperates with MMSET protein expression in myeloma pathogenesis and that WHSC1 histone methyltransferase activity is required for cooperation. We will co-express wild-type WHSC1 or HMT-dead WHSC1 alone or with ACA11 in cell lines and mice. Specific Aim 2: Aim 2: How does ACA11 affect levels of ROS and sensitivity to chemotherapy? What domains and partners of ACA11 are required for these effects? Our data suggest that ACA11 modulates reactive oxygen species and resistance to chemotherapy in myeloma. We will determine which residues of ACA11 are required for this function. We hypothesize that ACA11 RNA binding residues will be dispensable for ACA11's oxidative stress function, but that ACA11's protein-binding domains will be critical. Specific Aim 3: ACA11-mediated malignant transformation in the context of Rb1 deletion. The long arm of chromosome 13 is deleted in 50% of all MM patients, and in 90% of patients with the t(4;14). We hypothesize that RB1 loss cooperates with the t(4;14) in myeloma pathogenesis. We will test the effects of ACA11 and WHSC1 expression on B-cell development, oxidative stress and transformation in the context of Rb1 deficiency. Lastly, we will [identify target genes of t(4;14) by RNA- sequencing patient samples.] A betting understanding of how the t(4;14) contributes to myelomagenesis has broad implications to cancer biology and will facilitate the development of novel therapeutic approaches to patients with poor-prognosis MM.