ROLE OF ACA11, AN ORPHAN SMALL NUCLEOLAR RNA IN RESISTANCE TO CANCER CHEMOTHERAPY

描述（由申请人提供）：在20%的多发性骨髓瘤（MM）病例中发现的t（4;14）染色体易位导致本已无法治愈的疾病的生存率较短。从t（4;14）易位中过度表达的候选癌基因WHSC 1（MMSET）不能在培养中转化细胞或单独驱动小鼠的肿瘤发生。对t（4;14）断点周围的2 MB区域的检查揭示了125 bp孤儿H/ACA类非编码RNA ACA 11的过表达，ACA 11被证实在t（4;14）MM细胞系和患者样品中上调。进一步的初步研究表明，ACA 11定位于核仁作为一个小的核核糖核蛋白（snRNP）复合物的一部分。此外，ACA 11过表达降低了对氧化应激的反应性氧簇（ROS）水平，并增加了化疗药物存在下的细胞存活率。我们假设t（4;14）MM中ACA 11的过表达减少了ROS诱导的细胞死亡，从而导致MM的发展和/或进展。本提案的最终目标是阐明ACA 11对t（4;14）MM细胞系中ROS诱导的细胞周期抑制和细胞死亡发挥抑制作用的机制。我们假设t（4;14）MM中ACA 11 snoRNA的过表达导致参与细胞对ROS反应的特定RNA转录物的剪接改变。这些选定的转录本将编码对MM中B细胞存活至关重要的RNA或蛋白质。因此，ACA 11及其相关的snRNP将成为MM治疗或诊断的潜在新靶点。提出了该资助的三个具体目标：目标1：验证ACA 11必须与snRNP相互作用以发挥其对氧化应激诱导的细胞死亡的抑制作用的假设目标2：验证ACA 11通过调节核糖体蛋白转录物的snoRNA的剪接来调节ROS水平的假设目标3：为了验证ACA 11过表达导致核仁应激诱导的p53调节的ROS产生抑制的假设，

DESCRIPTION (provided by applicant): The t(4;14) chromosomal translocation found in 20% of multiple myeloma (MM) cases leads to a shorter survival rate in an already incurable disease. The candidate oncogene overexpressed from the t(4;14) translocation, WHSC1 (MMSET), is unable to transform cells in culture or drive tumorigenesis in mice on its own. Examination of a 2 MB region around the t(4;14) breakpoint revealed the overexpression of a 125 bp orphan H/ACA class non-coding RNA, ACA11, which was confirmed to be up-regulated in t(4;14) MM cell lines and patient samples. Further preliminary studies demonstrate ACA11 localizes to the nucleolus as part of an small nuclear ribonucleoprotein (snRNP) complex. In addition, ACA11 overexpression reduces the levels of reactive oxygen species (ROS) in response to oxidative stress and increases cell survival in the presence of chemotherapeutic agents. We hypothesize that the overexpression of ACA11 in t(4;14) MM reduces ROS-induced cell death leading to the development and/or progression of MM. The ultimate goal of this proposal is to elucidate the mechanism by which ACA11 exerts its inhibitory effects on ROS-induced cell cycle inhibition and cell death in t(4;14) MM cell lines. We hypothesize that the overexpression of the ACA11 snoRNA in t(4;14) MM results in the altered splicing of specific RNA transcripts involved in the cellular response to ROS. These selected transcripts will encode either RNA or proteins critical for B-cell survival in MM. Therefore, ACA11 and its associated snRNP's will be potential novel targets for MM treatment or diagnosis. Three specific aims of the grant are proposed: Aim 1: To test the hypothesis that ACA11 must interact with snRNPs to exert its inhibition of oxidative stress induced cell death Aim 2: To test the hypothesis that ACA11 regulates ROS levels through modulating splicing of snoRNAs from ribosomal protein transcripts Aim 3: To test the hypothesis that overexpression of ACA11 leads to an inhibition of nucleolar stress-induced, p53-regulated ROS production