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）染色体易位导致在已经无法治愈的疾病中较短的生存率。t（4;14）易位中过表达的候选癌基因WHSC1 （MMSET）不能在培养中转化细胞，也不能单独在小鼠中驱动肿瘤发生。对t（4;14）断点附近的2mb区域进行检查，发现125 bp的孤儿H/ACA类非编码RNA ACA11过表达，证实在t(4;14) MM细胞系和患者样本中ACA11上调。进一步的初步研究表明，ACA11作为小核核糖核蛋白（snRNP）复合物的一部分定位于核核。此外，ACA11过表达降低氧化应激反应中的活性氧（ROS）水平，并在化疗药物存在下提高细胞存活率。我们假设在t(4;14) MM中ACA11的过表达减少了ros诱导的细胞死亡，从而导致MM的发生和/或进展。本研究的最终目的是阐明ACA11在t(4;14) MM细胞系中发挥其抑制ros诱导的细胞周期抑制和细胞死亡的机制。我们假设在t(4;14) MM中ACA11 snoRNA的过表达导致参与细胞对ROS反应的特定RNA转录物剪接改变。这些选择的转录本将编码对MM中b细胞存活至关重要的RNA或蛋白质。因此，ACA11及其相关snRNP将成为MM治疗或诊断的潜在新靶点。该基金提出了三个具体目的：目的1：验证ACA11必须与snRNPs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；目的2：验证ACA11通过调节核糖体蛋白转录物的snoRNAs剪接来调节ROS水平的假设；目的3：验证ACA11过表达导致核核应激诱导的p53调节的ROS产生的抑制的假设

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