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

对t(4；14)断裂点周围2MB区域的检测发现，125bp的孤儿H/ACA类非编码RNA ACA11过表达，证实该RNA在t(4；14)MM细胞系和患者样本中上调。进一步的初步研究表明，ACA11定位于核仁，是小核核糖核蛋白(SnRNP)复合体的一部分。此外，在化疗药物存在的情况下，ACA11的过表达降低了氧化应激反应中的活性氧(ROS)水平，并提高了细胞的存活率。我们假设ACA11在t(4；14)MM中的过表达减少了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细胞系中抑制ROS诱导的细胞周期抑制和细胞死亡的机制。目标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标2：验证ACA11通过调节核糖体蛋白转录本中snoRNAs的剪接来调节ROS水平的假设目标3：验证ACA11过表达导致抑制核仁应激诱导的、P53调节的ROS产生的假设

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