TELOMERASE INACTIVATION BY RNASE L SIGNALS CELL DEATH

RNA酶 L 导致的端粒酶失活发出细胞死亡信号

• 批准号: 6443849
• 负责人: ROBERT H SILVERMAN
• 金额: $ 9.16万
• 依托单位: CLEVELAND CLINIC FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2002-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6443849
• 关键词: antineoplastics; antisense nucleic acid; apoptosis; biological signal transduction; chemical stability; double stranded RNA; endoribonucleases; enzyme inhibitors; enzyme mechanism; gene expression; gene induction /repression; laboratory mouse; neoplastic growth; nucleic acid metabolism; nucleic acid sequence; protein tyrosine kinase; synthetic nucleotide; telomerase; transcription factor

RNase L, a ubiquitous endoribonuclease in the IFN system, has been harnessed for the selective and catalytic cleavage of RNA targets that function in signal transduction and oncogenesis. Chimeric oligonucleotides (ODNs) are chemically-synthesized with a 2',5'-tetraadenylate activator (2- 5A) of RNase L covalently coupled to antisense ODNs. In essence, the 2- 5A portion of the chimera binds and activates RNase L while the antisense arm of the ODN binds the RNA target thus directing RNase L to degrade the RNA specifically. The goal of this project is to determine the molecular mechanism for the tumoricidal activity of 2-5A-antisense directed against human telomerase RNA (hTR) and thus better understand the role of telomerase in cancer and cell immortality. The hypothesis to be tested is that the tumoricidal effect of 2-5A-anti-hTR is due to inhibition of telomerase function which directly or indirectly triggers an apoptotic response. Different chemical forms of 2-5A-antisense will be designed to enhance biostability, hybridization affinity, cellular uptake and RNase L activation ability. We will probe the signaling events which lead to apoptosis in tumor cells treated with 2-5A-antisense to telomerase RNA. The contributions of caspases, STAT 1, and bcl-2 family members will be determined. Effects of 2-5A-antisense on global gene expression patterns, telomere length and chromosome stability will be determined. Because human but not murine RNase L is activated by 2-5A-antisense, an animal model for studying the anti-tumor effects of 2-5A-antisense against telomerase RNA will be generated by expressing human RNase L in RNase L-/- mice. The effects of IFN induction of RNase L will be determined in 2-5A-antisense treated cells and mice. Because 2-5A-anti- hTR is a potent experimental therapeutic agent for cancer, this proposal has the potential to make an impact on intractable forms of cancer, such as malignant glioma.

RNase L 是 IFN 系统中普遍存在的核糖核酸内切酶，已被用于选择性和催化切割在信号转导和肿瘤发生中发挥作用的 RNA 靶标。嵌合寡核苷酸 (ODN) 是用与反义 ODN 共价偶联的 RNase L 的 2',5'-四腺苷酸激活剂 (2-5A) 化学合成的。本质上，嵌合体的 2-5A 部分结合并激活 RNase L，而 ODN 的反义臂结合 RNA 靶标，从而指导 RNase L 特异性降解 RNA。该项目的目标是确定针对人端粒酶RNA（hTR）的2-5A反义分子的杀肿瘤活性的分子机制，从而更好地了解端粒酶在癌症和细胞永生中的作用。待检验的假设是2-5A-抗hTR的杀肿瘤作用是由于抑制端粒酶功能而直接或间接触发细胞凋亡反应。 2-5A-反义的不同化学形式将被设计来增强生物稳定性、杂交亲和力、细胞摄取和RNase L激活能力。我们将探讨导致用端粒酶 RNA 2-5A 反义处理的肿瘤细胞凋亡的信号转导事件。将确定 caspase、STAT 1 和 bcl-2 家族成员的贡献。将确定 2-5A-反义对整体基因表达模式、端粒长度和染色体稳定性的影响。由于2-5A-反义体激活人类而非小鼠RNase L，因此通过在RNase L-/-小鼠中表达人RNase L来产生用于研究2-5A-反义体针对端粒酶RNA的抗肿瘤作用的动物模型。 IFN 诱导 RNase L 的效果将在 2-5A 反义处理的细胞和小鼠中测定。由于 2-5A-抗 hTR 是一种有效的实验性癌症治疗剂，因此该提案有可能对恶性神经胶质瘤等难治性癌症产生影响。