UB-PROTEOLYSIS OF ALKYLTRANSFERASE IN GLIOMA THERAPY

神经胶质瘤治疗中烷基转移酶的 UB 蛋白水解

• 批准号: 6342034
• 负责人: KALKUNTE S SRIVENUGOPAL
• 金额: $ 6.84万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6342034
• 关键词: alkyltransferase; antineoplastics; athymic mouse; carmustine; combination cancer therapy; cytotoxicity; enzyme activity; enzyme inhibitors; gene expression; glioma; human therapy evaluation; human tissue; lymphocyte; messenger RNA; neoplasm /cancer chemotherapy; neoplasm /cancer remission /regression; neoplastic cell; nitrosourea; northern blottings; pharmacokinetics; proteasome; proteolysis; tissue /cell culture; ubiquitin; western blottings

DESCRIPTION: (Applicant's Abstract) Pediatric and adult brain tumors are among the most therapeutically unresponsive and lethal of human cancers and their incidence continues to rise in the United States. A major reason for this therapeutic failure is the overexpression of O6-alkylguanine-DNA alkyltransferase (AGT), which prevents the formation of G-C cross-links in DNA by the chloroethylnitrosourea (CENU) class of drugs. Currently, a strategy involving the inactivation of AGT by O6-benzylguanine (BG) followed by CENU treatment has shown excellent promise, and clinical trials are underway for its exploitation. However, an extended suppression of AGT activity is necessary to achieve therapeutic efficacy and a rapid repletion of AGT occurring soon after BG treatment poses a potentially severe limitation to successful chemotherapy. Based on the applicant's recent studies of AGT proteolysis through the ubiquitin (ub)-proteasome pathway and preliminary studies showing the inhibition of AGT regeneration by proteasome blockers, the primary goal of this project is to further enhance the BG-based CENU therapy by preventing the repletion of AGT. The applicant's hypothesis is that ubiquitin-mediated break-down of inactive AGT triggers a regeneration of active AGT by enhancing its translation in BG-treated cells. The applicant proposes that the ub-proteasome pathway regulates both the proteolysis and subsequent regeneration of AGT after BG treatment and that specific inhibitors of this pathway will reduce the repletion of AGT to enable increased sensitization of glioma cells to BG-CENU regimen. The specific aims are: 1) to quantitate the expression of ub-proteasome components in relation to AGT activity, the levels of AGT proteolysis after BG treatment, and the rate and extent of subsequent AGT regeneration in human glioma cell lines; 2) to examine the ub-requirement for AGT regeneration in a cell line, temperature-sensitive for ub-activation, and study increased translational efficiency of AGT in BG-treated glioma cells; 3) to evaluate ub-components and AGT in primary gliomas and lymphocytes, and to treat glioma cells and glioma xenografts in nude mice with specific inhibitors of the ub-proteasome pathway and examine AGT regeneration and BCNU cytotoxicity following BG treatment. Overall, this project promises to provide novel information on the biochemical modulation of AGT in BG-treated cells and rationalize alternative strategies to improve AGT-targeted chemotherapy of human brain tumors and other tumor types.

描述：(申请人摘要)儿童和成人脑肿瘤 在治疗上最无效和最致命的人类癌症中， 它们在美国的发病率继续上升。一个主要原因是 这种治疗的失败是O6-烷基鸟嘌呤-DNA的过度表达 烷基转移酶(AGT)，它阻止G-C交联链的形成 DNA由氯乙基亚硝脲(CENU)类药物制成。目前，一个 采用O6-苄基鸟嘌呤(BG)灭活AGT的策略 由CENU治疗显示出极好的前景，临床试验 正在对其进行开发。然而，对AGT的进一步抑制 运动是达到治疗效果和快速补充所必需的。 发生在BG治疗后不久的AGT可能会造成严重的 对成功化疗的限制。根据申请人最近的 泛素(UB)-蛋白酶体途径对AGT蛋白降解的研究 蛋白酶体抑制AGT再生的初步研究 拦截者，这个项目的主要目标是进一步提高 以BG为主的CENU治疗通过预防AGT的再充盈。申请人的 假设泛素介导的非活性AGT的分解触发了一种 通过增强活性AGT在BG处理细胞中的翻译再生活性AGT。 申请人提出，UB-蛋白酶体途径调节 BG处理后AGT的蛋白降解和随后的再生 这一途径的特定抑制剂将减少AGT的重复消耗 使胶质瘤细胞对BG-CENU方案增敏。这个 具体目的是：1)定量检测UB-蛋白酶体的表达 与AGT活性相关的组分、AGT蛋白降解水平 BG处理，以及后续AGT再生的速度和程度 人脑胶质瘤细胞株；2)检测UB-对AGT的需求 细胞系中的再生，对UB激活是温度敏感的，以及 研究提高AGT在BG处理的胶质瘤细胞中的翻译效率； 3)检测原发胶质瘤和淋巴细胞中的UB组分和AGT。 人脑胶质瘤细胞及其裸鼠移植瘤的实验研究 UB-蛋白酶体途径的抑制剂和检测AGT的再生和 BG治疗后的BCNU细胞毒性。总体而言，这个项目承诺 为BG治疗后AGT的生化调控提供新的信息 细胞和合理化替代战略，以提高AGT的针对性 人脑肿瘤和其他肿瘤类型的化疗。