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: 6489201
• 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 2002-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6489201
• 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：（申请人的摘要）儿科和成人脑肿瘤是 在人类癌症的治疗性最无反应和致命中， 他们的发病率在美国继续上升。 主要原因 这种治疗衰竭是O6-烷基鸟氨酸-DNA的过表达 烷基转移酶（AGT），可防止G-C交联在 DNA通过氯乙基硝基库（CENU）类药物的DNA。 目前， 随后涉及O6-苯二唑烷（BG）灭活AGT的策略 通过CENU治疗表现出了极好的希望，临床试验是 正在进行剥削。 但是，扩展了对AGT的抑制 活动对于实现治疗功效和快速填补是必要的 BG治疗后不久发生的AGT构成潜在的严重 成功化疗的限制。 根据申请人的最新 通过泛素（UB） - 头途径和 初步研究表明蛋白酶体抑制AGT再生 阻止者，该项目的主要目标是进一步增强 基于BG的CENU疗法通过预防AGT的补充。 申请人的 假设是泛素介导的非活性AGT触发的分解 活性AGT的再生通过增强其在BG处理的细胞中的翻译。 申请人建议UB-蛋白酶体途径调节这两个 BG治疗后的蛋白水解和随后的AGT再生 该途径的特定抑制剂将减少AGT的补充 能够增加神经胶质瘤细胞对BG-CENU方案的敏化。 这 具体目的是：1）定量UB-蛋白酶体的表达 与AGT活性有关的成分，Agt蛋白水解水平 BG治疗以及随后的AGT再生的速率和程度 人神经胶质瘤细胞系； 2）检查AGT的UB要求 细胞系中的再生，对UB激活的温度敏感，并且 研究提高了AGT在BG处理的神经胶质瘤细胞中的转化效率； 3）评估原发性神经胶质瘤和淋巴细胞中的UB组件和AGT，以及 在裸小鼠中治疗胶质瘤细胞和胶质瘤异种移植物 UB-蛋白酶体途径的抑制剂，检查AGT再生和 BG处理后的BCNU细胞毒性。 总体而言，这个项目有望 提供有关BG处理的AGT生化调制的新信息 细胞并合理化替代策略以改善AGT为目标 人脑肿瘤和其他肿瘤类型的化学疗法。

项目成果

Protein phosphorylation is a regulatory mechanism for O6-alkylguanine-DNA alkyltransferase in human brain tumor cells.

蛋白质磷酸化是人脑肿瘤细胞中 O6-烷基鸟嘌呤-DNA 烷基转移酶的调节机制。

• 发表时间: 2000
• 期刊: Cancer research.
• 作者: Srivenugopal,KS;Mullapudi,SR;Shou,J;Hazra,TK;Ali-Osman,F
• 通讯作者: Ali-Osman,F

Enforced expression of wild-type p53 curtails the transcription of the O(6)-methylguanine-DNA methyltransferase gene in human tumor cells and enhances their sensitivity to alkylating agents.

• 发表时间: 2001-05
• 期刊: Clinical cancer research : an official journal of the American Association for Cancer Research
• 作者: K. Srivenugopal;Jiang Shou;S. Mullapudi;Frederick F Lang;Jasti S. Rao;Francis Ali-Osman

Phosphorylation of O6-alkylguanine-DNA alkyltransferase: experience with a GST-fusion protein and a new pull-down assay.

O6-烷基鸟嘌呤-DNA 烷基转移酶的磷酸化：GST 融合蛋白和新 Pull-down 测定的经验。

• DOI: 10.1016/s0304-3835(01)00823-0
• 发表时间: 2002
• 期刊: Cancer letters
• 影响因子: 9.7
• 作者: Srivenugopal,KalkunteS;Mullapudi,SrinivasRS;Ali-Osman,Francis
• 通讯作者: Ali-Osman,Francis