MODULATION OF DNA REPAIR TO ENHANCE CHEMOTHERAPY

调节 DNA 修复以增强化疗效果

• 批准号: 6429988
• 负责人: Leonard C Erickson
• 金额: $ 22.01万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6429988
• 关键词: DNA repair; NOD mouse; SCID mouse; antineoplastics; carmustine; combination cancer therapy; crosslink; cytotoxicity; disease /disorder model; drug resistance; drug screening /evaluation; enzyme activity; genetic manipulation; human tissue; methyltransferase; neoplasm /cancer chemotherapy; neoplasm /cancer genetics; neoplastic cell; nitrosourea; pharmacokinetics; streptozotocin

Overwhelming evidence has demonstrated that the major mechanism of tumor cell resistance to the chloroethylnitrosoureas (CENU) results from the DNA repair activity of 06-methylguanine DNA methyltransferase (MGMT). This DNA repair protein is thought to protect cells from the cytotoxic DNA inter- strand crosslink (ISC) produced by the CENU by removing chloroethyl adducts from the 0-6 position of guanine before these adducts can rearrange to form a lethal crosslink. Studies conducts over the previous eight years have demonstrated that this DNA repair system can be temporarily inhibited by a variety of biochemical strategies including pre-incubation of tumor cells with DNA methylating agents such as streptozotocin (STZ) which product the natural substrate of MGMT, 06- methylguanine. Repair of this lesion depletes the tumor cell of MGMT due to MGMT's suicide repair activity. In addition, the free bases 06- methylguanine (MG) and 06-benzylguanine (6-BG) can also deplete cells of MGMT activity and subsequently sensitize tumor cells to treatment with BCNU. Recently, we have demonstrated that STZ combined with 6-BG and BCNU can produce a prolonged sensitization of resistant tumor cells in vitro and in xenograft tumors in vivo. Currently 6-BG plus BCNU is being tested in Phase I clinical trials at other institutions and 6-BG plus STZ plus BCNU will be tested at this institution. However, biochemical modulation strategies are not selective for tumor cells over normal cells. In this Project we propose to develop gene therapy strategies that will allow the protection for critical normal tissues while modulating tumor resistance to the CENU. The specific aims are: 1. To develop a in vitro and in vivo a 6-BG continuous exposure schedule using a bolus of 6-BG followed by a low dose continuous exposure to maximize the duration of MGMT depletion. 2. To determine the ability of transduced DNA repair genes to protect mouse and human cells from the cytotoxic killing by BCNU when combined with pretreatment regimens containing 6-BG or 6-BG plus STZ. 3. Using the NOD/SCID mouse model we will determine whether 6-BG (with and without STZ) and BCNU chemotherapy can be selectively administered to xenograft tumors in mice transplanted with human marrow. 4) To analyze MGMT activity and DNA cross linking in tumor cells from patients with relapsed B-cell malignancies from Phase 1 trials examining continuous infusion of 6-BG, or 6-BG in combination with STZ and BCNU.

大量证据表明，肿瘤发生的主要机制是 细胞对氯乙基亚硝基脲 (CENU) 的耐药性源自 DNA 06-甲基鸟嘌呤 DNA 甲基转移酶 (MGMT) 的修复活性。这个DNA 修复蛋白被认为可以保护细胞免受细胞毒性 DNA 的侵害 CENU 通过去除氯乙基产生的链交联 (ISC) 在这些加合物可以之前从鸟嘌呤的0-6位加合物 重新排列形成致命的交联。研究进行较以往 八年来的研究表明，这种 DNA 修复系统可以 被多种生化策略暂时抑制，包括 将肿瘤细胞与 DNA 甲基化剂预孵育，例如 链脲佐菌素 (STZ)，产生 MGMT 的天然底物，06- 甲基鸟嘌呤。该病变的修复会耗尽 MGMT 的肿瘤细胞，因为 MGMT 的自杀修复活动。此外，游离碱基06- 甲基鸟嘌呤 (MG) 和 06-苄基鸟嘌呤 (6-BG) 也可以消耗细胞 MGMT 活性，随后使肿瘤细胞对治疗敏感 BCNU。最近，我们证明了STZ与6-BG和BCNU结合 可以在体外对耐药肿瘤细胞产生长时间的致敏作用 以及体内异种移植肿瘤。目前6-BG加BCNU正在测试中 在其他机构和6-BG加STZ加的I期临床试验中 BCNU 将在该机构进行测试。然而，生化调节 与正常细胞相比，策略对肿瘤细胞没有选择性。在这个 我们建议开发基因治疗策略的项目，使 保护关键正常组织，同时调节肿瘤抵抗力 到CENU。具体目标是： 1. 开发体外和体内 6-BG 连续暴露计划，先推注 6-BG，然后再注射 低剂量连续暴露以最大限度地延长 MGMT 消耗的持续时间。 2. 确定转导的DNA修复基因的保护能力 结合使用时，小鼠和人类细胞免受 BCNU 的细胞毒性杀伤 采用含有 6-BG 或 6-BG 加 STZ 的预处理方案。 3. 使用 NOD/SCID小鼠模型我们将确定是否6-BG（有和没有STZ） BCNU化疗可以选择性地用于异种移植肿瘤 在移植了人类骨髓的小鼠中。 4) 分析 MGMT 活动并 复发 B 细胞患者肿瘤细胞中的 DNA 交联 来自检查连续输注 6-BG 的 1 期试验的恶性肿瘤，或 6-BG 与 STZ 和 BCNU 组合。