Telomerase Specific Caspase Transfer for Gliomas

描述(申请人提供)：我们治疗恶性胶质瘤的努力是 重点研究了将caspase基因转移到肿瘤的方法。因为 细胞凋亡途径在肿瘤中可能被破坏，而caspase是肿瘤的支柱 细胞凋亡计划，这种方法是最有希望的策略之一 癌症基因疗法。然而，如果caspase被转导到正常大脑 细胞，它们将经历细胞凋亡。限制对肿瘤细胞凋亡的诱导 细胞，我们需要建立肿瘤特异性表达系统的半胱氨酸天冬氨酸蛋白酶。 端粒酶是肿瘤靶向系统的一个特别有吸引力的靶点。 这是因为绝大多数恶性胶质瘤都有端粒酶活性， 而大多数正常的脑细胞则不是。端粒酶的激活密切相关 端粒酶催化亚单位转录水平的调控 (HTERT)。因此，我们假设通过使用hTERT启动子驱动的 载体系统中，caspase的表达可以限制在 端粒酶阳性的恶性胶质瘤。在初步研究中，我们构建了 Caspase-8(启动者caspase)或rev-caspase-6(执行者caspase) 含hTERT启动子的表达载体(hTERT/caspase-8或rev-caspase-6) 并证明了每一种构建物都能诱导端粒酶阳性的细胞凋亡 恶性胶质瘤细胞，但不存在于培养的缺乏端粒酶的星形胶质细胞中。 此外，裸鼠皮下肿瘤生长显著。 被hTERT/rev-caspase-6抑制。此外， HTERT/caspase-8或rev-caspase-6的抗肿瘤作用 与抗癌药物顺铂联合使用。这项提议的目标是 研究hTERT/caspase-8或rev-caspase-6治疗 构建是治疗端粒酶阳性恶性胶质瘤的有效方法 使用人类恶性胶质瘤的实验模型。具体目标是： 1)筛选hTERT/caspase-8体内治疗肿瘤模型体系 或rev-caspase-6构建，2)研究其抗肿瘤作用 HTERT/caspase-8或rev-caspase-6构建于颅内肿瘤，3)至 联合应用研究其体内外抗肿瘤作用 常规疗法(顺铂、替莫唑胺或伽玛射线)，以及4) 探讨其作用的分子机制。 HTERT/caspase-8或rev-caspase-6。这项工作的一个独特的重点是强调 半胱氨酸天冬氨酸酶的端粒酶特异性基因转移。我们预计， 目前提案中描述的研究将导致一种新颖和有希望的 表达端粒酶活性的恶性胶质瘤的靶向治疗。

DESCRIPTION (provided by applicant): Our efforts to treat malignant gliomas are focused on methods to transfer the caspase genes to tumors. Because the apoptotic pathway may be disrupted in tumors and caspases are the mainstay of apoptosis programs, this approach is one of the most promising strategies for cancer gene therapy. However, if caspases were transduced to normal brain cells, they will undergo apoptosis. To restrict induction of apoptosis to tumor cells, we need to establish a tumor specific expression system of caspases. Telomerase is a particularly attractive target for the tumor-targeting system. It is because a vast majority of malignant gliomas have telomerase activity, while most normal brain cells do not. Activation of telomerase is tightly regulated at the transcriptional level of the telomerase catalytic subunit (hTERT). Therefore, we hypothesize that by using the hTERT promoter-driven vector system, the expression of caspases can be restricted to telomerase-positive malignant gliomas. In preliminary studies, we constructed the caspase-8 (initiator caspase) or rev-caspase-6 (executioner caspase) expression vector with the hTERT promoter (hTERT/caspase-8 or rev-caspase-6) and demonstrated that each construct induced apoptosis in telomerase-positive malignant glioma cells, but not in cultured astrocytes lacking telomerase. Furthermore, the growth of subcutaneous tumors in nude mice was significantly suppressed by the treatment with the hTERT/rev-caspase-6. Additionally, the antitumor effect of hTERT/caspase-8 or rev-caspase-6 was enhanced by the combination with anticancer drug, cisplatin. The goal of this proposal is to investigate whether treatment with the hTERT/caspase-8 or rev-caspase-6 construct is an effective approach for telomerase-positive malignant gliomas using an experimental model of human malignant gliomas. The specific aims are: 1) to select tumor model systems for the in vivo treatment with hTERT/caspase-8 or rev-caspase-6 construct, 2) to investigate the antitumor effect of the hTERT/caspase-8 or rev-caspase-6 construct on intracranial tumors, 3) to investigate their in vitro and in vivo antitumor efficacy combined with conventional therapy (cisplatin, temozolomide, or gamma-irradiation), and 4) to investigate the molecular mechanisms underlying the effect of the hTERT/caspase-8 or rev-caspase-6. A unique focus of this work is the emphasis on the telomerase-specific gene transfer of caspases. We anticipate that the studies described in the current proposal will lead to a novel and promising targeting approach for malignant gliomas expressing telomerase activity.