Bio-Therapies for the Treatment of Cancer and Infectious Disease

治疗癌症和传染病的生物疗法

• 批准号: 8157214
• 负责人: DAVID FITZGERALD
• 金额: $ 77.91万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8157214
• 关键词: Communicable Diseases; cancer therapy

We use bacterial toxins as killing agents to eliminate cancer cells. To accomplish this, we modify the toxin so it no longer binds via its own cell-binding domain and substitute in place of the binding domain a monoclonal antibody. The antibody is chosen to bind cancer cells preferentially over normal cells. These toxin-antibody molecules are called immunotoxins. Immunotoxins are promising but imperfect anticancer agents. Our goal is to understand the interaction of various toxins with eukaryotic cells and use this information to design better agents for treating cancer. To study interactions, we add toxins to mammalian cells and study the pathway of death. In tracking the killing of cancer cells by immunotoxins, we made the observation that cells grown to high density are resistant to killing. We wish to understand this phenomenon and determine its relevance for cancer therapy in general. A convenient and potentially useful way to study cell-killing pathways is to use RNA interference to identify pathways that participate in toxin delivery to the cytosol - where it acts. Recently, we initiated studies with a newly described toxin from V cholera, called Vibrio Cholera Exotoxin (CET). This toxin is related to the exotoxin from Pseudomonas, exhibiting about 50% identity in selected domains (domains II and III). However, antibodies that neutralize the exotoxin from Pseudomonas do not neutralize CET, despite the close similarity. Truncated versions of Pseudomonas Exotoxin (PE) have been fused with antibody fragments to produce potent cytotoxic agents termed recombinant immunotoxins. These agents are targeted to kill cancer cells based on the binding specificity of the antibody fragment. Potency is derived from the enzymatic nature of the toxin as it translocates to the cytosol, ADP-ribosylates elongation factor 2 and terminates the synthesis of new cellular protein. Most prior investigations reported that PE and PE-immunotoxins kill cells via apoptosis. Here we report that PE and PE immunotoxin inhibit protein synthesis and cell growth of colon cancer cell lines but do not provoke an apoptotic response. However, the addition of the BH3-only mimetic, ABT-737 in combination with the immunotoxin produces a profound apoptotic response in these cells that neither agent alone can achieve.

我们使用细菌毒素作为杀灭剂来消除癌细胞。为了实现这一目标，我们修改了毒素，使其不再通过其自身的细胞结合结构域结合，并用单克隆抗体代替结合结构域。选择该抗体优先结合癌细胞而不是正常细胞。这些毒素抗体分子称为免疫毒素。免疫毒素是有前途但不完善的抗癌剂。我们的目标是了解各种毒素与真核细胞的相互作用，并利用这些信息设计更好的癌症治疗药物。为了研究相互作用，我们向哺乳动物细胞添加毒素并研究死亡途径。在追踪免疫毒素对癌细胞的杀伤作用时，我们观察到生长到高密度的细胞对杀伤具有抵抗力。我们希望了解这种现象并确定其与一般癌症治疗的相关性。研究细胞杀伤途径的一种方便且可能有用的方法是使用 RNA 干扰来识别参与毒素递送至细胞质（其作用所在）的途径。 最近，我们开始研究一种新描述的霍乱弧菌毒素，称为霍乱弧菌外毒素 (CET)。该毒素与假单胞菌的外毒素相关，在选定的结构域（结构域 II 和 III）中表现出约 50% 的同一性。然而，中和假单胞菌外毒素的抗体不会中和 CET，尽管两者非常相似。假单胞菌外毒素 (PE) 的截短版本已与抗体片段融合，产生称为重组免疫毒素的有效细胞毒性剂。这些药物基于抗体片段的结合特异性来靶向杀死癌细胞。效力源自毒素的酶性质，因为它易位至胞质溶胶、ADP-核糖基化延伸因子 2 并终止新细胞蛋白质的合成。大多数先前的研究报告称，PE 和 PE 免疫毒素通过细胞凋亡杀死细胞。在这里，我们报道 PE 和 PE 免疫毒素抑制结肠癌细胞系的蛋白质合成和细胞生长，但不会引起细胞凋亡反应。然而，添加仅 BH3 模拟物 ABT-737 与免疫毒素组合会在这些细胞中产生深远的凋亡反应，而单独使用任何一种药物都无法实现这一反应。