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死药物来消除癌细胞。为此，我们修改毒素，因此它不再通过其自己的细胞结合结构域结合并代替结合结构域A单克隆抗体。选择抗体优先结合正常细胞的癌细胞。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美的抗癌药。我们的目标是了解各种毒素与真核细胞的相互作用，并使用此信息来设计更好的药物来治疗癌症。为了研究相互作用，我们在哺乳动物细胞中添加毒素并研究死亡途径。在跟踪免疫毒素杀死癌细胞时，我们观察到，生长到高密度的细胞对杀伤具有抗性。我们希望理解这种现象，并确定其与癌症治疗的相关性。研究杀细胞的途径的一种方便且潜在的有用方法是使用RNA干扰来识别参与毒素递送到细胞质的途径。 最近，我们从V霍乱（称为Vibrio Cholera Exotoxin（CET））的新描述的毒素开始研究。该毒素与假单胞菌的外毒素有关，在选定域（II和III域）中显示出约50％的身份。然而，尽管相似，但中和假单胞菌中和毒素的抗体并不能中和CET。假单胞菌外毒素（PE）的截短版本已与抗体片段融合，以产生称为重组免疫毒素的有效细胞毒性剂。这些药物的目标是根据抗体片段的结合特异性杀死癌细胞。效力源自毒素的酶促性质，因为它易位到细胞质，ADP-核糖基延伸因子2，并终止合成新的细胞蛋白。大多数先前的研究报告说，PE和PE免疫毒素通过凋亡杀死细胞。在这里，我们报告说，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，但不会引起凋亡反应。然而，在这些细胞中，添加仅BH3的模拟物ABT-737与免疫毒素结合使用，从而产生了深刻的凋亡反应，这两种毒素都无法实现。