Research for natural compounds inducing apoptosis in leukemia cells without foxicity on normal immune cells.

血液毒性副作用，包括骨髓毒性或免疫毒性，严重阻碍化疗药物对白血病的有益应用，因为大多数抗白血病药物会导致宿主正常细胞的坏死细胞死亡。在本研究中，我开发了一种筛选系统，可以筛选出对人早幼粒细胞白血病HL-60细胞或人T淋巴细胞白血病MOLT-4细胞具有抗白血病活性的化合物，而不会对丝裂原刺激的人淋巴细胞产生毒性。该筛选系统还包括选择具有引起白血病细胞凋亡活性的化合物。琼脂糖凝胶电泳、细胞死亡检测ELISA、流式细胞术检测细胞凋亡。在测试的大约100种天然化合物中，我发现一些化合物选择性地对HL-60细胞表现出诱导凋亡的活性，而不会引起淋巴细胞毒性。橘皮素是一种从橘皮中提取的五甲基甲黄酮，它在体外对HL-60细胞的生长有很强的细胞抑制作用，对丝裂原刺激的人外周血淋巴细胞有诱导凋亡的能力，但不引起坏死。因此，这些数据提示橙皮素可能作为一种具有新机制和低免疫毒性的抗白血病药物的候选药物。

Hematotoxic side effects including myelotoxicity or immunotoxicity seriously prevent beneficial application of chemotherapeutic agents for leukemia, since most of anti-leukemic agents cause necrotic cell death in normal cells of the host. In the present study, I have developed a screening system which can select out compounds exibiting antileukemia activity against human promyelocytic leukemia HL-60 cells or human T lymphocytic leukemia MOLT-4 cells without causing toxicity on mitogen-stimulated human lymphocytes. The screening system also includes selection of the compounds having activity to cause apoptosis in leukemia cells.Apoptosis was detected with agarose gel electrophoresis, cell death detection ELISA,and flow cytometry. Among approximately 100 naturally-occurring compounds tested, I have discovered some compounds exhibiting apoptosis-inducing activity selectively against HL-60 cells without causing lymphocytotoxicity. Tangeretin, a pentamethoxyflavone from tangerine peer showed strong cytostatic activity on HL-60 cell growth in vitro and apoptosis-inducing ability without causing necrosis in mitogen-stimulated human peripheral-blood lymphocytes. Thus, the data suggest possible efficacy of tangeretin as a candidate for antileukemic agent with novel mechanism and low immunotoxicity.