Los M, Herr I, Friesen C, Fulda S, Schulze-Osthoff K, Debatin K M
Hematology/Oncology, University Children's Hospital, Ulm, Germany.
Blood. 1997 Oct 15;90(8):3118-29.
The cytotoxic effect of anticancer drugs has been shown to involve induction of apoptosis. We report here that tumor cells resistant to CD95 (APO-1/Fas) -mediated apoptosis were cross-resistant to apoptosis-induced by anticancer drugs. Apoptosis induced in tumor cells by cytarabine, doxorubicin, and methotrexate required the activation of ICE/Ced-3 proteases (caspases), similarly to the CD95 system. After drug treatment, a strong increase of caspase activity was found that preceded cell death. Drug-induced activation of caspases was also found in ex vivo-derived T-cell leukemia cells. Resistance to cell death was conferred by a peptide caspase inhibitor and CrmA, a poxvirus-derived serpin. The peptide inhibitor was effective even if added several hours after drug treatment, indicating a direct involvement of caspases in the execution and not in the trigger phase of drug action. Drug-induced apoptosis was also strongly inhibited by antisense approaches targeting caspase-1 and -3, indicating that several members of this protease family were involved. CD95-resistant cell lines that failed to activate caspases upon CD95 triggering were cross-resistant to drug-mediated apoptosis. Our data strongly support the concept that sensitivity for drug-induced cell death depends on intact apoptosis pathways leading to activation of caspases. The identification of defects in caspase activation may provide molecular targets to overcome drug resistance in tumor cells.
抗癌药物的细胞毒性作用已被证明与诱导细胞凋亡有关。我们在此报告，对CD95（APO-1/Fas）介导的细胞凋亡具有抗性的肿瘤细胞对抗癌药物诱导的细胞凋亡也具有交叉抗性。阿糖胞苷、阿霉素和甲氨蝶呤在肿瘤细胞中诱导的细胞凋亡需要ICE/Ced-3蛋白酶（半胱天冬酶）的激活，这与CD95系统类似。药物处理后，在细胞死亡之前发现半胱天冬酶活性大幅增加。在体外衍生的T细胞白血病细胞中也发现了药物诱导的半胱天冬酶激活。一种肽半胱天冬酶抑制剂和一种痘病毒衍生的丝氨酸蛋白酶抑制剂CrmA赋予了细胞对死亡的抗性。即使在药物处理数小时后添加该肽抑制剂也有效，这表明半胱天冬酶直接参与了药物作用的执行阶段而非触发阶段。靶向半胱天冬酶-1和-3的反义方法也强烈抑制了药物诱导的细胞凋亡，表明该蛋白酶家族的几个成员都参与其中。在CD95触发时未能激活半胱天冬酶的CD95抗性细胞系对药物介导的细胞凋亡具有交叉抗性。我们的数据有力地支持了这样一个概念，即对药物诱导的细胞死亡的敏感性取决于导致半胱天冬酶激活的完整细胞凋亡途径。鉴定半胱天冬酶激活中的缺陷可能为克服肿瘤细胞中的耐药性提供分子靶点。
