Hååg Petra, Olsson Magnus, Forsberg Jeremy, Lindberg Marita Lagergren, Stenerlöw Bo, Zong Dali, Kanter Lena, Lewensohn Rolf, Viktorsson Kristina, Zhivotovsky Boris, Stenke Leif
Department of Oncology-Pathology, Karolinska Institutet, SE-171 64, Solna, Sweden.
Institute of Environmental Medicine, Karolinska Institutet, SE-171 77, Stockholm, Sweden.
Cell Death Discov. 2022 Jun 11;8(1):284. doi: 10.1038/s41420-022-01071-9.
The antibody conjugate gemtuzumab ozogamicin (GO; Mylotarg) provides targeted therapy of acute myeloid leukemia (AML), with recent approvals for patients with CD33-positive disease at diagnosis or relapse, as monotherapy or combined with chemotherapeutics. While its clinical efficacy is well documented, the molecular routes by which GO induces AML cell death warrant further analyses. We have earlier reported that this process is initiated via mitochondria-mediated caspase activation. Here we provide additional data, focusing on the involvement of caspase-2 in this mechanism. We show that this enzyme plays an important role in triggering apoptotic death of human AML cells after exposure to GO or its active moiety calicheamicin. Accordingly, the caspase-2 inhibitor z-VDVAD-fmk reduced GO-induced caspase-3 activation. This finding was validated with shRNA and siRNA targeting caspase-2, resulting in reduced caspase-3 activation and cleavage of poly [ADP-ribose] polymerase 1 (PARP-1). We previously demonstrated that GO-induced apoptosis included a conformational change of Bax into a pro-apoptotic state. Present data reveal that GO-treatment also induced Bid cleavage, which was partially reduced by caspase-2 specific inhibition while the effect on GO-induced Bax conformational change remained unaltered. In mononuclear cells isolated from AML patients that responded to GO treatment in vitro, processing of caspase-2 was evident, whereas in cells from an AML patient refractory to treatment no such processing was seen. When assessing diagnostic samples from 22 AML patients, who all entered complete remission (CR) following anthracycline-based induction therapy, and comparing patients with long versus those with short CR duration no significant differences in baseline caspase-2 or caspase-3 full-length protein expression levels were found. In summary, we demonstrate that GO triggers caspase-2 cleavage in human AML cells and that the subsequent apoptosis of these cells in part relies on caspase-2. These findings may have future clinical implications.
抗体偶联物吉妥珠单抗奥唑米星（GO；Mylotarg）为急性髓系白血病（AML）提供靶向治疗，最近已获批用于诊断或复发时CD33阳性疾病的患者，可作为单一疗法或与化疗药物联合使用。虽然其临床疗效已有充分记录，但GO诱导AML细胞死亡的分子途径仍需进一步分析。我们之前报道过，这个过程是通过线粒体介导的半胱天冬酶激活启动的。在此，我们提供了更多数据，重点关注半胱天冬酶-2在此机制中的作用。我们表明，该酶在暴露于GO或其活性部分加利车霉素后触发人AML细胞凋亡死亡中起重要作用。因此，半胱天冬酶-2抑制剂z-VDVAD-fmk降低了GO诱导的半胱天冬酶-3激活。这一发现通过靶向半胱天冬酶-2的短发夹RNA（shRNA）和小干扰RNA（siRNA）得到验证，导致半胱天冬酶-3激活减少以及聚[ADP-核糖]聚合酶1（PARP-1）的切割减少。我们之前证明，GO诱导的细胞凋亡包括Bax构象转变为促凋亡状态。目前的数据显示，GO处理还诱导了Bid切割，半胱天冬酶-2特异性抑制可部分降低这种切割，而对GO诱导的Bax构象变化的影响保持不变。在体外对GO治疗有反应的AML患者分离的单核细胞中，半胱天冬酶-2的加工明显，而在对治疗难治的AML患者的细胞中未观察到这种加工。在评估22例AML患者的诊断样本时，所有患者在基于蒽环类药物的诱导治疗后均进入完全缓解（CR），比较CR持续时间长与短的患者，未发现基线半胱天冬酶-2或半胱天冬酶-3全长蛋白表达水平有显著差异。总之，我们证明GO在人AML细胞中触发半胱天冬酶-2切割，并且这些细胞随后的凋亡部分依赖于半胱天冬酶-2。这些发现可能具有未来的临床意义。
