Targeting Mcl-1 for multiple myeloma (MM) therapy: Drug-induced generation of Mcl-1 fragment Mcl-1128-350 triggers MM cell death via c-Jun upregulation
Targeting Mcl-1 for multiple myeloma (MM) therapy: Drug-induced generation of Mcl-1 fragment Mcl-1128-350 triggers MM cell death via c-Jun upregulation
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DOI：
10.1016/j.canlet.2013.09.042
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发表时间：
2014-02-28
期刊：
影响因子：
9.7
通讯作者：
Podar, Klaus
中科院分区：
文献类型：
--
作者：
Fan, Fengjuan;Tonon, Giovanni;Podar, Klaus
髓样细胞白血病-1（Mcl-1，HGNC：6943）是Bcl-2家族的促生存成员，在多发性骨髓瘤（MM）的发病机制和耐药性中起着至关重要的作用，因此代表了MM中有前途的治疗靶点。抑制Mcl-1活性的新策略是诱导泛素非依赖性Mcl-1降解。我们自己和其他先前的研究已经证明，28 kDa Mcl-1片段Mcl-1（128-350）的半胱天冬酶依赖性产生抑制MM细胞增殖和存活。在这里，我们发现与硼替佐米类似，新型蛋白酶体抑制剂卡非佐米和ixazomib以及星形孢菌素和阿达帕林诱导MM细胞中Mcl-1（128-350）的产生。接下来，描绘了介导其促凋亡活性的Mcl-1（128-350）下游的分子后遗症。令人惊讶的是，我们观察到药物诱导的或外源性过表达的Mcl-1（128-350）的核积累，随后c-Jun的mRNA和蛋白水平升高，以及AP-1报告基因活性增强。此外，药物诱导的AP-1活性被阻断后，引入一个点突变到高度保守的Mcl-1半胱天冬酶切割位点Asp 127，但不是Asp 157。因此，在用Mcl-1 D127 A转染的MM细胞中，药物触发的细胞死亡显著减少，但用Mcl-1 D157 A转染的MM细胞则没有。与这些数据一致，用硼替佐米处理触发了C-Jun上调，随后在Mcl-1（wt/wt）中发生凋亡，但在Mcl-1（Delta/null）鼠胚胎成纤维细胞（MEF）中没有。将携带Mcl-1（wt）的质粒转染到Mcl-1（Delta/null）MEFs中恢复了硼替佐米诱导的Mcl-1片段化、c-Jun上调和AP-1报告基因活性。最后，我们的数据表明，药物诱导产生的促凋亡Mcl-1片段，随后c-Jun上调也可能是其他肿瘤实体的一种新的治疗方法。(C)2013爱思唯尔爱尔兰有限公司版权所有。
Myeloid cell leukemia-1 (Mcl-1, HGNC: 6943), a pro-survival member of the Bcl-2 family, plays a crucial role in Multiple Myeloma (MM) pathogenesis and drug resistance, thus representing a promising therapeutic target in MM. A novel strategy to inhibit Mcl-1 activity is the induction of ubiquitin-independent Mcl-1 degradation. Our own and other previous studies have demonstrated, caspase-dependent generation of a 28 kDa Mcl-1 fragment, Mcl-1(128-350) which inhibits MM cell proliferation and survival. Here, we show that similar to bortezomib, the novel proteasome inhibitors carfilzomib and ixazomib, as well as staurosporine and adaphostin, induce the generation of Mcl-1(128-350) in MM cells. Next, the molecular sequelae downstream of Mcl-1(128-350), which mediate its pro-apoptotic activity, were delineated. Surprisingly, we observed nuclear accumulation of drug-induced or exogenously overexpressed Mcl-1(128-350), followed by elevated mRNA and protein levels of c-Jun, as well as enhanced AP-1 reporter activity. Moreover, drug-induced AP-1 activity was blocked after introducing a point mutation into the highly conserved Mcl-1 caspase-cleavage site Asp127, but not Asp157. Consequently, drug-triggered cell death was significantly decreased in MM cells transfected with Mcl-1 D127A, but not with Mcl-1 D157A. Consistent with these data, treatment with bortezomib triggered c-Jun upregulation followed by apoptosis in Mcl-1(wt/wt), but not Mcl-1(Delta/null) murine embryonic fibroblasts (MEFs). Transfection of a plasmid carrying Mcl-1(wt) into Mcl-1(Delta/null) MEFs restored bortezomib-induced Mcl-1 fragmentation, c-Jun upregulation and AP-1 reporter activity. Finally, our data indicate that drug-induced generation of a pro-apoptotic Mcl-1 fragment followed by c-Jun upregulation may also be a novel therapeutic approach in other tumor entities. (C) 2013 Elsevier Ireland Ltd. All rights reserved.