CDK inhibitors upregulate BH3-only proteins to sensitize human myeloma cells to BH3 mimetic therapies.
CDK inhibitors upregulate BH3-only proteins to sensitize human myeloma cells to BH3 mimetic therapies.
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DOI：
10.1158/0008-5472.can-12-1118
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发表时间：
2012-08-15
期刊：
影响因子：
11.2
通讯作者：
Grant S
中科院分区：
文献类型：
--
作者：
Chen S;Dai Y;Pei XY;Myers J;Wang L;Kramer LB;Garnett M;Schwartz DM;Su F;Simmons GL;Richey JD;Larsen DG;Dent P;Orlowski RZ;Grant S
拟BH3药物通过拮抗凋亡Bcl-2家族蛋白的活性诱导细胞死亡。细胞周期蛋白依赖性激酶（CDK）抑制剂作为转录抑制因子下调Bcl-2家族成员Mcl-1，并增加不能靶向该蛋白的选择性bh3模拟物的活性。在这项研究中，我们确定CDK抑制剂是否通过直接中和Mcl-1来增强泛bh3模拟物的活性。具体来说，我们评估了在Mcl-1对存活至关重要的多发性骨髓瘤（MM）细胞中，原型泛cdk抑制剂黄吡醇和泛bh3模拟obatoclax之间的相互作用。黄吡醇和obatoclax联合给药可协同触发初用药和耐药MM细胞的凋亡。机制研究表明，黄酮吡醇抑制Mcl-1的转录，但增加Bim的转录及其与Bcl-2/Bcl-xL的结合。Obatoclax阻止了Mcl-1的恢复，并增强了Bcl-2/Bcl-xL和Mcl-1中Bim的释放，同时激活了Bax/Bak。无论是单独给药还是与obatoclax联合给药，黄匹吡醇都能诱导多种BH3-only蛋白的上调，包括BimEL、BimL、Noxa和Bik/NBK。值得注意的是，在体外和体内，shRNA敲除Bim或Noxa可消除黄吡醇/obatoclax联合引起的致死率。总之，我们的研究结果表明，CDK抑制通过一种合作机制增强了泛bh3模拟活性，该机制涉及BH3-only蛋白的上调和其抗凋亡对应蛋白的协同下调。这些发现对基于BH3模拟物的治疗方法的临床试验设计具有直接意义，目前正在深入研究BH3模拟物治疗多种造血恶性肿瘤，包括致死性多发性骨髓瘤。
BH3 mimetic drugs induce cell death by antagonizing the activity of anti-apoptotic Bcl-2 family proteins. Cyclin-dependent kinase (CDK) inhibitors that function as transcriptional repressors down-regulate the Bcl-2 family member Mcl-1 and increase the activity of selective BH3-mimetics that fail to target this protein. In this study, we determined whether CDK inhibitors potentiate the activity of pan-BH3 mimetics by directly neutralizing Mcl-1. Specifically, we evaluated interactions between the prototypical pan-CDK inhibitor flavopiridol and the pan-BH3-mimetic obatoclax in multiple myeloma (MM) cells in which Mcl-1 is critical for survival. Co-administration of flavopiridol and obatoclax synergistically triggered apoptosis in both drug-naive and drug-resistant MM cells. Mechanistic investigations revealed that flavopiridol inhibited Mcl-1 transcription but increased transcription of Bim and its binding to Bcl-2/Bcl-xL. Obatoclax prevented Mcl-1 recovery and potentiated release of Bim from Bcl-2/Bcl-xL and Mcl-1, accompanied by activation of Bax/Bak. Whether administered singly or in combination with obatoclax, flavopiridol also induced up-regulation of multiple BH3-only proteins, including BimEL, BimL, Noxa, and Bik/NBK. Notably, shRNA knock-down of Bim or Noxa abrogated lethality triggered by the flavopiridol/obatoclax combination in vitro and in vivo. Together, our findings demonstrate that CDK inhibition potentiates pan-BH3-mimetic activity through a cooperative mechanism involving up-regulation of BH3-only proteins with coordinate down-regulation of their anti-apoptotic counterparts. These findings have immediate implications for the clinical trial design of BH3 mimetic-based therapies that are presently being studied intensively for the treatment of diverse hematopoietic malignancies, including lethal multiple myeloma.