Multiple components of the spliceosome regulate Mcl1 activity in neuroblastoma.
Multiple components of the spliceosome regulate Mcl1 activity in neuroblastoma.
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DOI：
10.1038/cddis.2014.40
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发表时间：
2014-02-20
影响因子：
9
通讯作者：
Hogarty MD
中科院分区：
文献类型：
--
作者：
Laetsch TW;Liu X;Vu A;Sliozberg M;Vido M;Elci OU;Goldsmith KC;Hogarty MD
肿瘤治疗诱导细胞应激，引发肿瘤细胞凋亡。许多癌症通过改变调节这一过程的Bcl2蛋白来抑制这些凋亡信号。针对这些特定生存偏差的治疗方法正在开发中，抑制Bcl2活性的药物已显示出对某些癌症的临床活性。Mcl1是一种没有有效拮抗剂的生存因子，因此它仍然是治疗耐药的主要介质，包括对Bcl2抑制剂的耐药。我们使用了一种合成致死筛选策略，以儿童肿瘤神经母细胞瘤（NB）为模型来鉴定调节Mcl1存活活性的基因，因为一个大的亚群在功能上被证实是Mcl1依赖和Bcl2抑制剂耐药的。靶向siRNA筛选发现了一些基因，这些基因的敲除可以恢复mcl1依赖性NBs对ABT-737的敏感性，ABT-737是Bcl2、BclXL和BclW的小分子抑制剂。我们鉴定并验证了三个改变ABT-737 IC50 >1日志的靶基因：PSMD14、UBL5和PRPF8。后两者是剪接体亚复合体的成员，该亚复合体与SART1一起负责酵母中非规范的5 '剪接序列识别。我们发现，SART1敲低类似地使MCL1依赖性NB对ABT-737致敏，UBL5/PRPF8/SART1的三重敲低导致了MCL1的直接敲低，而对bcl2依赖性NB没有影响。无论是基因剪接体敲除还是用sf3b相互作用的剪接体抑制剂如剪接抑素A处理，都会导致优先的促凋亡的Mcl1- s剪接，降低Mcl1蛋白的翻译和丰度。相比之下，BN82865抑制末端剪接体加工中的第二步酯交换，却没有这种作用。这些发现证明了剪接体在介导Mcl1活性方面的重要作用，并表明靶向特定UBL5/PRPF8/SART1亚复合物或SF3b功能的药物可能通过减轻许多癌症中存在的Mcl1生存偏倚而发挥癌症治疗作用。
Cancer treatments induce cell stress to trigger apoptosis in tumor cells. Many cancers repress these apoptotic signals through alterations in the Bcl2 proteins that regulate this process. Therapeutics that target these specific survival biases are in development, and drugs that inhibit Bcl2 activities have shown clinical activity for some cancers. Mcl1 is a survival factor for which no effective antagonists have been developed, so it remains a principal mediator of therapy resistance, including to Bcl2 inhibitors. We used a synthetic-lethal screening strategy to identify genes that regulate Mcl1 survival activity using the pediatric tumor neuroblastoma (NB) as a model, as a large subset are functionally verified to be Mcl1 dependent and Bcl2 inhibitor resistant. A targeted siRNA screen identified genes whose knockdown restores sensitivity of Mcl1-dependent NBs to ABT-737, a small molecule inhibitor of Bcl2, BclXL and BclW. Three target genes that shifted the ABT-737 IC50 >1 log were identified and validated: PSMD14, UBL5 and PRPF8. The latter two are members of a recently characterized subcomplex of the spliceosome that along with SART1 is responsible for non-canonical 5′-splice sequence recognition in yeast. We showed that SART1 knockdown similarly sensitized Mcl1-dependent NB to ABT-737 and that triple knockdown of UBL5/PRPF8/SART1 phenocopied direct MCL1 knockdown, whereas having no effect on Bcl2-dependent NBs. Both genetic spliceosome knockdown or treatment with SF3b-interacting spliceosome inhibitors like spliceostatin A led to preferential pro-apoptotic Mcl1-S splicing and reduced translation and abundance of Mcl1 protein. In contrast, BN82865, which inhibits the second transesterification step in terminal spliceosome processing, did not have this effect. These findings demonstrate a prominent role for the spliceosome in mediating Mcl1 activity and suggest that drugs that target either the specific UBL5/PRPF8/SART1 subcomplex or SF3b functions may have a role as cancer therapeutics by attenuating the Mcl1 survival bias present in numerous cancers.
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