Histone deacetylase inhibitors sensitize glioblastoma cells to TRAIL-induced apoptosis by c-myc-mediated downregulation of cFLIP
Histone deacetylase inhibitors sensitize glioblastoma cells to TRAIL-induced apoptosis by c-myc-mediated downregulation of cFLIP
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DOI：
10.1038/onc.2011.614
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发表时间：
2012-11-01
期刊：
影响因子：
8
通讯作者：
Fulda, S.
中科院分区：
文献类型：
--
作者：
Bangert, A.;Cristofanon, S.;Fulda, S.
胶质母细胞瘤是最常见的原发性脑肿瘤，预后非常差，需要新的治疗策略。在这里，我们提供了第一个证据表明，组蛋白去乙酰化酶抑制剂（HDACI）总理胶质母细胞瘤细胞肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导的凋亡至少部分通过c-myc介导的下调细胞FLICE抑制蛋白（cFLIP）。用不同的HDACI（MS 275、辛二酰苯胺异羟肟酸、丙戊酸）预处理显著增强了几种胶质母细胞瘤细胞系中TRAIL诱导的凋亡。监测一组凋亡调节蛋白显示，MS 275降低了cFLIP（L）和cFLIP（S）的表达。这导致cFLIP（L）和cFLIP（S）的募集减少，并增加caspase-8对TRAIL死亡诱导信号传导复合物的活化，导致caspase-8、-9和-3的切割增强以及caspase依赖性细胞凋亡。此外，MS 275促进TRAIL触发的Bid加工、Bax活化、线粒体膜电位损失和细胞色素c释放。MS 275介导的cFLIP下调发生在mRNA水平，不依赖于蛋白酶体或半胱天冬酶介导的降解，并且之前是c-myc（cFLIP的转录抑制因子）的核水平上调。值得注意的是，MS 275导致c-myc与cFLIP启动子的结合增加，并降低cFLIP启动子活性。事实上，c-myc的敲低部分地挽救了cFLIP（L）免于MS 275推断的下调，并显著降低了TRAIL和MS 275诱导的细胞凋亡。此外，cFLIP（L）或cFLIP（S）的过表达显著减少了MS 275和TRAIL诱导的细胞凋亡。重要的是，MS 275使原代培养的胶质母细胞瘤细胞对TRAIL敏感，并与TRAIL合作以减少胶质母细胞瘤细胞的长期克隆存活并抑制胶质母细胞瘤体内生长，这强调了该方法的临床相关性。因此，这些发现表明HDACI代表了通过靶向cFLIP引发胶质母细胞瘤进行TRAIL诱导的凋亡的有前景的策略。
Glioblastoma is the most common primary brain tumor with a very poor prognosis, calling for novel treatment strategies. Here, we provide first evidence that histone deacetylase inhibitors (HDACI) prime glioblastoma cells for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) -induced apoptosis at least in part by c-myc-mediated downregulation of cellular FLICE-inhibitory protein (cFLIP). Pretreatment with distinct HDACI (MS275, suberoylanilide hydroxamic acid, valproic acid) significantly enhances TRAIL-induced apoptosis in several glioblastoma cell lines. Monitoring a panel of apoptosis-regulatory proteins revealed that MS275 reduces the expression of cFLIP(L) and cFLIP(S). This leads to decreased recruitment of cFLIP(L) and cFLIP(S) and increased activation of caspase-8 to the TRAIL death-inducing signaling complex, resulting in enhanced cleavage of caspase-8, -9 and -3 and caspase-dependent apoptosis. Also, MS275 promotes TRAIL-triggered processing of Bid, activation of Bax, loss of mitochondrial membrane potential and release of cytochrome c. MS275-mediated downregulation of cFLIP occurs at the mRNA level independent of proteasome-or caspase-mediated degradation, and is preceded by upregulation of nuclear levels of c-myc, a transcriptional repressor of cFLIP. Notably, MS275 causes increased binding of c-myc to the cFLIP promoter and reduces cFLIP promoter activity. Indeed, knockdown of c-myc partially rescues cFLIP(L) from MS275-inferred downregulation and significantly decreases TRAIL-and MS275-induced apoptosis. Also, overexpression of cFLIP(L) or cFLIP(S) significantly reduces MS275- and TRAIL-induced apoptosis. Importantly, MS275 sensitizes primary cultured glioblastoma cells towards TRAIL and cooperates with TRAIL to reduce long-term clonogenic survival of glioblastoma cells and to suppress glioblastoma growth in vivo underscoring the clinical relevance of this approach. Thus, these findings demonstrate that HDACI represent a promising strategy to prime glioblastoma for TRAIL-induced apoptosis by targeting cFLIP.