期刊
ONCOGENE
卷 28, 期 35, 页码 3097-3110出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/onc.2009.161
关键词
caspase-8; apoptosis; TRAIL; HDACI; medulloblastoma
资金
- Deutsche Forschungsgemeinschaft
- Deutsche Krebshilfe [IAP6/18]
- European Community
Evasion of apoptosis can be caused by epigenetic silencing of caspase-8, a key component of the extrinsic apoptosis pathway. Loss of caspase-8 correlates with poor prognosis in medulloblastoma, which highlights the relevance of strategies to upregulate caspase-8 to break apoptosis resistance. Here, we develop a new combinatorial approach, that is treatment using histone deacetylase inhibitors (HDACI) together with interferon (IFN)-gamma, to restore caspase-8 expression and to overcome resistance to the death-receptor ligand TNF-related apoptosis-inducing ligand (TRAIL) in medulloblastoma in vitro and in vivo. HDACI, for example, valproic acid (VA), suberoylanilide hydroxamic acid (SAHA) and MS-275, cooperate with IFN-gamma to upregulate caspase-8 in cancer cells lacking caspase-8, thereby restoring sensitivity to TRAIL-induced apoptosis. Molecular studies show that VA promotes histone acetylation and acts in concert with IFN-gamma to stimulate caspase-8 promoter activity. The resulting increase in caspase-8 mRNA and protein expression leads to enhanced TRAIL-induced activation of caspase-8 at the death-inducing signaling complex, mitochondrial outer-membrane permeabilization and caspase-dependent cell death. Intriguingly, pharmacological or genetic inhibition of caspase-8 also abolishes the VA/IFN-gamma-mediated sensitization for TRAIL-induced apoptosis. It is important to note that VA and IFN-gamma restore caspase-8 expression and sensitivity to TRAIL in primary medulloblastoma samples and significantly potentiate TRAIL-mediated suppression of medulloblastoma growth in vivo. These findings provide the rationale for further (pre)clinical evaluation of VA and IFN-gamma to restore caspase-8 expression and apoptosis sensitivity in cancers with caspase-8 silencing and open new perspectives to overcome TRAIL resistance. Oncogene (2009) 28, 3097-3110; doi: 10.1038/onc.2009.161; published online 13 July 2009
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