Silencing of the XAF1 gene by promoter hypermethylation in cancer cells and reactivation to TRAIL-sensitization by IFN-beta.
Silencing of the XAF1 gene by promoter hypermethylation in cancer cells and reactivation to TRAIL-sensitization by IFN-beta.
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通过癌细胞中启动子过度甲基化对XAF1基因的沉默，并通过IFN-β对尾敏化的重新激活。
DOI：
10.1186/1471-2407-7-52
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发表时间：
2007-03-21
期刊：
影响因子：
3.8
通讯作者：
Korneluk, Robert G.
中科院分区：
文献类型：
--
作者：
Micali, O. Cristina;Cheung, Herman H.;Plenchette, Stephanie;Hurley, Sandra L.;Liston, Peter;LaCasse, Eric C.;Korneluk, Robert G.
xap相关因子1 （XAF1）是一种推定的肿瘤抑制因子，通过caspase依赖性和非依赖性两种方式发挥其促凋亡作用。通过启动子甲基化导致的XAF1表达缺失与多种癌症的肿瘤发生过程有关。在本报告中，我们研究了xaf1基础启动子甲基化在xaf1表达中的作用，并评估了癌细胞对IFN-β诱导xaf1的反应性。我们采用传统的亚硫酸盐DNA修饰和测序方法，测定了胶质母细胞瘤（SF539, SF295）、神经母细胞瘤（SK-N-AS）和宫颈癌（HeLa）细胞中xaf1启动子CpG位点的甲基化状态。我们分析了在未处理细胞以及短时间或长时间暴露于IFN-β下xaf1表达中基础xaf1启动子甲基化的状态和发生率。建立了稳定的XAF1胶质母细胞瘤敲除细胞系，以表征XAF1在IFN-β介导的trail诱导的细胞死亡致敏中的直接作用。我们发现，在所研究的四种癌细胞系中，xaf1启动子甲基化谱和对IFN-β的响应性具有很强的可变性。在基础水平上，异常启动子甲基化与xaf1基因沉默有关。在短时间暴露后，IFN-β介导的xaf1基因表达的再激活与基础启动子甲基化程度有关。然而，尽管持续的启动子超甲基化，我们发现IFN-β诱导短暂的xaf1表达，反过来，在长时间暴露后，启动子去甲基化。重要的是，我们首次证明了IFN-β介导的内源性XAF1的再激活在TRAIL诱导的细胞死亡中起着关键作用，因为XAF1敲除细胞系完全失去了IFN-β介导的TRAIL敏感性。总之，这些结果表明启动子去甲基化不是IFN-β处理下决定xaf1基因诱导的唯一因素。此外，我们的研究提供了证据，证明XAF1是干扰素刺激基因（ISG）在ifn诱导的癌症中对TRAIL致敏的关键介质。
XIAP-associated factor 1 (XAF1) is a putative tumor suppressor that exerts its proapoptotic effects through both caspase-dependent and – independent means. Loss of XAF1 expression through promoter methylation has been implicated in the process of tumorigenesis in a variety of cancers. In this report, we investigated the role of basal xaf1 promoter methylation in xaf1 expression and assessed the responsiveness of cancer cell lines to XAF1 induction by IFN-β. We used the conventional bisulfite DNA modification and sequencing method to determine the methylation status in the CpG sites of xaf1 promoter in glioblastoma (SF539, SF295), neuroblastoma (SK-N-AS) and cervical carcinoma (HeLa) cells. We analysed the status and incidence of basal xaf1 promoter methylation in xaf1 expression in non-treated cells as well as under a short or long exposure to IFN-β. Stable XAF1 glioblastoma knock-down cell lines were established to characterize the direct implication of XAF1 in IFN-β-mediated sensitization to TRAIL-induced cell death. We found a strong variability in xaf1 promoter methylation profile and responsiveness to IFN-β across the four cancer cell lines studied. At the basal level, aberrant promoter methylation was linked to xaf1 gene silencing. After a short exposure, the IFN-β-mediated reactivation of xaf1 gene expression was related to the degree of basal promoter methylation. However, in spite of continued promoter hypermethylation, we find that IFN-β induced a transient xaf1 expression, that in turn, was followed by promoter demethylation upon a prolonged exposure. Importantly, we demonstrated for the first time that IFN-β-mediated reactivation of endogenous XAF1 plays a critical role in TRAIL-induced cell death since XAF1 knock-down cell lines completely lost their IFN-β-mediated TRAIL sensitivity. Together, these results suggest that promoter demethylation is not the sole factor determining xaf1 gene induction under IFN-β treatment. Furthermore, our study provides evidence that XAF1 is a crucial interferon-stimulated gene (ISG) mediator of IFN-induced sensitization to TRAIL in cancer.
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DOI：
10.1196/annals.1322.017
发表时间：
2004-01-01
期刊：
SIGNAL TRANSDUCTION AND COMMUNICATION IN CANCER CELLS
影响因子：
--
作者：
Casciano, I;Banelli, B;Romani, M
通讯作者：
Romani, M
影响因子：
29.4
作者：
Wang, JD;Peng, Y;Wong, BCY
通讯作者：
Wong, BCY
影响因子：
4.4
作者：
Fong, WG;Liston, P;Korneluk, RG
通讯作者：
Korneluk, RG
影响因子：
8
作者：
Karpf, AR;Jones, DA
通讯作者：
Jones, DA
影响因子：
6.5
作者：
Ng, KCP;Campos, EI;Li, G
通讯作者：
Li, G