MicroRNA-199b-5p impairs cancer stem cells through negative regulation of HES1 in medulloblastoma.
MicroRNA-199b-5p impairs cancer stem cells through negative regulation of HES1 in medulloblastoma.
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DOI：
10.1371/journal.pone.0004998
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发表时间：
2009
期刊：
影响因子：
3.7
通讯作者：
Zollo M
中科院分区：
文献类型：
--
作者：
Garzia L;Andolfo I;Cusanelli E;Marino N;Petrosino G;De Martino D;Esposito V;Galeone A;Navas L;Esposito S;Gargiulo S;Fattet S;Donofrio V;Cinalli G;Brunetti A;Vecchio LD;Northcott PA;Delattre O;Taylor MD;Iolascon A;Zollo M
通过对基因表达的负性调控，microRNAs(MiRNAs)可以在癌症中发挥抑癌作用，并在各种肿瘤类型中表现出表达的变化。在这里，我们研究了髓母细胞瘤(MBS)，它源于小脑发育过程的早期损害，在小脑中，Notch信号参与了许多细胞命运决定阶段。MBS呈双峰型，高峰见于3-4岁和8-9岁，但也可发生在成人。Noch调节MB细胞的一个子集，这些MB细胞具有干细胞样属性，可以促进肿瘤生长。基于这一证据，我们假设针对Notch途径的miRNAs可以调节这些现象，并可用于抗癌治疗。在MB细胞系的筛选中，miRNA miR-199B-5p被认为是通过靶向转录因子HES1而调节Notch途径的。MiR-199B-5P下调HES1的表达对MB细胞的增殖速度和锚定非依赖性生长具有负性调节作用。MIR-199B-5P过表达阻断了几个癌症干细胞基因的表达，削弱了MB细胞在裸鼠小脑中的移植潜力，特别值得注意的是，减少了MB干细胞样亚群(CD133+)。在61例MB患者中，未转移组miR-199B-5p的表达显著高于转移组(P = 0.001)。在这些miR-199B高表达患者中，与低表达患者相比，总体生存期有提高的趋势。这些数据显示，miR-199B-5p在转移性MBS中下调，提示可能通过表观遗传或遗传改变而沉默机制。在用5-氮杂脱氧胞苷诱导去甲基化后，在一组MB细胞系中看到较低的miR-199B-5p表达，支持表观遗传调节机制。此外，两个细胞株(Med8a和UW228)在处理后miR-199B-5p的表达显著上调。在诱导的小鼠小脑异种移植模型中，MB细胞感染和携带miR-199B-5p的腺病毒的使用表明，通过miR-199B-5p对肿瘤生长和MB干细胞样细胞亚群的负面影响，临床受益，提供了进一步的概念证明。尽管我们对MB发病机制的了解取得了进展，但其中三分之一的患者仍然无法治愈，目前的治疗方法可能会对长期幸存者造成重大损害。在这里，我们表明miR-199B-5p的表达与转移扩散相关，为MB患者的低风险级别确定了一个新的分子标记。我们进一步证明，在异种移植模型中，MB肿瘤负担可以减轻，这表明miR199B-5P可作为术后辅助治疗，与放疗和化疗相结合，用于改善抗癌MB治疗和患者的生活质量。到目前为止，这是第一个关于miRNA表达可以耗尽肿瘤干细胞的报道，这表明在脑肿瘤中靶向这些细胞是一种有趣的治疗方法。
Through negative regulation of gene expression, microRNAs (miRNAs) can function in cancers as oncosuppressors, and they can show altered expression in various tumor types. Here we have investigated medulloblastoma tumors (MBs), which arise from an early impairment of developmental processes in the cerebellum, where Notch signaling is involved in many cell-fate-determining stages. MBs occur bimodally, with the peak incidence seen between 3–4 years and 8–9 years of age, although it can also occur in adults. Notch regulates a subset of the MB cells that have stem-cell-like properties and can promote tumor growth. On the basis of this evidence, we hypothesized that miRNAs targeting the Notch pathway can regulated these phenomena, and can be used in anti-cancer therapies. In a screening of MB cell lines, the miRNA miR-199b-5p was seen to be a regulator of the Notch pathway through its targeting of the transcription factor HES1. Down-regulation of HES1 expression by miR-199b-5p negatively regulates the proliferation rate and anchorage-independent growth of MB cells. MiR-199b-5p over-expression blocks expression of several cancer stem-cell genes, impairs the engrafting potential of MB cells in the cerebellum of athymic/nude mice, and of particular interest, decreases the MB stem-cell-like (CD133+) subpopulation of cells. In our analysis of 61 patients with MB, the expression of miR-199b-5p in the non-metastatic cases was significantly higher than in the metastatic cases (P = 0.001). Correlation with survival for these patients with high levels of miR-199b expression showed a positive trend to better overall survival than for the low-expressing patients. These data showing the down-regulation of miR-199b-5p in metastatic MBs suggest a potential silencing mechanism through epigenetic or genetic alterations. Upon induction of de-methylation using 5-aza-deoxycytidine, lower miR-199b-5p expression was seen in a panel of MB cell lines, supported an epigenetic mechanism of regulation. Furthermore, two cell lines (Med8a and UW228) showed significant up-regulation of miR-199b-5p upon treatment. Infection with MB cells in an induced xenograft model in the mouse cerebellum and the use of an adenovirus carrying miR-199b-5p indicate a clinical benefit through this negative influence of miR-199b-5p on tumor growth and on the subset of MB stem-cell-like cells, providing further proof of concept. Despite advances in our understanding of the pathogenesis of MB, one-third of these patients remain incurable and current treatments can significantly damage long-term survivors. Here we show that miR-199b-5p expression correlates with metastasis spread, identifying a new molecular marker for a poor-risk class in patients with MB. We further show that in a xenograft model, MB tumor burden can be reduced, indicating the use of miR199b-5p as an adjuvant therapy after surgery, in combination with radiation and chemotherapy, for the improvement of anti-cancer MB therapies and patient quality of life. To date, this is the first report that expression of a miRNA can deplete the tumor stem cells, indicating an interesting therapeutic approach for the targeting of these cells in brain tumors.
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