Histone methyltransferase G9a and H3K9 dimethylation inhibit the self-renewal of glioma cancer stem cells
Histone methyltransferase G9a and H3K9 dimethylation inhibit the self-renewal of glioma cancer stem cells
复制标题
组蛋白甲基转移酶G9a和H3K9二甲基化抑制胶质瘤干细胞的自我更新
DOI：
10.1007/s11010-014-2077-4
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发表时间：
2014-09-01
影响因子：
4.3
通讯作者：
Hu, Qikuan
中科院分区：
文献类型：
--
作者：
Tao, Hong;Li, Haiying;Hu, Qikuan
表观遗传修饰对于保持干细胞的自我更新和“干细胞”状态至关重要，而不是让它们分化。组蛋白3赖氨酸9二甲基化（H3K9me2）及其甲基转移酶G9a在这一过程中的实际作用尚不清楚，特别是在癌症干细胞中。在我们的研究中，我们发现了一个有趣的观察，即大多数CD133阳性细胞是H3K9me2阴性的，在胶质瘤组织和培养的细胞中，尽管大多数癌细胞被检测为H3K9me2免疫阳性。这意味着G9a依赖的H3K9me2是癌症干细胞自我更新的关键障碍之一。为了验证这一假设，我们检查了G9a的功能丧失和功能获得。我们发现G9a的选择性抑制剂bix01294可以刺激胶质瘤肿瘤干细胞的球体形成率，同时增加Sox 2和CD 133的表达。通过流式细胞术证实了CD133活性干细胞的增加。另一方面，G9a的过表达增加了H3K9me2的表达，降低了球体形成率以及CD 133和Sox 2的表达。由于H3K9me2修饰是主要的抑制开关，我们预测抑制性H3K9me2修饰可能发生在CD133启动子区域。通过染色质沉淀分析，我们证实了CD133和Sox 2启动子区域被H3K9me2修饰。因此，我们认为G9a依赖的H3K9me2对CD133和Sox2的抑制是胶质瘤干细胞自我更新的主要开关之一。
Epigenetic modification is crucial to keep the self-renewal and the "stemness" states of stem cells, not letting them to differentiate. The actual roles of Histone 3 Lysine 9 dimethylation (H3K9me2) and its methyltransferase G9a in this process are still unclear, especially in cancer stem cells. In our study, we found an interesting observation that most CD133-positive cells were H3K9me2 negative, both in glioma tissues and in cultured cells, although most cancer cells were detected to be H3K9me2 immunopositive. This implied that the G9a-dependent H3K9me2 was one of the crucial barriers of cancer stem cell self-renewal. To test the hypothesis, we examined the loss-of-function and gain-of-function of G9a. We found that bix01294, the selective inhibitor of G9a, can stimulate the sphere formation rate of glioma cancer stem cells, together with increasing Sox2 and CD133 expressions. The increase of CD133-active stem cells was confirmed by flow cytometry. On the other aspect, overexpression of G9a increased the H3K9me2 and decreased the sphere formation rate as well as the CD133 and Sox2 expressions. Since H3K9me2 modification is the major repressive switch, we predict that the repressive H3K9me2 modification may happen at the CD133 promoter regions. By chromatin precipitation assay, we confirmed that the CD133 and Sox2 promoter regions were modified by the H3K9me2. Therefore, we concluded that the G9a-dependent H3K9me2 repression on CD133 and Sox2 was one of the main switches of the self-renewal in glioma cancer stem cells.