Haffner Michael C, Chaux Alcides, Meeker Alan K, Esopi David M, Gerber Jonathan, Pellakuru Laxmi G, Toubaji Antoun, Argani Pedram, Iacobuzio-Donahue Christine, Nelson William G, Netto George J, De Marzo Angelo M, Yegnasubramanian Srinivasan
Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland, USA.
Oncotarget. 2011 Aug;2(8):627-37. doi: 10.18632/oncotarget.316.
DNA methylation at the 5-position of cytosines (5 mC) represents an important epigenetic modification involved in tissue differentiation and is frequently altered in cancer. Recent evidence suggests that 5 mC can be converted to 5-hydroxymethylcytosine (5 hmC) in an enzymatic process involving members of the TET protein family. Such 5 hmC modifications are known to be prevalent in DNA of embryonic stem cells and in the brain, but the distribution of 5 hmC in the majority of embryonic and adult tissues has not been rigorously explored. Here, we describe an immunohistochemical detection method for 5 hmC and the application of this technique to study the distribution of 5 hmC in a large set of mouse and human tissues. We found that 5 hmC was abundant in the majority of embryonic and adult tissues. Additionally, the level of 5 hmC closely tracked with the differentiation state of cells in hierarchically organized tissues. The highest 5 hmC levels were observed in terminally differentiated cells, while less differentiated tissue stem/progenitor cell compartments had very low 5 hmC levels. Furthermore, 5 hmC levels were profoundly reduced in carcinoma of the prostate, breast and colon compared to normal tissues. Our findings suggest a distinct role for 5 hmC in tissue differentiation, and provide evidence for its large-scale loss in cancers.
胞嘧啶5位的DNA甲基化（5 mC）是一种重要的表观遗传修饰，参与组织分化，且在癌症中经常发生改变。最近的证据表明，在涉及TET蛋白家族成员的酶促过程中，5 mC可转化为5-羟甲基胞嘧啶（5 hmC）。已知这种5 hmC修饰在胚胎干细胞和大脑的DNA中普遍存在，但尚未对大多数胚胎组织和成年组织中5 hmC的分布进行严格探究。在此，我们描述了一种用于检测5 hmC的免疫组织化学方法，并将该技术应用于研究大量小鼠和人类组织中5 hmC的分布。我们发现，5 hmC在大多数胚胎组织和成年组织中含量丰富。此外，在分层组织的组织中，5 hmC的水平与细胞的分化状态密切相关。在终末分化细胞中观察到最高的5 hmC水平，而分化程度较低的组织干/祖细胞区室的5 hmC水平非常低。此外，与正常组织相比，前列腺癌、乳腺癌和结肠癌中的5 hmC水平显著降低。我们的研究结果表明5 hmC在组织分化中具有独特作用，并为其在癌症中大规模缺失提供了证据。
