DNA methyltransferase and demethylase in human prostate cancer
DNA methyltransferase and demethylase in human prostate cancer
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DOI：
10.1002/mc.10033
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发表时间：
2002-03-01
影响因子：
4.6
通讯作者：
Dahiya, R
中科院分区：
文献类型：
--
作者：
Patra, SK;Patra, A;Dahiya, R
最近的研究表明，基因调控序列中 CpG 岛的胞嘧啶 5 甲基化是失活的关键机制之一。负责 CpG 甲基化的酶是 DNA 甲基转移酶 (DNMT) 1、DNMT3a 和 DNMT3b，负责去甲基化的酶是 DNA 去甲基化酶 (MBD2)。人类前列腺癌缺乏甲基化-去甲基化酶的研究。我们假设在人类前列腺癌中 MBD2 酶活性受到抑制，而 DNMT1 酶活性升高。为了检验这一假设，我们分析了人前列腺癌细胞系和组织中 MBD2 和 DNMT1、DNMT3a 和 DNMT3b 的酶活性、mRNA 和蛋白质水平。通过生化法分析DNMTs和MBD2的酶活性，通过逆转录酶-聚合酶链反应和Northern blotting分析mRNA表达。通过使用特异性抗体的免疫组织化学来测量蛋白质表达。这些实验结果表明：（1）与良性前列腺上皮细胞系（BPH-1）和良性前列腺增生（BPH）组织相比，癌细胞系和癌组织中DNMT的活性高出两倍至三倍； (2)MBD2活性在前列腺癌细胞系中缺乏，但在BPH-1细胞中存在； (3)免疫组化分析显示，与BPH-1细胞系和BPH组织相比，DNMT1在所有前列腺癌细胞系和癌组织中表达更高； (4)MBD2蛋白在BPH-1细胞中表达显着较高，而在前列腺癌细胞系中缺乏；在BPH组织中，与前列腺癌组织中不表达相比，在BPH组织中观察到MBD2蛋白表达较差； (5)与BPH-1相比，前列腺癌中DNMT1的mRNA表达上调，并且发现MBD2的mRNA表达在所有病例中均显着表达。这些研究的结果清楚地表明，在人类前列腺癌中，DNMT1 活性上调，而 MBD2 在翻译水平上受到抑制。这些结果可能证明前列腺癌中各种基因的CpG高甲基化的分子机制。 (C) 2002 Wiley-Liss, Inc.
Recent studies have shown that cytosine-5 methylation at CpG islands in the regulatory sequence of a gene is one of the key mechanisms of inactivation. The enzymes responsible for CpG methylation are DNA methyltransferase (DNMT) 1, DNMT3a, and DNMT3b, and the enzyme responsible for dernethylation is DNA demethylase (MBD2). Studies on methylation-demethylation enzymes are lacking in human prostate cancer. We hypothesize that MBD2 enzyme activity is repressed and that DNMT1 enzyme activity is elevated in human prostate cancer. To test this hypothesis, we analyzed enzyme activities, mRNA, and protein levels of MBD2 and DNMT1, DNMT3a, and DNMT3b in human prostate cancer cell lines and tissues. The enzyme activities of DNMTs and MBD2 were analyzed by biochemical assay, The mRNA expression was analyzed by reverse transcriptase-polymerase chain reaction and by Northern blotting. The protein expression was measured by immunohistochemistry with specific antibodies. The results of these experiments demonstrated that (1) the activity of DNMTs was twofold to threefold higher in cancer cell lines and cancer tissues, as compared with a benign prostate epithelium cell line (BPH-1) and benign prostatic hyperplasia (BPH) tissues; (2) MBD2 activity was lacking in prostate cancer cell lines but present in BPH-1 cells; (3) immunohistochemical analyses exhibited higher expression of DNMT1 in all prostate cancer cell lines and cancer tissues, as compared with BPH-1 cell lines and BPH tissues; (4) MBD2 protein expression was significantly higher in BPH-1 cells and lacking in prostate cancer cell lines and, in BPH tissues, MBD2 protein expression was poorly observed, as compared with no expression in prostate cancer tissues; and (5) mRNA expression for DNMT1 was upregulated in prostate cancer, as compared with BPH-1, and mRNA expression for MBD2 was found to be significantly expressed in all cases. The results of these studies clearly demonstrate that DNMT1 activity is upregulated, whereas MBD2 is repressed at the level of translation in human prostate cancer. These results may demonstrate molecular mechanisms of CpG hypermethylation of various genes in prostate cancer. (C) 2002 Wiley-Liss, Inc.