Cheng Jonathan C, Weisenberger Daniel J, Gonzales Felicidad A, Liang Gangning, Xu Guo-Liang, Hu Ye-Guang, Marquez Victor E, Jones Peter A
Department of Urology, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90089-9181, USA.
Mol Cell Biol. 2004 Feb;24(3):1270-8. doi: 10.1128/MCB.24.3.1270-1278.2004.
During tumorigenesis, tumor suppressor and cancer-related genes are commonly silenced by aberrant DNA methylation in their promoter regions. Recently, we reported that zebularine [1-(beta-D-ribofuranosyl)-1,2-dihydropyrimidin-2-one] acts as an inhibitor of DNA methylation and exhibits chemical stability and minimal cytotoxicity both in vitro and in vivo. Here we show that continuous application of zebularine to T24 cells induces and maintains p16 gene expression and sustains demethylation of the 5' region for over 40 days, preventing remethylation. In addition, continuous zebularine treatment effectively and globally demethylated various hypermethylated regions, especially CpG-poor regions. The drug caused a complete depletion of extractable DNA methyltransferase 1 (DNMT1) and partial depletion of DNMT3a and DNMT3b3. Last, sequential treatment with 5-aza-2'-deoxycytidine followed by zebularine hindered the remethylation of the p16 5' region and gene resilencing, suggesting the possible combination use of both drugs as a potential anticancer regimen.
在肿瘤发生过程中，肿瘤抑制基因和癌症相关基因通常在其启动子区域因异常的DNA甲基化而沉默。最近，我们报道了zebularine [1-(β-D-呋喃核糖基)-1,2-二氢嘧啶-2-酮] 作为一种DNA甲基化抑制剂，在体外和体内均表现出化学稳定性和最小的细胞毒性。在此我们表明，将zebularine持续应用于T24细胞可诱导并维持p16基因表达，并使5'区域去甲基化持续超过40天，防止重新甲基化。此外，持续的zebularine处理可有效且全面地使各种高甲基化区域去甲基化，尤其是CpG含量低的区域。该药物导致可提取的DNA甲基转移酶1 (DNMT1) 完全耗竭，DNMT3a和DNMT3b3部分耗竭。最后，先用5-aza-2'-脱氧胞苷处理，再用zebularine处理，可阻碍p16 5'区域的重新甲基化和基因重新沉默，这表明这两种药物可能联合使用作为一种潜在的抗癌方案。
