Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China.
Chem Res Toxicol. 2011 Nov 21;24(11):2040-3. doi: 10.1021/tx2003849. Epub 2011 Nov 1.
Aberrant cytosine methylation is known to be associated with cancer development. Here, we assessed how common cancer chemotherapeutic agents perturb cytosine methylation in Jurkat-T acute lymphoblastic leukemia cells. We tested six antitumor agents and found that cyclophosphamide induced the most pronounced increase in global DNA cytosine methylation after a 24-h treatment. Long-term treatment with cyclophosphamide led to a time-dependent increase in cytosine methylation level with up to 4 days of treatment, and the extent of cytosine methylation returned to normal level after 8 days. The trend of change in DNA methylation level paralleled that of the expression level of DNMT1 protein, whereas no significant increase in DNMT1 mRNA level was observed. Previous studies showed that the stability of endogenous DNMT1 protein is regulated by lysine methylation through histone lysine methyltransferase Set7 and lysine-specific demethylase 1 (LSD1), with the methylated DNMT1 being the target for proteasomal degradation. We observed that the elevated expression of DNMT1 protein at 4 days of treatment was correlated with the increased expression of LSD1 protein and with the decreased frequency of K142 methylation in DNMT1. Taken together, our results showed that cyclophosphamide perturbed temporarily global cytosine methylation in Jurkat-T cells via regulation of the lysine methylation level in DNMT1.
异常的胞嘧啶甲基化与癌症的发展有关。在这里，我们评估了常见的癌症化疗药物如何扰乱 Jurkat-T 急性淋巴细胞白血病细胞中的胞嘧啶甲基化。我们测试了六种抗肿瘤药物，发现环磷酰胺在 24 小时处理后诱导了最显著的全基因组 DNA 胞嘧啶甲基化增加。环磷酰胺的长期治疗导致胞嘧啶甲基化水平随时间呈依赖性增加，最长可达 4 天的治疗，并且在 8 天后胞嘧啶甲基化水平恢复正常。DNA 甲基化水平的变化趋势与 DNMT1 蛋白的表达水平平行，而 DNMT1 mRNA 水平没有明显增加。先前的研究表明，内源性 DNMT1 蛋白的稳定性通过组蛋白赖氨酸甲基转移酶 Set7 和赖氨酸特异性去甲基酶 1（LSD1）调控的赖氨酸甲基化来调节，其中甲基化的 DNMT1 是蛋白酶体降解的靶标。我们观察到，在 4 天的治疗中，DNMT1 蛋白表达的升高与 LSD1 蛋白表达的增加以及 DNMT1 中 K142 甲基化频率的降低相关。综上所述，我们的结果表明，环磷酰胺通过调节 DNMT1 中的赖氨酸甲基化水平暂时扰乱了 Jurkat-T 细胞中的全基因组胞嘧啶甲基化。
