Pfeifer G P, Steigerwald S D, Grünwald S
Zentrum der Biologischen Chemie, Universität Frankfurt, FRG.
Cell Biophys. 1989 Aug-Oct;15(1-2):79-86. doi: 10.1007/BF02991581.
The human melanoma cell line M21 can be induced to differentiate into oligodendrocyte-like cells with concommitant cessation of cell division. Cytosine-arabinoside, 5-aza-2'-deoxycytidine, hydroxyurea, aphidicolin, and phorbol-12-myristate-13-acetate were found to be potent differentiation inducers. We have analyzed the changes of methylation of DNA cytosines that occur after treatment of M21 cells with these compounds. Although DNA methylation levels remain unchanged in the presence of aphidicolin and phorbol ester, 5-aza-2'-deoxycytidine-induced differentiation of these cells results in a 40% DNA demethylation. On the other hand, hydroxyurea and cytosine-arabinoside treatment causes DNA hypermethylation, which, in the case of the cytidine analogue is of only transient nature. These results show that the differentiation of human melanoma cells can be accompanied by variable changes of DNA methylation levels. In another set of experiments, the DNA methylation levels have been analyzed during cytosine-arabinoside-induced differentiation of human K562 erythroleukemia cells. In this system, a transient DNA demethylation precedes the establishment of the differentiated phenotype. Since DNA replication is inhibited, this demethylation cannot be explained by inhibition of the maintenance activity of DNA methyltransferase, but is more likely caused by an active excision of 5-methylcytosine from DNA.
人黑色素瘤细胞系M21可被诱导分化为少突胶质细胞样细胞，同时细胞分裂停止。已发现阿糖胞苷、5-氮杂-2'-脱氧胞苷、羟基脲、阿非迪霉素和佛波醇-12-肉豆蔻酸酯-13-乙酸酯是有效的分化诱导剂。我们分析了用这些化合物处理M21细胞后DNA胞嘧啶甲基化的变化。尽管在阿非迪霉素和佛波醇酯存在下DNA甲基化水平保持不变，但5-氮杂-2'-脱氧胞苷诱导这些细胞分化会导致40%的DNA去甲基化。另一方面，羟基脲和阿糖胞苷处理会导致DNA高甲基化，就胞苷类似物而言，这种高甲基化只是短暂的。这些结果表明，人黑色素瘤细胞的分化可能伴随着DNA甲基化水平的可变变化。在另一组实验中，分析了阿糖胞苷诱导人K562红白血病细胞分化过程中的DNA甲基化水平。在这个系统中，短暂的DNA去甲基化先于分化表型的建立。由于DNA复制受到抑制，这种去甲基化不能用DNA甲基转移酶维持活性的抑制来解释，而更可能是由DNA中5-甲基胞嘧啶的主动切除引起的。
