Mixed lineage leukemia results from chromosomal rearrangements of the gene mixed lineage leukemia (MLL). MLL-AF9 is one such rearrangement that recruits the lysine methyltransferase, human disruptor of telomere silencing 1-like (DOT1L) and lysine specific demethylase 1 (LSD1), resulting in elevated expression of the Homeobox protein A9 (HOXA9), and leukemia. Inhibitors of LSD1 or DOT1L reduce HOXA9 expression, kill MLL-rearranged cells, and may treat leukemia. To quantify their effects on histone modifying enzyme activity and expression in MLL-rearranged leukemia, we tested inhibitors of DOT1L (EPZ-5676), LSD1 (GSK2879552), and HDAC (mocetinostat), in the MLL-AF9 cell line MOLM-13. All inhibitors reduced MOLM-13 viability but only mocetinostat induced apoptosis. EPZ-5676 increased total histone lysine dimethylation, which was attributed to a reduction in LSD1 expression, and was indistinguishable from direct LSD1 inhibition by GSK2879552. All compounds directly inhibit, or reduce the expression of, HOXA9, DOT1L and LSD1 by qPCR, increase total histone lysine methylation and acetylation by LC-MS/MS, and specifically reduce H3K79Me2 and increase H3K14Ac. Each inhibitor altered the expression of many histone modifying enzymes which may precipitate additional changes in expression. To the extent that this decreases HOXA9 expression it benefits mixed lineage leukemia treatment, all other expression changes are off-target effects.

中文翻译：

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选择性DOT1L，LSD1和HDAC I类抑制剂可降低MLL-AF9重排的白血病细胞中HOXA9的表达，但会调节许多组蛋白修饰酶的表达。

混合谱系白血病是由基因混合谱系白血病（MLL）的染色体重排导致的。MLL-AF9是一种这样的重排，它募集赖氨酸甲基转移酶，端粒沉默1样（DOT1L）和赖氨酸特异性脱甲基酶1（LSD1）的人类破坏者，导致同源盒蛋白A9（HOXA9）的表达升高和白血病。LSD1或DOT1L的抑制剂会降低HOXA9的表达，杀死MLL重排的细胞，并可能治疗白血病。为了量化它们对MLL重排的白血病中组蛋白修饰酶活性和表达的影响，我们在MLL-AF9细胞系MOLM-13中测试了DOT1L（EPZ-5676），LSD1（GSK2879552）和HDAC（mocetinostat）的抑制剂。所有抑制剂均降低了MOLM-13的活力，但只有Mocetinostat诱导了细胞凋亡。EPZ-5676增加了总的组蛋白赖氨酸二甲基化，这归因于LSD1表达的减少，与GSK2879552对LSD1的直接抑制没有区别。所有化合物均通过qPCR直接抑制或降低HOXA9，DOT1L和LSD1的表达，通过LC-MS / MS增加总组蛋白赖氨酸甲基化和乙酰化，特别是减少H3K79Me2和增加H3K14Ac。每种抑制剂都会改变许多组蛋白修饰酶的表达，这可能会导致表达的其他变化。在某种程度上，这降低了HOXA9表达，使其受益于混合谱系白血病治疗，所有其他表达变化都是脱靶效应。通过LC-MS / MS可提高总组蛋白赖氨酸甲基化和乙酰化程度，特别是降低H3K79Me2并增加H3K14Ac。每种抑制剂都会改变许多组蛋白修饰酶的表达，这可能会导致表达的其他变化。在某种程度上，这降低了HOXA9表达，使其受益于混合谱系白血病治疗，所有其他表达变化都是脱靶效应。通过LC-MS / MS可提高总组蛋白赖氨酸甲基化和乙酰化程度，特别是降低H3K79Me2并增加H3K14Ac。每种抑制剂都会改变许多组蛋白修饰酶的表达，这可能会导致表达的其他变化。在某种程度上，这降低了HOXA9表达，使其受益于混合谱系白血病治疗，所有其他表达变化都是脱靶效应。