Greenfield Graeme, McPherson Suzanne, Smith James, Mead Adam, Harrison Claire, Mills Ken, McMullin Mary Frances
Blood Cancer Research Group, Patrick G Johnston Centre for Cancer Research, Queen's University, Belfast BT9 7AE, UK.
Division of Genetics and Epidemiology, Institute of Cancer Research, London SW7 3RP, UK.
Cancers (Basel). 2020 Sep 18;12(9):2669. doi: 10.3390/cancers12092669.
Dysregulation of epigenetic processes is increasingly understood to play a role in the pathogenesis of myeloproliferative neoplasms (MPNs). Ruxolitinib, a JAK/STAT inhibitor, has proved a useful addition to the therapeutic arsenal for these disorders, but has limited disease modifying activity. We determined the effect of JAK inhibition on the histone landscape of MPN cells in cell line models of MPNs and validated using samples from the MAJIC randomised clinical trial of ruxolitinib in polycythaemia vera and essential thrombocythaemia. We demonstrated an epigenetic modifying effect of ruxolitinib using a histone modification assay. The majority of 21 histone H3 modifications were upregulated, with H3K27me3 and H3K36me2 significant in the combined cell line results. Chromatin immunoprecipitation and sequencing (CHIP-seq) for three marks of interest, H3K4me1, H3K4me3 and H3K27ac, was consistent with the histone modification assay showing a significant increase in H3K4me3 and H3K27ac peaks at promoter regions, both marks of active transcription. In contrast, RNA sequencing demonstrates a coordinated reduction in gene expression in a number of cell pathways including PI3K-AKT signalling, transcriptional misregulation in cancer and JAK-STAT signalling in spite of these histone changes. This highlights the complex mechanisms of transcriptional control within the cells which was reflected in analysis of the histone landscape in patient samples following ruxolitinib treatment.
表观遗传过程的失调在骨髓增殖性肿瘤（MPN）的发病机制中所起的作用越来越受到关注。鲁索替尼是一种JAK/STAT抑制剂，已被证明是治疗这些疾病的有效药物，但疾病修饰活性有限。我们在MPN的细胞系模型中确定了JAK抑制对MPN细胞组蛋白格局的影响，并使用鲁索替尼治疗真性红细胞增多症和原发性血小板增多症的MAJIC随机临床试验样本进行了验证。我们使用组蛋白修饰分析证明了鲁索替尼的表观遗传修饰作用。21种组蛋白H3修饰中的大多数上调，H3K27me3和H3K36me2在细胞系综合结果中显著。针对三个感兴趣的标记H3K4me1、H3K4me3和H3K27ac的染色质免疫沉淀和测序（CHIP-seq）与组蛋白修饰分析一致，显示启动子区域的H3K4me3和H3K27ac峰显著增加，这两个都是活跃转录的标记。相比之下，RNA测序表明，尽管有这些组蛋白变化，但包括PI3K-AKT信号传导、癌症中的转录失调和JAK-STAT信号传导在内的许多细胞途径中的基因表达都有协同降低。这突出了细胞内转录控制的复杂机制，这在鲁索替尼治疗后患者样本的组蛋白格局分析中得到了体现。
