Department of Pediatrics, Nippon Medical School Chiba Hokusoh Hospital, 1715 Kamagari, Inzai, Chiba, 270-1694, Japan.
Department of Pediatrics, Nippon Medical School, Inzai, Chiba, Japan.
Cancer Chemother Pharmacol. 2022 Jan;89(1):83-91. doi: 10.1007/s00280-021-04373-4. Epub 2021 Nov 26.
Drug resistance is a serious problem in leukemia therapy. A novel purine nucleoside analogue, nelarabine, is available for the treatment of children with T cell acute lymphoblastic leukemia. We investigated the mechanisms of drug resistance to nelarabine.
Nelarabine-resistant cells were selected by stepwise and continuous exposure to nelarabine using the limiting dilution method in human B and T cell lymphoblastic leukemia cell lines. Expression analysis was performed using real-time polymerase chain reaction, and epigenetic analysis was performed using methylation-specific polymerase chain reaction and chromatin immunoprecipitation.
The RNA expression level for deoxycytidine kinase (dCK) was decreased in nelarabine-resistant leukemia cells. There were no differences between the parental and nelarabine-resistant leukemia cells in the methylation status of the promoter region of the dCK gene. In the chromatin immune precipitation assay, decreased acetylation of histones H3 and H4 bound to the dCK promoter was seen in the nelarabine-resistant cells when compared to the parental cells. Furthermore, treatment with a novel histone deacetylase inhibitor, vorinostat, promoted the cytotoxic effect of nelarabine along with increased expression of the dCK gene, and it increased acetylation of both histones H3 and H4 bound to the dCK promoter in nelarabine-resistant leukemia cells. The combination index showed that the effect of nelarabine and vorinostat was synergistic.
This study reports that nelarabine with vorinostat can promote cytotoxicity in nelarabine-resistant leukemia cells through epigenetic mechanisms.
耐药性是白血病治疗中的一个严重问题。一种新型嘌呤核苷类似物，奈拉滨，可用于治疗儿童 T 细胞急性淋巴细胞白血病。我们研究了奈拉滨耐药的机制。
采用逐步和连续暴露于奈拉滨的有限稀释法，在人 B 和 T 细胞淋巴母细胞白血病细胞系中选择奈拉滨耐药细胞。采用实时聚合酶链反应进行表达分析，采用甲基化特异性聚合酶链反应和染色质免疫沉淀进行表观遗传分析。
奈拉滨耐药白血病细胞中脱氧胞苷激酶 (dCK) 的 RNA 表达水平降低。亲本白血病细胞和奈拉滨耐药白血病细胞的 dCK 基因启动子区甲基化状态无差异。在染色质免疫沉淀试验中，与亲本细胞相比，奈拉滨耐药细胞中与 dCK 启动子结合的组蛋白 H3 和 H4 的乙酰化减少。此外，新型组蛋白去乙酰化酶抑制剂伏立诺他治疗可促进奈拉滨的细胞毒性作用，同时增加 dCK 基因的表达，并增加与 dCK 启动子结合的组蛋白 H3 和 H4 的乙酰化。组合指数表明奈拉滨和伏立诺他的作用具有协同性。
本研究报告奈拉滨联合伏立诺他可通过表观遗传机制促进奈拉滨耐药白血病细胞的细胞毒性。
