Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou, PR China.
Cell Death Dis. 2013 Dec 5;4(12):e948. doi: 10.1038/cddis.2013.467.
Leukemia stem cells (LSCs) are considered to be the main reason for relapse and are also regarded as a major hurdle for the success of acute myeloid leukemia chemotherapy. Thus, new drugs targeting LSCs are urgently needed. Triptolide (TPL) is cytotoxic to LSCs. Low dose of TPL enhances the cytotoxicity of idarubicin (IDA) in LSCs. In this study, the ability of TPL to induce apoptosis in leukemic stem cell (LSC)-like cells derived from acute myeloid leukemia cell line KG1a was investigated. LSC-like cells sorted from KG1a were subjected to cell cycle analysis and different treatments, and then followed by in vitro methyl thiazole tetrazolium bromide cytotoxicity assay. The effects of different drug combinations on cell viability, intracellular reactive-oxygen species (ROS) activity, colony-forming ability and apoptotic status were also examined. Combination index-isobologram analysis indicates a synergistic effect between TPL and IDA, which inhibits the colony-forming ability of LSC-like cells and induces their apoptosis. We further investigated the expression of Nrf2, HIF-1α and their downstream target genes. LSC-like cells treated with both TPL and IDA have increased levels of ROS, decreased expression of Nrf2 and HIF-1α pathways. Our findings indicate that the synergistic cytotoxicity of TPL and IDA in LSCs-like cells may attribute to both induction of ROS and inhibition of the Nrf2 and HIF-1α pathways.
白血病干细胞（LSCs）被认为是复发的主要原因，也被认为是急性髓系白血病化疗成功的主要障碍。因此，迫切需要针对 LSCs 的新药。雷公藤内酯（TPL）对 LSCs 具有细胞毒性。低剂量 TPL 增强了 LSCs 中伊达比星（IDA）的细胞毒性。在这项研究中，研究了 TPL 诱导急性髓系白血病细胞系 KG1a 衍生的白血病干细胞（LSC）样细胞凋亡的能力。从 KG1a 中分选的 LSC 样细胞进行细胞周期分析和不同处理，然后进行体外噻唑蓝溴化甲基（MTT）细胞毒性测定。还检查了不同药物组合对细胞活力、细胞内活性氧（ROS）活性、集落形成能力和凋亡状态的影响。组合指数-等效应线分析表明 TPL 和 IDA 之间存在协同作用，抑制 LSC 样细胞的集落形成能力并诱导其凋亡。我们进一步研究了 Nrf2、HIF-1α及其下游靶基因的表达。用 TPL 和 IDA 处理的 LSC 样细胞中 ROS 水平增加，Nrf2 和 HIF-1α 通路的表达降低。我们的研究结果表明，TPL 和 IDA 在 LSCs 样细胞中的协同细胞毒性可能归因于 ROS 的诱导和 Nrf2 和 HIF-1α 通路的抑制。
