Xu Zhifei, Shao JinJin, Li Lin, Peng Xueming, Chen Min, Li Guanqun, Yan Hao, Yang Bo, Luo Peihua, He Qiaojun
Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Zijingang Campus, Hangzhou, 310058, Zhejiang, People's Republic of China.
BMC Cancer. 2016 Jan 5;16:2. doi: 10.1186/s12885-015-2010-6.
Chemotherapy is the only therapy option for the majority of AML patients, however, there are several limitations for this treatment. Our aim was to find a new chemotherapy strategy that is more effective and less toxic.
MTT assays and a xenograft mouse model were employed to evaluate the synergistic activity of all-trans retinoic acid (ATRA) combined with topotecan (TPT). Drug-induced DNA damage and apoptosis were determined by flow cytometry analysis with PI and DAPI staining, the comet assay and Western blots. Short hairpin RNA (shRNA) and a RARα plasmid were used to determine whether RARα expression influenced DNA damage and apoptosis.
We found that ATRA exhibited synergistic activity in combination with Topotecan in AML cells, and the enhanced apoptosis induced by Topotecan plus ATRA resulted from caspase pathway activation. Mechanistically, ATRA dramatically down regulated RARα protein levels and led to more DNA damage and ultimately resulted in the synergism of these two agents. In addition, the increased antitumor efficacy of Topotecan combined with ATRA was further validated in the HL60 xenograft mouse model.
Our data demonstrated, for the first time, that the combination of TPT and ATRA showed potential benefits in AML, providing a novel insight into clinical treatment strategies.
化疗是大多数急性髓系白血病（AML）患者唯一的治疗选择，然而，这种治疗存在若干局限性。我们的目标是找到一种更有效且毒性更小的新化疗策略。
采用MTT法和异种移植小鼠模型评估全反式维甲酸（ATRA）与拓扑替康（TPT）联合使用的协同活性。通过PI和DAPI染色的流式细胞术分析、彗星试验和蛋白质免疫印迹法测定药物诱导的DNA损伤和细胞凋亡。使用短发夹RNA（shRNA）和RARα质粒来确定RARα表达是否影响DNA损伤和细胞凋亡。
我们发现ATRA与拓扑替康联合使用时在AML细胞中表现出协同活性，并且拓扑替康加ATRA诱导的细胞凋亡增强是由半胱天冬酶途径激活所致。从机制上讲，ATRA显著下调RARα蛋白水平，导致更多DNA损伤，并最终导致这两种药物产生协同作用。此外，拓扑替康与ATRA联合使用时抗肿瘤疗效的增强在HL60异种移植小鼠模型中得到进一步验证。
我们的数据首次证明，TPT与ATRA联合使用在AML中显示出潜在益处，为临床治疗策略提供了新的见解。
