Shi Fangfang, Yang Xiaojing, Gong Yuping, Shi Rui, Yang Xi, Naren Duolan, Wu Jiahui
Department of Hematology, West China Hospital, Sichuan University, Chengdu, China.
Anticancer Drugs. 2015 Apr;26(4):410-21. doi: 10.1097/CAD.0000000000000200.
PP242 is a novel dual mammalian target of rapamycin (mTOR) inhibitor that simultaneously inhibits mTORC1 and mTORC2, and its antileukemia effect has been sufficiently investigated here. The human acute leukemia cell lines and primary blasts were treated with PP242 alone or in combination with daunorubicin (DNR). Cell proliferation was examined using an MTT assay. The phosphorylation expression of the Akt/mTORC1/eIF4E signaling pathway was assessed by western blot analysis. The assembly of the eIF4F translation initiation complex was examined using a 7-methyl-guanosine cap affinity assay. PP242 significantly induced cytotoxicity in human acute leukemia cells, especially in combination with DNR. The phosphorylation levels of eIF4E (p-eIF4E) at Ser209 influence the antileukemia roles of PP242. As expected, the antiproliferative effects of PP242 on leukemia cells with low p-eIF4E expression, such as the acute promyelocytic leukemia NB4 cell line and AML-M3 primary blasts, were poor. Surprisingly, the effects of PP242 in leukemia cells with high p-eIF4E expression, such as the acute myelomonocytic leukemia THP-1 cell line and M4-M5 primary blasts, were also weak. In contrast, PP242 exerted a significant antiproliferative effect in the Ph+ acute lymphoblastic leukemia SUP-B15 cell line and the mantle cell lymphoma JEKO-1 cell line, which had intermediate p-eIF4E levels. PP242 inhibited the translation of the antiapoptotic protein Mcl-1 by downregulating the Akt/mTORC1/eIF4E signaling pathway. More importantly, DNR activated the Akt/mTORC1/eIF4E signaling pathway, whereas PP242 effectively eliminated this deleterious side effect of DNR and synergistically enhanced the anticancer ability of DNR treatment. PP242, especially in combination with DNR, exerts significant antileukemia effects.
PP242是一种新型的双靶点哺乳动物雷帕霉素靶蛋白（mTOR）抑制剂，它能同时抑制mTORC1和mTORC2，本文已对其抗白血病作用进行了充分研究。人急性白血病细胞系和原代母细胞分别用PP242单独处理或与柔红霉素（DNR）联合处理。采用MTT法检测细胞增殖情况。通过蛋白质免疫印迹分析评估Akt/mTORC1/eIF4E信号通路的磷酸化表达。使用7-甲基鸟苷帽亲和试验检测eIF4F翻译起始复合物的组装情况。PP242显著诱导人急性白血病细胞产生细胞毒性，尤其是与DNR联合使用时。丝氨酸209位点的eIF4E（p-eIF4E）磷酸化水平影响PP242的抗白血病作用。正如预期的那样，PP242对p-eIF4E表达较低的白血病细胞（如急性早幼粒细胞白血病NB4细胞系和AML-M3原代母细胞）的抗增殖作用较差。令人惊讶的是，PP242对p-eIF4E表达较高的白血病细胞（如急性粒单核细胞白血病THP-1细胞系和M4-M5原代母细胞）的作用也较弱。相比之下，PP242在p-eIF4E水平中等的Ph+急性淋巴细胞白血病SUP-B15细胞系和套细胞淋巴瘤JEKO-1细胞系中发挥了显著的抗增殖作用。PP242通过下调Akt/mTORC1/eIF4E信号通路抑制抗凋亡蛋白Mcl-1的翻译。更重要的是，DNR激活了Akt/mTORC1/eIF4E信号通路，而PP242有效地消除了DNR的这种有害副作用，并协同增强了DNR治疗的抗癌能力。PP, 242，尤其是与DNR联合使用时，具有显著的抗白血病作用。
