Department of Hematology and Oncology, Faculty of Medicine, University of Fukui, Shimoaizuki 23-3, Mastuoka, Eiheiji-Chou, Fukui 910-1193, Japan; Translational Research Center, University of Fukui, Japan.
Department of Hematology and Oncology, Faculty of Medicine, University of Fukui, Shimoaizuki 23-3, Mastuoka, Eiheiji-Chou, Fukui 910-1193, Japan.
Biochem Pharmacol. 2014 Jul 1;90(1):16-24. doi: 10.1016/j.bcp.2014.04.002. Epub 2014 Apr 13.
Mutations of the FMS-like tyrosine kinase 3 (FLT3) have been reported in about a third of patients with acute myeloid leukemia (AML). The presence of FLT3 mutations confers a poor prognosis. Thus, pharmacological inhibitors of FLT3 are of therapeutic interest for AML. Gö6976 is an indolocarbazole with a similar structural backbone to staurosporine. In the present study, we demonstrated that Gö6976 displays a potent inhibitory activity against recombinant FLT3 using an in vitro kinase assay, with an IC50 value of 0.7nM. Gö6976 markedly inhibited the proliferation of human leukemia cells having FLT3-ITD such as MV4-11 and MOLM13. We also observed that Gö6976 showed minimal toxicity for human normal CD34(+) cells. Gö6976 suppressed the phosphorylation of FLT3 and downstream signaling molecules such as STAT3/5, Erk1/2, and Akt in MV4-11 and MOLM13 cells. Interestingly, induction of apoptosis by Gö6976 was associated with rapid and pronounced down-regulation of the anti-apoptotic protein survivin and MCL-1. Suppression of survivin protein expression by Gö6976 was due to the inhibition of transcription via the suppression of STAT3/5. On the other hand, Gö6976 induced proteasome-mediated degradation of MCL-1. Previously described FLT3 inhibitors such as PKC412 are bound by the human plasma protein, α1-acid glycoprotein, resulting in diminished inhibitory activity against FLT3. In contrast, we found that Gö6976 potently inhibited phosphorylation of FLT3 and exerted cytotoxicity in the presence of human serum. In conclusion, Gö6976 is a potent FLT3 inhibitor that displays a significant antiproliferative activity against leukemia cells with FLT3-ITD through the profound down-regulation of survivin and MCL-1.
FMS 样酪氨酸激酶 3（FLT3）的突变已在约三分之一的急性髓系白血病（AML）患者中被报道。FLT3 突变的存在预示着不良预后。因此，FLT3 的药理学抑制剂对 AML 具有治疗意义。Gö6976 是一种吲哚咔唑，其结构骨架与 staurosporine 相似。在本研究中，我们通过体外激酶测定证明 Gö6976 对重组 FLT3 显示出很强的抑制活性，IC50 值为 0.7nM。Gö6976 显著抑制了具有 FLT3-ITD 的人白血病细胞（如 MV4-11 和 MOLM13）的增殖。我们还观察到 Gö6976 对人正常 CD34(+) 细胞表现出最小的毒性。Gö6976 抑制了 MV4-11 和 MOLM13 细胞中 FLT3 和下游信号分子如 STAT3/5、Erk1/2 和 Akt 的磷酸化。有趣的是，Gö6976 诱导的凋亡与抗凋亡蛋白 survivin 和 MCL-1 的快速和显著下调有关。Gö6976 对 survivin 蛋白表达的抑制是由于通过抑制 STAT3/5 抑制转录所致。另一方面，Gö6976 诱导了 MCL-1 的蛋白酶体介导的降解。先前描述的 FLT3 抑制剂，如 PKC412，与人类血浆蛋白α1-酸性糖蛋白结合，导致对 FLT3 的抑制活性降低。相比之下，我们发现 Gö6976 在人血清存在的情况下能够强有力地抑制 FLT3 的磷酸化并发挥细胞毒性。总之，Gö6976 是一种有效的 FLT3 抑制剂，通过对 survivin 和 MCL-1 的深度下调，对具有 FLT3-ITD 的白血病细胞表现出显著的抗增殖活性。
