Kindler Thomas, Breitenbuecher Frank, Kasper Stefan, Estey Eli, Giles Francis, Feldman Eric, Ehninger Gerhard, Schiller Gary, Klimek Virginia, Nimer Stephen D, Gratwohl Alois, Choudhary Chuna Ram, Mueller-Tidow Constan, Serve Hubert, Gschaidmeier Harald, Cohen Pamela S, Huber Christoph, Fischer Thomas
Johannes-Gutenberg University Mainz, 3rd Med Department, Mainz, Germany.
Blood. 2005 Jan 1;105(1):335-40. doi: 10.1182/blood-2004-02-0660. Epub 2004 Sep 2.
Fms-like tyrosine kinase 3 (FLT3) receptor mutations as internal tandem duplication (ITD) or within the kinase domain are detected in up to 35% of patients with acute myeloid leukemia (AML). N-benzoyl staurosporine (PKC412), a highly effective inhibitor of mutated FLT3 receptors, has significant antileukemic efficacy in patients with FLT3-mutated AML. Mutation screening of FLT3 exon 20 in AML patients (n = 110) revealed 2 patients with a novel mutation (Y842C) within the highly conserved activation loop of FLT3. FLT3-Y842C-transfected 32D cells showed constitutive FLT3 tyrosine phosphorylation and interleukin 3 (IL-3)-independent growth. Treatment with PKC412 led to inhibition of proliferation and apoptotic cell death. Primary AML blasts bearing FLT3-Y842C mutations showed constitutive FLT3 and signal transducer and activator of transcription 5 (STAT-5) tyrosine phosphorylation. Ex vivo PKC412 treatment of primary blasts resulted in suppression of constitutive FLT3 and STAT-5 activation and apoptotic cell death. Inspection of the FLT3 structure revealed that Y842 is the key residue in regulating the switch from the closed to the open (= active) conformation of the FLT3 activation loop. Overall, our data suggest that mutations at Y842 represent a significant new activating mutation in AML blasts. Since FLT3 tyrosine kinase inhibitors (TKIs) such as PKC412 are currently being investigated in clinical trials in AML, extended sequence analysis of FLT3 may be helpful in defining the spectrum of TKI-sensitive FLT3 mutations in AML.
在高达35%的急性髓系白血病（AML）患者中可检测到Fms样酪氨酸激酶3（FLT3）受体突变，这些突变表现为内部串联重复（ITD）或位于激酶结构域内。N-苯甲酰星孢菌素（PKC412）是一种高效的突变型FLT3受体抑制剂，对FLT3突变的AML患者具有显著的抗白血病疗效。对110例AML患者的FLT3第20外显子进行突变筛查，发现2例患者在FLT3高度保守的激活环内存在一种新的突变（Y842C）。转染FLT3-Y842C的32D细胞表现出组成型FLT3酪氨酸磷酸化和白细胞介素3（IL-3）非依赖性生长。用PKC412处理可导致细胞增殖抑制和凋亡性细胞死亡。携带FLT3-Y842C突变的原发性AML原始细胞表现出组成型FLT3和信号转导及转录激活因子5（STAT-5）酪氨酸磷酸化。对原发性原始细胞进行PKC412体外处理可导致组成型FLT3和STAT-5激活的抑制以及凋亡性细胞死亡。对FLT3结构的研究表明，Y842是调节FLT3激活环从关闭构象转变为开放（=活性）构象的关键残基。总体而言，我们的数据表明，Y842处的突变代表了AML原始细胞中一种重要的新的激活突变。由于目前正在AML的临床试验中研究诸如PKC412等FLT3酪氨酸激酶抑制剂（TKIs），对FLT3进行扩展序列分析可能有助于确定AML中对TKI敏感的FLT3突变谱。
