Expression of c-Kit isoforms in multiple myeloma: differences in signaling and drug sensitivity
Expression of c-Kit isoforms in multiple myeloma: differences in signaling and drug sensitivity
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DOI：
10.3324/haematol.12171
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发表时间：
2008-05-31
期刊：
影响因子：
10.1
通讯作者：
Pandiella, Atanasio
中科院分区：
文献类型：
--
作者：
Carlos Montero, Juan;Lopez-Perez, Ricardo;Pandiella, Atanasio
背景c-Kit在30%的多发性骨髓瘤患者的浆细胞中表达。已经描述了两种不同的c-Kit亚型，其特征是在细胞外域中存在或不存在四肽序列GNNK。然而，它们在骨髓瘤细胞中的表达和功能尚不清楚。设计与方法用逆转录聚合酶链式反应检测c-Kit亚型在患者新鲜血浆细胞和骨髓瘤细胞系中的表达，分析c-Kit亚型在骨髓瘤细胞中表达的功能。使用针对几种信号蛋白激活形式的抗体，通过Western blotting研究信号转导。结果患者新鲜浆细胞和骨髓瘤细胞株均表达c-Kit两种异构体。用编码c-Kit-GNNK(+)或c-Kit-GNNK(-)形式的载体逆转录病毒感染骨髓瘤细胞，发现这些亚型之间的磷酸化动力学存在差异。干细胞因子诱导的GNNK(-)形式的激活比GNNK(+)形式的激活更快和更明显，而GNNK(+)形式的激活持续时间更长。C-Kit受体弱激活ERK1/2和ERK5通路。然而，这两种受体都有效地偶联到PI3K/Akt途径，并刺激p7036K激活。后者对mTOR抑制剂雷帕霉素敏感。药物敏感性研究表明，表达GNNK(-)形式的细胞对Bortezomib和Melphalan的抗骨髓瘤作用更具抵抗力。结论我们的数据表明，c-Kit在多发性骨髓瘤细胞中的表达是功能性的，并与可能调节细胞死亡的生存通路相耦合，以响应用于治疗该疾病的治疗化合物。
Backgroundc-Kit is expressed in the plasma cells from 30% of patients with multiple myeloma. Two different isoforms of c-Kit, characterized by the presence or absence of the tetrapeptide sequence GNNK in the extracellular domain, have been described. However, their expression and function in myeloma cells are unknown. We explored the function and expression of these c-Kit isoforms in myeloma cells.Design and MethodsExpression of c-Kit isoforms was investigated by reverse transcriptase polymerase chain reaction in fresh plasma cells from patients and cell lines.The function of these c-Kit isoforms was analyzed upon expression in myeloma cells. Signaling was investigated by western blotting using antibodies specific for activated forms of several signaling proteins. The impact of c-Kit on the action of drugs commonly used in the treatment of multiple myeloma was investigated by MTT proliferation assays.ResultsFresh plasma cells from patients as well as myeloma cell lines expressed the two isoforms of c-Kit. Retroviral infection of myeloma cells with vectors that code for c-Kit-GNNK(+) or c-Kit-GNNK(-) forms demonstrated differences in the kinetics of phosphorylation between these isoforms. Stem cell factor-induced activation of the GNNK(-) form was faster and more pronounced than that of the GNNK(+) form, whose activation, however, lasted for longer. The c-Kit receptors weakly activated the Erk1/2 and Erk5 pathways. Both receptors, however, efficiently coupled to the PI3K/Akt pathway, and stimulated p7036K activation. The latter was sensitive to the mTOR inhibitor, rapamycin. Studies of drug sensitivity indicated that cells expressing the GNNK(-) form were more resistant to the anti-myeloma action of bortezomib and melphalan.ConclusionsOur data indicate that c-Kit expression in multiple myeloma cells is functional, and coupled to survival pathways that may modulate cell death in response to therapeutic compounds used in the treatment of this disease.