Mechanisms of resistance to imatinib mesylate in gastrointestinal stromal tumors and activity of the PKC412 inhibitor against imatinib-resistant mutants
Mechanisms of resistance to imatinib mesylate in gastrointestinal stromal tumors and activity of the PKC412 inhibitor against imatinib-resistant mutants
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DOI：
10.1053/j.gastro.2004.11.020
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发表时间：
2005-02-01
期刊：
影响因子：
29.4
通讯作者：
Marynen, P
中科院分区：
文献类型：
--
作者：
Debiec-Rychter, M;Cools, J;Marynen, P
背景与目的：耐药是胃肠道间质瘤患者治疗中的一大挑战。我们研究了具有原发KIT突变的进展性GIST患者的耐药机制，以及激酶抑制剂PKC412抑制伊马替尼耐药突变的有效性。方法：我们对26例耐药患者进行了细胞遗传学分析，并筛查了KIT和PDGFRA激动域的突变。免疫印迹法检测试剂盒自身磷酸化状态。检测对伊马替尼耐药的GIST细胞和表达这些突变蛋白的BA/F3细胞对伊马替尼和PKC412的敏感性。结果：在12例进展期肿瘤中检测到6个不同的KIT继发突变，其中V654A和T670I为复发突变。1例进展期肿瘤显示获得性PDGFRA-DS42V突变。2例KIT或KIT/PDGFRA扩增。可用于分析的10个进展性肿瘤中有8个显示了磷酸化试剂盒。剩下的两个进展性肿瘤失去了KIT蛋白表达。携带KIT-del557-558/T670I或KIT-InsAY502-503/V654A突变的GIST细胞对伊马替尼耐药，而PKC412显著抑制这些突变体的自孢子化。用BA/F3细胞检测KIT-T670I和PDGFRA-D842V突变株对伊马替尼的耐药性和对PKC412的敏感性。结论。这项研究表明，继发性耐药患者中KIT/PDGFRA激动域的突变频率很高，并将KIT/PDGFRA的基因组扩增定义为耐药的替代原因。在一组患者中，癌细胞失去了对靶向酪氨酸激酶的依赖。我们的发现显示了耐伊马替尼的KIT-T670I和KIT-V654A以及PDGFRA-D842V突变体对PKC412的敏感性。
Background & Aims: Resistance is a major challenge in the treatment of patients with gastrointestinal stromal tumors (GISTS). We investigated the mechanisms of resistance in patients with progressive GISTs with primary KIT mutations and the efficacy of the kinase inhibitor PKC412 for the inhibition of imatinib-resistant mutants. Methods: We performed a cytogenetic analysis and screened for mutations of the KIT and PDGFRA kinase domains in 26 resistant GISTS. KIT autophosphorylation status was assessed by Western immunoblotting. Imatinib-resistant GIST cells and Ba/F3 cells expressing these mutant proteins were tested for sensitivity to imatinib and PKC412. Results: Six distinct secondary mutations in KIT were detected in 12 progressive tumors, with V654A and T670I found to be recurrent. One progressive tumor showed acquired PDGFRA-DS42V mutation. Amplification of KIT or KIT/PDGFRA was found in 2 patients. Eight of 10 progressive tumors available for analysis showed phosphorylated KIT. Two remaining progressive tumors lost KIT protein expression. GIST cells carrying KIT-del557-558/T670I or KIT-InsAY502-503/V654A mutations were resistant to imatinib, while PKC412 significantly inhibited autophosporylation of these mutants. Resistance to imatinib and sensitivity to PKC412 of KIT-T670I and PDGFRA-D842V mutants was confirmed using Ba/F3 cells. Conclusions. This study shows the high frequency of KIT/PDGFRA kinase domain mutations in patients with secondary resistance and defines genomic amplification of KIT/PDGFRA as an alternative cause of resistance to the drug. In a subset of patients, cancer cells lost their dependence on the targeted tyrosine kinase. Our findings show the sensitivity of the imatinib-resistant KIT-T670I and KIT-V654A and of PDGFRA-D842V mutants to PKC412.