A novel tyrosine kinase switch is a mechanism of imatinib resistance in gastrointestinal stromal tumors
A novel tyrosine kinase switch is a mechanism of imatinib resistance in gastrointestinal stromal tumors
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DOI：
10.1038/sj.onc.1210173
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发表时间：
2007-06-07
期刊：
影响因子：
8
通讯作者：
Bearss, D.
中科院分区：
文献类型：
--
作者：
Mahadevan, D.;Cooke, L.;Bearss, D.
KIT或α-血小板衍生生长因子受体(α-PDGFR)激活突变是胃肠道间质瘤(GIST)的致病机制。尽管甲磺酸伊马替尼(IM)有很好的疗效，但患者仍在复发。我们从IM敏感的GIST882细胞系(GIST-S)中培养获得了一株耐IM的GIST细胞株(GIST-R)。基因表达专家。GIST-S、GIST-R细胞和两名IM耐药的GIST患者的Ling(GEP)显示KIT下调，暗示在IM耐药中起主要作用。相反，GIST-R细胞通过在激酶开关中过度表达致癌受体酪氨酸激酶-Axl-来获得IM耐药性。此外，免疫组织化学(IHC)显示，两名IM耐药的GIST患者表达Ax1，而不表达c-Kit。实时逆转录聚合酶链式反应和GIST-S和GIST-R细胞的Western blotting证实了Kit向Ax1的转换。在GIST-R中，Ax1被酪氨酸磷酸化，其配体生长停滞特异基因6过表达，暗示自分泌激活。从纺锤体到上皮样细胞的形态变化与蛋白激酶的转换有关。对突变的c-Kit(V654A)和Ax1的激动域进行的分子模拟表明，它不能与IM结合，但能与一种新的c-Kit/Axl激酶抑制剂MP470结合。MP470与多西紫杉醇(紫杉醇)有协同作用，对GIST细胞有细胞毒作用。
KIT or alpha-platelet-derived growth factor receptor (alpha-PDGFR) activating mutations are the pathogenic mechanisms that characterize gastrointestinal stromal tumors (GIST). Despite excellent responses to imatinib mesylate (IM), patients are relapsing. We developed an IM-resistant GIST cell line (GIST-R) from the IM-sensitive GIST882 cell line (GIST-S) by growing these cells in IM. Gene expression pro. ling (GEP) of GIST-S, GIST-R cells and two IM resistant GIST patients demonstrated that KIT is downregulated implying a major role in IM resistance. Instead, GIST-R cells have acquired IM resistance by overexpressing the oncogenic receptor tyrosine kinase-AXL-in a kinase switch'. Further, the two IM resistant GIST patients express AXL and not c-Kit, seen by immunohistochemistry (IHC). Real time reverse transcriptase-polymerase chain reaction and Western blotting of the GIST-S and GIST-R cells confirmed the switch from Kit to AXL. In GIST-R, AXL is tyrosine phosphorylated and its ligand growth-arrest-specific gene 6 is overexpressed implying autocrine activation. The kinase switch is associated with a morphological change from spindle to epithelioid. Molecular modeling of the kinase domain of mutant c-Kit (V654A) and AXL showed no binding to IM but efficient binding to MP470, a novel c-Kit/ AXL kinase inhibitor. MP470 synergizes with docetaxel (taxotere) and is cytotoxic to GIST cells.