Guida Teresa, Anaganti Suresh, Provitera Livia, Gedrich Richard, Sullivan Elizabeth, Wilhelm Scott M, Santoro Massimo, Carlomagno Francesca
Istituto di Endocrinologia ed Oncologia Sperimentale del CNR, Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Naples, Italy.
Clin Cancer Res. 2007 Jun 1;13(11):3363-9. doi: 10.1158/1078-0432.CCR-06-2667.
Targeting of KIT and platelet-derived growth factor receptor (PDGFR) tyrosine kinases by imatinib is an effective anticancer strategy. However, mutations of the gatekeeper residue (T670 in KIT and T681 in PDGFRbeta) render the two kinases resistant to imatinib. The aim of this study was to evaluate whether sorafenib (BAY 43-9006), a multitargeted ATP-competitive inhibitor of KIT and PDGFR, was active against imatinib-resistant KIT and PDGFRbeta kinases.
We used in vitro kinase assays and immunoblot with phosphospecific antibodies to determine the activity of sorafenib on KIT and PDGFRbeta kinases. We also exploited reporter luciferase assays to measure the effects of sorafenib on KIT and PDGFRbeta downstream signaling events. The activity of sorafenib on interleukin-3-independent proliferation of Ba/F3 cells expressing oncogenic KIT or its imatinib-resistant T670I mutant was also tested.
Sorafenib efficiently inhibited gatekeeper mutants of KIT and PDGFRbeta (IC(50) for KIT T670I, 60 nmol/L; IC(50) for PDGFRbeta T681I, 110 nmol/L). Instead, it was less active against activation loop mutants of the two receptors (IC(50) for KIT D816V, 3.8 micromol/L; IC(50) for PDGFRbeta D850V, 1.17 micromol/L) that are also imatinib-resistant. Sorafenib blocked receptor autophosphorylation and signaling of KIT and PDGFRbeta gatekeeper mutants in intact cells as well as activation of AP1-responsive and cyclin D1 gene promoters, respectively. Finally, the compound inhibited KIT-dependent proliferation of Ba/F3 cells expressing the oncogenic KIT mutant carrying the T670I mutation.
Sorafenib might be a promising anticancer agent for patients carrying KIT and PDGFRbeta gatekeeper mutations.
伊马替尼靶向KIT和血小板衍生生长因子受体（PDGFR）酪氨酸激酶是一种有效的抗癌策略。然而，门卫残基的突变（KIT中的T670和PDGFRβ中的T681）使这两种激酶对伊马替尼产生耐药性。本研究的目的是评估索拉非尼（BAY 43-9006），一种KIT和PDGFR的多靶点ATP竞争性抑制剂，对伊马替尼耐药的KIT和PDGFRβ激酶是否具有活性。
我们使用体外激酶测定和磷酸化特异性抗体免疫印迹来确定索拉非尼对KIT和PDGFRβ激酶的活性。我们还利用报告荧光素酶测定来测量索拉非尼对KIT和PDGFRβ下游信号事件的影响。还测试了索拉非尼对表达致癌KIT或其伊马替尼耐药T670I突变体的Ba/F3细胞白介素-3非依赖性增殖的活性。
索拉非尼有效抑制KIT和PDGFRβ的门卫突变体（KIT T670I的IC50为60 nmol/L；PDGFRβ T681I的IC50为110 nmol/L）。相反，它对这两种受体的激活环突变体活性较低（KIT D816V的IC50为3.8 μmol/L；PDGFRβ D850V的IC50为1.17 μmol/L），这些突变体也对伊马替尼耐药。索拉非尼阻断完整细胞中KIT和PDGFRβ门卫突变体的受体自磷酸化和信号传导，以及分别激活AP1反应性和细胞周期蛋白D1基因启动子。最后，该化合物抑制表达携带T670I突变的致癌KIT突变体的Ba/F3细胞的KIT依赖性增殖。
索拉非尼可能是携带KIT和PDGFRβ门卫突变患者的一种有前景的抗癌药物。
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