Src mediates cigarette smoke-induced resistance to tyrosine kinase inhibitors in NSCLC cells.
Src mediates cigarette smoke-induced resistance to tyrosine kinase inhibitors in NSCLC cells.
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DOI：
10.1158/1535-7163.mct-12-1029
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发表时间：
2013-08
影响因子：
5.7
通讯作者：
Goldkorn T
中科院分区：
文献类型：
--
作者：
Filosto S;Baston DS;Chung S;Becker CR;Goldkorn T
EGF 受体 (EGFR) 是一种原癌基因，在包括非小细胞肺癌 (NSCLC) 在内的多种癌症中通常失调，因此是厄洛替尼等酪氨酸激酶抑制剂 (TKI) 治疗的目标。然而，尽管在携带 EGFR 致癌变异的 NSCLC 患者中观察到了疗效，但 TKI 对当前和既往吸烟者的 NSCLC 患者普遍无效，因此需要确定新的机制来克服这种现象。此前，我们发现，携带野生型 (WT) EGFR 或致癌突变体 (MT) L858R EGFR 的 NSCLC 细胞在暴露于香烟烟雾 (CS) 时会对 TKI 的作用产生抵抗，其自身磷酸化和延长的下游信号传导证明了这一点。在这里，我们将 Src 作为介导 WT EGFR 和 L858R MT EGFR 表达 NSCLC 细胞中 CS 诱导的 TKI 耐药性的靶标。首先，我们发现 A549 细胞的 CS 暴露导致 Src 的时间依赖性激活，然后 Src 异常地与 WT EGFR 结合，导致 TKI 耐药，这与之前观察到的非活性 Src 和 TKI 敏感的 L858R MT EGFR 之间的组成型结合形成对比。接下来，我们证明 Src 抑制可恢复暴露于 CS 的 NSCLC 细胞中的 TKI 敏感性，从而防止厄洛替尼存在下的 EGFR 自磷酸化。此外，我们发现显性失活 Src (Y527F/K295R) 的过度表达可恢复暴露于 CS 的 A549 的 TKI 敏感性。重要的是，即使在暴露于 CS 的 L858R EGFR 表达 NSCLC 细胞中也出现 TKI 耐药性，也可以通过 Src 抑制来消除。总之，这些发现为使用 Src 抑制剂治疗吸烟者中常见的 TKI 耐药 NSCLC 提供了新的原理。
The EGF Receptor (EGFR) is a proto-oncogene commonly dysregulated in several cancers including non-small cell lung cancer (NSCLC) and, thus, is targeted for treatment using tyrosine kinase inhibitors (TKIs) such as Erlotinib. However, despite the efficacy observed in NSCLC patients harboring oncogenic variants of the EGFR, general ineffectiveness of TKIs in NSCLC patients who are current and former smokers necessitates identification of novel mechanisms to overcome this phenomenon. Previously, we showed that NSCLC cells harboring either wild-type (WT) EGFR or oncogenic mutant (MT) L858R EGFR become resistant to the effects of TKIs when exposed to cigarette smoke (CS), evidenced by their auto-phosphorylation and prolonged downstream signaling. Here, we present Src as a target mediating CS-induced resistance to TKIs in both WT EGFR and L858R MT EGFR expressing NSCLC cells. First, we show that CS exposure of A549 cells leads to time-dependent activation of Src which then abnormally binds to the WT EGFR causing TKI resistance, contrasting previous observations of constitutive binding between inactive Src and TKI-sensitive L858R MT EGFR. Next, we demonstrate that Src inhibition restores TKI sensitivity in CS-exposed NSCLC cells, preventing EGFR auto-phosphorylation in the presence of Erlotinib. Furthermore, we show that over-expression of a dominant-negative Src (Y527F/K295R) restores TKI sensitivity to A549 exposed to CS. Importantly, the TKI resistance that emerges even in CS-exposed L858R EGFR expressing NSCLC cells could be eliminated with Src inhibition. Together, these findings offer new rationale for using Src inhibitors for treating TKI-resistant NSCLC commonly observed in smokers.