Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Richmond, Virginia.
Massachusetts General Hospital Cancer Center, Boston, Massachusetts.
Clin Cancer Res. 2018 Jan 1;24(1):197-208. doi: 10.1158/1078-0432.CCR-17-1577. Epub 2017 Oct 19.
Epithelial-to-mesenchymal transition (EMT) confers resistance to a number of targeted therapies and chemotherapies. However, it has been unclear why EMT promotes resistance, thereby impairing progress to overcome it. We have developed several models of EMT-mediated resistance to EGFR inhibitors (EGFRi) in -mutant lung cancers to evaluate a novel mechanism of EMT-mediated resistance. We observed that mesenchymal -mutant lung cancers are resistant to EGFRi-induced apoptosis via insufficient expression of BIM, preventing cell death despite potent suppression of oncogenic signaling following EGFRi treatment. Mechanistically, we observed that the EMT transcription factor ZEB1 inhibits BIM expression by binding directly to the BIM promoter and repressing transcription. Derepression of BIM expression by depletion of ZEB1 or treatment with the BH3 mimetic ABT-263 to enhance "free" cellular BIM levels both led to resensitization of mesenchymal -mutant cancers to EGFRi. This relationship between EMT and loss of BIM is not restricted to -mutant lung cancers, as it was also observed in -mutant lung cancers and large datasets, including different cancer subtypes. Altogether, these data reveal a novel mechanistic link between EMT and resistance to lung cancer targeted therapies. .
上皮间质转化 (EMT) 使多种靶向治疗和化疗药物产生耐药性。然而,EMT 促进耐药性的具体机制尚不清楚,这也阻碍了克服耐药性的研究进展。我们建立了多种 EMT 介导的对 EGFR 抑制剂(EGFRi)耐药的模型,用于评估 EMT 介导耐药的新机制。我们发现,间质型 - 突变肺癌对 EGFRi 诱导的细胞凋亡具有耐药性,这是由于 BIM 表达不足,尽管 EGFRi 治疗后致癌信号被强烈抑制,但仍能阻止细胞死亡。从机制上看,我们观察到 EMT 转录因子 ZEB1 通过直接结合 BIM 启动子并抑制转录,从而抑制 BIM 的表达。ZEB1 耗竭或使用 BH3 模拟物 ABT-263 上调 BIM 表达,可增加“游离”细胞 BIM 水平,从而使间质型 - 突变型肺癌对 EGFRi 重新敏感。EMT 与 BIM 缺失之间的这种关系不仅局限于 - 突变肺癌,在 - 突变肺癌和包括不同癌症亚型的大型数据集也观察到了这种关系。综上所述,这些数据揭示了 EMT 与肺癌靶向治疗耐药性之间的新的机制联系。