Wu D-W, Chen T-C, Huang H-S, Lee H
Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
Cell Death Dis. 2016 Jun 30;7(6):e2290. doi: 10.1038/cddis.2016.192.
Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) show a clinical benefit when used to treat patients with EGFR-mutated non-small-cell lung cancer (NSCLC), but this treatment unfortunately fails in patients with TKI-resistant tumors. We here provide evidence that TC-N19 (N19), a novel dual inhibitor of EGFR and cMET, efficiently overcomes the EGFR-TKI resistance in EGFR-mutated NSCLC cells via simultaneous degradation of both proteins by ubiquitin proteasomes. Comparison with HSP90 inhibitor treatment and knockdown of EGFR and cMET by small hairpin RNAs reveal that the reduction of EGFR and cMET expression by N19 is responsible for overcoming the intrinsic TKI resistance mediated by paxillin (PXN) in high PXN-expressing cells, PXN-overexpressing PC9 cells (PC9-PXN), the EGFR-T790M-mediated TKI resistance in H1975 and CL97 cells, and the acquired resistance to gefitinib in gefitinib-resistant PC9 cells (PC9GR). Annexin V-PI staining assay showed that the induction of apoptosis in NSCLC cells by N19 depended on the reduction in levels of both proteins. Xenograft tumor formation in nude mice induced by a PC9-PXN-stable clone and by PC9GR cells was nearly completely suppressed by N19 treatment, with no changes in animal body weight. MTT assays of normal lung cells and reticulocytes showed no cytotoxicity responses to N19. In summary, N19 may act as a novel dual inhibitor of EGFR and cMET that induces apoptosis in TKI-resistant EGFR-mutated NSCLC cells and suppresses xenograft tumor formation. We suggest that N19 may be a potential new-generation TKI or HSP90 inhibitor used for treatment of NSCLC patients who show resistance to current TKI-targeting therapies.
表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKIs）用于治疗表皮生长因子受体（EGFR）突变的非小细胞肺癌（NSCLC）患者时显示出临床疗效，但不幸的是，这种治疗方法对TKI耐药肿瘤患者无效。我们在此提供证据表明，新型EGFR和cMET双重抑制剂TC-N19（N19）通过泛素蛋白酶体同时降解这两种蛋白，有效克服了EGFR突变的NSCLC细胞中的EGFR-TKI耐药性。与HSP90抑制剂处理以及通过小发夹RNA敲低EGFR和cMET的比较表明，N19降低EGFR和cMET表达是克服高表达桩蛋白（PXN）的细胞、过表达PXN的PC9细胞（PC9-PXN）中由PXN介导的固有TKI耐药性、H1975和CL97细胞中EGFR-T790M介导的TKI耐药性以及吉非替尼耐药PC9细胞（PC9GR）中对吉非替尼获得性耐药的原因。膜联蛋白V-碘化丙啶染色分析表明，N19诱导NSCLC细胞凋亡取决于这两种蛋白水平的降低。N19处理几乎完全抑制了由PC9-PXN稳定克隆和PC9GR细胞诱导的裸鼠异种移植瘤形成，且动物体重无变化。对正常肺细胞和网织红细胞的MTT分析显示，它们对N19无细胞毒性反应。总之，N19可能作为一种新型的EGFR和cMET双重抑制剂诱导TKI耐药的EGFR突变NSCLC细胞凋亡并抑制异种移植瘤形成。我们认为，N19可能是一种潜在的新一代TKI或HSP90抑制剂，用于治疗对当前TKI靶向治疗耐药的NSCLC患者。
