We aimed to explore the molecular substrate underlying EGFR-TKI resistance and investigate the effects of N-acetylcysteine (NAC) on reversing EGFR-TKI resistance. In the current research, the effects of NAC in combination with gefitinib on reversing gefitinib resistance were examined using CCK-8 assay, combination index (CI) method, matrigel invasion assay, wound-healing assay, flow cytometry, western blot, and quantitative real-time PCR (qRT-PCR). CCK8 assay showed that NAC plus gefitinib combination overcame EGFR-TKI resistance in non-small cell lung cancer (NSCLC) cells by lowering the value of half maximal inhibitory concentration (IC50). CI calculations demonstrated a synergistic effect between the two drugs (CI < 1). Matrigel invasion assay and wound healing assay demonstrated a decrease in migration and invasion ability of PC-9/GR cells after NAC and gefitinib treatment. Flow cytometry displayed enhanced apoptosis in the combination group. Western blot and qRT-PCR revealed that increased E-cadherin and decreased vimentin in the combination group. When PP2 was administered with gefitinib, the same effects were seen. Our findings suggest that NAC could restore the sensitivity of gefitinib-resistant NSCLC cells to gefitinib via suppressing Src activation and reversing epithelial-mesenchymal transition.

中文翻译：

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N-乙酰半胱氨酸和吉非替尼的联合治疗克服了NSCLC细胞系对吉非替尼的耐药性。

我们旨在探讨潜在的EGFR-TKI耐药性的分子底物，并研究N-乙酰半胱氨酸（NAC）对逆转EGFR-TKI耐药性的影响。在当前的研究中，使用CCK-8分析，组合指数（CI）方法，基质胶侵袭分析，伤口愈合分析，流式细胞术，蛋白质印迹和定量真实检测了NAC与吉非替尼联用对逆转吉非替尼耐药的影响。实时PCR（qRT-PCR）。CCK8分析表明，NAC加吉非替尼联合治疗可通过降低半数最大抑制浓度（IC50）值来克服非小细胞肺癌（NSCLC）细胞中的EGFR-TKI耐药性。CI计算结果表明两种药物之间具有协同作用（CI <1）。基质胶侵袭试验和伤口愈合试验表明，NAC和吉非替尼治疗后PC-9 / GR细胞的迁移和侵袭能力降低。流式细胞术显示组合组细胞凋亡增强。Western blot和qRT-PCR显示，联合组的E-钙黏着蛋白增加，波形蛋白减少。当PP2与吉非替尼一起给药时，可以看到相同的效果。我们的研究结果表明，NAC可以通过抑制Src激活并逆转上皮-间质转化来恢复耐吉非替尼的NSCLC细胞对吉非替尼的敏感性。看到了相同的效果。我们的研究结果表明，NAC可以通过抑制Src激活并逆转上皮-间质转化来恢复耐吉非替尼的NSCLC细胞对吉非替尼的敏感性。看到了相同的效果。我们的研究结果表明，NAC可以通过抑制Src激活并逆转上皮-间质转化来恢复耐吉非替尼的NSCLC细胞对吉非替尼的敏感性。