Graduate Institute of Medical Sciences, National Defense Medical Center, #161 Sec. 6 Minquan E. Rd., Neihu Dist., Taipei City, Taiwan.
Am J Respir Crit Care Med. 2011 Apr 15;183(8):1071-9. doi: 10.1164/rccm.201009-1440OC. Epub 2010 Oct 29.
Non-small cell lung cancers carrying epidermal growth factor receptor (EGFR) mutations respond well to EGFR tyrosine kinase inhibitors (TKIs), but patients ultimately develop drug resistance and relapse. Although epithelial-mesenchymal transition (EMT) can predict resistance to EGFR TKIs, the molecular mechanisms are still unknown.
To examine the role of EMT regulators in resistance to gefitinib.
The expression level of EMT regulators in gefitinib-sensitive cells (PC9) and gefitinib-resistant cells (PC9/gef) was determined using quantitative real-time reverse transcription-polymerase chain reaction and Western blot analysis. Molecular manipulations (silencing or overexpression) were performed to investigate the effects of EMT regulators on gefitinib resistance in vitro, and a xenograft mouse model was used for in vivo confirmation. In addition, cancer cells from 44 patients with malignant pleural effusions of lung adenocarcinoma were collected for analysis of EMT regulator mRNA by quantitative real-time reverse transcription-polymerase chain reaction.
Slug expression, but not that of snail, twist, or zeb-1, was significantly increased in PC9/gef compared with PC9 cells. Slug knockdown in PC9/gef cells reversed resistance to gefitinib, and overexpression of Slug in PC9 cells protected cells from gefitinib-induced apoptosis. Silencing of Slug in gefitinib-resistant cells restored gefitinib-induced apoptosis primarily through Bim up-regulation and activation of caspase-9. Slug enhanced tumor growth in a xenograft mouse model, even with gefitinib treatment. In clinical samples, Slug expression was significantly higher in cancer cells with resistance to EGFR TKIs than in treatment-naive cancer cells.
Slug contributes to the resistance to gefitinib and may be a potential therapeutic target for treating resistance to EGFR TKIs.
携带表皮生长因子受体（EGFR）突变的非小细胞肺癌对 EGFR 酪氨酸激酶抑制剂（TKI）反应良好，但患者最终会产生耐药性并复发。虽然上皮-间充质转化（EMT）可以预测对 EGFR TKI 的耐药性，但分子机制尚不清楚。
研究 EMT 调节剂在吉非替尼耐药中的作用。
采用实时定量逆转录聚合酶链反应和 Western blot 分析检测吉非替尼敏感细胞（PC9）和吉非替尼耐药细胞（PC9/gef）中 EMT 调节剂的表达水平。进行分子操作（沉默或过表达）以研究 EMT 调节剂对体外吉非替尼耐药的影响，并使用异种移植小鼠模型进行体内验证。此外，收集 44 例肺腺癌恶性胸腔积液患者的癌细胞，通过实时定量逆转录聚合酶链反应分析 EMT 调节剂 mRNA。
与 PC9 细胞相比，PC9/gef 细胞中 Slug 的表达显著增加，而 snail、twist 或 zeb-1 的表达则没有增加。PC9/gef 细胞中 Slug 的敲低逆转了对吉非替尼的耐药性，而在 PC9 细胞中过表达 Slug 则保护细胞免受吉非替尼诱导的凋亡。在耐药细胞中沉默 Slug 主要通过上调 Bim 和激活 caspase-9 恢复吉非替尼诱导的凋亡。Slug 增强了异种移植小鼠模型中的肿瘤生长，即使给予吉非替尼治疗也是如此。在临床样本中，耐药性 EGFR TKI 的癌细胞中 Slug 的表达明显高于初治癌细胞。
Slug 有助于吉非替尼耐药，并可能成为治疗 EGFR TKI 耐药的潜在治疗靶点。
