Department of Medical Oncology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, People's Republic of China; Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Department of Surgery, Jiangyuan Hospital Affiliated to Jiangsu Institute of Nuclear Medicine, Jiangsu Province, 214063, People's Republic of China.
Lung Cancer. 2018 Jul;121:82-90. doi: 10.1016/j.lungcan.2018.04.024. Epub 2018 May 1.
Hypoxia-inducible factor 1 (HIF-1) and activator protein 1 (AP-1) are important transcription factors regulating expression of genes involved in cell survival. HIF-1α and c-Jun are key components of HIF-1 and AP-1, respectively, and are regulated by epidermal growth factor receptor (EGFR)-mediated cell signaling and tumor microenvironmental cues. The roles of HIF-1α and c-Jun in development of resistance to EGFR tyrosine kinase inhibitor (TKI) in non-small cell lung cancer (NSCLC) with activating mutation of EGFR have not been explored. In this study, we investigated the roles of HIF-1α and c-Jun in mediating primary and acquired resistance to gefitinib in NSCLC cells with activating mutation of EGFR.
Changes in HIF-1α protein and in total and phosphorylated c-Jun levels in relation to changes in total and phosphorylated EGFR levels before and after gefitinib treatment were measured using Western blot analysis in NSCLC cells sensitive or resistant to gefitinib. The impact of overexpression of a constitutively expressed HIF-1α (HIF-1α/ΔODD) or a constitutively active c-Jun upstream regulator (SEK1 S220E/T224D mutant) on cell response to gefitinib was also examined. The effect of pharmacological inhibition of SEK1-JNK-c-Jun pathway on cell response to gefitinib was evaluated.
Downregulation of HIF-1α and total and phosphorylated c-Jun levels correlated with cell inhibitory response to gefitinib better than decrease in phosphorylated EGFR did in NSCLC cells with intrinsic or acquired resistance to gefitinib. Overexpression of HIF-1α/ΔODD or SEK1 S220E/T224D mutant conferred resistance to gefitinib. There exists a positive feed-forward regulation loop between HIF-1 and c-Jun. The JNK inhibitor SP600125 sensitized gefitinib-resistant NSCLC cells to gefitinib.
HIF-1α and c-Jun functionally cooperate in development of resistance to gefitinib in NSCLC cells. The translational value of inhibiting HIF-1α/c-Jun cooperation in overcoming resistance to EGFR TKI treatment of NSCLC cells with activating mutation of EGFR deserves further investigation.
缺氧诱导因子 1（HIF-1）和激活蛋白 1（AP-1）是调节细胞存活相关基因表达的重要转录因子。HIF-1α和 c-Jun 分别是 HIF-1 和 AP-1 的关键组成部分，受表皮生长因子受体（EGFR）介导的细胞信号和肿瘤微环境线索的调节。HIF-1α 和 c-Jun 在非小细胞肺癌（NSCLC）中对 EGFR 酪氨酸激酶抑制剂（TKI）的耐药性发展中的作用尚未被探索。在这项研究中，我们研究了 HIF-1α 和 c-Jun 在介导 NSCLC 细胞对 EGFR 激活突变的吉非替尼原发性和获得性耐药中的作用。
使用 Western blot 分析检测对吉非替尼敏感或耐药的 NSCLC 细胞中 HIF-1α 蛋白和总 c-Jun 及磷酸化 c-Jun 水平与吉非替尼治疗前后总 EGFR 和磷酸化 EGFR 水平变化的关系。还研究了过表达组成型表达的 HIF-1α（HIF-1α/ΔODD）或组成型激活的 c-Jun 上游调节剂（SEK1 S220E/T224D 突变体）对细胞对吉非替尼的反应的影响。评估了 SEK1-JNK-c-Jun 通路的药理学抑制对细胞对吉非替尼的反应的影响。
在对吉非替尼具有内在或获得性耐药的 NSCLC 细胞中，HIF-1α 和总 c-Jun 及磷酸化 c-Jun 水平的下调与细胞抑制反应与吉非替尼的相关性优于磷酸化 EGFR 的下降。过表达 HIF-1α/ΔODD 或 SEK1 S220E/T224D 突变体赋予对吉非替尼的耐药性。HIF-1 和 c-Jun 之间存在正反馈调节环。JNK 抑制剂 SP600125 使吉非替尼耐药的 NSCLC 细胞对吉非替尼敏感。
HIF-1α 和 c-Jun 在 NSCLC 细胞对吉非替尼的耐药性发展中具有功能协同作用。抑制 HIF-1α/c-Jun 合作克服具有 EGFR 激活突变的 NSCLC 细胞对 EGFR TKI 治疗的耐药性的转化价值值得进一步研究。
