Hippo通路关键因子TAZ通过TEAD-AREG介导肺癌靶向治疗耐药的机制研究

Resistance is the bottleneck of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) target therapy for advanced lung cancer. It is "stemness" obtaining that is the root of drug resisitance of cancer. Hippo signaling regulates the self-renewal of cancer stem cells and crosstalks with EGFR cascade. So far, little is known about the regulation of Hippo cascade to tumor resisitance. TAZ, a key factor of Hippo, is newly discovered as an oncogene. We preliminary study found that TAZ expressed high in lung cancer cells, but not in human bronchial epithelial cells. Meanwhile, there are significantly statistical differences of TAZ expression between EGFR-TKIs sensitive and resisitant cells, and TAZ is positively correlated with the expression of AREG, a kind of EGFR actively ligands. In current study, we hypothesize that TAZ would participate in occurring of EGFR-TKIs resisitance and regulate resisitance through the way of AREG, which would be a candidate target for intervention to resisitance. We intend to use self-complementary adeno-associated virus serotype 5 (scAAV5)，which was confirmed efficient infection to human lung cancer cells, as carrier to downregulate TAZ expression and further investigate the influence and mechanisms of silent TAZ treatment to drug-resistant lung cancer from the molecular, cellular and animal levels. We will provide the theoretical basis and experimental foundation for selecting target of lung cancer targeted therapy resistant from the cancer stem cell pathways and exploring the methods and mechanisms to reduce resistance.

EGFR-TKIs靶向治疗耐药是限制晚期肺癌治疗疗效的瓶颈。肿瘤细胞"干性"获得是耐药发生的重要原因。Hippo信号调控肿瘤干细胞自我更新，与EGFR级联交互；迄今Hippo级联对肿瘤耐药调控尚未明了。Hippo关键因子TAZ是新发现的癌基因；我们初步研究发现：TAZ在人支气管上皮细胞不表达，在肺癌细胞高表达，在EGFR-TKIs敏感或耐药细胞的表达有显著差异，且TAZ与EGFR激活型配体AREG的表达正相关；我们提出假说：TAZ参与肺癌EGFR-TKIs耐药发生，并通过AREG等途径调控耐药，是肺癌靶向治疗耐药干预的候选靶点。我们拟以前期研究证实的高效感染人肺癌细胞的scAAV5为载体，特异性下调TAZ表达，分别从分子、细胞和整体水平，探讨沉默癌基因TAZ对肺癌靶向治疗耐药的影响及机制，为从肿瘤干细胞通路中遴选出肺癌靶向治疗耐药的靶点，探索减少耐药的方法和机制，提供理论基础和实验依据。

EGFR-TKIs靶向治疗耐药是限制晚期肺癌治疗疗效的瓶颈。EGFR20外显子T790M突变是TKIs治疗获得性耐药的最主要原因之一。Hippo信号调控肿瘤干细胞自我更新，与EGFR信号级联交互作用；新近，Hippo信号关键因子TAZ被发现系肺癌癌基因，在肺癌发生发展中发挥重要作用。本研究通过多种分子生物学方法阐明Hippo信号核心因子TAZ在吉非替尼耐药细胞PC9/GR和H1975细胞核中表达增高，且较药物敏感PC9细胞有显著性差异。在吉非替尼耐药肺癌细胞，TAZ介导吉非替尼耐药PC9/GR细胞上皮间质转化，调控PC9/GR细胞迁移及侵袭能力，干预TAZ基因表达水平，调控吉非替尼治疗敏感性。小鼠模型中，TAZ调控吉非替尼耐药肺癌细胞肿瘤形成能力及吉非替尼治疗敏感性。机制上，TAZ可能通过TAZ-TEAD-CTGF复合物调控肺癌吉非替尼药物敏感性。此外，外壳蛋白酪氨酸残基点突变的腺相关病毒5载体可提高肺癌基因治疗的转导效率。综上，TAZ过表达可能是EGFR T790M所致EGFR-TKIs继发性耐药的内在机制之一，联合靶向EGFR和TAZ治疗可能提高靶向治疗敏感性。