Poster Presentation 26th Lorne Cancer Conference 2014

Defining the role of ZEB1 in the pathogenesis of non-small cell lung cancer (NSCLC) using immortalized human bronchial epithelial cells (HBECs) (#188)

Jill E Larsen 1 , Jihan K Osborne 2 , Alexander Augustyn 2 , James P Sullivan 2 , Luc Girard 2 , Mitsuo Sato 3 , Adi F Gazdar 2 , John D Minna 2
  1. QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
  2. University of Texas Southwestern Medical Center, Dallas, TX, USA
  3. Nagoya University Graduate School of Medicine, Nagoya, Japan

Lung cancer is the most common cause of cancer death and NSCLC accounts for >80% of cases. Mounting evidence has demonstrated involvement of epithelial-to-mesenchymal transition (EMT) in cancer progression, where it can promote cellular invasion and motility. Our previous studies of tumorigenic progression in HBECs found fully malignant HBECs (transformed with the introduction of oncogenic mutations) underwent EMT. This study sought to characterize the role of EMT in driving tumorigenesis in HBECs and lung cancer cells.

Methods: Genetic manipulations were introduced into cell lines using siRNA/shRNA or over-expression constructs. Tumorigenicity was measured using in vitro and in vivo methods.

Results: Analysis of EMT-promoting transcription factors found high induction of ZEB1 in our isogenic series of oncogenically-manipulated HBECs. Functional studies confirmed ZEB1 was a significant driver of tumorigenic phenotypes in both oncogenic HBECs and human lung cancer cell lines, both in vitro and in vivo. Using five-independent mRNA datasets to identify ZEB1-associated genes, we found ZEB1 directly represses ESRP1, leading to increased mesenchymal splicing of CD44, a target of ESRP1. Mesenchymal CD44 conferred a CD44hi profile, which, in turn, could select for a highly tumorigenic subpopulation in partially transformed HBECs. By screening ZEB1-upregulated genes in a siRNA-invasion assay we found PMP22 and CD70 could phenocopy ZEB1 in terms of promoting cellular invasion in NSCLC cells. CD70 may represent a prime therapeutic target for anti-metastatic growth in NSCLC. Importantly, an anti-CD70 monoclonal antibody inhibited invasion of NSCLC cell lines comparably to siCD70 and siZEB1.

Conclusion: We demonstrate in vitro models of oncogenic HBEC transformation provide an invaluable tool to study lung cancer progression where EMT is an important mediator. ZEB1 is a significant driver of oncogenic progression in both HBECs and NSCLC cells and identification of CD70 and PMP22 as downstream targets of ZEB1 may represent novel therapeutic targets for lung cancer.