Introduction and objectives Improving the early detection and chemoprevention of lung cancer are key to improving outcomes. The pathobiology of early squamous lung cancer is poorly understood. We have shown in a previous publication that amplification of SOX2 is an early and consistent event in the pathogenesis of this disease but its functional oncogenic potential remains uncertain. We aimed to test the impact of deregulated SOX2 expression in a novel organotypic system that recreates both the molecular and microenvironmental context in which squamous carcinogenesis occurs.
Our objectives are:
To develop a 3D in vitro model of bronchial dysplasia that recapitulates key molecular and phenotypic characteristics of the human disease.
To test the hypothesis that SOX2 deregulation is a key initiating event in the pathogenesis of bronchial dysplasia.
Methods We use lentiviral transduction to facilitate the inducible activation of SOX2 in immortalised bronchial epithelial cells iBECs. We use lentiviral shRNA and cutting edge CRISPR genome editing technology to introduce specific defects in key tumour suppressor pathways in order to recapitulate the molecular context seen in vivo. We incorporate the genetically manipulated iBECs at the air-liquid interface in a 3-dimensional tissue culture system that also comprises a stromal equivalent with embedded pulmonary fibroblasts and carefully defined media to build an organotypic model of bronchial dysplasia.
Results We develop a model that recapitulates human bronchial dysplasia. SOX2 deregulation does not cause an obvious phenotype in standard tissue culture conditions, but can initiate the dysplastic phenotype in 3D culture systems. Loss of TP53 and PTEN are co-operating genetic events that potentiate the dysplastic phenotype. The alterations in cell signalling pathways recapitulate signatures seen in invasive squamous cell lung cancer.
Conclusions In the appropriate molecular and microenvironmental context acute deregulation of SOX2 expression initiates and drives bronchial dysplasia. This confirms it’s oncogenic potential in human cells. This model can be used to test the impact of therapeutic agents aimed at chemoprevention and the potential for co-operating genetic lesions to drive disease progression.