Summary of the Talk
Tractable, patient relevant models are needed to investigate the essential components of normal cell transformation. We have developed and phenotypically characterised a unique model of early lung squamous cell carcinoma (LUSC) genetic alterations and driver pathway dysregulation using genetically modified primary human bronchial basal cells (hBCs), the most widely accepted cells-of-origin of LUSC. The co-operation of ubiquitous and early LUSC alterations (TP53 and CDKN2A loss) and commonly deregulated pathways including squamous differentiation (SOX2), PI3K signalling (PTEN) and the oxidative stress response (KEAP1) was investigated using a combinatorial approach, culminating in a panel hBC mutants harbouring cumulative pathway alterations in a TP53-/-/CDKN2A-/- background. Phenotypes indicative of mutant hBC transformation, comprising epithelial morphology, invasiveness and gene expression, were investigated using a wide range of in vitro and in vivo assays. Organotypic cultures revealed LUSC pathway alterations to drive dramatic changes in airway histology, ranging from a normal epithelium to severe dysplasia. Furthermore, these analyses confirmed the role of SOX2-overexpression in initiating transformation by inducing squamous cell commitment and anchorage independent growth. We also identified a co-operation of SOX2-overexpression with the oxidative stress response and PI3K pathways to drive more advanced lesions with evidence of invasiveness in-vivo and in-vitro. Importantly, we were able to map changes in the expression of immunomodulatory factors with the pathway dysregulation and delineate a likely evolutionary trajectory in LUSC. We have demonstrated that this strategy constitutes an alternative and patient-relevant system to model LUSC and identify genotype-phenotype correlations relevant for LUSC medicine and early detection.