Loss of Lkb1 and Pten Leads to Lung Squamous Cell Carcinoma with Elevated Pdl1 Expression: Epithelial Cells

Lung squamous cell carcinoma (SCC) is a deadly disease for which current treatments are inadequate. We demonstrate that bi-allelic inactivation of Lkb1 and Pten in the mouse lung led to SCC that recapitulated the histology, gene expression and microenvironment found in human disease. Lkb1/Pten-null (LP) tumors expressed the squamous markers Krt5, p63 and Sox2, and transcriptionally resembled the basal subtype of human SCC. In contrast to mouse adenocarcinomas, the LP tumors contained immune populations enriched for tumor-associated neutrophils. Sca1+/Ngfr+ fractions were enriched for tumor propagating cells (TPCs) that could serially transplant the disease in orthotopic assays. TPCs in the LP model and Ngfr+ cells in human SCCs highly expressed Pdl1, suggesting a novel mechanism of immune escape for TPCs. We used microarrays to detail the gene expression profles among lung SCC tumor epitheial cell, lung ADC tumor epithelia cell and normal epithelial cells. Normal EpCAM+, Kras tumor EpCAM+ and LP tumor EpCAM+ were sorted by FACS, the cells were gating as EpCAM+/CD45-/CD31-