TMPRSS11B promotes an acidified microenvironment and immune suppression in squamous lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. Existing therapeutic options have limited efficacy, particularly for lung squamous cell carcinoma (LUSC), underscoring the critical need for the identification of new therapeutic targets. We previously identified the Transmembrane Serine Protease TMPRSS11B as a novel gene that promotes transformation of human bronchial epithelial cells and enhances lactate export in LUSC. To determine the impact of TMPRSS11B activity on the host immune system and the tumor microenvironment (TME), we evaluated the effect of Tmprss11b depletion in syngeneic and autochthonous mouse models. Tmprss11b depletion significantly reduced tumor burden in immunocompetent mice and triggered an infiltration of immune cells. RNA FISH analysis and spatial transcriptomics in the Rosa26LSL-Sox2-IRES-GFP; Nkx2-1 fl/fl; Lkb1fl/fl (SNL) model revealed an enrichment of Tmprss11b expression in LUSC tumors, specifically in Krt13+ hillock-like cells. Ultra-pH sensitive nanoparticle imaging and metabolite analysis identified regions of acidification, elevated lactate, and enrichment of macrophages in LUSC tumors. These results demonstrate that TMPRSS11B promotes an acidified and immunosuppressive TME and suggests a potential to therapeutically target this enzyme in LUSC. Overall design: Rosa26LSL-SOX2-IRES-GFP; Nkx2-1fl/fl ;Lkb1fl/fl (SNL) mice were intratracheally administered Cre expressing adenovirus virus to initiate tumorigenesis. At around 11-12 months post-infection , the mice were euthanized and lungs were inflated and perfused through the trachea with 4% paraformaldehyde (PFA), fixed overnight, washed in 1xPBS for 24-48h, then transferred to 70% ethanol and subsequently embedded in paraffin. Sections were cut and stained with H&E. Spatial transcriptomic analysis was then performed on these sections to investigate the gene expression patterns among the heterogeneous tumors (LUSC, Adenosquamous, and LUAD) formed in these lungs.