Club cells employ regeneration mechanisms during lung tumorigenesis

Lung adenocarcinoma (LUAD) is one of the deadliest malignancies worldwide. Dynamic lineage changes within the lung epithelium and the high plasticity of these epithelial cells confound the correct identification of the cell-of-origin of LUAD. Here, we combined lineage-tracing mouse models with an autochthonous cell type-independent LUAD model in order to discover the cellular origin of ALK-translocated LUAD. We identified Club and AT2 cells as the cells-of-origin of LUAD. Moreover, we uncovered epigenetic imprints in the tumours originating from Club or AT2 cells by whole-genome bisulfite sequencing. Single-cell transcriptomes of Club cells at different stages of tumour development identified two trajectories of Club cell evolution. On both routes, tumours lose their Club cell identity and gain an AT2-like phenotype. Together, this study highlights the role of Club cells in LUAD initiation and unveils key mechanisms conferring LUAD heterogeneity. Tumor and normal bulk samples from lineage tracing models: 5 normal and 4 tumor from the CCSP+ lineage, 4 controls and 2 tumors from the HOPX+ lineage, 6 controls and 4 tumors from the SPC+ lineage