Project description:The high plasticity of lung epithelial cells, has for many years, confounded the correct identification of the cell-of-origin of lung adenocarcinoma (LUAD), one of the deadliest malignancies worldwide. Here, we employ lineage-tracing mouse models to investigate the cell of origin of Eml4-Alk LUAD, and show that Club and Alveolar type 2 (AT2) cells give rise to tumours. We focus on Club cell originated tumours and find that Club cells experience an epigenetic switch by which they lose their lineage fidelity and gain an AT2-like phenotype after oncogenic transformation. Single-cell transcriptomic analyses identified two trajectories of Club cell evolution which are similar to the ones used during lung regeneration, suggesting that lung epithelial cells leverage on their plasticity and intrinsic regeneration mechanisms to give rise to a tumour. Together, this study highlights the role of Club cells in LUAD initiation, identifies the mechanism of Club cell lineage infidelity, confirms the presence of these features in human tumours, and unveils key mechanisms conferring LUAD heterogeneity.
Project description: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.
Project description: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.
Project description:The A/J mouse is highly susceptible to lung tumor induction and has been widely used as a screening system in carcinogenicity testing and chemoprevention studies. However, the A/J mouse model has several disadvantages. Most notably, it develops tumors spontaneously. Moreover, there is a considerable gap in our understanding of the underlying mechanisms of pulmonary chemical carcinogenesis in the A/J mouse. Therefore, we examined the differences between spontaneous and cigarette smoke-related lung tumors in the A/J mouse using transcriptomics and microRNA (miRNA) profiling. Male A/J mice were exposed whole-body to mainstream cigarette smoke (MS) for 18 months. Gene expression analysis of lung tumors and surrounding non-tumorous parenchyma samples from animals that were exposed to either 300 mg/m3 MS or sham-exposed to fresh air indicated significant differential expression of 296 genes. Ingenuity Pathway Analysis illustrated an overall suppression of the humoral immune response, which was accompanied by a disruption of sphingolipid and glycosaminoglycan metabolism in tumors of MS-exposed A/J mice. Thus, we propose that MS exposure leads to severe perturbations in pathways essential for tumor recognition by the immune system, thereby potentiating the ability of tumor cells to escape from immune surveillance. Further, exposure to MS appeared to affect expression of miRNA which have previously been implicated in carcinogenesis and are thought to contribute to tumor progression. Finally, we identified a 50-gene signature and show its utility in distinguishing between the cigarette smoke-related and spontaneous lung tumors.
Project description:The A/J mouse is highly susceptible to lung tumor induction and has been widely used as a screening system in carcinogenicity testing and chemoprevention studies. However, the A/J mouse model has several disadvantages. Most notably, it develops tumors spontaneously. Moreover, there is a considerable gap in our understanding of the underlying mechanisms of pulmonary chemical carcinogenesis in the A/J mouse. Therefore, we examined the differences between spontaneous and cigarette smoke-related lung tumors in the A/J mouse using transcriptomics and microRNA (miRNA) profiling. Male A/J mice were exposed whole-body to mainstream cigarette smoke (MS) for 18 months. Gene expression analysis of lung tumors and surrounding non-tumorous parenchyma samples from animals that were exposed to either 300 mg/m3 MS or sham-exposed to fresh air indicated significant differential expression of 296 genes. Ingenuity Pathway Analysis illustrated an overall suppression of the humoral immune response, which was accompanied by a disruption of sphingolipid and glycosaminoglycan metabolism in tumors of MS-exposed A/J mice. Thus, we propose that MS exposure leads to severe perturbations in pathways essential for tumor recognition by the immune system, thereby potentiating the ability of tumor cells to escape from immune surveillance. Further, exposure to MS appeared to affect expression of miRNA which have previously been implicated in carcinogenesis and are thought to contribute to tumor progression. Finally, we identified a 50-gene signature and show its utility in distinguishing between the cigarette smoke-related and spontaneous lung tumors.
Project description:Regeneration of lung epithelium is vital for maintaining airway function and integrity. An imbalance between epithelial damage and repair is at the basis of numerous chronic lung diseases such as asthma, COPD, pulmonary fibrosis and lung cancer. IGF (Insulin-like Growth Factors) signaling has been associated with most of these respiratory pathologies, although their mechanisms of action in this tissue remain poorly understood. Expression profiles analyses of IGF system genes performed in mouse lung support their functional implication in pulmonary ontogeny. Immuno-localization revealed high expression levels of Igf1r (Insulin-like Growth Factor 1 Receptor) in lung epithelial cells, alveolar macrophages and smooth muscle. To further understand the role of Igf1r in pulmonary homeostasis, two distinct lung epithelial-specific Igf1r mutant mice were generated and studied. The lack of Igf1r disturbed airway epithelial differentiation in adult mice, and revealed enhanced proliferation and altered morphology in distal airway club cells. During recovery after naphthalene-induced club cell injury, the kinetics of terminal bronchiolar epithelium regeneration was hindered in Igf1r mutants, revealing increased proliferation and delayed differentiation of club and ciliated cells. Amid airway restoration, lungs of Igf1r deficient mice showed increased levels of Igf1, Insr, Igfbp3 and epithelial precursor markers, reduced amounts of Scgb1a1 protein, and alterations in IGF signaling mediators. These results support the role of Igf1r in controlling the kinetics of cell proliferation and differentiation during pulmonary airway epithelial regeneration after injury.