ABSTRACT
Patients with small-cell lung cancer (SCLC) are in dire need of more effective therapeutic options. Frequent disruption of the G1 checkpoint in SCLC cells creates a dependency on the G2/M checkpoint to maintain genomic integrity. Indeed, in pre-clinical models, inhibiting the G2/M checkpoint kinase WEE1 shows promise in inhibiting SCLC growth. However, toxicity and acquired resistance limit the clinical effectiveness of this strategy. Here, using CRISPR-Cas9 knockout screens in vitro and in vivo, we identified multiple factors influencing the response of SCLC cells to the WEE1 kinase inhibitor AZD1775, including the GCN2 kinase and other members of its signaling pathway. Rapid activation of GCN2 upon AZD1775 treatment triggers a stress response in SCLC cells. Pharmacological or genetic activation of the GCN2 pathway enhances cancer cell killing by AZD1775. Thus, activation of the GCN2 pathway represents a promising strategy to increase the efficacy of WEE1 inhibitors in SCLC.
Subject(s)
Cell Cycle Proteins , Lung Neoplasms , Protein Kinase Inhibitors , Protein Serine-Threonine Kinases , Protein-Tyrosine Kinases , Pyrimidinones , Small Cell Lung Carcinoma , Humans , Small Cell Lung Carcinoma/drug therapy , Small Cell Lung Carcinoma/pathology , Small Cell Lung Carcinoma/genetics , Small Cell Lung Carcinoma/metabolism , Protein-Tyrosine Kinases/metabolism , Protein-Tyrosine Kinases/antagonists & inhibitors , Lung Neoplasms/drug therapy , Lung Neoplasms/pathology , Lung Neoplasms/metabolism , Lung Neoplasms/genetics , Cell Line, Tumor , Cell Cycle Proteins/metabolism , Cell Cycle Proteins/antagonists & inhibitors , Cell Cycle Proteins/genetics , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Protein Serine-Threonine Kinases/metabolism , Protein Serine-Threonine Kinases/antagonists & inhibitors , Animals , Pyrimidinones/pharmacology , Pyrimidinones/therapeutic use , Pyrazoles/pharmacology , Mice , Signal Transduction/drug effects , Mice, NudeABSTRACT
Intratumoral heterogeneity is a seminal feature of human tumors contributing to tumor progression and response to treatment. Current technologies are still largely unsuitable to accurately track phenotypes and clonal evolution within tumors, especially in response to genetic manipulations. Here, we developed epitopes for imaging using combinatorial tagging (EpicTags), which we coupled to multiplexed ion beam imaging (EpicMIBI) for in situ tracking of barcodes within tissue microenvironments. Using EpicMIBI, we dissected the spatial component of cell lineages and phenotypes in xenograft models of small cell lung cancer. We observed emergent properties from mixed clones leading to the preferential expansion of clonal patches for both neuroendocrine and non-neuroendocrine cancer cell states in these models. In a tumor model harboring a fraction of PTEN-deficient cancer cells, we observed a non-autonomous increase of clonal patch size in PTEN wild-type cancer cells. EpicMIBI facilitates in situ interrogation of cell-intrinsic and cell-extrinsic processes involved in intratumoral heterogeneity.