Gastric Organoid-Based Ectopic and Orthotopic In Vivo CRISPR Screening for Tumor Suppressors in Gastric Cancer

BACKGROUND & AIMS: CRISPR-Cas9 screening is a powerful tool for the in vivo discovery of cancer dependencies. The aim of this study was to perform in vivo CRISPR knockout screening for gastric tumor suppressors using gastric murine organoids in a subcutaneous as well as a surgical model of orthotopic tumor growth. METHODS: In vivo screening was performed using a custom library targeting 49 putative gastric tumor suppressor genes, as well as a "cancer genome-wide" library targeting 5000 genes, in immunocompetent and -deficient mice, and in the presence or absence of the gastric pathogen Helicobacter pylori. The top hits were selected for individual validation and mechanistic follow-up. RESULTS: neutrophils. CONCLUSIONS: In summary, we describe here a versatile model of gastric carcinogenesis that uncouples the genetics of the tumor and the host, and that faithfully recapitulates key risk factors of the malignancy.