In Vivo CRISPR Screens in Gastric Organoids: Gastroenterology | March 2026
Introduction
Understanding which genes restrain gastric tumor growth—and how host factors like Helicobacter pylori shape tumor biology—remains central to precision prevention and therapy. CRISPR-Cas9 loss-of-function screening offers a scalable way to discover tumor suppressors, but most screens are performed in vitro and miss key in vivo pressures such as immunity and microbial influences. This study builds an organoid-based in vivo CRISPR platform to identify gastric tumor suppressors in both ectopic (subcutaneous) and orthotopic (stomach) settings.
Summary (≈200 words)
Using murine gastric organoids, the authors performed in vivo CRISPR knockout screening with (1) a custom library targeting 49 putative gastric tumor suppressors and (2) a genome-scale “cancer” library targeting ~5000 genes. Screens were conducted across immunocompetent and immunodeficient mice, with and without H pylori infection, and in both subcutaneous and surgically implanted orthotopic tumor models. Recurrently enriched guides identified Pten, Fbxw7, and multiple TGF-β pathway components (Smad4, Tgfbr1, Tgfbr2, Acvr2a) as consistent tumor suppressor hits across models; genome-scale screening confirmed these and revealed additional candidates. The top hits were individually validated in vivo. Mechanistically, Pten loss drove large, highly vascular tumors with neutrophil recruitment and T-cell exclusion, highlighting an immune-evasive, pro-angiogenic state. In contrast, loss of Smad4, Tgfbr1, or Acvr2a produced lesions resembling early gastric precancer states, including Alcian blue–positive intestinal metaplasia and compensatory hyperplasia. Notably, H pylori did not change the tumor mutational landscape; instead, it primarily reshaped the tumor microenvironment, promoting influx of tumour-supporting SiglecF⁺ neutrophils. Overall, the work introduces a versatile in vivo organoid-CRISPR platform that separates tumor genetics from host factors while capturing clinically relevant gastric cancer biology.
