Abstract 262: Gastrin-dependent suppression of CCK2R+ antrum stem cells inhibits gastric atrophy and cancer initiation in C57BL/6 mice

Abstract Background The cholecystokin-2/gastrin receptor (CCK2R) is expressed by rare epithelial cells in the gastric antrum that are bone fide +4 gastric stem cells. CCK2R+ antral stem cells are relatively quiescent, divide asymmetrically, and lineage trace entire antral glands. Their stemness is sustained over time through gastrin/CCK2R signaling (Cell Stem Cell 26, 739-754, May 7, 2020). However, the role of gastrin/CCK2R signaling in antral stem cells during mucosal injury and regeneration has not been explored. Methods We generated CCK2R-CreERT2; Gastrin-BAC-DTR-P2A-TdTomato; Rosa26-ZsGreen mice in a C57BL/6 background. Hypogastrinemia was induced through diphtheria toxin-dependent ablation of antral G cells, while hypergastrinemia was achieved via Alzet pump gastrin infusion. Lineage tracing from antrum CCK2R+ stem cells was assessed quantitatively during homeostasis and also during injury in chronic H. pylori infection and MNU injury models. Results Our findings revealed that G cell ablation increased lineage tracing of CCK2R+ antral stem cells at day 14 and increased proliferation of antral epithelial cells (Ki67+ cells) (P0. 05). Moreover, sorted antrum CCK2R+ cells (24 hours post-tamoxifen induction) from DT-treated mice had increased organoids forming capacity and in vitro cell growth, consistent with an increase in active progenitors, while hypergastrinemia reduced their growth (P0. 05). Numb staining showed that G cell ablation led to increased symmetric division of CCK2R+ stem cells, while gastrin infusion maintained asymmetric division (P0. 05). In the chronic H. pylori infection model, after 3 months of infection, the G cell ablation group exhibited more severe gastric antral atrophy compared to controls. In the MNU injury model, after 18 weeks of injury, the G cell ablation group had a higher dysplasia score, with dysplastic lesions largely derived from CCK2R+ cells (P0. 05). In our ongoing studies of MNU injury, the G cell ablation group at 36 weeks showed significantly greater tumor number and size than the control groups. Single-cell RNA-seq data showed that G cell ablation led to the proliferation and expansion of CCK2R+ antral stem/progenitor cells. Conclusions In conclusion, while gastrin maintains long-term antral stem cell quiescence and self-renewal, hypogastrinemia over the short-term leads to expansion and proliferation of CCK2R+ antral stem cells, thus predisposing over the long-term to antral atrophy and cancer initiation. In C57BL/6 mice, hypergastrinemia appears to be a protective factor against antral cancer development. Citation Format: Biyun Zheng, Guodong Lian, Ermanno Malagola, Hiroki Kobayashi, Ruhong Tu, Feijing Wu, Jin Qian, Quin T. Waterbury, Yosuke Ochiai, Leah B Zamechek, Timothy C Wang. Gastrin-dependent suppression of CCK2R+ antrum stem cells inhibits gastric atrophy and cancer initiation in C57BL/6 mice abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 262.