Abstract 2199: Molecular dissection of a novel, highly proliferative lineage in a model of Helicobacter pylori-driven gastric metaplasia and dysplasia

Abstract

Abstract At least 80% of gastric cancer cases are attributed to stomach infection with the bacterium Helicobacter pylori (Hp), which causes lifelong chronic inflammation. In some individuals, this inflammation can cause gastric atrophy, metaplasia (conversion of one normal cell type to another), dysplasia (presence of abnormal cells) and finally cancer, but the specific mechanism(s) through which Hp triggers this cascade are not well understood. Similar preneoplastic changes are recapitulated in a mouse model through tamoxifen-induced expression of active KRAS in the chief cells of the stomach (KRAS+ mice). We found that Hp infection of KRAS+ mice exacerbated disease: compared to Hp-KRAS+ mice, Hp+KRAS+ mice had an altered trajectory of metaplasia and accelerated dysplasia. In accordance with the hypothesis that Hp causes cancer through eliciting chronic inflammation, Hp+KRAS+ mice had severe inflammation marked by a ten-fold increase in T cells compared to Hp-KRAS+ mice. To understand gene expression changes in gastric cells in the context of metaplasia with and without active Hp infection, we performed single cell RNA-sequencing (scRNA-seq) on eight mouse stomachs (+/- Hp, +/- KRAS) using the 10x Chromium platform. Cluster analyses followed by UMAP (Uniform Manifold Approximation and Projection) visualization allowed us to identify 25 clusters, including epithelial and immune cell types. Hp+KRAS+ mice had a striking expansion of a population of metaplastic cells (most similar to surface mucus-producing “pit” cells), which comprised ~40% of epithelial cells in these mice. Metaplastic pit cells expressed markers of intestinal metaplasia and gastric cancer, and their abundance in the stomach was correlated with helper T cell abundance. Analysis of RNA velocity suggested that metaplastic pit cells arose from a progenitor cell type, rather than arising from pit cells directly. As well, a 10x Visium spatial gene expression experiment revealed the spatial organization of metaplastic pit cells near the lumen of the gastric epithelium. Finally, antibiotic eradication of Hp prevented metaplastic pit cell development and other disease phenotypes. Taken together, these studies provide new understanding of how Hp infection and inflammation cause gastric preneoplastic progression. Citation Format: Valerie Phoebe O'Brien, William C. Young, Greg Finak, Raphael Gottardo, Nina R. Salama. Molecular dissection of a novel, highly proliferative lineage in a model of Helicobacter pylori-driven gastric metaplasia and dysplasia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2199.