Project Summary The rapid increase in the incidence of Barrett’s esophagus (BE), its malignant form esophageal adenocarcinoma (EAC), and junctional gastric cancer has produced serious health and financial burdens in the U.S. Thus far, effective treatment options for these diseases are limited in part due to an incomplete understanding of the molecular mechanisms driving the initial metaplasia and subsequent neoplastic progression. This application, by two PIs with complementary expertise, seeks to address the issue through combining scRNA-sequencing analysis, innovative BE mouse models and organoid modeling. We previously demonstrated that gastric cardia progenitor cells and transitional basal cell (TBCs) contribute to BE in the transitional zone of the gastro-esophageal junction (GEJ). However, how these progenitor cells behave in BE-dysplasia-EAC progression remains unclear. Additionally, the molecular mechanism driving the disease progression is also unknown. Our preliminary data suggest GEJ metaplasia and its progression towards EAC involves progenitor plasticity facilitated by p53 loss, an early genetic lesion in BE. Furthermore, we found that Barrett’s metaplasia and EAC is associated with the enrichment of tuft cells. Therefore we hypothesize that Barrett’s metaplasia and dysplasia originate from GEJ progenitor cells, modulated by the presence of p53 mutation and tuft cell expansion. Three specific aims are formulated to test the hypothesis: Aim 1 is to determine the origins and evolution of BE metaplasia from progenitor cells at the EGJ. Aim 2 is to elucidate the mechanisms by which p53 mutation promotes BE progression, and Aim 3 is to clarify the role of tuft cells in BE pathogenesis and progression. Combining our joint expertise on mouse genetics, cell biology, chromatin biology and epigenomics, this work will provide novel mechanistic insights into the mechanisms underlying Barrett’s metaplasia and its malignant progression, offering new approaches to treat these diseases.

Narrative Although stem/progenitor cells at the gastroesophageal junction have been shown in preclinical models to contribute to Barrett’s esophagus, their precise characteristics and mechanisms involved in neoplastic progression remain undefined. This proposed study will not only provide the molecular profile of mouse and human Barrett’s stem/progenitor cells but also offer insights into the role of p53 mutation and tuft cells in Barrett’s metaplasia and progression. The knowledge gained will provide a framework for identifying new therapy for reducing the risk of Barrett’s progression towards malignancy.