Abstract 2177: Postbiotic metabolites secreted by L. acidophilus reduce DNA damage in an experimental model of Barrett’s tumorigenesis

Abstract The origins of esophageal adenocarcinoma (EAC) are commonly attributed to the progression from gastroesophageal reflux disease (GERD) to Barrett’s Esophagus (BE) and finally to esophageal adenocarcinoma. During GERD, various types of bile induce oxidative stress and generate reactive oxygen species (ROS), resulting in DNA damage and inflammation in cells. Although there has been much research documenting the shift in the esophageal microbiome from gram-positive to gram-negative bacteria during this progression, there has also been an observed increase in the presence of Lactobacillus, a gram-positive commensal bacterium with probiotic qualities, in the esophagus during the progression from GERD to BE and eventually to EAC. Our previous research has demonstrated the ability of Lactobacillus spp. to not only colonize the esophagus under in vitro conditions of GERD, but also their anti-inflammatory and anti-genotoxic properties on esophageal cells exposed to bile. To assess the extent of reflux-induced DNA damage and oxidative stress during the progression of BE, we exposed two BE cell lines, CP-B and BAR-T, and the EAC cell line FLO-1 to ox bile or deoxycholic acid. Both bile types demonstrated significant increases in phosphorylated H2AX, as a marker for pronounced DNA damage repair. Next, we supplemented both live L. acidophilus and its postbiotic metabolites to cells exposed to ox bile and deoxycholic acid. We show a significant reduction in DNA damage as measured by pH2AX with both the live treatment and the treatment with postbiotic metabolites when compared to untreated, bile-exposed cells at various stages of BE and EAC. Ongoing experiments include assessing anti-genotoxic effects of postbiotic metabolites through DNA repair protein RAD51, reductions in oxidative stress though ROS marker 8-oxo-guanine, and anti-inflammatory effects through NFkB-associated inflammation. BE and EAC cell viability and proliferation upon bile exposure and postbiotic metabolite administration will also be assessed. This study aims to determine the supplementation with Lactobacillus postbiotic metabolites in the prevention and intervention of esophageal adenocarcinoma development. Citation Format: Divya Joshi, Claudia Andl. Postbiotic metabolites secreted by L. acidophilus reduce DNA damage in an experimental model of Barrett’s tumorigenesis 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 2177.