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Background & aims: Gastroesophageal reflux disease (GERD) is a common digestive disorder that is characterized by esophageal tissue damage produced by exposure of the esophageal lining to the gastric refluxate. GERD can raise the risk of multiple serious complications including esophageal tumors. At the molecular levels, GERD-affected tissues are characterized by strong oxidative stress and the formation of reactive isolevuglandins (isoLGs). These products of lipid peroxidation rapidly interact with cellular proteins forming protein adducts. Here, we investigated the interrelationship between isoLG adduction and aggregation of cellular proteins. Methods: Protein misfolding and aggregation were analyzed using multiple protein misfolding and aggregation assays. Pathologic consequences of protein adduction and aggregation were studied using human and murine esophageal tissues. Surgical model of esophageal reflux injury and L2-IL1β transgenic mice were used to investigate the mechanisms of protein misfolding and aggregation. Results: Our studies demonstrate that gastroesophageal reflux causes protein misfolding and aggregation that is associated with severity of GERD. Dysregulation of proteostasis induces ferroptotic cell death and is mediated by modification of cellular proteins with reactive isoLGs that can be prevented by isoLG scavengers. Conclusions: GERD causes dysregulation of cellular proteostasis, accumulation of isoLG protein adducts, misfolded, and aggregated proteins that promote ferroptotic cell death. Taken together, this study suggests that GERD has similarities to other known pathologic conditions that are characterized by protein misfolding and aggregation.

Summary: p53 is a key tumor suppressor that is frequently mutated in human tumors. In this study, we investigated how p53 is regulated in precancerous lesions prior to mutations in the p53 gene. Analyzing esophageal cells in conditions of genotoxic stress that promotes development of esophageal adenocarcinoma, we find that p53 protein is adducted with reactive isolevuglandins (isoLGs), products of lipid peroxidation. Modification of p53 protein with isoLGs diminishes its acetylation and binding to the promoters of p53 target genes causing modulation of p53-dependent transcription. It also leads to accumulation of adducted p53 protein in intracellular amyloid-like aggregates that can be inhibited by isoLG scavenger 2-HOBA in vitro and in vivo. Taken together, our studies reveal a posttranslational modification of p53 protein that causes molecular aggregation of p53 protein and its non-mutational inactivation in conditions of DNA damage that may play an important role in human tumorigenesis.