Protein adduction causes non-mutational inhibition of p53 tumor suppressor

Modification-specific Proteomic Analysis Reveals Cysteine S-Palmitoylation Involved in Esophageal Cancer Cell Radiation

This study aimed to investigate the effects of radiation (RT) on protein and protein S-palmitoylation levels in esophageal cancer (EC) cell lines. EC cells (N = 6) were randomly divided into RT and negative control. The results revealed that 592 proteins were identified in the RT group, including 326 upregulation proteins and 266 downregulation proteins. These differentially expressed proteins were involved in cellular biological processes. S-palmitoylation sequencing analysis revealed that 830 and 899 S-palmitoylation cysteine sites were upregulated and downregulated, respectively. Differential S-palmitoylation proteins were primarily found in cellular processes, anatomical entities, and binding activities. Kyoto encyclopedia of genes and genomes (KEGG) pathway and protein-protein interaction analysis revealed that differential S-palmitoylation proteins are involved in proteoglycans in cancer, shigellosis, EGFR tyrosine kinase inhibitor resistance, nucleocytoplasmic transport, and mineral absorption. In conclusion, this study demonstrated that RT significantly affects protein expression and S-palmitoylation levels in EC cell lines, which has implications for cancer biology-related cellular processes and pathways. These findings enhance understanding of the molecular mechanisms underlying the response of EC cells to RT treatment.

Chronic Gastroesophageal Reflux Dysregulates Proteostasis in Esophageal Epithelial Cells

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.

Esophageal adenocarcinoma models: a closer look

Esophageal adenocarcinoma (EAC) is a subtype of esophageal cancer with significant morbidity and mortality rates worldwide. Despite advancements in tumor models, the underlying cellular and molecular mechanisms driving EAC pathogenesis are still poorly understood. Therefore, gaining insights into these mechanisms is crucial for improving patient outcomes. Researchers have developed various models to better understand EAC and evaluate clinical management strategies. However, no single model fully recapitulates the complexity of EAC. Emerging technologies, such as patient-derived organoids and immune-competent mouse models, hold promise for personalized EAC research and drug development. In this review, we shed light on the various models for studying EAC and discuss their advantages and limitations.

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

Repetitive sulfur dioxide exposure in mice models post-deployment respiratory syndrome

Soldiers deployed to Iraq and Afghanistan have a higher prevalence of respiratory symptoms than nondeployed military personnel and some have been shown to have a constellation of findings on lung biopsy termed post-deployment respiratory syndrome (PDRS). Since many of the subjects in this cohort reported exposure to sulfur dioxide (SO2), we developed a model of repetitive exposure to SO2 in mice that phenocopies many aspects of PDRS, including adaptive immune activation, airway wall remodeling, and pulmonary vascular (PV) disease. Although abnormalities in small airways were not sufficient to alter lung mechanics, PV remodeling resulted in the development of pulmonary hypertension and reduced exercise tolerance in SO2-exposed mice. SO2 exposure led to increased formation of isolevuglandins (isoLGs) adducts and superoxide dismutase 2 (SOD2) acetylation in endothelial cells, which were attenuated by treatment with the isoLG scavenger 2-hydroxybenzylamine acetate (2-HOBA). In addition, 2-HOBA treatment or Siruin-3 overexpression in a transgenic mouse model prevented vascular remodeling following SO2 exposure. In summary, our results indicate that repetitive SO2 exposure recapitulates many aspects of PDRS and that oxidative stress appears to mediate PV remodeling in this model. Together, these findings provide new insights regarding the critical mechanisms underlying PDRS.NEW & NOTEWORTHY We developed a mice model of "post-deployment respiratory syndrome" (PDRS), a condition in Veterans with unexplained exertional dyspnea. Our model successfully recapitulates many of the pathological and physiological features of the syndrome, revealing involvement of the ROS-isoLGs-Sirt3-SOD2 pathway in pulmonary vasculature pathology. Our study provides additional knowledge about effects and long-term consequences of sulfur dioxide exposure on the respiratory system, serving as a valuable tool for future PDRS research.