The present study used caerulein stimulation of AR42J rat pancreatic cells as an in vitro acute pancreatitis (AP) model to investigate proteins differentially expressed in apoptosis and necrosis. AR42J cells were stimulated with 10-8mol/l caerulein and incubated for 24 h. Apoptosis and necrosis were detected using flow cytometry. The sorted Annexin V-positive cells (apoptotic) and the Annexin V/propidium iodide double-positive cells (necrotic) were analysed using proteomics. Results showed that numerous proteins were differentially expressed in these 2 groups. Functional enrichment analysis was performed on the differentially expressed genes using the Database for Annotation, Visualization and Integrated Discovery. High mobility group box-1 protein (HMGB1) was specifically expressed in the necrosis group. Models of varying degrees of AP were established using caerulein at concentrations of 10-9, 10-8, 10-7, 10-6 and 10-5 mol/l. The percentage of apoptotic and necrotic cells in each group was determined using flow cytometry. Protein expression levels of HMGB1 were detected by western blot analysis. The present study showed that as the concentration of caerulein increased, the percentage of necrotic cells and the protein expression levels of HMGB1 increased. HMGB1 is involved in many biological processes, including the chromosomal protein glycyl lysine isopeptide cross-link. HMGB1 may be involved in the early stage of pancreatitis, potentially by inducing the development of cell death by necrosis. These results provide an experimental basis for clinical intervention in AP.

Background: Somatic mutations are strongly linked to cancer. Tumor mutation burden (TMB), PD-L1, and CTLA-4 are considered to be important biomarkers for selecting patients with stomach adenocarcinoma (STAD) for immune checkpoint inhibitors (ICIs) therapy. Nonetheless, whether specific gene mutations are related to prognosis, TMB, sensitivity to ICIs, and tumor-infiltrating immune cells remains unclear.Methods: Mutation data for STAD are derived from the Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC) database. Mutation data were analyzed by R software to calculate gene mutation frequency and TMB. Kaplan-Meier survival analysis and Log rank test assessed patient prognosis, and univariate and multivariate Cox regression analyses were used to identify independent risk factors. The limma package of R software was used for differential analysis. Gene set enrichment analysis (GSEA) was performed by GSEA4.1.0. TISIDB was used to validate the correlation of OBSCN mutations with immune cell infiltration in STAD TME.Results: 16 genes both mutated in TCGA and ICGC. Although all of the 16 genes mutations are correlated to high TMB, only patients with OBSCN mutation enjoyed a better prognosis in STAD. Univariate and multivariate Cox regression analyses showed that OBSCN mutation was an independent predictor for prognosis in STAD patients. Gene Set Enrichment Analysis showed that OBSCN mutations were mainly related to peroxisome, MTORC1 signaling, and Oxidative phosphorylation. Then, compared with the OBSCN wild type (WT) group, four genes in the OBSCN mutant type (MT) group are up-regulated, and 26 genes are down-regulated. Finally, we observed higher infiltration of T cell follicular helper, NK cells, Th1 cells, Th2 cells, CD8+ T cells, central memory CD8+ T cells, and activated CD4+ T cells but lower mast cells in the OBSCN MT group. Additionally, we found STAD patients with OBSCN mutation are more sensitive to ICIs treatment and certain chemotherapy drugs such as cisplatin, 5-Fluorouracil, and Docetaxel, which are most commonly used for STAD.Conclusions: OBSCN mutations serve as a biomarker for predicting STAD prognosis and sensitivity to ICIs and are associated with anti-tumor immunity.