RESUMO
BACKGROUND: The gastric microbiome and inflammation play a key role in gastric cancer (GC) by regulating the immune response in a complex manner and by inflammatory events supporting carcinogenesis. Meprin ß is a zinc endopeptidase and participates in tissue homeostasis, intestinal barrier function and immunological processes. It influences local inflammatory processes, dysbiosis and the microbiome. Here, we tested the hypothesis that meprin ß is expressed in GC and of tumor biological significance. PATIENTS AND METHODS: Four hundred forty whole mount tissue sections of patients with therapy-naive GC were stained with an anti-meprin ß antibody. The histoscore and staining pattern were analyzed for each case. Following dichotomization at the median histoscore into a "low" and "high" group, the expression was correlated with numerous clinicopathological patient characteristics. RESULTS: Meprin ß was found intracellularly and at the cell membrane of GC. Cytoplasmic expression correlated with the phenotype according to Lauren, microsatellite instability and PD-L1 status. Membranous expression correlated with intestinal phenotype, mucin-1-, E-cadherin-, ß-catenin status, mucin typus, microsatellite instability, KRAS mutation and PD-L1-positivity. Patients with cytoplasmic expression of meprin ß showed a better overall and tumor-specific survival. CONCLUSIONS: Meprin ß is differentially expressed in GC and has potential tumor biological relevance. It might function as a tumor suppressor or promotor depending on histoanatomical site and context.