Analysis of the expression and genetic alteration of CLDN18 in gastric cancer.

Claudin 18 (CLDN18) is a transmembrane protein that localizes to apical regions to form tight junction complexes. Abnormal expression of has been reported in gastric cancer (GC). The expression, genetic alterations, and prognostic role of were analyzed using public data from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Human Protein Atlas (HPA) databases using multiple online tools. The biological network of was determined using GeneMANIA. Expression of was restricted to lung and stomach in normal tissues, was significantly downregulated in GC, but was ectopically overexpressed in some other cancer types. There was no correlation between mRNA expression of and the clinicopathology of GC, although expression was higher in the Epstein-Barr virus (EBV)-positive subgroup than other subgroups. Genetic alteration of was not a common event in GC; the main alteration was gene fusion with . expression did not predict the overall survival (OS) of GC patients. This study summarizes the expression features of in GC and suggests it may serve as a biomarker and therapy target for GC.