Research Paper Volume 12, Issue 14 pp 14271—14284

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

Jian Li1, , Yao Zhang1, , Dengmin Hu1, , Tuping Gong1, , Run Xu1, , Jun Gao1, ,

  • 1 Department of General Surgery, The Third Hospital of Mianyang, Sichuan Mental Health Center, Mianyang 621000, Sichuan, China

Received: February 15, 2020       Accepted: May 27, 2020       Published: July 15, 2020      

https://doi.org/10.18632/aging.103457
How to Cite

Copyright: © 2020 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Claudin 18 (CLDN18) is a transmembrane protein that localizes to apical regions to form tight junction complexes. Abnormal expression of CLDN18 has been reported in gastric cancer (GC). The expression, genetic alterations, and prognostic role of CLDN18 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 CLDN18 was determined using GeneMANIA. Expression of CLDN18 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 CLDN18 and the clinicopathology of GC, although expression was higher in the Epstein-Barr virus (EBV)-positive subgroup than other subgroups. Genetic alteration of CLDN18 was not a common event in GC; the main alteration was gene fusion with ARHGAP26. CLDN18 expression did not predict the overall survival (OS) of GC patients. This study summarizes the expression features of CLDN18 in GC and suggests it may serve as a biomarker and therapy target for GC.

Abbreviations

ACC: adrenocortical carcinoma; ACRG: Asian Cancer Research Group; ADCC: antibody-dependent cellular cytotoxicity; BLCA: bladder urothelial carcinoma; BRCA: breast invasive carcinoma; CDC: complement-dependent cytotoxicity; CIs: confidence intervals; CESC: cervical and endocervical cancer; CG: chronic gastritis; CHOL: cholangiocarcinoma; CIN: chromosomal instability; CNAs: copy number alterations; CLDN: claudin; COAD: olon adenocarcinoma; DEGs: differentially expressed genes; DLBC: diffuse large b-cell lymphoma; EBV: Epstein-Barr virus-positive; EGC: early gastric cancer; EMT: epithelial-mesenchymal transition; ESCA: esophageal carcinoma; FC: fold change; FDRs: false discovery rates; GAP: GTPase-activating protein; GBM: glioblastoma multiforme; GC: gastric cancer; GEO: Gene Expression Omnibus; GEPIA2: Gene Expression Profiling Interactive Analysis 2; GS: genomically stable; GTEx: Genotype-Tissue Expression; HGIN: high grade intraepithelial neoplasia; HM: high mutation; HNSC: head and neck cancer; HPA: The Human Protein Atlas; HRs: hazard ratios; IM: intestinal metaplasia; KICH: kidney chromophobe; KIRC: kidney renal clear cell carcinoma; KIRP: kidney renal papillary cell carcinoma; LGG: lower grade glioma; LGIN: low grade intraepithelial neoplasia; MSI: microsatellite instability; MSS: microsatellite stable; LIHC: liver hepatocellular carcinoma; LUAD: lung adenocarcinoma; LUSC: lung squamous cell carcinoma; MESO: mesothelioma; MSS: microsatellite stable; ORR: objective response rate; OS: overall survival; OV: ovarian serous cystadenocarcinoma; PAAD: pancreatic adenocarcinoma; PATJ: crumbs cell polarity complex component; PCPG: pheochromocytoma and paraganglioma; PPI: protein-protein interaction; PRAD: prostate adenocarcinoma; READ: rectum adenocarcinoma; SARC: sarcoma; SKCM: skin cutaneous melanoma; SNV: single nucleotide variants; TGCT: testicular germ cell tumors; STAD: stomach adenocarcinoma; TCGA: theCancer Genome Atlas; THCA: thyroid carcinoma; THYM: thymoma; TJP: tight junction protein 1; TPM: transcripts per kilobase of exon per million mapped reads; UCEC: uterine corpus endometrial carcinoma; UCS: uterine carcinosarcoma; UVM: uveal melanoma.