Expression of PTTG1 in gastric adenocarcinoma tissues and its relationship with prognosis

Objective: To identify new prognostic markers and therapeutic targets for gastric adenocarcinoma. Methods: The public datasets of gastric adenocarcinoma collected from GEO database (GSE33335 and GSE63089) were downloaded for analysis. There were 70 GC tissues and paired normal tissues in the two profile datasets. Differentially expressed genes (DEGs) between GC tissues and normal stomach tissues were selected by the R software. Protein-protein interaction (PPI) of these DEGs were visualized by the Search Tool for the Retrieval of Interacting Genes (STRING). The key gene sets were analyzed by Cytoscape and Molecular Complex Detection (MCODE). The mRNA and protein expression levels of prognosis related genes identified by public database were confirmed by using GC tissues and paired normal tissues collected from July 2019 to September 2019 in Affiliated Hospital of Nantong University. Results: DEGs were identified in the two datasets by using R software. A total of 128 DEGs were detected, including 85 up-regulated genes (log(2)FC>1.2 and FDR<0.01) and 43 down-regulated genes (log(2)FC<-1.2 and FDR<0.01) in the GC tissues. PPI network model and MCODE model were established by using the Online String tool and Cytoscape software, and 27 key genes were obtained, including 25 genes related with prognosis of GC patients (P<0.05). We identified 14 significant DEGs in GC tissues, including cyclin B1 (CCNB1), polo-like kinase 1 (PLK1) and pituitary-tumor transforming gene (PTTG1), which were significantly enriched in the cell cycle pathway through KEGG pathway enrichment analysis. The positive expression rate of PTTG1 in GC tissues was 68.8% (22/32), significantly higher than 18.8% (6/32) in normal gastric tissues (P<0.05). Conclusions: The expression of PTTG1 is different in GC and gastric tissues, implicates it is the key gene in gastric carcinogenesis. The prognoses of GC patients with higher PTTG1 expression are worse. PTTG1 might participate in the development of gastric adenocarcinoma by regulating cell cycle.