[Increased expression of SEMA5B in gastric adenocarcinoma predicts poor prognosis: a study based on TCGA data]

Objective: To evaluate the expression of semaphorin 5B (SEMA5B) in gastric adenocarcinoma and its relationship with prognosis. Methods: In November 2019, the clinicopathological characteristics and SEMA5B mRNA expression data of 341 patients with gastric adenocarcinoma were collected through TCGA database. The relationship between SEMA5B expression in gastric adenocarcinoma tissues and clinical pathologic features and overall survival were analyzed. Gene Set Enrichment Analysis (GSEA) was used to analyze the signaling pathways regulated by SEMA5B. Results: The expression level of SEMA5B mRNA in 341 gastric adenocarcinoma tissues was 0.577±0.587, in adjacent normal tissues was 0.132±0.075, the difference was statistically significant (P<0.001). The median survival time of 109 patients with high expression of SEMA5B mRNA was 14.5 months, 232 patients with low expression of SEMA5B mRNA was 17.9 months (P=0.047). Univariate analysis showed that the expression of SEMA5B mRNA was correlated with histological grade and T stage (P<0.05). The multivariate analysis revealed that age<65 years remained independently associated with overall survival, with a hazard ratio(HR) of 1.042 (95%CI: 1.021-1.064). The multivariate analysis revealed that high expression of SEMA5b mRNA remained independently associated with overall survival, with a HR of 1.195 (95%CI: 0.925-2.551). GSEA showed that malignant tumor signaling pathways (P=0.008), MAPK signaling pathways (P=0.047) and Notch signaling pathways (P=0.029) were differentially enriched in SEMA5B highly expressed phenotype. Conclusions: SEMA5B expression may be a potential prognostic molecular marker for prognosis of GAC patients. Moreover, malignant tumor signaling pathway, MAPK signaling pathway and Notch signaling pathway may be the key pathway regulated by SEMA5B in GAC.