Objective To explore the expression of gamma-glutamyl transferase 5 (GGT5) in hepatocellular carcinoma (HCC) and analyze its correlations with prognosis and immune infiltration.

Methods The protein and gene expression levels of GGT5 in HCC tissues were analyzed by TCGA, HPA and TIMER online websites. The UALCAN database was used to analyze the correlation of GGT5 with clinical features. The Kaplan-Meier analysis was used to explore the influence of GGT5 expression level on the prognosis of HCC patients. The Linked Omics database was used to explore GGT5-associated genes and co-expressed genes. Involvement of GGT5 in related biological processes and signaling pathways were evaluated by data from Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The correlation between GGT5 and tumor immune infiltration was evaluated by TIMER online website.

Results Compared with adjacent paracancerous tissues, the expression of GGT5 was reduced in liver cancer tissues, and the low expression of GGT5 was significantly correlated with tumor staging. HCC patients with low GGT5 expression had a shorter overall survival (OS). Functional analysis showed that GGT5 was involved in proteasomal reorganization in liver cancer cells. The low expression of GGT5 was positively correlated with the level of immune cell infiltration.

Conclusion GGT5 is associated with prognosis and immune infiltration in HCC, and it may be a potential therapeutic target for HCC.