Functions of CXC chemokines as biomarkers and potential therapeutic targets in the hepatocellular carcinoma microenvironment

BACKGROUND: Several studies have indicated that CXC chemokines influence the prognosis and therapy in patients with hepatocellular carcinoma (HCC). However, there are limited studies on the roles of CXC chemokines in HCC based on data acquired from various databases. This study aimed to conduct an in-depth and comprehensive bioinformatic analysis of the expression and functions of CXC chemokines in HCC. METHODS: Data was obtained from various databases including ONCOMINE, UALCAN, STRING, GeneMinia, DAVID, Kaplan-Meier plotter, TIMER, GSCALite and NetworkAnalyst for the analysis of the expression and functions of the CXC chemokines in HCC. RESULTS: Analysis of the differential expression levels of CXC chemokines between HCC and adjacent normal tissues revealed that the mRNA expression levels of CXCL1/2/5/6/7/12/14 were significantly lower in HCC tissues than those in adjacent normal tissues, whereas the mRNA expression levels of CXCL9/16/17 were significantly higher in HCC tissues. Analysis of the relationship between CXC chemokines and overall survival revealed that high mRNA expression levels of CXCL1/3/5/6/8 were associated with poor overall survival, whereas high mRNA expression levels of CXCL2/4/7/9/10/12 were associated with better overall survival. The functions of CXC chemokines and related genes were associated with cytokine-cytokine receptor interactions and chemokine signaling pathway. Analysis of the association between CXC chemokines and activity of cancer pathways indicated that the DNA damage response and hormone androgen receptor (AR) signaling pathways were inhibited, whereas apoptosis, epithelial-mesenchymal transition (EMT) and Ras/mitogen-activated protein kinase (MAPK) signaling pathways were activated. The expression of CXC chemokines was positively correlated with the infiltration of six types of immune cells (B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils and dendritic cells). CONCLUSIONS: This study has demonstrated that CXC chemokines can influence survival of patients with HCC by recruiting different types of immune cells into the tumor microenvironment.