Overexpression of CXCL5 mediates neutrophil infiltration and indicates poor prognosis for hepatocellular carcinoma

UNLABELLED: CXCL5 (epithelial neutrophil-activating peptide-78) is a member of a proangiogenic subgroup of the CXC-type chemokine family of small, secreted proteins. Recently, evidence that CXCL5 is involved in carcinogenesis and cancer progression has emerged. To investigate the role of CXCL5 in tumor growth, invasion, and prognosis of hepatocellular carcinoma (HCC), we examined CXCL5 messenger RNA (mRNA) and protein levels in HCC cell lines with various metastatic potentials and in three independent cohorts of 919 HCC patients. We found that CXCL5 expression was increased in the highly metastatic HCC cell lines and in tumor tissues from patients with recurrent HCC compared to controls. CXCL5 activated the PI3K-Akt and ERK1/2 signaling pathways in HCC cells and promoted proliferation, migration, and invasion. Furthermore, we found that CXCL5 had a direct chemoattractant effect on neutrophils in vitro. In animal studies, the up-regulation of CXCL5 in HCC cells promoted tumor growth, lung metastasis, and intratumoral neutrophil infiltration. Conversely, down-regulation of CXCL5 in HCC cells reduced tumor growth, metastasis, and intratumoral neutrophil infiltration. Immunohistochemical analysis in HCC samples showed that overexpression of CXCL5 was well correlated with intratumoral neutrophil infiltration, shorter overall survival, and tumor recurrence. Multivariate analysis revealed that CXCL5 overexpression alone, or combined with the presence of intratumoral neutrophils, was an independent prognostic indicator for overall survival and cumulative recurrence. CONCLUSION: CXCL5 promotes HCC cell proliferation, invasion, and intratumoral neutrophil infiltration. CXCL5 overexpression, alone or combined with intratumoral neutrophil presence, is a novel prognostic predictor, and CXCL5 is a potential therapeutic target for HCC.