Fractalkine-CX3CR1 axis regulates tumor cell cycle and deteriorates prognosis after radical resection for hepatocellular carcinoma

Background and Objectives: Fractalkine is the only CX3C chemokine, and its receptor, CX3CR1, is expressed on NK cells, CD8+ T cells, monocytes, and dendritic cells (DC). Although studies have reported that fractalkine regulates the host immune response, the roles of the fractalkine-CX3CR1 axis in tumor biology and the clinical results of hepatocellular carcinoma (HCC) remain unknown. Methods: Fractalkine and CX3CR1 expression in HCC were evaluated and compared with the clinicopathologic features, including tumor progression determined by proliferating cell nuclear antigen (PCNA) antibody and patient prognosis after surgery. Results: Tumors with high expression of both fractalkine and CX3CR1 had significantly fewer intra- and extrahepatic recurrences, a low PCNA labeling index (PCNALI), and different histological grades. Patients with tumors that expressed both had a significantly better prognosis in terms of disease-free (DFS) and overall survival (OAS), and this finding was identified as one of the independent prognostic factors in the multivariate analysis. Conclusions: Our results suggest that the fractalkine-CX3CR1 axis plays a pivotal role in the prognosis of patients with HCC, which might arise from the known modulation of the host immune response, and that of the cell cycle in HCC.