High expression of AP-4 predicts poor prognosis for hepatocellular carcinoma after curative hepatectomy

The aim of this study was to evaluate the association between activating enhancer binding protein 4 (AP-4) tissue expression and patient prognosis in hepatocellular carcinoma (HCC). The levels of AP-4 mRNA and protein in tumor and para-tumor tissue were evaluated in 30 HCC cases by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Additionally, AP-4 protein expression in 112 HCC was analyzed by immunohistochemistry. The correlation of AP-4 expression and patients' clinicopathological parameters was evaluated. Survival analysis was performed using the Kaplan-Meier method and Cox's proportional hazards model. By RT-PCR and Western blot, the levels of AP-4 mRNA and protein were significantly higher in HCC, compared to that in para-tumor tissue (p < 0.001). Immunohistochemical staining revealed that AP-4 was highly expressed in 53.6 % of the HCC patients. The AP-4 expression level was closely associated with serum alpha fetoprotein elevation, tumor size, histological differentiation, tumor recurrence, tumor metastasis, and tumor stage. Kaplan-Meier survival analysis showed that a high expression level of AP-4 resulted in a significantly poor prognosis of HCC patients. Multivariate analysis revealed that AP-4 expression level was an independent prognostic parameter for the overall survival rate of HCC patients. These findings provide evidence that a high expression level of AP-4 serves as a biomarker for poor prognosis for HCC. Thus, we speculate that AP-4 may be a potential target of antiangiogenic therapy for HCC.