High expression of high mobility group box 1 (hmgb1) predicts poor prognosis for hepatocellular carcinoma after curative hepatectomy

Background: High mobility group box 1(HMGB1) overexpression has been reported in a variety of human cancers. However, the role of HMGB1 in hepatocellular carcinoma (HCC) remains unclear. The aim of present study was to analyze HMGB1 protein expression in tumor, para-tumor and normal tissue and to assess its prognostic significance for HCC after curative hepatectomy. Methods: The levels of HMGB1 mRNA and protein in tumor, para-tumor and normal tissue were evaluated in 11 HCC cases by Reverse Transcription-polymerase chain reaction (RT-PCR) and Western blot. Additionally, HMGB1 protein expression in 161 HCC was analyzed by immunohistochemistry and correlated with clinicopathological characteristics and survivals. Student's t-test, spearman's rank correlation, Kaplan-Meier plots and Cox proportional hazards regression model were used to analyze the data. Results: By RT-PCR and Western blot, the levels of HMGB1 mRNA and protein were significantly higher in HCC, compared to that in para-tumor (p<0.001) and normal tissue (p<0.001). Immunohistochemical staining revealed that high expression of HMGB1 was detected in 42.9% (69/161) HCC cases. High expression of HMGB1 was significantly associated with incomplete encapsulation (p = 0.035) and advanced TNM stage (p = 0.036). Multivariate analysis showed that high expression of HMGB1 was an independent prognostic factor for both overall (p = 0.009, HR = 1.834, 95% CI: 1.167-2.881) and disease-free survival (p = 0.018, HR = 1.622, 95% CI: 1.088-2.419), along with tumor size. Subgroup analysis revealed that high expression of HMGB1 predicted poorer overall survival only for tumor >5 cm (p = 0.031), but not for tumor <= 5 cm (p = 0.101). Conclusions: HMGB1 protein might contribute to the malignant progression of HCC, high expression of HMGB1 predicts poor prognosis for patients with HCC after curative hepatectomy, especially for patients with tumor >5 cm.