Abstract:
Objective:To investigate the effect of expression of Cullin 4B (CUL4B) on the prognosis of patients after liver transplantation for hepatocellular carcinoma (HCC).
Methods:The retrospective case-control study was conducted. The clinicopathological data of 79 patients who underwent liver transplantation for HCC in the First Affiliated Hospital of Sun Yat-sen University between January 1, 2014 and June 30, 2015 were collected. The specimens of HCC tissues were collected and embedded in paraffin, and then were detected by immunohistochemistry staining. Observation indicators: (1) expression of CUL4B in HCC tissues; (2) followup and survival; (3) prognostic factors analysis after liver transplantation; (4) association between expression of CUL4B and recurrence and metastasis of tumor after liver transplantation. Followup using outpatient examination and telephone interview was performed to detect tumor recurrence or metastasis and survival up to June 2018. Measurement data with normal distribution were represented as

±s. The comparison between groups of count data was done using the chisquare test. The survival curve drawn using the KaplanMeier method, and the survival analysis was done by Logrank test. The univariate and multivariate analysis were respectively done using the COX regression model. The association analysis was done using the Pearson test.
Results:(1) Expression of CUL4B in HCC tissues: immunohistochemistry staining showed that CUL4B was mainly expressed in the cytoplasm, with a powerful brownishyellow staining. The high expression and low expression of CUL4B in HCC tissues were detected in 64 and 15 patients, respectively. (2) Followup and survival: 79 patients were followed up for 38-56 months, with an average time of 46 months. During the followup, 37 patients had no tumor recurrence and 42 had tumor recurrence (32 with tumor extrahepatic metastasis and 10 with intrahepatic metastasis); 36 had survival and 43 died; the 1 and 3year overall survival rates were respectively 86.84% and 63.25%, and 1 and 3year tumorfree survival rates were respectively 62.31% and 51.27%. (3) Prognostic factors analysis after liver transplantation: ① Results of univariate analysis showed that preoperative alphafetoprotein (AFP), ChildPugh score, maximum tumour dimension, capsular invasion, intravascular tumor thrombus, Edmonson pathological grading and expression of CUL4B were related factors affecting the 3year overall survival rate of patients after liver transplantation for HCC [Hazard Ratio (HR)=2.17, 3.36, 3.66, 2.43, 2.19, 3.36, 2.84, 95% confidence interval (CI): 1.17-4.04, 1.53-7.42, 2.10-6.42, 1.33-4.17, 1.08-9.04, 1.58-7.59, 1.17-6.32, P<0.05]. The preoperative alphafetoprotein (AFP), ChildPugh score, maximum tumour dimension, capsular invasion, intravascular tumor thrombus, Edmonson pathological grading and expression of CUL4B were related factors affecting the 3year tumorfree survival rate of patients after liver transplantation for HCC (HR=2.06, 3.72, 3.16, 2.36, 2.83, 3.21, 1.69, 95%CI: 1.34-4.85, 1.72-8.63, 1.79-7.31, 1.46-4.86, 1.19-8.63, 1.19-7.92, 1.06-4.87, P<0.05). ② Results of multivariate analysis showed that maximum tumour dimension, intravascular tumor thrombus and expression of CUL4B were independent factors affecting the 3year overall survival rate of patients after liver transplantation for HCC [Odds ratio(OR)=3.43, 3.69, 2.81, 95%CI: 1.16-6.02, 1.96-9.38, 1.04-9.63, P<0.05]. The maximum tumour dimension, intravascular tumor thrombus and expression of CUL4B were independent factors affecting the 3year tumorfree survival rate of patients after liver transplantation for HCC (OR=2.25, 4.72, 2.74, 95%CI: 1.16-4.02, 1.98-9.47, 1.03-7.10, P<0.05). The 3year overall survival rate in patients with high and lowexpressions of CUL4B was respectively 66.7% and 32.8%, with a statistically significant difference (x
2=5.69, P<0.05). The 3year tumorfree survival rate in patients with high and lowexpressions of CUL4B was respectively 73.3% and 18.6%, with a statistically significant difference (x
2=4.63, P<0.05). (4) Association between expression of CUL4B and recurrence and metastasis of tumor after liver transplantation: results of Pearson test showed that expression of CUL4B was significantly associated with HCC recurrence and metastasis after liver transplantation (r=0.62, P<0.05). The further analysis showed that expression of CUL4B was significantly associated with extrahepatic metastasis after liver transplantation (r=0.84, P<0.05).
Conclusion:The expression of CUL4B is associated with HCC recurrence after liver transplantation, and it can be as a predictor for HCC recurrence and distant metastasis after liver transplantation.