[Relationship between expression of decoy receptor 3 and apoptosis in hepatocellular carcinoma]

Abstract

Objective: To study the expression of decoy receptor 3 (DcR3) and its relationship with apoptosis and prognosis in hepatocellular carcinoma (HCC).

Methods: The expression of DcR3 protein in 43 cases of HCC and 16 cases of non-cancerous liver (including cirrhotic liver tissue and normal liver tissue adjacent to cavernous hemangioma) was studied by immunohistochemistry (using EnVision method). The status of apoptosis was evaluated by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) technique. Statistic analysis was carried out to assess the correlation between DcR3 expression, apoptotic index (AI) and clinicopathologic parameters.

Results: DcR3 protein was expressed in the cytoplasm of HCC cells. The positivity rate of DcR3 in HCC was 74.42% (32/43), which was significantly higher than that in the non-cancerous group (43.75%, P < 0.05). The positivity rate of DcR3 in HCC with metastasis detected within 20 months of diagnosis was 100% (22/22). This was significantly higher than that in HCC without metastasis (52.94%, P < 0.01). The DcR3 expression in HCC also correlated with serum alpha-fetoprotein level (r = 0.444, P < 0.01) and presence of tumor embolus in portal vein (r = 0.414, P < 0.01). However it had no relationship with the patient's age, sex, cirrhotic status, liver capsule invasion, number of tumor nodules and histologic differentiation (P > 0.05). The AI in HCC (0.78 +/- 0.64)% was significantly lower than that in the non-cancerous group [(3.32 +/- 1.81)%, P < 0.01]. The AI in clinical TNM stage I and II tumors (1.03 +/- 0.69)% was significantly higher than that in stage III and IV tumors [(0.52 +/- 0.48)%, P < 0.01]. The AI in HCC without metastasis (1.10 +/- 0.72)% was significantly higher than that in HCC without metastasis [(0.44 +/- 0.27)%, P < 0.05]. The AI correlated with serum alpha-fetoprotein level (r = -0.468, P < 0.01), presence of tumor embolus in portal vein (r = -0.434, P < 0.01) and liver capsule invasion (r = -0.331, P < 0.05). On the other hand, it had no relationship with patient's age, sex, cirrhotic status, number of tumor nodules and histologic differentiation (P > 0.05). The AI in DcR3-positive group (including both HCC and non-cancerous tissues) was significantly lower than that in DcR3-negative group (P < 0.01).

Conclusions: The expression of DcR3 in HCC correlates with apoptosis of tumor cells and may play a crucial role in tumor pathogenesis and progression. DcR3 protein expression and AI may also serve as important biologic indicators in predicting prognosis of HCC.