Abstract
We previously identified apolipoprotein D (Apo D) as a novel tumor suppressor gene based on the pharmacological unmasking of epigenetic silencing. We analyzed Apo D expression using real‐time reverse transcription‐PCR and evaluated its expression status based on the clinicopathological parameters of 70 patients with hepatocellular carcinoma (HCC). Immunohistochemical staining was also performed. We determined the methylation status of Apo D gene promoter by methylation‐specific PCR (MSP). The Apo D gene‐expression in tumor tissue was significantly lower than that in nontumor tissue (p = 0.011). A low Apo D expression significantly correlated with less‐differentiated HCC (p = 0.019). Immunohistochemical studies confirmed a decreased Apo D expression in poorly differentiated tumors. The prognosis of patients with a lower Apo D gene‐expression was significantly worse than that in those with a higher expression (p = 0.028). The Apo D gene‐expression was an independent prognostic factor (relative risk: 2.36, p = 0.018). An MSP assay showed a low‐level of methylation in well differentiated HCC and a high‐level of methylation in less differentiated tumors. Apo D may be a novel tumor suppressor gene of HCC, and its expression status may be a useful biomarker for predicting the patient outcome. © 2005 Wiley‐Liss, Inc.