AIM: To investigate the expression of selenoprotein P mRNA (SePmRNA) in tissues of normal liver, liver cirrhosis and hepatocellular carcinoma (HCC), and its relationship with HCC occurrence and development. METHODS: The expression of SePmRNA in tissues of normal liver, liver cirrhosis and HCC were detected by in situ hybridization using a cDNA probe. RESULTS: The enzyme digesting products of PBluescript-H uman Selenoprotein P were evaluated by electrophoresis. The positive expression of SePmRNA was found in the tissues of normal liver, liver cirrhosis and HCC. The expression of SeP mRNA was found in hepatic interstitial substance, especially in endothelial cells and lymphocytes of vasculature. The positive rate of SePmRNA in normal liver tissue was 84.6% (11/13) and the positive signals appeared in the nucleus and cytoplasm, mostly in the nucleolus, and the staining granules were larger in the nucleolus and around the nucleus. The positive rate of SePmRNA in liver cirrhosis tissue was 45.0% (9/20) and the positive signals were mainly in the nucleolus and cytoplasm, being less around the nucleus and inner nucleus than that in normal liver tissue. The positive rate of SePmRNA in HCC tissue was 30.0% (9/30) and the positive signals were in the cytoplasm, but less in the nucleus. CONCLUSION: SePmRNA expression in the tissues of normal liver and HCC is significantly different (84.6% vs 30.0%, P = 0.003), suggesting that SeP might play a role in the occurrence and development of HCC. AIM: To investigate the expression of selenoprotein P mRNA (SeP mRNA) in tissues of normal liver, liver cirrhosis and hepatocellular carcinoma (HCC), and its relationship with HCC occurrence and development. METHODS: The expression of SeP mRNA in tissues of normal liver, liver cirrhosis and HCC were detected by in situ hybridization using a cDNA probe. RESULTS: The enzyme digesting products of PBluescript-H uman Selenoprotein P were evaluated by electrophoresis. The positive expression of SeP mRNA was found in the tissues of normal liver, liver cirrhosis and HCC . The expression of SeP mRNA was found in hepatic interstitial substance, especially in endothelial cells and lymphocytes of vasculature. The positive rate of SeP mRNA in normal liver tissue was 84.6% (11/13) and the positive signals appeared in the nucleus and cytoplasm, mostly in the nucleolus, and the staining granules were in the nucleolus and around the nucleus. The positive rate of SeP mRNA in liver cirrhosis tissue was 45.0% (9/20) and the positive signals were mainly in the nucleolus and cytoplasm, being less around the nucleus and inner nucleus than that in normal liver tissue. The positive rate of SeP mRNA in HCC tissue was 30.0% (9/30) and the positive signals were in the cytoplasm, but less in the nucleus. CONCLUSION: SeP mRNA expression in the tissues of normal liver and HCC was significantly different (84.6% vs 30.0%, P = 0.003), suggesting that SeP might play a role in the occurrence and development of HCC