Liver stem cells: implications for hepatocarcinogenesis

Multiple cells of origin in cholangiocarcinoma underlie biological, epidemiological and clinical heterogeneity

Recent histological and molecular characterization of cholangiocarcinoma (CCA) highlights the heterogeneity of this cancer that may emerge at different sites of the biliary tree and with different macroscopic or morphological features. Furthermore, different stem cell niches have been recently described in the liver and biliary tree, suggesting this as the basis of the heterogeneity of intrahepatic (IH)- and extrahepatic (EH)-CCAs, which are two largely different tumors from both biological and epidemiological points of view. The complexity of the organization of the liver stem cell compartments could underlie the CCA clinical-pathological heterogeneity and the criticisms in classifying primitive liver tumors. These recent advances highlight a possible new classification of CCAs based on cells of origin and this responds to the need of generating homogenous diagnostic, prognostic and, hopefully, therapeutic categories of IH- and EH-CCAs.

Expressions of cytokeratin 18 and cytokeratin 19 in hepatocellular carcinoma tissues

AIM: To observe the expressions of cytoketatin18 (CK18) and cytoketatin19 (CK19) in tissues of hepatocellular carcinoma, liver cirrhosis, and normal liver.

METHODS: Immunohistochemical streptavidin-peroxidase (SP) method was adopted to examine the expression of CK18 and CK19 in tissue samples of normal liver (n = 8), liver cirrhosis (n = 27), and hepatocellular carcinoma (n = 43).

RESULTS: The positive rates of CK18 expression in hepatic cirrhosis and normal liver tissues had no significant differences. However, CK18 expression was significantly different between hepatocellular carcinoma and liver cirrhosis (65.1% vs 29.6%, P < 0.01). The positive rates of CK19 expression in cirrhosis of liver and normal liver had no significant differences. But the expression of CK19 was markedly higher in hepatocellular carcinoma than that in hepatic cirrhosis (69.8% vs 25.9%, P < 0.01). Oval cells with strongly positive staining could be seen in the portal area of cirrhosis cases (20/27) and in the brink of carcinoma cases (35/43), and there were significant differences (CK18: 6.57 ± 1.69 vs 10.70 ± 2.31; CK19: 5.37 ± 1.17 vs 10.45 ± 2.15, P < 0.01) in the numbers between cirrhosis of liver and hepatocellular carcinoma.

CONCLUSION: CK18 and CK19 are involved in hepatocarcinogenesis. Oval cells are strongly positive for CK18 and CK19 in cirrhosis of liver and hepatocellular carcinoma. Oval cells are associated with regeneration of liver, and are probably original cells of hepatocellular carcinoma.