Histochemical studies of glucose-6-phosphatase activity in the early proliferative stage of liver carcinogenesis

Summary

The cytochemical localization and activity of glucose-6-phosphatase was studied in the early proliferative stage of liver carcinogenesis. In diffuse oval cell proliferation prior to the occurrence of typical hepatocyte differentiation, glucose-6-phosphatase activity was established in individual oval cells. Formation of small liver nodules from oval cells subjected to hepatocyte differentiation was clearly observed in this study. In the separate bile ducts as well as in the epithelium of adenofibrous nodules, however, such activity was lacking.

It may be suggested that in the early stages of liver carcinogenesis the loss of glucose-6-phosphatase activity obviously does not develop in the initial transformational steps toward neoplasia. It is probable that in severe injury of the parenchyma in adult liver, regenerative and proliferative processes take place from primitive cells which may differentiate as hepatocytes, cholangiole cells or or bile duct cells.

Zusammenfassung

Bei der Carcinogenese konnte in der Phase der diffusen Proliferation der ovalen Zellen, bevor sich diese in typische Hepatocyten differenzieren, eine Glucose-6-Phosphatase-Aktivität in vereinzelten solchen Zellen nachgewiesen werden. Bei der Differenzierung dieser ovalen Zellen in Leberzellen bilden sich kleinere Knoten. In den Gallengängen und in dem Epithel dieser Knoten fehlte eine derartige Enzymaktivität. Der Verlust der Glucose-6-Phosphatase-Aktivität in den frühen Stadien der Cancerogenese tritt offenbar nicht während der ersten Umwandlungsschritte zur Neoplasie hin auf. Es ist vielmehr wahrscheinlich, daß bei schweren Parenchymschäden der Erwachsenenleber regeneratorische und proliferative Prozesse ablaufen, wobei primitive Stammzellen sich in Hepatocyten oder die Zellen kleinerer und größerer Gallengänge differenzieren.