Expression of Oct4, a Stem Cell Marker, in the Hamster Pancreatic Cancer Model

Background: Oct4 has been shown to present a stem cell marker that is expressed in embryonic cells and in germ cell tumors. Recently, its expression in a few human tissues and cancer cells has been reported. Because in the hamster pancreatic cancer model most tumors develop from within islets presumably from stem cells, we investigated the expression of Oct4 in this model.Methods: Two normal pancreases and 15 pancreatic cancers induced by /V-nitrosobis(2-oxypropyl)amine (BOP) were processed for immunohistochemistry using a monoclonal Oct4 antibody at a concentration of 1:500.Results: In the normal pancreas, Oct4 was expressed only in islet cells in a diffuse cytoplasmic pattern. No nuclear staining was found in any cells. In 14 of the pancreatic cancers, nuclear staining was detected in many cells or in small foci. Diffuse cytoplasmic but no nuclear staining was found in one tumor and a mixed Golgi type and nuclear staining in two cases. Nuclear staining was also identified in early intrainsular ductular and in Ca in situ lesions. Conclusions: BOP reactivates the Oct4 gene and can be considered an early tumor marker in this model.