Possible stem cell origin of human cholangiocarcinoma.

AIM: To investigate the expression of CD34 and c-kit (receptor of stem cell factor) in cholangiocarcinoma.
METHODS: Fifteen cases of intrahepatic cholangiocarcinoma and 17 cases of extrahepatic cholangiocarcinoma were studied in this experiment. Using Envision detection system, paraffin-embedded sections of the resected cholangiocarcinoma tissue were stained with antibodies against CD34 and c-kit, respectively. The sections were counterstained with hematoxylin, and the results were examined under light microscope. Normal tonsil and mammary tissues were used as positive controls for CD34 and c-kit, respectively.
RESULTS: CD34 was positive in all sections, but only in capillary endothelial cells of tumor tissue. No cholangiocarcinoma cells were positive for CD34. In one case of extrahepatic cholangiocarcinoma, a few tumor cells (about 5%) were immunoreactive with c-kit.
CONCLUSION: CD34 or c-kit positive cells in liver tissue may represent liver stem cells, as they can differentiate into mature biliary cells in vitro. The expression of c-kit by some cholangiocarcinoma cells suggests that cholangiocarcinoma might originate from liver stem cells. However, other mechanisms of hepatocarcinogenesis, such as de-differentiation of mature cholangiocytes, may also exist.