Expression pattern of stem cell markers in a tissue microarray of human biliary tract cancer

Aims: Referring to the recently updated ‘hallmarks of cancer’ by Hanahan and Weinberg (Cell, 2011) the cancer stem cell model is now accepted as a valid concept of carcinogenesis. The aim of this study was to investigate the expression of putative markers of stem and progenitor cells in a human biliary tract cancer (BTC) tissue microarray (TMA). Materials and Methods: Specimens (n=34) from surgically resected BTC between 1997 and 2010 with complete clinical follow-up data and histopathological records were included to prepare TMAs from tumor center and margin as well as adjacent normal tissue. These TMAs were characterized for proliferation (cell cycle proteins) and for markers of differentiation (intermediate filaments) and of stem- and progenitor cells (BMI–1, Sox–2, Nestin, CD133, CD44 and Nanog) by immunohistochemistry. Results: Nanog exhibited the highest protein level followed by CD133, CD44, BMI, Nestin and Sox2 by a decreasing level. Expression of stem cell markers showed a dependency of intratumor distribution and were significantly correlated with markers of differentiation (CK19, β-Catenin), de-differentiation (Vimentin) as well as with cell-cycle-associated markers (p27, Ki–67) – all with a p value < 0.05. Finally, the survival rates were associated with tumor growth pattern as well as with the expression pattern of putative stem cell markers. Conclusion: The expression and distribution patterns of putative stem cell markers in human BTC is significantly linked to differentiation, proliferation and outcome, thus supporting the cancer stem cell model and suggesting possible therapeutic targets for BTC.