Evidence of brain tumor stem progenitor-like cells with low proliferative capacity in human benign pituitary adenoma

Tumor stem cells have been implicated as cancer-initiating cells in malignant brain tumors. However, whether benign brain tumors also contain tumor stem cells are largely unexplored. Here, we investigated whether tumor stem-like cells were present in pituitary adenoma similar to malignant brain tumors. By immunocytochemistry, we found that pituitary adenoma tissues expressed neural stem cell marker. These cells could form neurospheres in vitro, expressed neural stem/progenitor cell markers and generated daughter cells with the capacity to differentiate into three neural lineages. Importantly, compared with non-invasive pituitary adenomas, we found that CD133 expression was significantly increased in invasive pituitary adenomas, suggesting that the proliferative capacity was correlated with the malignance of pituitary adenomas. Finally, invasive pituitary adenomas cells displayed lower proliferative ability than glioblastoma. Our data indicate that a subpopulation of stem/progenitor-like cells are present in pituitary adenomas, and these cells may be responsible for benign tumor initiation and maintenance.