Endocrine Abstracts

The tumor microenvironment can comprise more than 50% of the tumor mass and includes resident and infiltrative non-tumor cells, as well as extracellular matrix proteins, signaling molecules, and blood and lymph vessels (Balkwill et al., 2012). In recent years, the tumor microenvironment has begun to be considered both a prognostic tool and a therapeutic target (Hui and Chen, 2015). While the existence of the tumor microenvironment is well accepted and described in numerous cancers, little is known about the tumor microenvironement of pituitary neuroendocrine tumors. Even less is known about the folliculostellate cells in the context of the microenvironment of pituitary neuroendocrine tumors. Folliculostellate cells are resident cells of the normal anterior pituitary, comprising 5–10% of the normal anterior pituitary. Beside the role folliculostellate cells have in the normal anterior pituitary, their identification in pituitary neuroendocrine tumors suggests they may also have a major implication in these tumors. Therefore, better characterization of pituitary neuroendocrine tumor-associated folliculostellate cells and understanding of their contribution and their functional interactions with tumor cells and tumor-associated stroma may provide important indications regarding the mechanisms that drive tumorigenesis-associated processes such as immune escape, proliferation, local invasion, dedifferentiation, and ultimately tumor aggressiveness. The research project in which I was involved during the fellowship aimed at better characterizing folliculostellate cells within pituitary neuroendocrine tumors, and it involved a combined exploration of their histological characteristics and of their cellular properties.