Stem/progenitor cells in pituitary organ homeostasis and tumourigenesis

Abstract

Evidence for the presence of pituitary gland stem cells has been provided over the last decade using a combination of approaches including in vitro clonogenicity assays, flow cytometric side population analysis, immunohistochemical analysis and genetic approaches. These cells have been demonstrated to be able to self-renew and undergo multipotent differentiation to give rise to all hormonal lineages of the anterior pituitary. Furthermore, evidence exists for their contribution to regeneration of the organ and plastic responses to changing physiological demand. Recently, stem-like cells have been isolated from pituitary neoplasms raising the possibility that a cytological hierarchy exists, in keeping with the cancer stem cell paradigm. In this manuscript, we review the evidence for the existence of pituitary stem cells, their role in maintaining organ homeostasis and the regulation of their differentiation. Furthermore, we explore the emerging concept of stem cells in pituitary tumours and their potential roles in these diseases.

Transcriptome and methylome analysis reveals three cellular origins of pituitary tumors

“…These results also suggest that PA progenitor cells do not originate early in the cytodifferentiation process but derive instead from an already partially committed cell. Undoubtedly, further elucidation of the mechanisms underlying pituitary stem cell self-renewal, differentiation and programmed death may lead to a better understanding of pituitary homeostasis, plasticity and tumorigenesis 15 .…”

Molecular Mechanisms of Pituitary Cell Plasticity

“…Although activation of this cell population has been observed under conditions of acute experimental stress, e.g., hormone cell type-specific cell oblation and organ loss, the extent to which this mechanism contributes to pituitary homeostasis and functional plasticity is unclear (27). Adult stem cells have also been implicated in mediating pituitary neo-plastic growth, and this pathological aspect of pituitary plasticity has been extensively covered in recent excellent reviews (28,29).…”

Pituitary Hyperplasia, Hormonal Changes and Prolactinoma Development in Males Exposed to Estrogens—An Insight From Translational Studies

“…Su et al [37] analyzed the expression pattern of tumor stem-like cells isolated from MMQ rat prolactinoma cells and found that Bcl 2, VegfA, Pten, Jun, Fos, and Apc2 gene expressions were upregulated and the expression of Myc was downregulated in these cells. The model of cancer stem cell proposes that a small population of cells with stem-like properties initiates and maintains tumorigenesis and may be more resistant to therapy than other tumor cells [100,101]. The resistance is probably due to their often slow cycling, nonproliferative states [102] and/or the expression of ABC transporters, and high levels of aldehyde dehydrogenases [100].…”