Isolation and characterization of progenitor mesenchymal cells in human pituitary tumors

Abstract

The Cancer Stem Cells (CSCs) theory suggests that genetic alterations in stem cells are the direct cause for cancer. The evidence for a CSC population that results in pituitary tumors is poor. Some studies report the isolation of CSCs, but a deep characterization of the stemness of these cells is lacking. Here, we report the isolation and detailed characterization of progenitor mesenchymal cells (PMCs) from both growth hormone-secreting (GH(+)) and non-secreting (NS) pituitary adenomas, determining the immunophenotype, the expression of genes related to stemness or to pituitary hormone cell types, and the differentiative potential towards osteo-, chondro- and adipogenic lineages. Finally, the expression of CD133, known as a marker for CSCs in other tumors, was analyzed. Isolated cells, both from GH(+) and NS tumors, satisfy all the criteria for the identification of PMCs and express known stem cell markers (OCT4, SOX2, KLF4, NANOG), but do not express markers of pituitary hormone cell types (PITX2, PROP1, PIT1). Finally, PMCs express CD133. We demonstrated that pituitary tumors contain a stem cell population that can generate cell types characteristic of mesenchymal stem cells, and express CD133, which is associated with CSCs in other tumors.

The identification of human pituitary adenoma-initiating cells

“…A subset of tumors that are non-functional or do not secrete hormones are termed null cell (NC) adenomas [2]. While the multicellular milieu and hormonal subtypes of these tumors contribute to intra- and intertumoral heterogeneity, respectively, the initiation and maintenance of human PAs remains poorly understood [3, 19, 35, 36]. …”

“…By applying culture conditions and assays used to characterize normal neural stem cells (NSCs), we were among the first researchers to identify such cells from a variety of human brain tumors termed brain tumor-initiating cells (BTICs) [25, 26]. While TICs have traditionally been isolated and characterized using flow cytometric cell-sorting, no study has prospectively isolated and characterized TICs in human PAs [1, 3, 5–7, 10, 19, 35]. A unique property by which TICs may induce oncogenesis is self-renewal [23], defined as the ability of the parental cell to generate an identical daughter cell and a second daughter cell of the same or different phenotype and genotype [24].…”

Comparative study between amniotic-fluid mesenchymal stem cells and retinal pigmented epithelium (RPE) stem cells ability to differentiate towards RPE cells

“…Interestingly, both cellular samples failed the adipogenic differentiation; the inability to form adipocytes has already been reported for AF-MSCs (Orciani et al 2011;Lazzarini et al 2014) but it was not still stated for RPESCs. In our previous works, we successfully differentiated MSCs in adipocytes using the same protocol (Orciani et al 2013(Orciani et al , 2015; the molecular analysis by miRNAs profiling (Lazzarini et al, 2014) of AF-MSCs evidenced the fine regulation of adipogenic differentiation by different members of the Smad protein family. The proteins with a pro-adipogenic role were less expressed than proteins related to anti-adipogenic mechanisms.…”

Pituitary Stem Cells During Normal Physiology and Disease

“…However, progenitor cells or even differentiated cells could give rise to cells fulfilling CSC criteria upon transformation (Valent et al 2012;Clevers 2011). Several groups have reported the presence of putative CSCs in human pituitary adenomas and from mouse pituitary tumour models Xu et al 2009;Donangelo et al 2014;Lloyd et al 2013;Mertens et al 2015;Orciani et al 2015;van Rijn et al 2013;Yunoue et al 2011;Hosoyama et al 2010). It remains unknown if CSCs arise from PSCs, although their properties can be similar; for example, both are capable of in vitro self-renewal and differentiation and PSCs are likely to be chemoresistant like CSCs, since PSCs are found within the 'side population' generated by dye efflux, utilising the same transporter properties as chemoresistance (Chen et al 2009).…”