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Cox B, Roose H, Vennekens A, Vankelecom H. Pituitary stem cell regulation: who is pulling the strings? J Endocrinol 2017; 234:R135-R158. [PMID: 28615294 DOI: 10.1530/joe-17-0083] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 06/14/2017] [Indexed: 12/28/2022]
Abstract
The pituitary gland plays a pivotal role in the endocrine system, steering fundamental processes of growth, metabolism, reproduction and coping with stress. The adult pituitary contains resident stem cells, which are highly quiescent in homeostatic conditions. However, the cells show marked signs of activation during processes of increased cell remodeling in the gland, including maturation at neonatal age, adaptation to physiological demands, regeneration upon injury and growth of local tumors. Although functions of pituitary stem cells are slowly but gradually uncovered, their regulation largely remains virgin territory. Since postnatal stem cells in general reiterate embryonic developmental pathways, attention is first being given to regulatory networks involved in pituitary embryogenesis. Here, we give an overview of the current knowledge on the NOTCH, WNT, epithelial-mesenchymal transition, SHH and Hippo pathways in the pituitary stem/progenitor cell compartment during various (activation) conditions from embryonic over neonatal to adult age. Most information comes from expression analyses of molecular components belonging to these networks, whereas functional extrapolation is still very limited. From this overview, it emerges that the 'big five' embryonic pathways are indeed reiterated in the stem cells of the 'lazy' homeostatic postnatal pituitary, further magnified en route to activation in more energetic, physiological and pathological remodeling conditions. Increasing the knowledge on the molecular players that pull the regulatory strings of the pituitary stem cells will not only provide further fundamental insight in postnatal pituitary homeostasis and activation, but also clues toward the development of regenerative ideas for improving treatment of pituitary deficiency and tumors.
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Affiliation(s)
- Benoit Cox
- Department of Development and RegenerationCluster of Stem Cell and Developmental Biology, Unit of Stem Cell Research, University of Leuven (KU Leuven), Leuven, Belgium
| | - Heleen Roose
- Department of Development and RegenerationCluster of Stem Cell and Developmental Biology, Unit of Stem Cell Research, University of Leuven (KU Leuven), Leuven, Belgium
| | - Annelies Vennekens
- Department of Development and RegenerationCluster of Stem Cell and Developmental Biology, Unit of Stem Cell Research, University of Leuven (KU Leuven), Leuven, Belgium
| | - Hugo Vankelecom
- Department of Development and RegenerationCluster of Stem Cell and Developmental Biology, Unit of Stem Cell Research, University of Leuven (KU Leuven), Leuven, Belgium
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Vankelecom H, Roose H. The Stem Cell Connection of Pituitary Tumors. Front Endocrinol (Lausanne) 2017; 8:339. [PMID: 29255445 PMCID: PMC5722833 DOI: 10.3389/fendo.2017.00339] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/16/2017] [Indexed: 12/13/2022] Open
Abstract
Tumors in the pituitary gland are typically benign but cause serious morbidity due to compression of neighboring structures and hormonal disruptions. Overall, therapy efficiency remains suboptimal with negative impact on health and comfort of life, including considerable risk of therapy resistance and tumor recurrence. To date, little is known on the pathogenesis of pituitary tumors. Stem cells may represent important forces in this process. The pituitary tumors may contain a driving tumor stem cell population while the resident tissue stem cells may be directly or indirectly linked to tumor development and growth. Here, we will briefly summarize recent studies that afforded a glance behind the scenes of this stem cell connection. A better knowledge of the mechanisms underlying pituitary tumorigenesis is essential to identify more efficacious treatment modalities and improve clinical management.
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Affiliation(s)
- Hugo Vankelecom
- Department of Development and Regeneration, Cluster of Stem Cell and Developmental Biology, Unit of Stem Cell Research, University of Leuven (KU Leuven), Leuven, Belgium
- *Correspondence: Hugo Vankelecom,
| | - Heleen Roose
- Department of Development and Regeneration, Cluster of Stem Cell and Developmental Biology, Unit of Stem Cell Research, University of Leuven (KU Leuven), Leuven, Belgium
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Vankelecom H. Pituitary Stem Cells: Quest for Hidden Functions. STEM CELLS IN NEUROENDOCRINOLOGY 2016. [DOI: 10.1007/978-3-319-41603-8_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Vankelecom H, Chen J. Pituitary stem cells: where do we stand? Mol Cell Endocrinol 2014; 385:2-17. [PMID: 23994027 DOI: 10.1016/j.mce.2013.08.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/12/2013] [Accepted: 08/20/2013] [Indexed: 01/21/2023]
Abstract
Some 5 years ago, the stem cells of the adult pituitary gland were discovered. Subsequent in-depth characterization revealed expression of several stemness markers and embryo-typical factors. Now, the quest is open to decipher their role in the gland. When and how pituitary stem cells differentiate to contribute to the mature hormone-producing cell populations is not known. New research models support their involvement in cell regeneration after injury in the gland, and suggest a possible role in pituitary tumor formation. From their expression phenotype, pituitary stem cells seem to re-use embryonic developmental programs during the creation of new hormonal cells. Here, we will review the latest progression in the domain of pituitary stem cells, including the uncovering of some new molecular flavors and of the first potential functions. Eventually, we will speculate on their differentiation programs towards hormonal cells, with a particular focus on gonadotropes.
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Affiliation(s)
- Hugo Vankelecom
- Department of Development and Regeneration, Cluster Stem Cell Biology and Embryology, Research Unit of Stem Cell Research, University of Leuven (KU Leuven), B-3000 Leuven, Belgium.
| | - Jianghai Chen
- Department of Hand Surgery, Tongji Medical College, Union Hospital, Huazhong University of Science & Technology (HUST), Wuhan, Hubei 430022, PR China.
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Wouters J, Stas M, Gremeaux L, Govaere O, Van den broeck A, Maes H, Agostinis P, Roskams T, van den Oord JJ, Vankelecom H. The human melanoma side population displays molecular and functional characteristics of enriched chemoresistance and tumorigenesis. PLoS One 2013; 8:e76550. [PMID: 24098529 PMCID: PMC3789681 DOI: 10.1371/journal.pone.0076550] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/26/2013] [Indexed: 01/10/2023] Open
Abstract
Melanoma remains the most lethal skin cancer, mainly because of high resistance to therapy. Side population (SP) cells are found in many types of cancer and are usually enriched in therapy-resistant as well as tumorigenic cells. Here, we identified a Hoechst dye-effluxing SP in a large series of human melanoma samples representing different progression phases. The SP size did not change with disease stage but was correlated with the prognostic “Breslow’s depth” in the primary (cutaneous) tumors. When injected into immunodeficient mice, the SP generated larger tumors than the bulk “main population” (MP) melanoma cells in two consecutive generations, and showed tumorigenic capacity at lower cell numbers than the MP. In addition, the SP reconstituted the heterogeneous composition of the human A375 melanoma cell line, and its clonogenic activity was 2.5-fold higher than that of the MP. Gene-expression analysis revealed upregulated expression in the melanoma SP (versus the MP) of genes associated with chemoresistance and anti-apoptosis. Consistent with these molecular characteristics, the SP increased in proportion when A375 cells were exposed to the melanoma standard chemotherapeutic agent dacarbazine, and to the aggravating condition of hypoxia. In addition, the SP showed enhanced expression of genes related to cell invasion and migration, as well as to putative (melanoma) cancer stem cells (CSC) including ABCB1 and JARID1B. ABCB1 immunoreactivity was detected in a number of tumor cells in human melanomas, and in particular in clusters at the invasive front of the primary tumors. Together, our findings support that the human melanoma SP is enriched in tumorigenic and chemoresistant capacity, considered key characteristics of CSC. The melanoma SP may therefore represent an interesting therapeutic target.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Animals
- Antineoplastic Agents/pharmacology
- Cell Line, Tumor
- Cell Proliferation
- Cell Transformation, Neoplastic/genetics
- Dacarbazine/pharmacology
- Disease Progression
- Drug Resistance, Neoplasm/genetics
- Gene Expression Regulation, Neoplastic
- Humans
- Jumonji Domain-Containing Histone Demethylases/genetics
- Jumonji Domain-Containing Histone Demethylases/metabolism
- Male
- Melanoma/genetics
- Melanoma/metabolism
- Melanoma/pathology
- Mice
- Mice, SCID
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Neoplasm Staging
- Neoplasm Transplantation
- Neoplastic Stem Cells/drug effects
- Neoplastic Stem Cells/metabolism
- Neoplastic Stem Cells/pathology
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Side-Population Cells/drug effects
- Side-Population Cells/metabolism
- Side-Population Cells/pathology
- Skin Neoplasms/genetics
- Skin Neoplasms/metabolism
- Skin Neoplasms/pathology
- Tumor Burden
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Affiliation(s)
- Jasper Wouters
- Translational Cell & Tissue Research, Dept. of Imaging and Pathology, University of Leuven (KU Leuven), Leuven, Belgium
- Research Unit of Stem Cell Research (Lab. of Tissue Plasticity), Cluster Stem Cell Biology and Embryology, Dept. of Development and Regeneration, University of Leuven (KU Leuven), Leuven, Belgium
| | - Marguerite Stas
- Surgical Oncology, Dept. of Oncology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Lies Gremeaux
- Research Unit of Stem Cell Research (Lab. of Tissue Plasticity), Cluster Stem Cell Biology and Embryology, Dept. of Development and Regeneration, University of Leuven (KU Leuven), Leuven, Belgium
| | - Olivier Govaere
- Translational Cell & Tissue Research, Dept. of Imaging and Pathology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Anke Van den broeck
- Research Unit of Stem Cell Research (Lab. of Tissue Plasticity), Cluster Stem Cell Biology and Embryology, Dept. of Development and Regeneration, University of Leuven (KU Leuven), Leuven, Belgium
- Abdominal Surgical Oncology, Dept. of Oncology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Hannelore Maes
- Lab. of Cell Death Research & Therapy, Dept. of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
| | - Patrizia Agostinis
- Lab. of Cell Death Research & Therapy, Dept. of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
| | - Tania Roskams
- Translational Cell & Tissue Research, Dept. of Imaging and Pathology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Joost J. van den Oord
- Translational Cell & Tissue Research, Dept. of Imaging and Pathology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Hugo Vankelecom
- Research Unit of Stem Cell Research (Lab. of Tissue Plasticity), Cluster Stem Cell Biology and Embryology, Dept. of Development and Regeneration, University of Leuven (KU Leuven), Leuven, Belgium
- * E-mail:
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Wouters J, Stas M, Govaere O, Van den Eynde K, Vankelecom H, van den Oord JJ. Gene expression changes in melanoma metastases in response to high-dose chemotherapy during isolated limb perfusion. Pigment Cell Melanoma Res 2012; 25:454-65. [PMID: 22486811 DOI: 10.1111/j.1755-148x.2012.01004.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Despite recent advances in melanoma therapy, disseminated melanoma still lacks effective treatment, and recurrence of the tumor frequently occurs, even after high-dose chemotherapy. The mechanisms responsible for this chemoresistance or for the formation of new relapses remain poorly understood. Using a human 'model', in which the isolated limb is perfused with high doses of the chemotherapeutic melphalan (ILP), we identified a five-gene set (ATF3, CYR61, IER5, IL6, and PTGS2) of stress-induced genes that was consistently upregulated after ILP in all in-transit metastatic melanoma samples as well as in three melphalan-treated melanoma cell lines. Early post-ILP relapses retained these elevated expressions, whereas the expression of these genes returned to their original levels in late post-ILP recurrences. In addition, we identified upregulation of these genes in the A375 cell line's side population (SP) and melanospheres, established methods to enrich for candidate cancer stem cells (CSCs), which are considered chemoresistant and tumorigenic, and thus proposed to be responsible for tumor relapse. Our data identify an immediate and short-term upregulation of early stress-responsive genes that are potentially linked to chemoresistance and CSCs.
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Affiliation(s)
- Jasper Wouters
- Translational Cell & Tissue Research, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
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Abstract
The pituitary gland represents the endocrine core of the body, and its hormonal output governs many key physiological processes. Because endocrine demands frequently change, the pituitary has to flexibly remodel its hormone-producing cell compartment. One mechanism of pituitary plasticity may rely on the generation of new hormonal cells from resident stem/progenitor cells. Existence of such 'master' cells in the pituitary has in the past repeatedly been postulated. Only recently, however, very plausible candidates have been identified that express stem cell-associated markers and signalling factors, and display the stem/progenitor cell characteristics of multipotency, efflux capacity (side population phenotype) and niche-like organization. In other adult tissues, stem cells recapitulate the embryonic developmental path on their course towards mature specialized cells. Interestingly, the pituitary stem/progenitor cell compartment shows prominent expression of transcriptional regulators and signalling factors that play a pivotal role during pituitary embryogenesis. This review summarizes the recent progress in pituitary stem/progenitor cell identification, highlights their potential embryonic phenotype, sketches a tentative stem/progenitor cell model, and discusses further research and challenges. Recognizing and scrutinizing the pituitary stem/progenitor cells as embryonic players in the adult gland may profoundly impact on our still poor understanding of the mechanisms underlying pituitary cell turnover and plasticity.
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Affiliation(s)
- Hugo Vankelecom
- Laboratory of Tissue Plasticity, Department of Molecular Cell Biology, University of Leuven (K.U.Leuven), B-3000 Leuven, Belgium.
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Vankelecom H, Gremeaux L. Stem cells in the pituitary gland: A burgeoning field. Gen Comp Endocrinol 2010; 166:478-88. [PMID: 19917287 DOI: 10.1016/j.ygcen.2009.11.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 11/02/2009] [Accepted: 11/10/2009] [Indexed: 12/21/2022]
Abstract
The pituitary gland represents the endocrine core of the organism, and is well-known for its cellular plasticity in order to meet the body's fluctuating hormonal demands. In the past, it has repeatedly been postulated that the pituitary harbors tissue-specific stem cells that participate in the generation of new endocrine cells during this dynamic cell remodeling, as well as during the slow but robust homeostatic turnover of the gland. However, their presence and identity remained elusive until this conundrum recently attracted renewed interest. Our discovery of a 'side population' using flow cytometry was the first step towards a more convincing candidate stem/progenitor cell population in the endocrine anterior pituitary. Since then, several other groups have endeavored to search for pituitary stem/progenitor cells, which finally culminated in the identification of very strong candidates. Multiple markers were put forward, among which the pluripotency transcription factor Sox2 occupies center stage. Now that very plausible pituitary stem/progenitor cells can be isolated and assayed, detailed characterization of their involvement in pituitary cell remodeling during basal renewal, dynamic adaptation and potential response to injury is around the corner, and is expected to significantly advance our knowledge on pituitary biology. In addition, a comprehensive study of the stem/progenitor cells may guide us to a better understanding of pituitary hormonal deficiencies, as well as of pituitary tumorigenesis in which 'cancer stem cells' may play a central role. Nevertheless, many questions remain to be resolved, and future challenges are huge. In this review, we provide a detailed overview of the exciting recent developments in the pituitary stem cell quest. In addition we pinpoint some discordant findings and include a number of cautionary and critical reflections. The recent acceleration in pituitary stem cell research may initiate a very exciting era in the pituitary field. May we say that "La nouvelle hypofyse est arrivée"?
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Affiliation(s)
- Hugo Vankelecom
- Laboratory of Tissue Plasticity, Department of Molecular Cell Biology, University of Leuven (K.U.Leuven), B-3000 Leuven, Belgium.
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