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Alberto Fernandez, Michael Brada, Lina Zabuliene, Niki Karavitaki, and John A H Wass

The hypothalamic–pituitary unit is a particularly radiosensitive region in the central nervous system. As a consequence, hypopituitarism commonly develops after radiation treatments for sellar and parasellar neoplasms, extrasellar brain tumours, head and neck tumours, and following whole body irradiation for systemic malignancies. Increasing tumour-related survival rates provide an expanding population at risk of developing hypopituitarism. In this population, long-term monitoring tailored to the individual risk profile is required to avoid the sequelae of untreated pituitary hormonal deficiencies and resultant decrease in the quality of life. This review analyses the pathogenesis, prevalence and consequences of radiation-induced hypopituitarism (RIH) in diverse subgroups at risk. Also discussed is the impact of modern radiotherapy techniques in the prevalence of RIH, the spectrum of endocrine disorders and radiation-induced brain conditions that also occur in patients with RIH.

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Lautaro Zubeldía-Brenner, Catalina De Winne, Sofía Perrone, Santiago A Rodríguez-Seguí, Christophe Willems, Ana María Ornstein, Isabel Lacau-Mengido, Hugo Vankelecom, Carolina Cristina, and Damasia Becu-Villalobos

Preclinical and clinical studies support that Notch signaling may play an important oncogenic role in cancer, but there is scarce information for pituitary tumors. We therefore undertook a functional study to evaluate Notch participation in pituitary adenoma growth. Tumors generated in Nude mice by subcutaneous GH3 somatolactotrope cell injection were treated in vivo with DAPT, a γ-secretase inhibitor, thus inactivating Notch signaling. This treatment led to pituitary tumor reduction, lower prolactin and GH tumor content and a decrease in angiogenesis. Furthermore, in silico transcriptomic and epigenomic analyses uncovered several tumor suppressor genes related to Notch signaling in pituitary tissue, namely Btg2, Nr4a1, Men1, Zfp36 and Cnot1. Gene evaluation suggested that Btg2, Nr4a1 and Cnot1 may be possible players in GH3 xenograft growth. Btg2 mRNA expression was lower in GH3 tumors compared to the parental line, and DAPT increased its expression levels in the tumor in parallel with the inhibition of its volume. Cnot1 mRNA levels were also increased in the pituitary xenografts by DAPT treatment. And the Nr4a1 gene was lower in tumors compared to the parental line, though not modified by DAPT. Finally, because DAPT in vivo may also be acting on tumor microenvironment, we determined the direct effect of DAPT on GH3 cells in vitro. We found that DAPT decreases the proliferative, secretory and migration potential of GH3 cells. These results position selective interruption of Notch signaling as a potential therapeutic tool in adjuvant treatments for aggressive or resistant pituitary tumors.

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Albert Beckers, Maya Beth Lodish, Giampaolo Trivellin, Liliya Rostomyan, Misu Lee, Fabio R Faucz, Bo Yuan, Catherine S Choong, Jean-Hubert Caberg, Elisa Verrua, Luciana Ansaneli Naves, Tim D Cheetham, Jacques Young, Philippe A Lysy, Patrick Petrossians, Andrew Cotterill, Nalini Samir Shah, Daniel Metzger, Emilie Castermans, Maria Rosaria Ambrosio, Chiara Villa, Natalia Strebkova, Nadia Mazerkina, Stéphan Gaillard, Gustavo Barcelos Barra, Luis Augusto Casulari, Sebastian J Neggers, Roberto Salvatori, Marie-Lise Jaffrain-Rea, Margaret Zacharin, Beatriz Lecumberri Santamaria, Sabina Zacharieva, Ee Mun Lim, Giovanna Mantovani, Maria Chaira Zatelli, Michael T Collins, Jean-François Bonneville, Martha Quezado, Prashant Chittiboina, Edward H Oldfield, Vincent Bours, Pengfei Liu, Wouter W de Herder, Natalia Pellegata, James R Lupski, Adrian F Daly, and Constantine A Stratakis

X-linked acrogigantism (X-LAG) is a new syndrome of pituitary gigantism, caused by microduplications on chromosome Xq26.3, encompassing the gene GPR101, which is highly upregulated in pituitary tumors. We conducted this study to explore the clinical, radiological, and hormonal phenotype and responses to therapy in patients with X-LAG syndrome. The study included 18 patients (13 sporadic) with X-LAG and microduplication of chromosome Xq26.3. All sporadic cases had unique duplications and the inheritance pattern in two families was dominant, with all Xq26.3 duplication carriers being affected. Patients began to grow rapidly as early as 2–3 months of age (median 12 months). At diagnosis (median delay 27 months), patients had a median height and weight standard deviation scores (SDS) of >+3.9 SDS. Apart from the increased overall body size, the children had acromegalic symptoms including acral enlargement and facial coarsening. More than a third of cases had increased appetite. Patients had marked hypersecretion of GH/IGF1 and usually prolactin, due to a pituitary macroadenoma or hyperplasia. Primary neurosurgical control was achieved with extensive anterior pituitary resection, but postoperative hypopituitarism was frequent. Control with somatostatin analogs was not readily achieved despite moderate to high levels of expression of somatostatin receptor subtype-2 in tumor tissue. Postoperative use of adjuvant pegvisomant resulted in control of IGF1 in all five cases where it was employed. X-LAG is a new infant-onset gigantism syndrome that has a severe clinical phenotype leading to challenging disease management.

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Annamaria Colao, Carolina Di Somma, Rosario Pivonello, Antongiulio Faggiano, Gaetano Lombardi, and Silvia Savastano

Surgery is the first-line treatment of patients with clinically non-functioning pituitary adenomas (NFAs). Because of lack of clinical syndrome these tumours are diagnosed with a variable delay, when patients suffer from compression symptoms (hypopituitarism, headache and visual field defects) due to the extension of the tumour outside the pituitary fossa. Surgery is followed by residual tumour tissue in most patients. In these cases, radiotherapy is generally used to prevent tumour regrowth. However, NFA cell membranes, in analogy with GH- and PRL-secreting adenomas, express somatostatin and dopamine receptors. Treatment with somatostatin analogues (SSA) and dopamine agonists (DA) induced some beneficial effects on visual field defects and was also followed by tumour shrinkage in a minority of cases. DA seem to be more effective on tumour shrinkage than SSA. More recently, a combination treatment with both SSA and DA have been tested in a few patients with interesting results. Lack of randomized, placebo-controlled trials prevents any conclusion on the efficacy of these drugs. By contrast, use of gonatotrophin-releasing hormone analogues has been abandoned.

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Ines Donangelo, Song-Guang Ren, Tamar Eigler, Clive Svendsen, and Shlomo Melmed

The role of tumor stem cells in benign tumors such as pituitary adenomas remains unclear. In this study, we investigated whether the cells within pituitary adenomas that spontaneously develop in Rb + /− mice are hierarchically distributed with a subset being responsible for tumor growth. Cells derived directly from such tumors grew as spheres in serum-free culture medium supplemented with epidermal growth factor and basic fibroblast growth factor. Some cells within growing pituitary tumor spheres (PTS) expressed common stem cell markers (Sca1, Sox2, Nestin, and CD133), but were devoid of hormone-positive differentiated cells. Under subsequent differentiating conditions (matrigel-coated growth surface), PTS expressed all six pituitary hormones. We next searched for specific markers of the stem cell population and isolated a Sca1+ cell population that showed increased sphere formation potential, lower mRNA hormone expression, higher expression of stem cell markers (Notch1, Sox2, and Nestin), and increased proliferation rates. When transplanted into non-obese diabetic-severe combined immunodeficiency gamma mice brains, Sca1+ pituitary tumor cells exhibited higher rates of tumor formation (brain tumors observed in 11/11 (100%) vs 7/12 (54%) of mice transplanted with Sca1+ and Sca1 cells respectively). Magnetic resonance imaging and histological analysis of brain tumors showed that tumors derived from Sca1+ pituitary tumor cells were also larger and plurihormonal. Our findings show that Sca1+ cells derived from benign pituitary tumors exhibit an undifferentiated expression profile and tumor-proliferative advantages, and we propose that they could represent putative pituitary tumor stem/progenitor cells.

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Cristina L Ronchi, Silviu Sbiera, Barbara Altieri, Sonja Steinhauer, Vanessa Wild, Michaela Bekteshi, Matthias Kroiss, Martin Fassnacht, and Bruno Allolio

Previous SNP array analyses have revealed genomic alterations of the Notch pathway as being the most frequent abnormality in adrenocortical tumors (ACTs). The aim of the present study was to evaluate the expression of components of Notch signaling in ACTs and to correlate them with clinical outcome. The mRNA expression of JAG1, NOTCH1, and selected target genes of NOTCH1 (HES1, HES5, and HEY2) was evaluated in 80 fresh frozen samples (28 normal adrenal glands (NAGs), 24 adenomas (ACAs), and 28 carcinomas (ACCs)) by quantitative RT-PCR. Immunohistochemistry was performed in 221 tissues on paraffin slides (16 NAGs, 27 ACAs, and 178 ACCs) for JAG1, activated NOTCH1 (aNOTCH1), and HEY2. An independent ACC validation cohort (n=77) was then also investigated. HEY2 mRNA expression was higher in ACCs than it was in ACAs (P<0.05). The protein expression of all of the factors was high (H-score 2–3) in a larger proportion of ACCs as compared to ACAs and NAGs (JAG1 in 27, 15, and 10%; aNOTCH1 in 13, 8, and 0%; HEY2 in 66, 61, and 33% respectively, all P<0.001). High JAG1 expression was associated with earlier tumor stages and lower numbers of metastases in ACCs (both P=0.08) and favorably impacted overall and progression-free survival (PFS) (131 vs 30 months, hazard ratio (HR) 0.45, and 37 vs 9 months, HR 0.51, both P<0.005). This impact on overall survival (OS) was confirmed in the validation cohort. No such association was observed for aNOTCH1 or HEY2. In conclusion, different components of the Notch1 signaling pathway are overexpressed in ACCs, which suggests a role for the pathway in malignant transformation. However, JAG1 is overexpressed in a subgroup of ACCs with a better clinical outcome.

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Hongyu Chen, Dan Liu, Zhengyan Yang, Limin Sun, Que Deng, Shuo Yang, Lu Qian, Liang Guo, Ming Yu, Meiru Hu, Ming Shi, and Ning Guo

Angiogenesis is an important factor in invasive tumor growth, progression, and metastasis. Multiple proangiogenic mechanisms are involved in tumor angiogenesis. In this study, we showed that the neurotransmitter norepinephrine upregulated VEGF (VEGFA) expression in breast cancer cells and that the culture supernatant from norepinephrine-treated breast cancer cells promoted the formation of the capillary-like network of endothelial cells. However, the effects of norepinephrine were further enhanced when the endothelial cells were cocultured with breast cancer cells, indicating a critical role of tumor cell–endothelial cell contacts in norepinephrine-induced tumor angiogenesis. Interestingly, norepinephrine dramatically induced the activation of the Notch pathway, which is a cell-contact-mediated intercellular signaling pathway and tightly linked to tumor cell–stromal cell interaction and angiogenesis, in the endothelial cells that had been cocultured with breast cancer cells. Furthermore, the expression of the Notch ligand Jagged 1 was significantly upregulated by norepinephrine at both mRNA and protein levels in breast cancer cells. Inhibitors of β2-adrenergic receptor (β2-AR), protein kinase A (PKA), and mTOR could reverse norepinephrine-induced Jagged 1 upregulation, indicating that the β2-AR–PKA–mTOR pathway participates in this process. Knockdown of Jagged 1 expression in breast cancer cells not only repressed norepinephrine-induced activation of the Notch pathway in cocultured endothelial cells but also evidently impaired the effects of norepinephrine on capillary-like sprout formation. These data demonstrate that tumor angiogenesis mediated by the Jagged 1/Notch intercellular signaling is governed by the norepinephrine-activated β2-AR–PKA–mTOR pathway.

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Brandi B Knight, Gabriela M Oprea-Ilies, Arumugam Nagalingam, Lily Yang, Cynthia Cohen, Neeraj K Saxena, and Dipali Sharma

Obese breast cancer patients exhibit a higher risk for larger tumor burden and an increased likelyhood of metastasis. The molecular effects of obesity on carcinogenesis are mediated by the autocrine and paracrine effects of the adipocytokine leptin. Leptin participates in the tumor progression and metastasis of human breast. We show that leptin induces clonogenicity and increases the migration potential of breast cancer cells. We found that survivin expression is induced in response to leptin. In this study, we examine the role and leptin-mediated regulation of survivin. Leptin treatment leads to survivin upregulation, due in part to the activation of Notch1 and the release of a transcriptionally active Notch1 intracellular domain (NICD). Chromatin immunoprecipitation analysis shows that NICD gets recruited to the survivin promoter at the CSL (CBF1/RBP-Jk, Su(H), Lag-1) binding site in response to leptin treatment. Inhibition of Notch1 activity inhibits leptin-induced survivin upregulation. Leptin-induced transactivation of epidermal growth factor receptor (EGFR) is involved in leptin-mediated Notch1 and survivin upregulation, demonstrating a novel upstream role of leptin–EGFR–Notch1 axis. We further show that leptin-induced migration of breast cancer cells requires survivin, as overexpression of survivin further increases, whereas silencing survivin abrogates leptin-induced migration. Using a pharmacological approach to inhibit survivin, we show that 3-hydroxy-3-methylglutaryl-coenzyme-A-reductase inhibitors, such as lovastatin, can effectively inhibit leptin-induced survivin expression and migration. Importantly, leptin increased breast tumor growth in nude mice. These data show a novel role for survivin in leptin-induced migration and put forth pharmacological survivin inhibition as a potential novel therapeutic strategy. This conclusion is supported by in vivo data showing the overexpression of leptin and survivin in epithelial cells of high-grade ductal carcinomas in situ and in high-grade invasive carcinomas.

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Y Capodanno, F O Buishand, L Y Pang, J Kirpensteijn, J A Mol, and D J Argyle

Insulinomas (INS) are the most common neuroendocrine pancreatic tumours in humans and dogs. The long-term prognosis for malignant INS is still poor due to a low success rate of the current treatment modalities, particularly chemotherapy. A better understanding of the molecular processes underlying the development and progression of INS is required to develop novel targeted therapies. Cancer stem cells (CSCs) are thought to be critical for the engraftment and chemoresistance of many tumours, including INS. This study was aimed to characterise and target INS CSCs in order to develop novel targeted therapies. Highly invasive and tumourigenic human and canine INS CSC-like cells were successfully isolated. These cells expressed stem cell markers (OCT4, SOX9, SOX2, CD133 and CD34), exhibited greater resistance to 5-fluorouracil (5-FU) and demonstrated a more invasive and tumourigenic phenotype in vivo compared to bulk INS cells. Here, we demonstrated that Notch-signalling-related genes (NOTCH2 and HES1) were overexpressed in INS CSC-like cells. Protein analysis showed an active NOTCH2-HES1 signalling in INS cell lines, especially in cells resistant to 5-FU. Inhibition of the Notch pathway, using a gamma secretase inhibitor (GSI), enhanced the sensitivity of INS CSC-like cells to 5-FU. When used in combination GSI and 5-FU, the clonogenicity in vitro and the tumourigenicity in vivo of INS CSC-like cells were significantly reduced. These findings suggested that the combined strategy of Notch signalling inhibition and 5-FU synergistically attenuated enriched INS CSC populations, providing a rationale for future therapeutic exploitation.

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María Andrea Camilletti, Alejandra Abeledo-Machado, Pablo A Perez, Erika Y Faraoni, Fernanda De Fino, Susana B Rulli, Jimena Ferraris, Daniel Pisera, Silvina Gutierrez, Peter Thomas, and Graciela Díaz-Torga

Membrane progesterone receptors are known to mediate rapid nongenomic progesterone effects in different cell types. Recent evidence revealed that mPRα is highly expressed in the rat pituitary, being primarily localized in lactotrophs, acting as an intermediary of P4-inhibitory actions on prolactin secretion. The role of mPRs in prolactinoma development remains unclear. We hypothesize that mPR agonists represent a novel tool for hyperprolactinemia treatment. To this end, pituitary expression of mPRs was studied in three animal models of prolactinoma. Expression of mPRs and nuclear receptor was significantly decreased in tumoral pituitaries compared to normal ones. However, the relative proportion of mPRα and mPRβ was highly increased in prolactinomas. Interestingly, the selective mPR agonist (Org OD 02-0) significantly inhibited PRL release in both normal and tumoral pituitary explants, displaying a more pronounced effect in tumoral tissues. As P4 also regulates PRL secretion indirectly, by acting on dopaminergic neurons, we studied mPR involvement in this effect. We found that the hypothalamus has a high expression of mPRs. Interestingly, both P4 and OrgOD 02-0 increased dopamine release in hypothalamus explants. Moreover, in an in vivo treatment, that allows both, pituitary and hypothalamus actions, the mPR agonist strongly reduced the hyperprolactinemia in transgenic females carrying prolactinoma. Finally, we also found and interesting gender difference: males express higher levels of pituitary mPRα/β, a sex that does not develop prolactinoma in these mice models. Taken together, these findings suggest mPRs activation could represent a novel tool for hyperprolactinemic patients, especially those that present resistance to dopaminergic drugs.