Cabergoline reduces cell viability in non functioning pituitary adenomas by inhibiting vascular endothelial growth factor secretion

Somatostatin and Somatostatin Receptors in Tumour Biology

Somatostatin (SST), a growth hormone inhibitory peptide, is expressed in endocrine and non-endocrine tissues, immune cells and the central nervous system (CNS). Post-release from secretory or immune cells, the first most appreciated role that SST exhibits is the antiproliferative effect in target tissue that served as a potential therapeutic intervention in various tumours of different origins. The SST-mediated in vivo and/or in vitro antiproliferative effect in the tumour is considered direct via activation of five different somatostatin receptor subtypes (SSTR1-5), which are well expressed in most tumours and often more than one receptor in a single cell. Second, the indirect effect is associated with the regulation of growth factors. SSTR subtypes are crucial in tumour diagnosis and prognosis. In this review, with the recent development of new SST analogues and receptor-specific agonists with emerging functional consequences of signaling pathways are promising therapeutic avenues in tumours of different origins that are discussed.

The dopaminergic control of Cushing's syndrome

Cushing's Syndrome (CS), or chronic endogenous hypercortisolism, is a rare and serious disease due to corticotroph pituitary (Cushing's disease, CD) and extra-pituitary (ectopic CS) tumours overproducing ACTH, or cortisol-secreting adrenal tumours or lesions (adrenal CS). The first-line treatment for CS is represented by the surgical removal of the responsible tumour, but surgery might be unfeasible or ineffective and medical treatment can be required in a relevant percentage of patients with CS, especially CD and ectopic CS. Corticotroph pituitary and extra-pituitary tumours, as well as adrenal tumours and lesions responsible for CS express dopamine receptors (DRs), which have been found to mediate inhibition of hormone secretion and/or cell proliferation in experimental setting, suggesting that dopaminergic system, particularly DRs, might represent a target for the treatment of CS. Dopamine agonists (DAs), particularly cabergoline (CAB), are currently used as off-label treatment for CD, the most common form of CS, demonstrating efficacy in controlling hormone secretion and tumour growth in a relevant number of cases, with the improvement of clinical picture, and displaying good safety profile. Therefore, CAB may be considered a reasonable alternative treatment for persistent or recurrent CD after pituitary surgery failure, but occasionally also before pituitary surgery, as adjuvant treatment, or even instead of pituitary surgery as first-line treatment in case of surgery contraindications or refusal. A certain beneficial effect of CAB has been also reported in ectopic CS. However, the role of DAs in the clinical management of the different types of CS requires further evaluations.

Current and Emerging Medical Therapies in Pituitary Tumors

Pituitary tumors (PT) represent in, the majority of cases, benign tumors for which surgical treatment still remains, except for prolactin-secreting PT, the first-line therapeutic option. Nonetheless, the role played by medical therapies for the management of such tumors, before or after surgery, has evolved considerably, due in part to the recent development of well-tolerated and highly efficient molecules. In this review, our aim was to present a state-of-the-art of the current medical therapies used in the field of PT and the benefits and caveats for each of them, and further specify their positioning in the therapeutic algorithm of each phenotype. Finally, we discuss the future of PT medical therapies, based on the most recent studies published in this field.

Quantitative Analysis of Somatostatin and Dopamine Receptors Gene Expression Levels in Non-functioning Pituitary Tumors and Association with Clinical and Molecular Aggressiveness Features

The primary treatment for non-functioning pituitary tumors (NFPTs) is surgery, but it is often unsuccessful. Previous studies have reported that NFPTs express receptors for somatostatin (SST_1-5) and dopamine (DRDs) providing a rationale for the use of dopamine agonists and somatostatin analogues. Here, we systematically assessed SST_1-5 and DRDs expression by real-time quantitative PCR (RT-qPCR) in a large group of patients with NFPTs (n = 113) and analyzed their potential association with clinical and molecular aggressiveness features. SST_1-5 expression was also evaluated by immunohistochemistry. SST₃ was the predominant SST subtype detected, followed by SST₂, SST₅, and SST₁. DRD2 was the dominant DRD subtype, followed by DRD4, DRD5, and DRD1. A substantial proportion of NFPTs displayed marked expression of SST₂ and SST₅. No major association between SST_s and DRDs expression and clinical and molecular aggressiveness features was observed in NFPTs.

Cabergoline in the Management of Residual Nonfunctioning Pituitary Adenoma: A Single-Center, Open-Label, 2-Year Randomized Clinical Trial

BACKGROUND

Complete tumor removal by transsphenoidal surgery is usually difficult for large nonfunctioning pituitary adenomas (NFPAs). A validated medical treatment may be useful for their management. This study evaluates the clinical efficacy of the dopaminergic agonist cabergoline for residual NFPA.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a randomized, parallel, open-label clinical trial that compared cabergoline with nonintervention in patients with residual NFPA after transsphenoidal surgery over 2 years. The primary outcome was clinical efficacy (tumor reduction). The secondary outcome was the relationship between tumor dopamine D2 receptor (D2R) expression and clinical responsiveness. Tumor measurements and clinical evaluations were performed every 6 months.

RESULTS

In total, 59 and 57 individuals were randomly assigned to the study and control groups, respectively. At the end of the study, residual tumor shrinkage, stabilization, and enlargement were observed in 28.8%, 66.1%, and 5.1% of patients, respectively, in the medical-therapy group and in 10.5%, 73.7%, and 15.8% of patients, respectively, in the control group (P=0.01). The progression-free survival rate was 23.2 and 20.8 months for the study and control groups, respectively (P=0.01). D2R was not associated with cabergoline responsiveness. No major side effects were related to cabergoline use.

CONCLUSIONS

Cabergoline was an effective drug for treating residual NFPA, and its use was associated with a high rate of tumor shrinkage (ClinicalTrials.gov NCT03271918).

Antibody array strategy for human growth factor secretome profiling of GH-secreting adenomas

PURPOSES

To test if the antibody array strategy could be utilized to simultaneously detect the secretion of multiple growth factors by human pituitary GH-adenomas and to measure octreotide-induced alterations.

METHODS

Specimens of human pituitary adenomas were cultured and incubated with or without octreotide for 24 h. Conditional media were analyzed by human growth factor antibody array and VEGF concentrations were measured by ELISA. Media were also analyzed for GH concentrations. p21 expression levels were examined by Western blot of the specimens lysates.

RESULTS

The antibody arrays successfully identified growth factors secreted by GH-adenomas in vitro. Octreotide treatment induced both elevations and reductions in growth factors secretion. GH response to octreotide was measured, and in this small-sized study resistant and sensitive GH-adenomas presented with no unique secretome pattern of each of the groups. Octreotide-induced VEGF alterations analyzed by the antibody array and by ELISA were not fully matched.

CONCLUSIONS

This study suggests that the broad proteomic strategy of antibody arrays may be utilized to study the growth factors secretion pattern of GH-adenomas and its regulation by somatostatin analogs or other compounds.

Cytoskeleton actin-binding proteins in clinical behavior of pituitary tumors

Although generally benign, pituitary tumors are frequently locally invasive, with reduced success of neurosurgery and unresponsive to pharmacological treatment with somatostatin or dopamine analogues. The molecular basis of the different biological behavior of pituitary tumors are still poorly identified, but a body of work now suggests that the activity of specific cytoskeleton proteins is a key factor regulating both the invasiveness and drug resistance of these tumors. This review recapitulates the experimental evidence supporting a role for the actin-binding protein filamin A (FLNA) in the regulation of somatostatin and dopamine receptors expression and signaling in pituitary tumors, thus in determining the responsiveness to currently used drugs, somatostatin analogues and dopamine receptor type 2 agonists. Regarding the regulation of invasive behavior of pituitary tumoral cells, we bring evidence to the role of the actin-severing protein cofilin, whose activation status may be modulated by dopaminergic and somatostatinergic drugs, through FLNA involvement. Molecular mechanisms involved in the regulation of FLNA expression and function in pituitary tumors will also be discussed.

Molecular Network Basis of Invasive Pituitary Adenoma: A Review

Cases with pituitary adenoma comprise 10-25% of intracranial neoplasm, being the third most common intracranial tumor, most of the adenomas are considered to be benign. About 35% of pituitary adenomas are invasive. This review summarized the known molecular basis of the invasiveness of pituitary adenomas. The study pointed out that hypoxia-inducible factor-1α, pituitary tumor transforming gene, vascular endothelial growth factor, fibroblast growth factor-2, and matrix metalloproteinases (MMPs, mainly MMP-2, and MMP-9) are core molecules responsible for the invasiveness of pituitary adenomas. The reason is that these molecules have the ability to directly or indirectly induce cell proliferation, epithelial-to-mesenchymal transition, angiogenesis, degradation, and remodeling of extracellular matrix. HIF-1α induced by hypoxia or apoplexy inside the adenoma might be the initiating factor of invasive transformation, followed with angiogenesis for overexpressed VEGF, EMT for overexpressed PTTG, degradation of ECM for overexpressed MMPs, creating a suitable microenvironment within the tumor. Together, they form a complex interactive network. More investigations are required to further elucidate the mechanisms underlying the invasiveness of pituitary adenomas.

Involvement of vascular endothelial growth factor (VEGF) and mitogen-activated protein kinases (MAPK) in the mechanism of neuroleptic drugs

BACKGROUND

Recent evidence suggests that the mitogen activated protein kinase (MAPK)-associated signaling pathway in the frontal cortical areas demonstrates abnormal activity in cases of schizophrenia. Moreover, schizophrenia patients often display alterations in the regional cellular energy metabolism and blood flow of the brain; these are shown to parallel changes in angiogenesis primarily mediated by vascular endothelial growth factor (VEGF).

METHODS

The present study examines the differential effects of time-dependent treatment with haloperidol, olanzapine and amisulpride (20μM) on VEGF and MAPK mRNA expression and VEGF level, using the T98 cell line as an example of nerve cells. For the purposes of comparison, the effect of neuroprotective pituitary adenylate cyclase-activating polypeptide (PACAP) on the expression of VEGF mRNA and secretion were also evaluated in this cell model.

RESULTS

RT-PCR analysis revealed that all the tested neuroleptics increased VEGF mRNA expression after 72-h incubation; however, only haloperidol and olanzapine also increased the level of VEGF detected by ELISA, and they demonstrated significantly stronger effects than PACAP. Haloperidol and olanzapine, but not amisulpride, decreased MAPK14 mRNA expression in T98G cells after 72-h incubation.

CONCLUSION

The obtained results suggest that haloperidol and olanzapine can trigger the MAPK and VEGF signaling pathway, which may contribute to their neuroprotective mechanism of action.

Pathogenesis of non-functioning pituitary adenomas

The pathogenesis of non functioning pituitary adenomas (NFPA) is a complex process involving several factors, from molecular to genetic and epigenetic modifications, where tumor suppressor genes, oncogenes, cell cycle derangements have been demonstrated to play an important role. MicroRNAs (miRNAs) have also been identified as possible players in NFPA tumorigenesis and pituitary stem cells have been investigated for their potential role in pituitary tumor initiation. However, a critical role for paracrine signalling has also been highlighted. This review focuses on the current knowledge on the involvement of these factors in NFPA pathogenesis.

Recent Progress in the Medical Therapy of Pituitary Tumors

Management of pituitary tumors is multidisciplinary, with medical therapy playing an increasingly important role. With the exception of prolactin-secreting tumors, surgery is still considered the first-line treatment for the majority of pituitary adenomas. However, medical/pharmacological therapy plays an important role in controlling hormone-producing pituitary adenomas, especially for patients with acromegaly and Cushing disease (CD). In the case of non-functioning pituitary adenomas (NFAs), pharmacological therapy plays a minor role, the main objective of which is to reduce tumor growth, but this role requires further studies. For pituitary carcinomas and atypical adenomas, medical therapy, including chemotherapy, acts as an adjuvant to surgery and radiation therapy, which is often required to control these aggressive tumors. In the last decade, knowledge about the pathophysiological mechanisms of various pituitary adenomas has increased, thus novel medical therapies that target specific pathways implicated in tumor synthesis and hormonal over secretion are now available. Advancement in patient selection and determination of prognostic factors has also helped to individualize therapy for patients with pituitary tumors. Improvements in biochemical and "tumor mass" disease control can positively affect patient quality of life, comorbidities and overall survival. In this review, the medical armamentarium for treating CD, acromegaly, prolactinomas, NFA, and carcinomas/aggressive atypical adenomas will be presented. Pharmacological therapies, including doses, mode of administration, efficacy, adverse effects, and use in special circumstances are provided. Medical therapies currently under clinical investigation are also briefly discussed.

Differential Expression of Stem Cell Markers in Human Adamantinomatous Craniopharyngioma and Pituitary Adenoma

BACKGROUND/AIMS

Although craniopharyngioma (CP) is histologically benign, it is a pituitary tumour that grows rapidly and often recurs. Adamantinomatous CP (ACP) was associated with an activating mutation in β-catenin, and it has been postulated that pituitary stem cells might play a role in oncogenesis in human ACP. Stem cells have also been identified in pituitary adenoma. Our aim was to characterize the expression pattern of ABCG2, CD44, DLL4, NANOG, NOTCH2, POU5F1/OCT4, SOX2, and SOX9 stem cell markers in human ACP and pituitary adenoma.

METHODS AND RESULTS

We studied 33 patients (9 ACP and 24 adenoma) using real-time quantitative PCR (RT-qPCR) and immunohistochemistry. SOX9 was up-regulated in ACP, exhibiting positive immunostaining in the epithelium and stroma, with the highest expression in patients with recurrence. CD44 was overexpressed in ACP as confirmed by immunohistochemistry. SOX2 did not significantly differ among the tumour types. The RT-qPCR array showed an increased expression of MKI67,OCT4/POU5F1, and DLL4 in all tumours. NANOG was decreased in ACP. ABCG2 was down-regulated in most of the tumours. NOTCH2 was significantly decreased in the adenomas.

CONCLUSION

Our results confirm the presence of stem cell markers in human pituitary tumours as well as the different expression patterns of ACP and adenoma. These findings suggest that ACP may originate from a more undifferentiated cell cluster. Additionally, SOX9 immunodetection in the stroma and the highest expression levels related to the relapse of patients suggest a contribution to the aggressive behaviour and high recurrence of this tumour type.

Suction Filter in Endoscopic Endonasal Surgery: A Technical Note

BACKGROUND

The collection of the greatest possible amount of pathologic tissue is of paramount importance in neurosurgery to achieve the most accurate histopathologic diagnosis, to perform all of the necessary biomolecular tests on the pathologic specimen, and to collect biological material for basic or translational science studies. This problem is particularly relevant in pituitary surgery because of the possible small size and soft consistency of tumors, which make them suitable for removal through suction, reducing the amount of available pathologic tissue. To solve this issue, we adopted a filter connected to the suction tube, which allows the surgeon to collect all of the tissue aspirated during surgery.

METHODS

Our experience of 1734 endoscopic endonasal procedures, performed adopting this device since 1998 to December 2015, has been revised to assess its advantages and limitations.

RESULTS

This system is easy-to-use, does not impair the surgical maneuvers, and does not add any relevant cost to the surgery. The tissue collected through the filter proved useful for diagnostic histologic and biomolecular analyses and for research purposes, without any relevant artifacts as a result of this method of collection.

CONCLUSIONS

The use of a filter has allowed us to obtain the greatest amount possible of pathologic tissue at each surgery. This surgical material has revealed to be helpful both for diagnostic and basic science purposes. The use of the filter has proven to be of particular importance for microadenomas, soft tumors, and supradiaphragmatic or skull base lesions with heterogeneous features, improving the accuracy of histopathologic diagnosis.

Nonfunctioning giant pituitary adenomas: Invasiveness and recurrence

BACKGROUND

We report our surgical series of 35 patients with giant nonfunctioning pituitary adenomas (GNFPA). We analyzed the rule of Ki-67 antigen expression in predicting recurrence.

METHODS

Thirty-five patients were operated between 2000 and 2010. Suprassellar extension of the tumors were classified according to Hardy and Mohr based on magnetic resonance (MR) studies. Pituitary endocrine function and MR scans were assessed preoperatively and at 1, 6, and 12 months postoperatively. Immunohistochemical studies were based in regard to the expression of the proliferative Ki-67 index and the hormonal receptor for luteinizing hormone, follicle stimulating hormone, growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, and prolactin. Tumors specimens were obtained from 35 patients with GNFPA. Endoscopic transsphenoidal surgery was the approach of choice.

RESULTS

Thirty-five patients were submitted to 49 surgeries, 44 (89.8%) were transsphenoidal and 5 (10.2%) were transcranial. The most frequent preoperative complaints were visual acuity impairment and visual field defect in 25 (71.2%) and 23 (65.7%) cases, respectively. Improvement of visual acuitiy and visual field deficit after surgery was seen in 20 (80%) and 17 (73.9%) patients, respectively. Endocrinological deficits were encountered in 20 patients (57.1%). After surgery, 18 patients (51.4%) required hormonal replacement. Three patients had visual symptoms related to pituitary apoplexy and recovered after surgery. The Ki-67 labeling index (LI) ranged from <1% to 4.8%. The rate of recurrence in tumors with Ki-67 <3% was 7.7% (2 patients), Ki-67 >3% was present in 5 patients and the recurrence committed 3 patients.

CONCLUSION

In our series, regardless the improvement of visual function and compressing symptoms, 5 patients with expression of Ki-67 LI more than 3% experienced a recurrence.

The expression of the truncated isoform of somatostatin receptor subtype 5 associates with aggressiveness in medullary thyroid carcinoma cells

The truncated somatostatin receptor variant sst5TMD4 associates with increased invasiveness and aggressiveness in breast cancer. We previously found that sst5 activation may counteract sst2 selective agonist effects in a medullary thyroid carcinoma (MTC) cell line, the TT cells, and that sst5TMD4 is overexpressed in poorly differentiated thyroid cancers. The purpose of this study is to evaluate sst5TMD4 expression in a series of human MTC and to explore the functional role of sst5TMD4 in TT cells. We evaluated sst5TMD4 and sst5 expression in 36 MTC samples. Moreover, we investigated the role of sst5TMD4 in TT cells evaluating cell number, DNA synthesis, free cytosolic calcium concentration ([Ca(2+)]i), calcitonin and vascular endothelial growth factor levels, cell morphology, protein expression, and invasion. We found that in MTC the balance between sst5TMD4 and sst5 expression influences disease stage. sst5TMD4 overexpression in TT cells confers a greater growth capacity, blocks sst2 agonist-induced antiproliferative effects, modifies the cell phenotype, decreases E-cadherin and phosphorylated β-catenin levels, increases vimentin, total β-catenin and phosphorylated GSK3B levels (in keeping with the development of epithelial to mesenchymal transition), and confers a greater invasion capacity. This is the first evidence indicating that sst5TMD4 is expressed in human MTC cells, where it associates with more aggressive behavior, suggesting that sst5TMD4 might play a functionally relevant role.

Alterations in plasma vascular endothelial growth factor levels in patients with schizophrenia before and after treatment

Vascular endothelial growth factor (VEGF), a potent angiogenetic factor, is a known neurotrophic factor. In this study, we examined plasma levels of VEGF in 50 patients with schizophrenia (SPR) and 50 healthy control subjects. We also explored any changes in plasma VEGF levels after 6-week treatment with antipsychotic agents in patients with schizophrenia. All subjects with schizophrenia were either medication-naïve or medication-free for at least 4 weeks before assessment. Plasma VEGF levels in all subjects were significantly correlated with smoking duration, which was considered to be a significant covariate. Pre-treatment plasma VEGF levels in patients with schizophrenia were significantly lower than those in healthy controls. Post-treatment VEGF levels were significantly increased in patients with schizophrenia. Plasma VEGF levels in patients with schizophrenia did not exhibit significant correlation with the total or subscale scores of the Positive and Negative Syndrome Scale (PANSS) either at baseline or at the end of the 6-week treatment. In conclusion, our findings reveal that plasma VEGF levels before treatment were lower in patients with schizophrenia and that their VEGF levels increased after treatment. Thus, VEGF may have a neuroprotective role in the improvement of schizophrenia or in the treatment effects of antipsychotics.

Dopamine receptor subtype 2 expression profile in nonfunctioning pituitary adenomas and in vivo response to cabergoline therapy

OBJECTIVES

To determine the dopamine receptor subtype 2 (DR2) mRNA levels and protein expression and to evaluate the effect of adjuvant cabergoline therapy on tumour volume (TV) in patients with postoperative residual nonfunctioning pituitary adenoma (NFPA).

METHODS

The mRNA expression was quantified by real-time RT-PCR (TaqMan(®)), and protein expression was evaluated by immunohistochemistry. Tumours were classified according to the percentage of immunostained cells for DR2 as scores 1 (<50% of stained cells) or 2 (≥50%). Cabergoline was started at least 6 months after surgery in nine patients with residual tumours (3 mg/week). The cabergoline effect was prospectively evaluated by magnetic resonance imaging using three-dimensional volume calculation. TV reduction >25% was considered significant.

RESULTS

The DR2 mRNA expression was variable but was observed in 100% of the samples (N = 20). DR2 protein expression was also observed in all the tumours (N = 34). Twenty-nine tumours (85%) were classified as score 2. The median DR2 mRNA expression was higher in the tumours classified as score 2 compared with score 1 (P = 0·007). TV reduction with cabergoline therapy was observed in 67% of the patients (6/9). The median TV before and after 6 months of treatment was 1·90 cm(3) (0·61-8·74) and 1·69 cm(3) (0·36-4·20) [P = 0·02], respectively.

CONCLUSION

In conclusion, DR2 is expressed in all adenomas and the majority of the patients in this study displayed tumour shrinkage on cabergoline (CAB) therapy. Thus, CAB might be useful in adjuvant therapy in NFPA patients with residual tumours after surgery.

Pituitary side effects of old and new drugs

INTRODUCTION

Pituitary function is influenced by several drugs, including anti-depressant, opioids, glucocorticoids, chemotherapeutic agents, immunomodulators and the newly developed tyrosine kinase inhibitors. In most instances, treatment with these drugs negatively affects pituitary function, but in rare cases an activation of specific hypothalamic-pituitary axes may be observed. Several of the observed pituitary side effects are reversible after drug withdrawal, but pituitary function deficiency may persist long-term. In addition to the well known drugs, recent evidence shows that also non-steroidal anti-inflammatory drugs impair gonadal axis at pituitary level, while antipsychotic phenothiazines alter TSH response to TRH and TSH levels. Atypical antipsychotics may decrease TRH-stimulated TSH. Tricyclic antidepressant drugs interfere with the hypothalamo-pituitary-thyroid axis by decreasing TSH response to TRH. Anabolic-androgenic steroids, marijuana, cocaine, methamphetamines, and opioid narcotics negatively impact fertility, also acting at hypothalamic-pituitary level.

CONCLUSIONS

Many of the drugs administered routinely in the intensive care unit significantly impact the hypothalamic-pituitary axis. Therefore, an increased awareness on pituitary side effects of drugs commonly used in clinical practice is necessary in order to rule out possible pharmacological interference when assessing patients with pituitary deficiencies.

The expression profile of Dopamine D2 receptor, MGMT and VEGF in different histological subtypes of pituitary adenomas: a study of 197 cases and indications for the medical therapy

BACKGROUND

To study the expression of D2R, MGMT and VEGF for clinical significance in pituitary adenomas, and to predict the potential curative medical therapy of dopamine agonists, temozolomide and bevacizumab on pituitary adenomas.

METHODS

Immunohistochemistry and western blot were performed to detect the expression of expression of D2R, MGMT and VEGF in pituitary adenoma tissue samples. The ratio of high expression of D2R, MGMT or VEGF in different subtypes of PA was compared by the use of chi-squared tests. The relationships between D2R, MGMT and VEGF expression were assessed by the Spearman rank correlation test. The association between their expression and clinical parameters was analyzed using a chi-squared test, or Fisher's exact probability test when appropriate.

RESULTS

The data showed that in 197 different histological subtypes of pituitary adenomas (PAs), 64.9% of them were D2R high expression, 86.3% were MGMT low expression and 58.9% were VEGF high expression. D2R high expression existed more frequently in PRL- and GH- secreting PAs. MGMT low expression existed in all PA subtypes. VEGF high expression existed more frequently in PRL, ACTH, FSH secreting and non-functioning PAs. The data of western blot also support the results. Spearman's rank correlation analysis showed that expression of MGMT was positively associated with D2R (r = 0.154, P = 0.031) and VEGF (r = 0.161, P = 0.024) in PAs, but no correlation was showed between D2R and VEGF expression (r = -0.025, P = 0.725 > 0.05). The association between their expression and clinical parameters was analyzed using a chi-squared test, or Fisher's exact probability test when appropriate, but the result showed no significant association.

CONCLUSIONS

PRL-and GH-secreting PAs exist high expression of D2R, responding to dopamine agonists; Most PAs exist low expression of MGMT and high expression of VEGF, TMZ or bevacizumab treatment could be applied under the premise of indications.

Aggressive pituitary adenomas--diagnosis and emerging treatments

The WHO categorizes pituitary tumours as typical adenomas, atypical adenomas and pituitary carcinomas, with typical adenomas constituting the major class. However, the WHO classification does not provide an accurate correlation between histopathological findings and clinical behaviour. Tumours lacking typical histological features are classified as atypical, but not all are clinically atypical or exhibit aggressive behaviour. Pituitary carcinomas, by definition, have craniospinal or systemic metastases, although not all display classical cytological features of malignancy. Aggressive pituitary adenomas, defined from a clinical perspective, have earlier and more frequent recurrences and can be resistant to conventional treatments. Specific biomarkers have not yet been identified that can distinguish between clinically aggressive and nonaggressive pituitary adenomas, although the antigen Ki-67 proliferation index might be of value. This Review highlights the need to develop new biomarkers to facilitate the early detection of clinically aggressive pituitary adenomas and discusses emerging markers that hold promise for their identification. Defining aggressiveness is of crucial importance for improving the management of patients by enhancing prognostic predictions and effectiveness of treatment. New drugs, such as temozolomide, have potential use in the management of these patients; anti-VEGF therapy, mTOR and tyrosine kinase inhibitors are also potentially useful in managing selected patients.

Correlations of pituitary tumor transforming gene expression with human pituitary adenomas: a meta-analysis

OBJECTIVE

Pituitary tumor transforming gene (PTTG) is an important paracrine growth factor involved in early lactotrope transformation and early onset of angiogenesis in pituitary hyperplasia. Emerging evidences have shown that PTTG expression may contribute to the etiology of pituitary adenomas; but individually published studies showed inconclusive results. This meta-analysis aimed to derive a more precise estimation of the correlations of PTTG expression with human pituitary adenomas.

METHODS

A range of electronic databases were searched: MEDLINE (1966∼2013), the Cochrane Library Database (Issue 12, 2013), EMBASE (1980∼2013), CINAHL (1982∼2013), Web of Science (1945∼2013) and the Chinese Biomedical Database (CBM) (1982∼2013) without language restrictions. Meta-analysis was performed using the STATA 12.0 software. Crude odds ratio (OR) or standard mean difference (SMD) with its corresponding 95% confidence interval (95%CI) were calculated.

RESULTS

Twenty-four clinical cohort studies were included with a total of 1,464 pituitary adenomas patients. The meta-analysis results revealed that patients with invasive pituitary adenomas had higher positive expression of PTTG than those of non-invasive patients (OR  = 6.68, 95%CI  = 3.72-11.99, P<0.001). We also found a significant difference in microvessel density between invasive and non-invasive patients (SMD  = 1.81, 95%CI  = 0.39-3.23, P = 0.013). However, there were no significant difference in PTTG expression between functional and non-functional patients with pituitary adenomas (OR  = 1.11, 95%CI  = 0.58-2.10, P = 0.753). No publication bias was detected in this meta-analysis (all P>0.05).

CONCLUSION

This present meta-analysis suggests that PTTG expression may be associated with tumor invasiveness and microvessel density of pituitary adenomas, while no correlations with functional status was found.

Inhibitory effects of mitotane on viability and secretory activity in mouse gonadotroph cell lines

Mitotane represents the mainstay medical treatment for metastatic, inoperable or recurrent adrenocortical carcinoma. Besides the well-known adverse events, mitotane therapy is associated also with endocrinological effects, including sexual and reproductive dysfunction. The majority of male patients undergoing adjuvant mitotane therapy show a picture of hypogonadism, characterized by low free testosterone and high sex hormone binding globulin levels and unmodified LH concentrations. Since mitotane has been shown to have direct pituitary effects, we investigated whether mitotane may influence both cell viability and function of gonadotroph cells in the settings of two pituitary cell lines. We found that mitotane reduces cell viability, induces apoptosis, modifies cell cycle phase distribution and secretion of gonadotroph cells. The present data strengthen previous evidence showing a direct mitotane effect at pituitary level and represent a possible explanation of the lack of LH increase following decrease in free testosterone in patients undergoing adjuvant mitotane therapy.