The cytogenesis and pathogenesis of pituitary adenomas

Total Barley Maiya Alkaloids Prevent Increased Prolactin Levels Caused by Antipsychotic Drugs and Reduce Dopamine Receptor D2 via Epigenetic Mechanisms

Background: The dopamine D2 receptor (DRD2) plays an important role in the increased prolactin (PRL) levels associated with the pathogenesis of antipsychotic drugs (ADs). Elevated prolactin levels can affect people’s quality of life. Maiya alkaloids has been used to treat diseases associated with high PRL levels. Maiya, is a processed product of the mature fruits of Hordeum vulgare L. (a gramineous plant) after sprouting and drying and also a common Chinese herbal drug used in the clinic, is traditionally used to treat abnormal lactation, and is currently used clinically for the treatment of abnormal PRL levels.

Aims: Epigenetic mechanisms can be related to DRD2 expression. We investigated the role of DRD2 methylation in the induction of PRL expression by ADs and the mechanism underlying the effects of total barley maiya alkaloids (TBMA) on this induction.

Methods: The methylation rate of DRD2 in 46 people with schizophrenia who took risperidone was detected by MassARRAY sequencing. Humans were long term users of Ris. Seventy Sprague Dawley female rats were divided into seven groups. A rat model of risperidone-induced PRL was established, and the potential protective effects of TBMA and its components [e.g., hordenine (Hor)] on these increased PRL levels were investigated. The PRL concentration was detected by Enzyme-linked immunosorbent assay. PRL, DRD2, and DNA methyltransferase (DNMT1, DNMT3α, and DNMT3β) protein and mRNA expression were detected by western blotting and real-time polymerase chain reaction (RT-PCR), respectively. The positive rate of methylation in the DRD2 promoter region of rats was detected by MassARRAY sequencing.

Results: Clinical studies showed that the positive rate of DRD2 methylation associated with increased PRL levels induced by ADs was significantly higher than in the normal prolactinemia (NPRL) group. In vivo and vitro, TBMA and Hor inhibited this induction of PRL expression and increased DRD2 expression by inhibiting the expression of the DNMTs.

Conclusions: TBMA and hordenine increased DRD2 expression by inhibiting DNMT-dependent DRD2 methylation.

Aggressive nonfunctioning pituitary neuroendocrine tumors

Nonfunctioning pituitary neuroendocrine tumors (NF-PitNETs) are tumors that are not associated with clinical evidence of hormonal hypersecretion. According to the World Health Organization (WHO), there are some subtypes of PitNETs that exhibit more aggressive behavior than others. Among the types of potentially aggressive PitNETs, three are nonfunctional: silent sparsely granulated somatotropinomas, silent corticotropinomas, and poorly differentiated PIT-1 lineage tumors. Several biological markers have been investigated in NF-PitNETs. However, there is no single biomarker able to independently predict aggressive behavior in NF-PitNETs. Thus, a more complex and multidisciplinary proposal of a comprehensive definition of aggressive NF-PitNETs is necessary. Here, we suggest a combined and more complete criterion for the NF-PitNETs classification. We propose that aggressiveness is due to a multifactorial combination, and we emphasize the need to include new emerging markers that are involved in the aggressiveness of NF-PitNETs and the need to identify.

Classification of neuroendocrine neoplasms: lights and shadows

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplastic proliferations showing different morphological features, immunophenotype, molecular background, clinical presentation, and outcome. They can virtually originate in every organ of the human body and their classification is not uniform among different sites. Indeed, as they have historically been classified according to the organ in which they primarily arise, the different nomenclature that has resulted have created some confusion among pathologists and clinicians. Although a uniform terminology to classify neuroendocrine neoplasms arising in different systems has recently been proposed by WHO/IARC, some issues remain unsolved or need to be clarified. In this review, we discuss the lights and shadows of the current WHO classifications used to define and characterize NENs of the pituitary gland, lung, breast and those of the head and neck region, and digestive and urogenital systems.

Pre- and postoperative 68 Ga-DOTATOC positron emission tomography for hormone-secreting pituitary neuroendocrine tumours

OBJECTIVES

Somatostatin receptors (SSTRs) are potential targets for detecting pituitary neuroendocrine tumours (PitNETs) that can be visualized effectively with ⁶⁸ Ga-labelled PET tracers. With this study, we have evaluated the diagnostic properties of such a tracer, ⁶⁸ Ga-DOTATOC, in patients with hormone-producing PitNETs before and after surgery.

DESIGN/METHODS

This prospective case-control study presents preoperative positron emission tomography (PET) and histopathological data in 18 patients with somatotroph (n = 8), corticotroph (n = 7) and thyrotroph (n = 3) PitNETs. Patients were scanned pre- and postoperatively with ⁶⁸ Ga-DOTATOC PET. For the postoperative part of the study, patients with gonadotroph tumours (n = 7) were also included. Fifteen pituitary healthy controls underwent the same protocol once. The maximum standard uptake value (SUV_max ) was analysed in manually outlined regions around the tumour in patients and around the pituitary gland in controls. specimens were collected during surgery in subjects for assessment of adenohypophyseal tumour cell type and the SSTR expression.

RESULTS

Thyrotroph tumours showed higher uptake (median SUV_max 41.1; IQR 37.4-60.0) and corticotroph tumours lower uptake (SUV_max 6.8; 2.6-9.3) than normal pituitary gland (SUV_max 13.8; 12.1-15.5). The uptake in somatotroph tumours (SUV_max 15.9; 11.6-19.7) was similar to the uptake in the pituitary gland. There was a strong correlation between SUV_max and SSTR2 expression (r = .75 (P < .01)). In the postoperative evaluation, PET was able to correlate tracer uptake with biochemical cure and noncure in patients with an abnormal postoperative magnetic resonance image and a preoperative tumour uptake SUV_max  > 13.8.

CONCLUSIONS

⁶⁸ Ga-DOTATOC PET can be used to detect thyrotroph tumours in the pre- and postoperative imaging assessment. Corticotroph tumours had a significantly lower uptake compared to the pituitary gland but without a distinct increased tumour uptake the clinical postoperative value is limited.

Challenges in the Diagnosis of Pituitary Neuroendocrine Tumors

Detailed analysis of cytodifferentiation and hormone production has classified pituitary neuroendocrine tumors (PitNETs) in a formal system that reflects the lineage differentiation of nontumorous adenohypophysial cells as well as subtypes of tumors that have predictive value. In addition, tumors composed of cells that lack terminal differentiation are well characterized. To comply with the proposal to create an overarching classification of neuroendocrine neoplasia, these tumors are now called PitNETs rather than adenomas. The next important step will be to relinquish the term "pituitary carcinoma" for metastatic PitNETs that remain well differentiated, and to alter the terminology used for tumors that are not terminally differentiated to reflect only their immature lineage. The existence of mixed neuroendocrine and non-neuroendocrine neoplasms (MiNENs) similar to those at other body sites is proven by mixed craniopharyngiomas with PitNETs. As with other NETs, these neoplasms should be reported with synoptic data that guide completeness of reporting. A formal system of grading should be created, but not only based on proliferation, as these tumors have shown the prognostic value of cytodifferentiation. A formal system of staging should also be devised to complement grade in the thorough and accurate diagnosis of tumors that arise from adenohypophysial cells.

The electrophysiological tests in the early detection of the visual pathway dysfunction in patients with microadenoma

PURPOSE

To evaluate the validity of electrophysiological tests in the early diagnosis of a ganglion cells and/or optic nerve dysfunction in patients with pituitary microadenoma.

METHODS

66 eyes, from 33 patients with microadenoma with no evidence of the optic chiasm compression in magnetic resonance imaging (MRI) and the visual impairment in the routine ophthalmological examination, standard static perimetry (24-2 white on white) and optical coherence tomography (HD-OCT), were analysed. The pattern electroretinogram (PERG), standard pattern visual evoked potentials (PVEPs) and multichannel visual evoked potentials (mVEPs) (ISCEV standards) were performed. The results obtained from the electrophysiological tests were compared to the same number of age-matched healthy controls.

RESULTS

Statistically significant differences between the patients with microadenoma and healthy controls were detected in all electrophysiological tests (p < 0.001). The most frequent abnormalities were observed in mVEPs (25/33 patients, 75.8%; 43/66 eyes, 65.2%). The most frequent features registered in this test were: (1°4')-an increase in the P100wave latency from uncrossed fibres (13/33 patients, 39.39%; 21/66 eyes, 31.8%) and (0°16')-an amplitude reduction of this wave from the crossed fibres (11/33 patients, 33.33%; 19/66 eyes, 28.8%). The changes in PVEPs (15/33 patients, 45.5%; 25/66 eyes, 37.9%) and PERG (10/33 patients, 30.3%; 15/66 eyes, 22.7%) were also registered. Of all the tests and parameters analysed in the study, the greatest diagnostic value in detecting the visual pathway dysfunction in this group of patients was the amplitude of P100 wave from the crossed fibres of the mVEPs (1°4') with a sensitivity of 60.6% and a specificity of 93.8%. These parameters suggest that this type of dysfunction is downstream to the chiasm and can also indicate the visual pathway dysfunction severity.

CONCLUSIONS

In patients with microadenoma, the abnormalities in the electrophysiological tests are registered even without clinical evidence of visual impairment from the routine ophthalmological examination, SAP, OCT and chiasmal compression in MRI. The mVEPs have the most significant role in the diagnosis of the visual pathway dysfunction in patients with microadenoma.

Identifying critical protein-coding genes and long non-coding RNAs in non-functioning pituitary adenoma recurrence

Non-functioning pituitary adenoma (NFPA) is a very common type of intracranial tumor. Monitoring and predicting the postoperative recurrence of NFPAs is difficult, as these adenomas do not present with serum hormone hypersecretion. Long non-coding RNAs (lncRNAs) and protein-coding genes (PCGs) play critical roles in the development and progression of numerous tumors. However, the complex network of RNA interactions related to the mechanisms underlying the postoperative recurrence of NFPA is still unclear. In the present study, 73 patients with NFPA were investigated using high-throughput sequencing and follow-up investigations. In total, 6 of these patients with recurrence within 1 year after surgery were selected as the fast recurrence group, and 6 patients with recurrence 5 years after surgery were selected as the slow recurrence group. By performing differential expression analysis of the fast recurrence and slow recurrence groups, a set of differentially expressed PCGs and lncRNAs were obtained (t-test, P<0.05). Next, protein-protein interaction coregulatory networks and lncRNA-mRNA coexpression networks were identified. In addition, the hub lncRNA-mRNA modules related to NFPA recurrence were further screened and transcriptome expression markers for NFPA regression were identified (log-rank test, P<0.05). Finally, the ability of the hub and module genes to predict recurrence and progression-free survival in patients with NFPA was evaluated. To confirm the credibility of the bioinformatic analyses, nucleolar protein 6 and LL21NC02-21A1.1 were randomly selected from among the genes with prognostic significance for validation by reverse transcription-quantitative PCR in another set of NFPA samples (n=9). These results may be helpful for evaluating the slow and rapid recurrence of NFPA after surgery and exploring the mechanisms underlying NFPA recurrence. Future effective biomarkers and therapeutic targets may also be revealed.

Pituitary incidentalomas in paediatric population: Incidence and characteristics

OBJECTIVE

To determine the incidence of pituitary incidentalomas in the paediatric population and among its different age subgroups as well as to identify the characteristics of these lesions. Additionally, we aim to give a perspective on the management and follow-up of these patients.

DESIGN AND PATIENTS

We retrospectively studied MRI of children aged 18 years or below who underwent MRI with sellar region within their field of view between January 2010 and December 2018.

MEASUREMENTS

Pituitary lesions were considered incidental according to the definition by the Endocrine Society. We reported the size, location and signal characteristics of each lesion. Medical charts of the subjects were reviewed for age, sex, the MRI indication and the hormonal assays levels.

RESULTS

We identified 40 pituitary lesions of which 31 were incidental lesions. The incidence of pituitary incidentaloma in our cohort was 22 per 1000 patients with female predisposition ( 64.5%) and a mean age of 11 ± 6 years. Rathke's cleft cyst was the most prevalent lesion, accounting for 67.7% followed by cystic pituitary lesions and microadenomas. The most common indications for imaging were growth disturbance (12.9%) followed by headache (9.7%). Abnormal laboratory workup was present in 13% of the subjects. Incidental lesions were more common in the older age groups compared to young children.

CONCLUSION

Incidental pituitary lesions in the paediatric population are relatively infrequent and increases with age. Rathke's cleft cyst is the most common incidentally encountered pituitary lesion followed by cystic pituitary lesions and microadenomas.

Lower 68 Ga-DOTATOC uptake in nonfunctioning pituitary neuroendocrine tumours compared to normal pituitary gland-A proof-of-concept study

OBJECTIVES

⁶⁸  Ga-DOTATOC PET targets somatostatin receptors (SSTRs) and is well established for the detection of SSTR-expressing tumors, such as gastrointestinal neuroendocrine tumors. Pituitary adenomas, recently designated as pituitary neuroendocrine tumors (PitNETs), also express SSTRs, but there has been no previous evaluations of ⁶⁸  Ga-DOTATOC PET in PitNET patients. The aim of this pilot study was to evaluate the diagnostic properties of ⁶⁸  Ga-DOTATOC PET in the most common PitNET, ie non-functioning (NF)-PitNET.

DESIGN/PATIENTS

NF-PitNET patients (n = 9) and controls (n = 13) were examined preoperatively with ⁶⁸  Ga-DOTATOC PET for 45 min after tracer injection in dynamic list mode. Tumor specimens were collected during surgery in patients. MRI and PET images were co-registered using PMOD software. The maximum standard uptake value (SUV_max ) was analyzed in manually outlined regions of interest (ROI) around the tumor in patients and around the pituitary gland in controls. Immunohistochemical analyses were conducted on tumor specimens for assessment of tumor cell type and SSTR expression.

RESULTS

Median SUV_max (IQR) was lower in patients than in controls (3.9 [3.4-8.5] vs 14.1 [12.5-15.9]; P < .01]. In ROC analysis, the area under the curve was 0.87 (P < .01) for SUV_max , with 78% sensitivity and 92% specificity. Immunohistochemical analysis showed NF-PitNETs were of gonadotroph (n = 7) and corticotroph (n = 2) origin. SSTR expression was high for SSTR3, low-to-moderate for SSTR2, and low for SSTR1 and SSTR5.

CONCLUSIONS

This proof-of-concept study shows that ⁶⁸ Ga-DOTATOC PET can be used to differentiate between normal pituitary tissue and NF-PitNET.

Identification of CDK6 and RHOU in Serum Exosome as Biomarkers for the Invasiveness of Non-functioning Pituitary Adenoma

Objective To explore circulating biomarkers for screening the invasiveness of non-functioning pituitary adenomas (NF-PAs). Methods The exosomal RNAs were extracted from serum of patients with invasive NF-PA (INF-PA) or noninvasive NF-PA (NNF-PA). Droplet digital PCR was adapted to detect the mRNA expression of candidate genes related to tumor progression or invasion, such as cyclin dependent kinase 6 (CDK6), ras homolog family member U (RHOU), and spire type actin nucleation factor 2 (SPIRE2). Student's t-test was used to analyze the statistical difference in the mRNA expression of candidate genes between the two groups. Receiver operating characteristic (ROC) curve was used to establish a model for predicting the invasiveness of NF-PAs. The accuracy, sensitivity, specificity and precision of the model were then obtained to evaluate the diagnostic performance. Results CDK6 (0.2600±0.0912 vs. 0.1789±0.0628, t=3.431, P=0.0013) and RHOU mRNA expressions (0.2696±0.1118 vs. 0.1788±0.0857, t=2.946, P=0.0052) were upregulated in INF-PAs patients' serum exosomes as compared to NNF-PAs. For CDK6, the area under the ROC curve (AUC) was 0.772 (95% CI: 0.600-0.943, P=0.005), the accuracy, sensitivity, specificity and precision were 77.27%, 83.33%, 75.00% and 55.56% to predict the invasiveness of NF-PAs. For RHOU, the AUC was 0.757 (95% CI: 0.599-0.915, P=0.007), the accuracy, sensitivity, specificity and precision were 72.73%, 83.33%, 68.75% and 50.00%. In addition, the mRNA levels of CDK6 and RHOU in serum exosomes were significantly positively correlated (r=0.935, P<0.001). After combination of the cut-off scores of the two genes, the accuracy, sensitivity, specificity and precision were 81.82%, 83.33%, 81.25% and 62.50%. Conclusions CDK6 and RHOU mRNA in serum exosomes can be used as markers for predicting invasiveness of NF-PAs. Combination of the two genes performs better in distinguishing INF-PAs from NNF-PAs. These results indicate CDK6 and RHOU play important roles in the invasiveness of NF-PAs, and the established diagnostic method is valuable for directing the clinical screening and postoperative treatment.

Difference in the incidence of cerebrospinal fluid leakage and residual tumors between functional and nonfunctional pituitary adenomas treated by endoscopic transsphenoidal pituitary adenomectomy

Objective

This study compared the incidence of cerebrospinal fluid (CSF) leakage and residual tumors between functional and nonfunctional pituitary adenomas treated with the endoscopic endonasal transsphenoidal approach (EETA).

Methods

All patients underwent endocrine examinations and brain magnetic resonance imaging before and after surgery. The length of admission, incidence of central diabetes insipidus, incidence of CSF leakage, symptom relief, and presence of residual tumors were compared between patients with functional and nonfunctional pituitary adenomas.

Results

Thirty-eight patients were enrolled, among whom 12 and 26 had functional and nonfunctional pituitary adenomas, respectively. The incidence of CSF leakage was significantly higher in patients with nonfunctional adenomas; a hard or elastic tumor character accounted for the difference. A large tumor size and cavernous sinus invasion were risk factors for residual tumors. No significant differences were found in sex, length of admission, operative times, incidence of diabetes insipidus, or number of residual tumors between the two groups. The hormone levels were lower postoperatively than preoperatively in patients with nonfunctional adenomas.

Conclusion

Nonfunctional pituitary macroadenomas resulted in more CSF leakage. Use of the rescue nasoseptal flap reduced unnecessary nasal destruction. Cooperation between a neurosurgeon and otolaryngologist was safer and more effective when using the EETA.

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.

Diagnosis of Invasive Nonfunctional Pituitary Adenomas by Serum Extracellular Vesicles

The invasiveness evaluation of nonfunctional pituitary adenoma (NFPAs) is crucial for the prediction of the malignant potential and for making surgical plans of NFPAs. Current invasiveness evaluation of NFPAs is based on neuroimaging, which can hardly predict the invasive potential and dynamically monitor disease progress. Here we used microbead-assisted flow cytometry to detect and analyze the serum extracellular vesicles (EVs) from 30 NFPAs patients (15 invasive and 15 noninvasive). Lower expressions of folate receptor 1 (FOLR1) and epithelial cell adhesion molecule (EpCAM) were found in serum EVs from the invasive NFPAs patients compared to the noninvasive ones [area under the curve (AUC) of 0.94 for FOLR1 and 0.88 for EpCAM]. Meanwhile, increased mRNA expression of vimentin and N-cadherin, two mesenchymal markers, was found in serum EVs from the invasive NFPAs patients compared to the noninvasive ones. Consistent results were observed in the tumor tissue that invasive NFPAs have lower expression of the epithelial markers while higher expression of the mesenchymal markers. These results suggested the possible role of epithelial-mesenchymal transition (EMT) in the invasiveness of NFPAs. Pituitary tumor transforming gene 1 (PTTG1) mRNA in serum EVs was also found to be an indicator for invasive NFPAs and is related with EMT. These results provide a method for the blood-based diagnosis and invasiveness evaluation of NFPAs and would be beneficial to the diagnosis, prognosis prediction, and surgical risk evaluation of NFPAs.

MicroRNA-186 targets SKP2 to induce p27Kip1-mediated pituitary tumor cell cycle deregulation and modulate cell proliferation

Pituitary tumors are usually benign but can occasionally exhibit hormonal and proliferative behaviors. Dysregulation of the G1/S restriction point largely contributes to the over-proliferation of pituitary tumor cells. F-box protein S-phase kinase-interacting protein-2 (SKP2) reportedly targets and inhibits the expression of p27^Kip1, a well-known negative regulator of G1 cell cycle progression. In this study, SKP2 expression was found to be upregulated while p27^Kip1 expression was determined to be downregulated in rat and human pituitary tumor cells. Furthermore, SKP2 knockdown induced upregulation of p27^Kip1 and cell growth inhibition in rat and human pituitary tumor cells, while SKP2overexpression elicited opposite effects on p27^Kip1 expression and cell growth. The expression of microRNA-186 (miR-186) was reported to be reduced in pituitary tumors. Online tools predicted SKP2 to be a direct downstream target of miR-186, which was further confirmed by luciferase reporter gene assays. Moreover, miR-186 could modulate the cell proliferation and p27^Kip1-mediated cell cycle alternation of rat and human pituitary tumor cells through SKP2. As further confirmation of these findings, miR-186 and p27^Kip1 expression were downregulated, while SKP2 expression was upregulated in human pituitary tumor tissue samples; thus, SKP2 expression negatively correlated with miR-186 and p27^Kip1 expression. In contrast, miR-186 expression positively associated with p27^Kip1 expression. Taken together, we discovered a novel mechanism by which miR-186/SKP2 axis modulates pituitary tumor cell proliferation through p27^Kip1-mediated cell cycle alternation.

Phosphoproteome profiling revealed abnormally phosphorylated AMPK and ATF2 involved in glucose metabolism and tumorigenesis of GH-PAs

PURPOSE

Protein phosphorylation plays a key role in tumorigenesis and progression. However, little is known about the phosphoproteome profiles of growth hormone-secreting pituitary adenomas (GH-PAs). The aim of this study was to identify critical biomarkers and signaling pathways that might play important roles in GH-PAs and may, therefore, represent potential therapeutic targets.

METHODS

The differential phosphoprotein expression patterns involved in GH-PAs were investigated by nano-LC-MS/MS in a group of samples. The phosphoprotein expression data were analyzed by bioinformatics. The expression levels of the candidate phosphorylated AMPK (ser496) and ATF2 (ser112) were validated by Western blot analysis in another group of samples.

RESULTS

A total of 1213 phosphorylated protein sites corresponding to 667 proteins were significantly different between GH-PAs and healthy pituitary glands. Among these phosphorylated sites, 871 exhibited lower levels of phosphorylation in GH-PAs. Moreover, 140 novel phosphosites corresponding to 93 proteins were differentially phosphorylated between GH-PAs and healthy pituitary glands, 101 of which showed decreased phosphorylation in GH-PAs. The majority of differentially expressed phosphorylated proteins were significantly enriched in glycolysis and the AMPK signaling pathway in GH-PAs. The AMPK signaling pathway was demonstrated to be inhibited in GH-PAs by pathway activity analysis (z score = - 2.324). Notably, the phosphorylated levels of AMPK (ser496) and ATF2 (ser112) were significantly lower in GH-PAs than in healthy pituitary glands.

CONCLUSION

These findings suggest that decreased phosphorylation of the AMPK/ATF2 pathway may be critical for glucose metabolism and tumorigenesis in GH-PAs.

Identification of Serum miRNA-423-5p Expression Signature in Somatotroph Adenomas

Circulating miRNAs are novel disease biomarkers that are valuable for diagnosis and prognosis. But the circulating miRNAs profile in somatotroph adenomas is still unknown. Therefore, serum exosomal miRNAs expression profiling in somatotroph adenomas was performed on 6 somatotroph adenomas and 6 normal controls. From the exosomal miRNAs expression profiling, we found 169 miRNAs differently expressed between somatotroph adenomas and healthy pituitary samples (p< 0.05, FC > 2). Among the 169 miRNAs, miR-423-5p was expressed lower in somatotroph adenomas than in healthy pituitary samples, which was proved by miRSCan Panel Chip™ qPCR. PTTG1 and SYT1 were the target mRNAs of miR-423-5p, and transcriptomics and proteomics profile both indicated the high expression of PTTG1 and SYT1 in somatotroph adenomas. H-scores were 223.1 ± 34.7 for PTTG1 and 163.4 ± 42.3 for SYT1 in 62 somatotroph adenomas specimens and 84.2 ± 21.3 for PTTG1 and 47.4 ± 17.2 for SYT1 in 6 healthy pituitary specimens by IHC. miR-423-5p inhibited the expression of SYT1 and PTTG1 at the mRNA and protein levels. Dual luciferase reporter gene assay shown was significantly reduced in the presence of miR-423-5p in GH3 cells transfected with wild-type PTTG1 3'UTR luciferase reporter plasmid but not reduced when transfected with the mutation PTTG1 3'UTR luciferase reporter plasmid (p<0.01). In vitro experiments showed that miR-423-5p induced cell apoptosis, inhibited cell proliferation, and reduced growth hormone release and migration of GH3 cells. The activity of miR-423-5p in GH3 cell was nearly blocked by its inhibitor. These results verified the central role of low miR-423-5p in promoting tumorigenesis in somatotroph adenomas. PTTG1 may act as biomarkers for clinical treatment of somatotroph adenomas.

The importance of the electrophysiological tests in the early diagnosis of ganglion cells and/or optic nerve dysfunction coexisting with pituitary adenoma: an overview

BACKGROUND AND METHODS

Based on the available literature, it is suggested, in the clinical evaluation of the chiasmal tumors, that the following electrophysiological tests: visual evoked potentials to pattern-reversal stimulation, multifocal visual evoked potentials (mfVEPs), and pattern electroretinogram (PERG) play an important role in the diagnosis of the optic nerve and retinal dysfunction in the course of pituitary tumors.

RESULTS

Macroadenomas and also microadenomas may cause dysfunction of retinal ganglion cells (RGCs) and their axons, even in the absence of changes in the routine ophthalmological examination, retinal sensitivity in standard automated perimetry, and retinal nerve fiber layer thickness in optical coherent tomography. The most frequently observed changes in electrophysiological tests were as follows: in PVEPs-the crossed/uncrossed asymmetry distribution, altered waveform, increase in P100-wave peak time, and/or reduction in amplitude; in mfVEPs-the peak time prolongation and/or amplitude reduction in C1-wave; in PERG-the reduction in N95-wave amplitude and decreased N95:P50 amplitude ratio. Hemifield PVEPs were more often abnormal than full-field PVEPs. Multi-channel recording is recommended for the assessment of the anterior visual pathway. The use of mfVEP offers the possibility to register localized disturbances of the optic nerve and ganglion cells. Additionally, an amplitude of N95-wave reduction in PERG correlated with a lack of postoperative visual acuity recovery. The postoperative improvement in the visual field was found to be associated with a normal N95:P50 amplitude ratio. The RGCs dysfunction manifested by decrease in PhNR/b-wave amplitude ratio was associated with the worse visual fields outcome. A review of the literature summarizing the electrophysiological testing in the pituitary adenoma is discussed.

CONCLUSION

In patients with pituitary tumor, detection of the early dysfunction of the visual pathway may lead to modification of the medical treatment regimen and reduce the incidence of irreversible optic nerve damage.

Differential gene expression of sirtuins between somatotropinomas and nonfunctioning pituitary adenomas

Sirtuins 1-7 (SIRT) are a highly conserved family of histone deacetylases involved in the regulation of longevity that have a considerable impact in transcription, DNA repair regulation, telomeric stability, cell senescence and apoptosis. In the present study, SIRT1-7 mRNA levels were evaluated in 37 somatotropinomas and 31 nonfunctioning pituitary adenomas (NFPAs) using qPCR and relation to tumor size, invasiveness and Ki-67 proliferative index was made. Overexpression of SIRT1 was observed in 86.5% of somatotropinomas versus 41.9% of NFPAs (P < 0.01). SIRT3 was more underexpressed in NFPAs than somatotropinomas (77.4 and 40.5%, respectively, P < 0.01) as well as SIRT4 and SIRT7. Despite the lack of association between sirtuins and invasiveness or Ki-67 index, SIRT1 and SIRT3 expressions were related to tumor size. Mean of the largest diameter was smaller in adenomas with SIRT1 overexpression than with normal expression (P < 0.01) and SIRT3 underexpression was associated with larger tumors (P < 0.01). In conclusion, a pronounced difference in sirtuins expression was identified between pituitary adenomas, suggesting that these genes are potential markers of pituitary adenomas and could be employed in the characterization of somatotropinomas and NFPAs. The role of sirtuins in pathogenesis of pituitary tumors merits further investigation and possibly will provide new molecular insight about their progression.

Refractory pituitary adenoma: a novel classification for pituitary tumors

Pituitary adenomas are classified as typical or atypical, invasive or noninvasive, and aggressive or nonaggressive based on pathological features, radiological findings, and clinical behavior. Only pituitary tumors with cerebrospinal and/or systemic metastasis are considered malignant carcinomas. However, some pituitary adenomas with high Ki-67 indexes exhibit aggressive behaviors, such as rapid growth, early and frequent recurrence, and resistance to conventional treatment, even in the absence of metastasis. Novel terminology is needed to define these tumors. Here, we propose the use of the term “refractory pituitary adenoma” to define malignant pituitary tumors exhibiting 1) a high Ki-67 index and rapid growth, 2) early and high frequency of recurrence, 3) resistance to conventional treatments and/or salvage treatment with temozolomide (TMZ), 4) poor prognosis, 5) and a lack of cerebrospinal or systemic metastases. To illustrate the utility of this refractory pituitary adenoma classification and the difficulty in managing disease in these patients, we examined twelve clinical cases. Correctly identifying refractory pituitary adenomas is crucial for improving patient prognoses. Early identification might encourage the early use of aggressive therapeutic strategies to prevent or delay recurrence.

Expression of E-cadherin, Slug and NCAM and its relationship to tumor invasiveness in patients with acromegaly

Pituitary adenomas account for 10–15% of primary intracranial tumors. Growth hormone (GH)-secreting adenomas account for 13% of all pituitary adenomas and cause acromegaly. These tumors can be aggressive, invade surrounding structures and are highly recurrent. The objective of this study was to evaluate E-cadherin, Slug and neural cell adhesion molecule (NCAM) expression in GH-secreting pituitary adenomas and its relationship to tumor invasiveness. A cross–sectional study of patients who underwent hypophysectomy due to GH-secreting pituitary adenoma from April 2007 to December 2014 was carried out. The medical records were reviewed to collect clinical data. Immediately after surgery, tumor samples were frozen in liquid nitrogen and stored in a biofreezer at –80°C for assessment of E-cadherin 1 (CDH1), SLUG (SNAI2), and NCAM (NCAM1) by real-time PCR. The samples were fixed in formalin and embedded in paraffin for immunohistochemical analysis of E-cadherin and NCAM. Thirty-five patients with acromegaly were included in the study. Of these, 65.7% had invasive tumors. Immunohistochemically, E-cadherin was expressed in 96.7% of patients, and NCAM in 80% of patients. There was no statistically significant relationship between tumor grade or invasiveness and immunohistochemical expression of these markers. Regarding gene expression, 50% of cases expressed CDH1, none expressed SNAI2, and 53.3% expressed NCAM1. There was no statistically significant relationship between tumor grade or invasiveness and gene expression of CDH1, SNAI2, and NCAM1. The absence of Slug overexpression and of E-cadherin and NCAM suppression suggests that expression of these markers is not associated with tumor invasiveness in GH-secreting pituitary adenomas.

Relation among Aromatase P450 and Tumoral Growth in Human Prolactinomas

The pituitary gland is part of hypothalamic-pituitary–gonadal axis, which controls development, reproduction, and aging in humans and animals. In addition, the pituitary gland is regulated mainly by hormones and neurotransmitters released from the hypothalamus and by systemic hormones secreted by target glands. Aromatase P450, the enzyme responsible for the catabolization of aromatizable androgens to estrogens, is expressed in different parts of body, including the pituitary gland. Moreover, aromatase P450 is involved in sexual dimorphism where alteration in the level of aromatase can initiate a number of diseases in both genders. On the other hand, the direct actions of estrogens, mainly estradiol, are well known for stimulating prolactin release. Numerous studies have shown that changes in the levels of estrogens, among other factors, have been implicated in the genesis and development of prolactinoma. The pituitary gland can produce estradiol locally in several types of endocrine cells, and it is possible that aromatase could be responsible for the maintenance of the population of lactotroph cells and the modulation of the action of central or peripheral regulators. Aromatase overexpression due to inappropriate gene regulation has clinical effects such as the pathogenesis of prolactinomas. The present study reports on the synthesis of pituitary aromatase, its regulation by gonadal steroids, and the physiological roles of aromatase on pituitary endocrine cells. The involvement of aromatase in the pathogenesis of pituitary tumors, mainly prolactinomas, through the auto-paracrine production of estradiol is reviewed.

Efficacy of sellar opening in the pituitary adenoma resection of transsphenoidal surgery influences the degree of tumor resection

Background

Endonasal transsphenoidal microsurgery is often adopted in the resection of pituitary adenoma, and has showed satisfactory treatment and minor injuries. It is important to accurately localize sellar floor and properly incise the bone and dura matter.

Methods

Fifty-one patients with pituitary adenoma undergoing endonasal transsphenoidal microsurgery were included in the present study. To identify the scope of sellar floor opening, CT scan of the paranasal sinus and MRI scan of the pituitary gland were performed for each subject. Intraoperatively, internal carotid artery injury, leakage of cerebrospinal fluid, and tumor texture were recorded, and postoperative complications and residual tumors were identified.

Result

The relative size of sellar floor opening significantly differed among the pituitary micro-, macro- and giant adenoma groups, and between the total and partial tumor resection groups. The ratio of sellar floor opening area to maximal tumor area was significantly different between the total and partial resection groups. Logistic regression analysis revealed that the ratio of sellar floor opening area to the largest tumor area, tumor texture, tumor invasion and age were independent prognostic factors. The vertical distance between the top point of sellar floor opening and planum sphenoidale significantly differed between the patients with and without leakage of cerebrospinal fluid.

Conclusion

These results together indicated that relatively insufficient sellar floor opening is a cause of leading to residual tumor, and the higher position of the opening and closer to the planum sphenoidale are likely to induce the occurrence of leakage of cerebrospinal fluid.

Apparent diffusion coefficient and pituitary macroadenomas: pre-operative assessment of tumor atypia

RATIONALE AND OBJECTIVES

Pituitary macroadenomas are predominantly benign intracranial neoplasms that can be locally aggressive with invasion of adjacent structures. Biomarkers of aggressive behavior have been identified in the pathology literature, including the proliferative marker MIB-1. In the radiology literature, diffusion weighted imaging and low ADC values provide similar markers of aggressive behavior in brain tumors. The purpose of this study was to determine if there is a correlation between ADC and MIB-1 in pituitary macroadenomas.

MATERIALS AND METHODS

A retrospective review of diffusion imaging and immunohistochemical characteristics of pituitary macroadenomas was performed. The ADC ratio and specimen Ki-67 (MIB-1) indices were measured. Linear regression analysis of normalized ADC values and MIB-1 indices was used to compare these parameters.

RESULTS

There were 17 patients with available ADC maps and MIB-1 indices. Local invasion was confirmed by imaging and intraoperative visualization in 11 patients. The mean ADC ratio for the invasive group was 0.68, with a mean MIB-1 index of 2.21 %. In the noninvasive group, the mean ADC ratio was 1.05, with a mean MIB-1 index of 0.9 %. Linear regression analysis of normalized ADC values versus MIB-1 demonstrates a negative correlation, with a linear slope significantly different from zero (p = 0.003, correlation coefficient of 0.77, and r squared = 0.59).

CONCLUSION

We determine a strong correlation of low ADC values and MIB-1, demonstrating the potential of diffusion imaging as a possible biomarker for atypical, proliferative adenomas, which may ultimately affect the surgical approach and postoperative management.

Demographic study of pituitary adenomas undergone trans-sphenoidal surgery in Loghman Hakim Hospital, Tehran, Iran 2001-2013

BACKGROUND

Pituitary adenomas (PAs) are abnormal benign tumors that develop in the pituitary gland. This study aimed to assess the prevalence of different types of PAs with an indication for trans-sphenoidal surgery in a well-defined population referred to Loghman Hakim Hospital during 2001-2013.

SUBJECTS AND METHODS

In this retrospective study, the prevalence rate and symptoms associated with pituitary mass and hormone excess in operated patients were investigated. The diagnosis was verified after retrieval of clinical, hormonal, radiological, and pathological data. Demographic data were collected in all cases. Descriptive analysis, t-test, one-way analysis of variance and Fischer exacts test were used.

RESULTS

A total of 278 patients with PAs who underwent surgical interventions were evaluated. Most of the patients were aged 40-50 years with an average of 41 ± 14. The most prominent complaint was pressure effect, which was detected in 153 cases (55.2%). At the second place, hormonal disorders were observed in 125 cases (44.8%). Type of pituitary tumors were: Prolactinomas (29.1%), growth hormone (GH)-producing tumors (25%), nonfunctioning PAs (28.4%), adrenocorticotropic hormone (ACTH)-producing tumors (2.1%), thyroid stimulating hormone (TSH)-producing tumors (0.7%), GH/prolactin (13.6%), GH/ACTH (0.3%), and TSH/ACTH (0.3%). Fifty-seven patients presented with recurrent adenomas. Pituitary apoplexy was found in 11 patients. One case of Sheehan syndrome was recorded among these. The correlations between clinical symptoms and patients, age and sex were not significant.

CONCLUSION

The overview of demographic characteristics in Iranian patients with PAs with surgical indication has been discussed in the present investigation. The prevalence of different types of PAs and the most common clinical symptoms have been demonstrated.

Fetal Alcohol Exposure Reduces Dopamine Receptor D2 and Increases Pituitary Weight and Prolactin Production via Epigenetic Mechanisms

Recent evidence indicated that alcohol exposure during the fetal period increases the susceptibility to tumor development in mammary and prostate tissues. Whether fetal alcohol exposure increases the susceptibility to prolactin-producing tumor (prolactinoma) development in the pituitary was studied by employing the animal model of estradiol-induced prolactinomas in Fischer 344 female rats. We employed an animal model of fetal alcohol exposure that simulates binge alcohol drinking during the first two trimesters of human pregnancy and involves feeding pregnant rats with a liquid diet containing 6.7% alcohol during gestational day 7 to day 21. Control rats were pair-fed with isocaloric liquid diet or fed ad libitum with rat chow diet. Adult alcohol exposed and control female offspring rats were used in this study on the day of estrus or after estrogen treatment. Results show that fetal alcohol-exposed rats had increased levels of pituitary weight, pituitary prolactin (PRL) protein and mRNA, and plasma PRL. However, these rats show decreased pituitary levels of dopamine D2 receptor (D2R) mRNA and protein and increased pituitary levels of D2R promoter methylation. Also, they show elevated pituitary mRNA levels of DNA methylating genes (DNMT1, DNMT3b, MeCP2) and histone modifying genes (HDAC2, HDAC4, G9a). When fetal alcohol exposed rats were treated neonatally with a DNA methylation inhibitor 5-Aza deoxycytidine and/or a HDAC inhibitor trichostatin-A their pituitary D2R mRNA, pituitary weights and plasma PRL levels were normalized. These data suggest that fetal alcohol exposure programs the pituitary to increase the susceptibility to the development of prolactinomas possibly by enhancing the methylation of the D2R gene promoter and repressing the synthesis and control of D2R on PRL-producing cells.

Pituitary adenomas: historical perspective, surgical management and future directions

Pituitary adenomas are among the most common central nervous system tumors. They represent a diverse group of neoplasms that may or may not secrete hormones based on their cell of origin. Epidemiologic studies have documented the incidence of pituitary adenomas within the general population to be as high as 16.7%. A growing body of work has helped to elucidate the pathogenesis of these tumors. Each subtype has been shown to demonstrate unique cellular changes potentially leading to tumorigenesis. Surgical advancements over several decades have included microsurgery and the employment of the endoscope for surgical resection. These advancements increase the likelihood of gross-total resection and have resulted in decreased patient morbidity.

Single-Cell Phenotypic Characterization of Human Pituitary GHomas and Non-Functioning Adenomas Based on Hormone Content and Calcium Responses to Hypothalamic Releasing Hormones

Human pituitary tumors are generally benign adenomas causing considerable morbidity due to excess hormone secretion, hypopituitarism, and other tumor mass effects. Pituitary tumors are highly heterogeneous and difficult to type, often containing mixed cell phenotypes. We have used calcium imaging followed by multiple immunocytochemistry to type growth hormone secreting (GHomas) and non-functioning pituitary adenomas (NFPAs). Individual cells were typed for stored hormones and calcium responses to classic hypothalamic releasing hormones (HRHs). We found that GHomas contained growth hormone cells either lacking responses to HRHs or responding to all four HRHs. However, most GHoma cells were polyhormonal cells responsive to both thyrotropin-releasing hormone (TRH) and GH-releasing hormone. NFPAs were also highly heterogeneous. Some of them contained ACTH cells lacking responses to HRHs or polyhormonal gonadotropes responsive to LHRH and TRH. However, most NFPAs were made of cells storing no hormone and responded only to TRH. These results may provide new insights on the ontogeny of GHomas and NFPAs.

Null cell adenomas of the pituitary gland: an institutional review of their clinical imaging and behavioral characteristics

The aim of the study was to establish if the null cell adenoma (NCA) forms a distinct subgroup with unique clinicopathological characteristics within the nonfunctioning pituitary adenoma group particularly in relation to the silent gonadotroph adenomas (SGAs). We identified 31 patients with the pathological diagnosis of NCA verified by routine histology and immunohistochemistry with distinct differentiation from SGAs by an established negative testing for SF-1 at the Toronto Western Hospital between December 2004 and August 2010. We reviewed their demographic data, clinical features, magnetic resonance imaging, and the histologic variables: MIB-1, FGFR4, and P27. We compared these to 63 SGAs identified within the same period. All the NCAs were macroadenomas with diameter ranging from 15-57 mm and tumor volumes between 1.95-53.5 mm(3). Preoperative cavernous sinus tumor growth was able to predict the presence of a residual after surgery (p = 0.023). Furthermore, preoperative cavernous sinus extension (p = 0.002) and negative P27 expression (p = 0.035) were able to independently predict the subsequent growth of the postoperative tumor residual. Comparing the NCA to SGA, we found that MIB-1 was higher in NCA (mean ± SD = 3.43 ± 2.76 %) compared to SGAs (mean ± SD = 2.49 ± 1.41 %) (p = 0.044). The preoperative and postoperative tumor volume doubling times (TVDTs) displayed a negative correlation in the SGA (r = -0.855, p = 0.002) while in the NCA, a positive correlation was evident (r = 0.718, p = 0.029). Our study suggests that the NCAs are a distinct group with differing behavioral characteristics from the SGAs. It also appears that the finding of cavernous sinus extension on preoperative imaging and a negative P27 expression on immunohistochemistry in NCAs may be valuable tools in predicting residual tumor growth which may impact on postoperative care.

Expression of the pituitary stem/progenitor marker GFRα2 in human pituitary adenomas and normal pituitary

PURPOSE

Recent studies suggest that adult pituitary stem cells may play a role in pituitary tumorigenesis. We sought to explore whether the Glial cell-line derived neurotrophic factor receptor alpha 2 (GFRα2), a recently described pituitary stem/progenitor marker, might be differentially expressed in pituitary adenomas versus normal pituitary.

METHODS

The expression of GFRα2 and other members of the GFR receptor family (GFRα1, α3, α4) were analyzed using RT-PCR, western blot, and immunohistochemistry in 39 pituitary adenomas, 14 normal pituitary glands obtained at autopsy, and cDNA from 3 normal pituitaries obtained commercially.

RESULTS

GFRα2 mRNA was ~2.6 fold under-expressed in functioning adenomas (p < 0.01) and ~3.5 fold over-expressed in non-functioning adenomas (NFAs) (p < 0.05) compared to normal pituitary. Among NFAs, GFRα2 was significantly over-expressed (~5-fold) in the gonadotropinoma subtype only (p < 0.05). GFRα2 protein expression appeared to be higher in most NFAs, although there was heterogeneity in protein expression in this group. GFRα2 protein expression appeared consistently lower in functioning adenomas by IHC and western blot. In normal pituitary, GFRα2 was localized in Rathke's remnant, the putative pituitary stem cell niche, and in corticotropes.

CONCLUSION

Our results suggest that the pituitary stem cell marker GFRα2 is under-expressed in functioning adenomas and over-expressed in NFAs, specifically gonadotropinomas. Further studies are required to elucidate whether over-expression of GFRα2 in gonadotropinomas might play a role in pituitary tumorigenesis.

Clinical characteristics and treatment outcome of 485 patients with nonfunctioning pituitary macroadenomas

Background. Nonfunctioning pituitary adenomas (NFPAs) are the most common benign lesions of the pituitary gland. Objective. To describe our experience with the management of NFPA. Study Design and Methods. Retrospective evaluation of NFPA patients managed between 2008 and 2013. We analyzed data regarding clinical presentation, imaging diagnosis, hormonal status, surgical, radiotherapeutic, and pharmacological treatment, and outcome. Results. 485 patients (54% men, mean age 53 ± 14 years) were followed for a median of 6.5 years. Visual field abnormalities and headaches were the presenting complaints in 87% and 66%, respectively. The diagnosis of NFPA was made incidentally in 6.2%, and 8% presented with clinical evidence of apoplexy. All patients harbored macroadenomas, with a median volume of 10306 mm(3); 57.9% had supra- or parasellar invasion and 19.6% had tumors larger than 4 cm. Central hypothyroidism, hypogonadism, and hypocortisolism were present in 47.2%, 35.9%, and 27.4%, respectively. Surgical resection was performed at least once in 85.7%. Tumor persistence was documented in 27% and was related to the size and invasiveness of the lesion. In selected cases, radiotherapy proved to be effective in controlling or preventing tumor growth. Conclusions. The diagnosis and treatment of NFPA are complex and require a multidisciplinary approach.

Identification of differentially expressed genes in pituitary adenomas by integrating analysis of microarray data

Pituitary adenomas, monoclonal in origin, are the most common intracranial neoplasms. Altered gene expression as well as somatic mutations is detected frequently in pituitary adenomas. The purpose of this study was to detect differentially expressed genes (DEGs) and biological processes during tumor formation of pituitary adenomas. We performed an integrated analysis of publicly available GEO datasets of pituitary adenomas to identify DEGs between pituitary adenomas and normal control (NC) tissues. Gene function analysis including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction (PPI) networks analysis was conducted to interpret the biological role of those DEGs. In this study we detected 3994 DEGs (2043 upregulated and 1951 downregulated) in pituitary adenoma through an integrated analysis of 5 different microarray datasets. Gene function analysis revealed that the functions of those DEGs were highly correlated with the development of pituitary adenoma. This integrated analysis of microarray data identified some genes and pathways associated with pituitary adenoma, which may help to understand the pathology underlying pituitary adenoma and contribute to the successful identification of therapeutic targets for pituitary adenoma.

Evaluation of prognostic utility of MIB-1 and p53 expression in pituitary adenomas: correlations with clinical behaviour and follow-up results

Pituitary adenomas (PAs) show a broad clinicomorphological spectrum. The proliferation activity, evaluated by MIB-1 labelling index (LI), and p53 expression have been pointed as predictive markers for invasiveness and progression. The aim of this study was to evaluate the proliferation rate and p53 expression and to look for any relationships with the clinical behaviour and follow-up results in a series of Bulgarian patients with PAs. A total of 93 patients with PAs (81 hormone-secreting, 12 non-functioning), who were operated on and followed up for a period of five years, were included. The MIB-1 LI and p53 expressions were determined by immunohistochemistry and correlated with various clinical and tumour variables. The whole group of PAs showed a low proliferation rate with evident variations in a small number of cases (MIB-1 LI – 0.50 ± 0.56, from 0.1 to 3.30). MIB-1 LI correlated with tumour size (p = 0.012) and was positively related with male gender (p = 0.23) and partial surgical resection (p = 0.036). We found no significant differences regarding the age, functional activity, invasion (n = 33), expansion (n = 37) and tumour recurrences (seven cases). Only 10 cases (10.8%) showed a focal, nuclear p53 immunoreactivity. The p53 positive tumours had higher proliferation rate (p = 0.0001) but no relationship with the other clinical and tumour variables. Among all cases, there was only one case with higher MIB-1 LI (3.3%), positive p53 expression and tumour recurrence after surgery. Our results show that most PAs have a low proliferation rate and lack of p53 expression, as well as no relationship with tumour invasion or postsurgical progression.

Symptomatic Rathke's cleft cyst with a co-existing pituitary tumor; Brief review of the literature

Pituitary adenomas and Rathke's cleft cysts (RCCs) share a common embryological origin. Occasionally, these two lesions can present within the same patient. We present a case of a 39-year-old male who was found to have a large sellar lesion after complaints of persistent headaches and horizontal nystagmus. Surgical resection revealed components of a RCC co-existing with a pituitary adenoma. A brief review of the literature was performed revealing 38 cases of co-existing Rathke's cleft cysts and pituitary adenomas. Among the cases, the most common symptoms included headache and visual changes. Rathke's cleft cysts and pituitary adenomas are rarely found to co-exist, despite having common embryological origins. We review the existing literature, discuss the common embryology to these two lesions and describe a unique case from our institution of a co-existing Rathke's cleft cyst and pituitary adenoma.

Craniocaudal extension as an indication of surgical outcome in transsphenoidal surgery for pituitary adenomas

Transsphenoidal approach is considered the treatment of choice for pituitary adenoma removal. Suprasellar extension is regarded a drawback for complete removal of these tumors through this approach. Evaluate the correlation between the preoperative radiologic craniocaudal extension on MRI of pituitary adenomas and the extent of tumor removal. A retrospective study. Tertiary care hospital. 560 patients underwent transsphenoidal removal of pituitary adenomas. The degree of removal of pituitary tumor in the follow-up imaging of the patients was correlated with the preoperative extension in mid-Coronal T1 W Gd. Tumors with suprasellar extension can be classified into: Type I tumors with extension confined to the sellar boundaries, resulted in complete removal in all cases (100%), type II tumors with suprasellar extension reaching the floor of the 3rd ventricle, resulted in complete removal in 70.2% of the cases, type III tumors with suprasellar extension above the 3rd ventricle, had only 13.5% of complete removal. Integration of radiologic findings into a scheme for the preoperative determination of possibility of total removal of the tumor through transsphenoidal approach, can give better correlation to the surgical outcome of pituitary tumors.

Collision tumors of the sella: coexistence of pituitary adenoma and craniopharyngioma in the sellar region

Collision tumors of the sellar region are relatively uncommon and consist mainly of more than one type of pituitary adenoma or a cyst or cystic tumor. The association of a pituitary adenoma and a craniopharyngioma is particularly rare. This study describes a rare occurrence in which a pituitary adenoma and a craniopharyngioma coexisted in the sellar region. The case involves a 47-year-old woman who underwent transsphenoidal surgery with subtotal tumor resection and reoperation using an interhemispheric transcallosal approach for total microsurgical resection of the tumor because the visual acuity in her left eye had re-deteriorated. Histopathological and immunohistochemical examinations of the excised tissue revealed a pituitary adenoma in the first operation and a craniopharyngioma in the second operation. Retrospective analysis found the coexistence of a pituitary adenoma and a craniopharyngioma, known as a collision tumor. Instead of the transsphenoidal approach, a craniotomy should be performed, to explore the suprasellar region.

Silencing of RASSF3 by DNA hypermethylation is associated with tumorigenesis in somatotroph adenomas

The pathogenic mechanisms underlying pituitary somatotroph adenoma formation, progression are poorly understood. To identify candidate tumor suppressor genes involved in pituitary somatotroph adenoma tumorigenesis, we used HG18 CpG plus Promoter Microarray in 27 human somatotroph adenomas and 4 normal human adenohypophyses. RASSF3 was found with frequent methylation of CpG island in its promoter region in somatotroph adenomas but rarely in adenohypophyses. This result was confirmed by pyrosequencing analysis. We also found that RASSF3 mRNA level correlated negatively to its gene promoter methylation level. RASSF3 hypermethylation and downregulation was also observed in rat GH3 and mouse GT1.1 somatotroph adenoma cell lines. 5-Aza-2′ deoxycytidine and trichostatin-A treatment induced RASSF3 promoter demethylation, and restored its expression in GH3 and GT1.1 cell lines. RASSF3 overexpression in GH3 and GT1.1 cells inhibited proliferation, induced apoptosis accompanied by increased Bax, p53, and caspase-3 protein and decreased Bcl-2 protein expression. We also found that the antitumor effect of RASSF3 was p53 dependent, and p53 knockdown blocked RASSF3-induced apoptosis and growth inhibition. Taken together, our results suggest that hypermethylation-induced RASSF3 silencing plays an important role in the tumorigenesis of pituitary somatotroph adenomas.

Establishing a protein expression profile database for the normal human pituitary gland using two-dimensional high-performance liquid chromatography combined with LTQ-Orbitrap mass spectrometry

In this study, we selected adult normal pituitary gland tissues from six patients during operations for pituitary microadenomas via the transsphenoidal approach for extended normal pituitary tissue resection around the tumor, and analyzed the protein expression of human normal pituitary using two-dimensional high-performance liquid chromatography combined with LTQ-Orbitrap mass spectrometry proteomics technology. The ten most highly expressed proteins in normal human pituitary were: alpha 3 type VI collagen isoform 5 precursor (abundance among tall pituitary proteins, 1.30%), fibrinogen beta chain preproprotein (0.99%), vimentin (0.73%), prolactin (0.69%), ATP synthase, H+ transporting and mitochondrial F1 complex beta subunit precursor (0.52%), keratin I (0.49%), growth hormone (0.45%), carbonic anhydrase I (0.40%), heat shock protein 90 kDa I (0.31%), and annexin V (0.30%). Based on the biological function classifications of these proteins, the top three categories by content were neuroendocrine proteins (abundance among all pituitary proteins, 40.1%), catalytic and metabolic proteins (28.3%), and cell signal transduction proteins (9.8%). Based on cell positioning classification, the top three categories were cell organelle (24.5%), membrane (20.8%), and cytoplasm (13.0%). Based on biological process classification, the top three categories of proteins are involved in physiological processes (42.9%), cellular processes (40.4%), and regulation of biological processes (9.1%). Our experimental findings indicate that a protein expression profile database of normal human pituitary can be precisely and efficiently established by proteomics technology.

The Dual Role of TGFβ in Human Cancer: From Tumor Suppression to Cancer Metastasis

The transforming growth factor-beta (TGFβ) superfamily encompasses widespread and evolutionarily conserved polypeptide growth factors that regulate and orchestrate growth and differentiation in all cell types and tissues. While they regulate asymmetric cell division and cell fate determination during early development and embryogenesis, TGFβ family members play a major regulatory role in hormonal and immune responses, cell growth, cell death and cell immortalization, bone formation, tissue remodeling and repair, and erythropoiesis throughout adult life. The biological and physiological functions of TGFβ, the founding member of this family, and its receptors are of central importance to human diseases, particularly cancer. By regulating cell growth, death, and immortalization, TGFβ signaling pathways exert tumor suppressor effects in normal cells and early carcinomas. Thus, it is not surprising that a high number of human tumors arise due to mutations or deletions in the genes coding for the various TGFβ signaling components. As tumors develop and progress, these protective and cytostatic effects of TGFβ are often lost. TGFβ signaling then switches to promote cancer progression, invasion, and tumor metastasis. The molecular mechanisms underlying this dual role of TGFβ in human cancer will be discussed in depth in this paper, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the prometastatic arm of the TGFβ signaling pathway without affecting its tumor suppressive effects.

Expression of cell growth negative regulators MEG3 and GADD45γ is lost in most sporadic human pituitary adenomas

We aimed at the evaluation of MEG3 and GADD45γ expression in sporadic functioning and clinically non-functioning human pituitary adenomas, morphologically characterized by immunohistochemistry analysis and their association with clinical features. Thirty eight patients who had undergone hypophysectomy at São José Hospital of Irmandade Santa Casa de Misericórdia in Porto Alegre, Brazil, were included in this study. We evaluated tumor-type specific MEG3 and GADD45γ expression by qRT-PCR in the pituitary adenomas, and its association with clinical features, as age, gender and tumor size, obtained from medical records. The patients consisted of 21 males and 17 females and the mean age was 47 ± 14 (mean ± SD), ranging from 18 to 73 years-old. Of these 14 were clinically non-functioning, 10 GH-secreting, 9 PRL-secreting, and 5 ACTH-secreting pituitary adenomas. All samples were macroadenomas, except four ACTH-secreting tumors, which were microadenomas. In summary, MEG3 and GADD45γ expression was significantly lost in most clinically non-functioning adenomas (78 and 92%, respectively). Other assessed pituitary tumor phenotypes expressed both genes at significantly different levels, and, in some cases, with overexpression. There was no significant association between gene expression and the analyzed clinical features. Our results confirm the previous report, which indicated that MEG3 and GADD45γ expression is lost in the majority of human pituitary tumors, mainly in clinically-nonfunctioning adenomas. Functioning tumors had differences of relative expression levels. The two groups of tumors are probably genetically different and may have a different natural history.

Functional screen analysis reveals miR-26b and miR-128 as central regulators of pituitary somatomammotrophic tumor growth through activation of the PTEN-AKT pathway

MicroRNAs (miRNAs) have been involved in the pathogenesis of different types of cancer; however, their function in pituitary tumorigenesis remains poorly understood. Cyclic-AMP-dependent protein kinase-defective pituitaries occasionally form aggressive growth-hormone (GH)-producing pituitary tumors in the background of hyperplasia caused by haploinsufficiency of the protein kinase's main regulatory subunit, PRKAR1A. The molecular basis for this development remains unknown. We have identified a 17-miRNA signature of pituitary tumors formed in the background of hyperplasia (caused in half of the cases by PRKAR1A-mutations). We selected two miRNAs on the basis of their functional screen analysis: inhibition of miR-26b expression and upregulation of miR-128 suppressed the colony formation ability and invasiveness of pituitary tumor cells. Furthermore, we identified that miR-26b and miR-128 affected pituitary tumor cell behavior through regulation of their direct targets, PTEN and BMI1, respectively. In addition, we found that miR-128 through BMI1 direct binding on the PTEN promoter affected PTEN expression levels and AKT activity in the pituitary tumor cells. Our in vivo data revealed that inhibition of miR-26b and overexpression of miR-128 could suppress pituitary GH3 tumor growth in xenografts. Taken together, we have identified a miRNA signature for GH-producing pituitary tumors and found that miR-26b and miR-128 regulate the activity of the PTEN-AKT pathway in these tumors. This is the first suggestion of the possible involvement of miRNAs regulating the PTEN-AKT pathway in GH-producing pituitary tumor formation in the context of hyperplasia or due to germline PRKAR1A defects. MiR-26b suppression and miR-128 upregulation could have therapeutic potential in GH-producing pituitary tumor patients.

MicroRNAs in the human pituitary

MicroRNAs (miRNAs) represent a novel class of small RNA molecules that play a crucial role as post-transcriptional regulators of gene expression. As evidence for the involvement of miRNAs in various cellular processes increases, it is important to examine how miRNAs regulate gene expression. In the pituitary, aberrant miRNA expression is strongly linked with neoplasia, thus suggesting they play a role in the control of cell proliferation in adenomas. Research has built fundamental connections between aberrant miRNA expression and clinicopathological features of pituitary adenomas. Moreover, deregulated expression of miRNA target genes is often implicated in important biological pathways and thus provides significant insight into the role of miRNAs in tumorigenesis. This review will assess the significance of miRNAs in pituitary pathology.

The pseudocapsule surrounding a pituitary adenoma and its clinical significance

The transsphenoidal approach is currently considered the preferred first-line treatment for pituitary adenoma. With the discovery and application of the pseudocapsule surrounding a pituitary adenoma, transsphenoidal surgery of pituitary adenoma further falls into two categories: "extracapsular" and traditional "intracapsular" resection methods, on the basis of where dissection is performed with respect to the pseudocapsule. Thus, the pseudocapsule can be used as a plane to guide the operation, helps in total resection of pituitary adenoma, and can guide subsequent treatment after surgery.

A Postnatal Pax7 Progenitor Gives Rise to Pituitary Adenomas

Pituitary adenomas are classified into functioning and nonfunctioning (silent) tumors on the basis of hormone secretion. However, the mechanism of tumorigenesis and the cell of origin for pituitary adenoma subtypes remain to be elucidated. Employing a tamoxifen-inducible mouse model, we demonstrate that a novel postnatal Pax7(+) progenitor cell population in the pituitary gland gives rise to silent corticotroph macro-adenomas when the retinoblastoma tumor suppressor is conditionally deleted. While Pax transcriptional factors are critical for embryonic patterning as well as postnatal stem cell renewal for many organs, we have discovered that Pax7 marks a restricted cell population in the postnatal pituitary intermediate lobe. This Pax7(+) early progenitor cell population is overlapping but ontologically downstream of the Nestin(+) pituitary stem cell population, yet upstream of another newly discovered Myf6(+) late progenitor cell population. Interestingly, the Pax7(+) progenitor cell population is evolutionarily conserved in primates and humans, and Pax7 expression is maintained not only in murine tumors but also in human functioning and silent corticotropinomas. Taken together, our results strongly suggest that human silent corticotroph adenomas may in fact arise from a Pax7 lineage of the intermediate lobe, a region of the human pituitary bearing closer scientific interest as a reservoir of pituitary progenitor cells.

Prevalence of double pituitary adenomas in a surgical series: Clinical, histological and genetic features

BACKGROUND

The term double pituitary adenomas (DPA) is usually referred to those rare lesions showing two distinct cellular components. Genetic background may sustain the proliferation of more than one cell at the same time but no information is available on the presence of aip mutations in these patients.

AIM

We report the prevalence and the endocrinological, neuroradiological, histopathological and genetic features of DPA detected in a large surgical series. The contribution of pituitary transcription factor immunostains in DPA was also evaluated.

SUBJECTS AND METHODS

One-hundred-forty-four patients undergoing surgery for tumors of the sellar region were evaluated. Histopathology, immunohistochemistry and the mutational analysis for the entire coding region of the AIP and MEN1 genes were performed.

RESULTS

One-hundred-seventeen patients out of 144 had a pituitary adenoma. DPA was found in 3 (2.6%) out of 117 patients with pituitary adenoma. Immunohistochemistry and transcription factors analysis demonstrated two not yet described histotype associations in DPA. The coexistence of somatotroph-lactotroph and silent mammosomatotroph histotype in 1 case and the coexistence of sparsely granulated lactotroph and null cell adenomas in the remaining two cases were first identified. Sequencing data for the coding region of the aip and the menin gene resulted in wild type sequences in all patients with DPA.

CONCLUSIONS

The prevalence of DPA observed in our unselected surgical series is not negligible (2.6%). Furthermore, the evaluation of the treatment outcome would suggest that the clinical management of DPAs requires a careful diagnostic approach and follow- up.

Female mice expressing constitutively active mutants of FSH receptor present with a phenotype of premature follicle depletion and estrogen excess

Strong gain-of-function mutations have not been identified in humans in the FSH receptor (FSHR), whereas such mutations are common among many other G protein-coupled receptors. In order to predict consequences of such mutations on humans, we first identified constitutively activated mutants of the mouse (m) Fshr and then expressed them under the human anti-Müllerian hormone promoter in transgenic mice or created knock-in mutation into the mouse genome. We show here that mutations of Asp580 in the mFSHR significantly increase the basal receptor activity. D580H and D580Y mutations of mFSHR bind FSH, but the activity of the former is neither ligand-dependent nor promiscuous towards LH/human choriogonadotropin stimulation. Transgenic expression of mFshr(D580H) in granulosa cells leads to abnormal ovarian structure and function in the form of hemorrhagic cysts, accelerated loss of small follicles, augmented granulosa cell proliferation, increased estradiol biosynthesis, and occasional luteinized unruptured follicles or teratomas. The most affected mFshr(D580H) females are infertile with disturbed estrous cycle and decreased gonadotropin and increased prolactin levels. Increased estradiol and prolactin apparently underlie the enhanced development of the mammary glands, adenomatous pituitary growth, and lipofuscin accumulation in the adrenal gland. The influence of the mFSHR(D580Y) mutation is milder, mainly causing hemorrhagic cysts in transgenic mFSHR(D580Y) and mFSHR(D580Y) -knock-in mice. The results demonstrate that gain-of-function mutations of the FSHR in mice bring about distinct and clear changes in ovarian function, informative in the search of similar mutations in humans.

Determination of cell proliferation using Mcm2 antigen and evaluation of apoptosis and TGF-beta1 expression in GH-secreting or clinically nonfunctioning pituitary adenomas

Pituitary adenomas (PA) occasionally show aggressive behavior, with invasion of the surrounding tissues. The identification of markers able to recognize aggressive PA in early stages remains a challenge. We aimed to determine the expression of a new cell proliferation marker, Mcm2, and the presence of apoptosis in PA, and to evaluate the association of clinicopathological features with the apoptotic and proliferative indices. Additionally, the TGF-beta1 expression, an inducer of apoptosis, was determined. The proliferative index was determined in GH-secreting or clinically nonfunctioning PA using immunohistochemical (IH) methods for Mcm2 and Ki-67 antigens. The apoptosis was assessed by the TUNEL method and the TGF-beta1 expression by IH. A significant positive correlation was found between log Mcm2 index and log Ki-67 index (p < 0.001). Mcm2 and Ki-67 detected a similar number of proliferating cells. Mcm2 index showed a significant association with tumor extension (p = 0.02), but not with tumor invasion. Apoptosis was detected in 17% of the adenomas, with a maximum apoptotic index of 0.77%. Immunoreactivity to TGF-beta1 was observed in 77% of the adenomas, showing an association with tumor extension. We concluded that, in this sample, Mcm2 was similar to Ki-67 in the identification of the proliferating cells and that apoptosis was rare.

Collision sellar lesions: experience with eight cases and review of the literature

The concomitant presence of a pituitary adenoma with a second sellar lesion in patients operated upon for pituitary adenoma is an uncommon entity. Although rare, quite a great variety of lesions have been indentified coexisting with pituitary adenomas. In fact, most combinations have been described before, but an overview with information on the frequency of combined pathologies in a large series has not been published. We present a series of eight collision sellar lesions indentified among 548 transsphenoidally resected pituitary adenomas in two Neurosurgical Departments. The histological studies confirmed a case of sarcoidosis within a non-functioning pituitary adenoma, a case of intrasellar schwannoma coexisting with growth hormone (GH) secreting adenoma, two Rathke's cleft cysts combined with pituitary adenomas, three gangliocytomas associated with GH-secreting adenomas, and a case of a double pituitary adenoma. The pertinent literature is discussed with emphasis on pathogenetic theories of dual sellar lesions. Although there is no direct evidence to confirm the pathogenetic relationship of collision sellar lesions, the number of cases presented in literature makes the theory of an incidental occurrence rather doubtful. Suggested hypotheses about a common embryonic origin or a potential interaction between pituitary adenomas and the immune system are presented.

The pathogenesis of pituitary tumors

Recently there has been significant progress in our understanding of pituitary development, physiology, and pathology. New information has helped to clarify the classification of pituitary tumors. Epidemiologic analyses have identified a much higher incidence of pituitary tumors than previously thought. We review the pathogenetic factors that have been implicated in pituitary tumorigenesis and the application of novel targeted therapies that underscore the increasingly important role of the pathologist in determining accurate diagnoses and facilitating appropriate treatment of patients with these disorders.