Pituitary adenomas are one of the most frequent intracranial tumors and occur with a prevalence of approximately 1:1000 in the developed world. Pituitary adenomas have a serious disease burden, and their management involves neurosurgery, biological therapies, and radiotherapy. Early diagnosis of pituitary tumors while they are smaller may help increase cure rates. Few genetic predictors of pituitary adenoma development exist. Recent years have seen two separate, complimentary advances in inherited pituitary tumor research. The clinical condition of familial isolated pituitary adenomas (FIPA) has been described, which encompasses the familial occurrence of isolated pituitary adenomas outside of the setting of syndromic conditions like multiple endocrine neoplasia type 1 and Carney complex. FIPA families comprise approximately 2% of pituitary adenomas and represent a clinical entity with homogeneous or heterogeneous pituitary adenoma types occurring within the same kindred. The aryl hydrocarbon receptor interacting protein (AIP) gene has been identified as causing a pituitary adenoma predisposition of variable penetrance that accounts for 20% of FIPA families. Germline AIP mutations have been shown to associate with the occurrence of large pituitary adenomas that occur at a young age, predominantly in children/adolescents and young adults. AIP mutations are usually associated with somatotropinomas, but prolactinomas, nonfunctioning pituitary adenomas, Cushing disease, and other infrequent clinical adenoma types can also occur. Gigantism is a particular feature of AIP mutations and occurs in more than one third of affected somatotropinoma patients. Study of pituitary adenoma patients with AIP mutations has demonstrated that these cases raise clinical challenges to successful treatment. Extensive research on the biology of AIP and new advances in mouse Aip knockout models demonstrate multiple pathways by which AIP may contribute to tumorigenesis. This review assesses the current clinical and therapeutic characteristics of more than 200 FIPA families and addresses research findings among AIP mutation-bearing patients in different populations with pituitary adenomas.

Familial Isolated Pituitary Adenomas (FIPA) and the Pituitary Adenoma Predisposition due to Mutations in the Aryl Hydrocarbon Receptor Interacting Protein (AIP) Gene

Context: Pegvisomant is a GH receptor antagonist. The ACROSTUDY is a global safety surveillance study of long-term treatment of acromegaly with pegvisomant. Objective: The objective of the study was to monitor long-term safety and treatment outcomes. Design: ACROSTUDY is open to all patients with acromegaly who are treated with pegvisomant. We report an interim analysis of data captured from 1288 subjects enrolled before a database freeze of December 31, 2009. Setting: This was a global noninterventional surveillance study. Main Outcome Measure(s): Long-term monitoring of safety, including central magnetic resonance imaging (MRI) reading and treatment outcomes, was measured. Results: Subjects (n = 1288) were treated with pegvisomant for a mean of 3.7 yr and followed up in ACROSTUDY for a mean of 2.1 yr. A total of 1147 adverse events (AE) were recorded in 477 subjects (37%), among which 192 AE in 124 subjects (9.6%) were considered to be related to pegvisomant. Serious AE were recorded in 159 subjects (12...

/pdf/long-term-safety-of-pegvisomant-in-patients-with-acromegaly-19qaahc61g.pdf

Long-Term Safety of Pegvisomant in Patients with Acromegaly: Comprehensive Review of 1288 Subjects in ACROSTUDY

Responses of GH-secreting adenomas to multimodal management of acromegaly vary widely between patients. Understanding the behavioral patterns of GH-secreting adenomas by identifying factors predictive of their evolution is a research priority. The aim of this study was to clarify the relationship between the T2-weighted adenoma signal on diagnostic magnetic resonance imaging (MRI) in acromegaly and clinical and biological features at diagnosis. An international, multicenter, retrospective analysis was performed using a large population of 297 acromegalic patients recently diagnosed with available diagnostic MRI evaluations. The study was conducted at ten endocrine tertiary referral centers. Clinical and biochemical characteristics, and MRI signal findings were evaluated. T2-hypointense adenomas represented 52.9% of the series, were smaller than their T2-hyperintense and isointense counterparts (P<0.0001), were associated with higher IGF1 levels (P=0.0001), invaded the cavernous sinus less frequently (P=0.0002), and rarely caused optic chiasm compression (P<0.0001). Acromegalic men tended to be younger at diagnosis than women (P=0.067) and presented higher IGF1 values (P=0.01). Although in total, adenomas had a predominantly inferior extension in 45.8% of cases, in men this was more frequent (P<0.0001), whereas in women optic chiasm compression of macroadenomas occurred more often (P=0.0067). Most adenomas (45.1%) measured between 11 and 20 mm in maximal diameter and bigger adenomas were diagnosed at younger ages (P=0.0001). The T2-weighted signal differentiates GH-secreting adenomas into subgroups with particular behaviors. This raises the question of whether the T2-weighted signal could represent a factor in the classification of acromegalic patients in future studies.

/pdf/pituitary-mri-characteristics-in-297-acromegaly-patients-2l5lbyay40.pdf

Pituitary MRI characteristics in 297 acromegaly patients based on T2-weighted sequences

The molecular pathogenesis of prolactinomas has resisted elucidation; with the exception of a RAS mutation in a single aggressive prolactinoma, no mutational changes have been identified. In prolactinomas, a further obstacle has been the paucity of surgical specimens suitable for molecular analysis since prolactionomas are infrequently removed due to the availability and effectiveness of medical therapy. In the absence of mutational events, gene expression changes have been sought and detected. Using high-throughput analysis from a large bank of human pituitary adenomas, we examined these tumors according to their molecular profiles rather than traditional immunohistochemistry. We examined six prolactinomas and eight normal pituitary glands using oligonucleotide GeneChip microarrays, reverse transcription-real time quantitative polymerase chain reaction using 10 prolactinomas, and proteomic analysis to examine protein expression in four prolactinomas. Microarray analyses identified 726 unique genes that were statistically significantly different between prolactinomas and normal glands, whereas proteomic analysis identified four differently up-regulated and 19 down-regulated proteins. Several components of the Notch pathway were altered in prolactinomas, and there was an increased expression of the Pit-1 transcription factor, and the survival factor BAG1 but decreased E-cadherin and N-cadherin expression. Taken together, expression profiling and proteomic analyses have identified molecular features unique to prolactinomas that may contribute to their pathogenesis. In the current era of molecular medicine, these findings greatly enhance our understanding and supercede immunohistochemical diagnosis.

Molecular pathogenesis of human prolactinomas identified by gene expression profiling, RT-qPCR, and proteomic analyses

pdf/prospective-enterprise-level-molecular-genotyping-of-a-3dcs7gnxwd.pdf

Prospective enterprise-level molecular genotyping of a cohort of cancer patients

Gsα, the α-subunit of the heterotrimeric GTP-binding protein, is coded from the GNAS gene, which is imprinted in a tissue-specific manner. Gsα is paternally silenced in normal pituitary, but Gsα imprinting relaxation is found in some tumoral tissue. In addition, Gsα mRNA levels are high in some somatotroph adenomas not bearing the active Gsα mutant, the gsp oncogene. In this study, the impact of loss of imprinting on Gsα expression level and on tumoral phenotype has been investigated. We compared the expression and imprinting of 4 transcripts of GNAS locus (NESP55, XLαs, exon 1A, Gsα) of 60 somatotroph adenomas with those of 23 lactotroph adenomas. The paternal and maternal transcripts were quantified using allele-specific real-time PCR and FokI polymorphism. Moreover, the methylation of exon 1A DMR was analyzed. As is the case for the gsp oncogene, high Gsα expression in gsp- tumors was associated with smaller tumor size and better octreotide sensitivity. A strong imprinting relaxation (percentage of paternal Gsα expression ≥7.5%) was found only in gsp- tumors. The loss of Gsα imprinting was associated with a decrease in exon 1A mRNA expression. Unexpectedly, the methylation status of exon 1A DMR was not modified in relaxed tumors. Maternal Gsα mRNA level decreased with exon 1A level, and consequently the loss of Gsα imprinting did not induce the expected Gsα overexpression. Finally, XLαs mRNA level correlated with that of paternal Gsα and of NESP55 showing the complexity of gene regulation in the GNAS locus. © 2007 Wiley-Liss, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ijc.22816

Gs alpha overexpression and loss of Gs alpha imprinting in human somatotroph adenomas: association with tumor size and response to pharmacologic treatment.

Despite important advances in human therapeutics, no specific treatment for both non-functioning gonadotroph and resistant somatotroph adenomas is available. Gene transfer by viral vectors can be considered as a promising way to achieve a specific and efficient treatment. Here we show the possibility of efficient gene transfer in human pituitary adenoma cells in vitro using a human immunodeficiency virus (HIV)-type 1-derived vector. Using enhanced green fluorescent protein (eGFP) gene as a marker placed under the phosphoglycerate kinase (PGK) promoter, gonadotroph and somatotroph adenomas were transduced even with moderate viral loads. The expression started at day 2, reached a peak at day 5, and it was still present at day 90. For targeting somatotroph and gonadotroph adenomas, human growth hormone (GH) promoter (GH -481, +54 bp) and two fragments of the human glycoprotein hormone alpha-subunit promoter (alpha-subunit 1 -520, +33 bp, and alpha-subunit 2 -907, +33 bp) were tested. In gonadotroph adenomas, the percentage of identified fluorescent cells and the fluorescence intensity analyzed by fluorescence-activated cell sorting indicated that the strength of the alpha-subunit 1 and alpha-subunit 2 promoters were comparable to that of the PGK promoter. Primary cultures of rat pituitary cells showed that alpha-subunit 1 is more selective to thyreotroph and gonadotroph phenotypes than alpha-subunit 2. GH promoter activity appeared weak in somatotroph adenomas. The human GH enhancer did not increase the GH promoter activity at all but the human prolactin promoter (-250 bp) allowed 4-fold more fluorescent cells to be obtained than the GH promoter. Several cell lines appeared too permissive to test cell-specificity of pituitary promoters. However, on human non-pituitary cell cultures, the tested pituitary promoters seemed clearly selective to target endocrine pituitary phenotypes. This study gives a starting point for a gene-therapy program using lentiviral vectors to transfer therapeutic genes in human pituitary adenomas.

/pdf/lentiviral-vectors-efficiently-transduce-human-gonadotroph-1mijekmo10.pdf

Lentiviral vectors efficiently transduce human gonadotroph and somatotroph adenomas in vitro. Targeted expression of transgene by pituitary hormone promoters.

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Gs alpha overexpression and loss of Gs alpha imprinting in human somatotroph adenomas: association with tumor size and response to pharmacologic treatment.

Lentiviral vectors efficiently transduce human gonadotroph and somatotroph adenomas in vitro. Targeted expression of transgene by pituitary hormone promoters.