Pituitary adenomas are common neoplasms of the anterior pituitary gland. Germ-line mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene cause pituitary adenoma predisposition (PAP), a recent discovery based on genetic studies in Northern Finland. In this population, a founder mutation explained a significant proportion of all acromegaly cases. Typically, PAP patients were of a young age at diagnosis but did not display a strong family history of pituitary adenomas. To evaluate the role of AIP in pituitary adenoma susceptibility in other populations and to gain insight into patient selection for molecular screening of the condition, we investigated the possible contribution of AIP mutations in pituitary tumorigenesis in patients from Europe and the United States. A total of 460 patients were investigated by AIP sequencing: young acromegaly patients, unselected acromegaly patients, unselected pituitary adenoma patients, and endocrine neoplasia-predisposition patients who were negative for MEN1 mutations. Nine AIP mutations were identified. Because many of the patients displayed no family history of pituitary adenomas, detection of the condition appears challenging. Feasibility of AIP immunohistochemistry (IHC) as a prescreening tool was tested in 50 adenomas: 12 AIP mutation-positive versus 38 mutation-negative pituitary tumors. AIP IHC staining levels proved to be a useful predictor of AIP status, with 75% sensitivity and 95% specificity for germ-line mutations. AIP contributes to PAP in all studied populations. AIP IHC, followed by genetic counseling and possible AIP mutation analysis in IHC-negative cases, a procedure similar to the diagnostics of the Lynch syndrome, appears feasible in identification of PAP.immunohistochemistry ͉ growth hormone/prolacting-secreting adenomas ͉ acromegaly

Objective Pituitary corticotroph adenomas commonly cause Cushing’s disease (CD) but part of these tumours are hormonally inactive (silent corticotroph adenomas, SCA). USP8 mutations are well-known driver mutations in corticotrophinomas. Differences in transcriptomic profiles between functioning and silent tumours or tumours with different USP8 status have not been investigated. Design and methods Forty-eight patients (28 CD, 20 SCA) were screened for USP8 mutations with Sanger sequencing. Twenty-four patients were included in transcriptomic profiling with Ampliseq Transcriptome Human Gene Expression Core Panel. The entire patients group was included in qRT-PCR analysis of selected genes expression. Immunohistochemistry was used for visualization of selected protein. Results We found USP8 mutation in 15 patients with CD and 4 SCAs. USP8 mutations determine molecular profile of the tumours as showed by hierarchical clustering and identification of 1648 genes differentially expressed in USP8-mutated and USP8-wild-type tumours. Mutations affect many molecular pathways as observed in Gene Set Enrichment analysis. USP8-mutated adenomas showed higher level of POMC, CDC25A, MAPK4 but lower level of CCND2, CDK6, CDKN1B than USP8-wt tumours. Eighty-seven genes differentially expressed between CD-related adenomas and SCAs were found, including those involved in cell signalling (GLI2, DLC1, TBX2, RASSF6), cell adhesion (GJA1, CDH6), ion transport (KCNN4, KCNJ5) and GABA signalling (GABBR2, GABRD). Conclusion USP8 mutations occur in functioning and silent corticotrophinomas. They have pleiotropic effect, not limited to EGFR signalling, and affect expression levels of many genes involved in different pathways. Expression of GABA-related genes GABBR2, GNAL, GABARD and KCNJ5 correspond to functional status of the tumours.

ObjectiveCorticotroph macroadenomas are a rare cause of Cushing's disease (CD), but their properties are not well-recognised. The aim of this study was to evaluate the clinical and pathological aspects of corticotroph macroadenomas with particular emphasis on proliferation markers and their associations with the efficacy of surgical treatment.DesignA prospective cohort study was conducted in a tertiary referral centre in Poland.MethodsIn total, 59 patients with CD (20 macroadenomas and 39 microadenomas) were included in this study. Hormonal and imaging parameters, histopathological and ultrastructural features of the corticotroph tumours and the early surgical outcomes were evaluated.ResultsACTH and ACTH/cortisol ratios were higher in macroadenomas (P<0.001 and P=0.002 respectively). Greater tumour volumes were associated with higher Ki-67 and p53 expression (Ptrend=0.009 and Ptrend=0.024 respectively) and the rates of sparsely granulated adenomas (Ptrend=0.036). Immediate postoperative remission and early biochemical remission rates were lower in macroadenomas compared to microadenomas (P<0.001). A logistic regression model showed that the immediate postoperative remission or early biochemical remission depended on tumour volume (P=0.005 and P=0.006 respectively) and invasiveness based on Knosp grades 3 and 4 for macroadenomas and a lack of surgical pseudocapsule for microadenomas (P=0.004 and P=0.007 respectively).ConclusionCorticotroph macroadenomas differ from the more common microadenomas not only in terms of hormonal and imaging characteristics but also in terms of immunohistochemical and ultrastructural features and proliferation markers. The early effectiveness of surgery depends primarily on tumour volume and invasiveness.

While mutations were absent in non-GH-secreting adenoma patients, germline AIP mutations can be found in children and adolescents with GH-secreting tumours, even in the absence of family history. The present study reports the AIP mutation analysis results on patients of a single ethnic origin. Clearly, further studies are needed to improve our knowledge on the role of AIP in paediatric pituitary adenomas.

PurposeMCM7 (minichromosome maintenance complex component 7), a DNA replication licensing factor, is a host gene for the oncogenic miR-106b~25 cluster. It has been recently revealed as a relevant prognostic biomarker in a variety of cancers, including pituitary adenomas. The purpose of this study was to assess whether miR-106b~25 and MCM7 levels correlate with tumor invasiveness in a cohort of ACTH-immunopositive adenomas.MethodsTissue samples were obtained intraoperatively from 25 patients with pituitary adenoma. Tumor invasiveness was assessed according to the Knosp grading scale. MCM7, Ki-67 and TP53 levels were assessed by immunohistochemical staining, while the expression of miR-106b-5p, miR-93-5p, miR-93-3p and miR-25-3p were measured using quantitative real-time PCR performed on RNA isolated from FFPE tissues.ResultsWe have found a significant increase in MCM7 and Ki-67 labeling indices in invasive ACTHomas. Moreover, MCM7 was ubiquitously overexpressed in Crooke’s cell adenomas. The expression of miR-93-5p was significantly elevated in invasive compared to noninvasive tumors. In addition, all four microRNAs from the miR-106b~25 cluster displayed marked upregulation in Crooke’s cell adenomas. Remarkably, MCM7 and miR-106b-5p both strongly correlated with Knosp grade. A combination of MCM7 LI and miR-106b~25 cluster expression was able to accurately differentiate invasive from noninvasive tumors and had a significant discriminatory ability to predict postoperative tumor recurrence/progression.ConclusionsmiR-106b~25 and its host gene MCM7 are potential novel biomarkers for invasive ACTH-immunopositive pituitary adenomas. Additionally, they are both significantly upregulated in rare Crooke’s cell adenomas and might therefore contribute to their aggressive phenotype.