Relevance of mutations in protein deubiquitinases genes and TP53 in corticotroph pituitary tumors

Introduction

Corticotroph pituitary neuroendocrine tumors (PitNETs) develop from ACTH-producing cells. They commonly cause Cushing's disease (CD), however, some remain clinically silent. Recurrent USP8, USP48, BRAF and TP53 mutations occur in corticotroph PitNETs. The aim of our study was to determine frequency and relevance of these mutations in a possibly large series of corticotroph PitNETs.

Methods

Study included 147 patients (100 CD and 47 silent tumors) that were screened for hot-spot mutations in USP8, USP48 and BRAF with Sanger sequencing, while 128 of these patients were screened for TP53 mutations with next generation sequencing and immunohistochemistry.

Results

USP8 mutations were found in 41% CD and 8,5% silent tumors, while USP48 mutations were found in 6% CD patients only. Both were more prevalent in women. They were related to higher rate of biochemical remission, non-invasive tumor growth, its smaller size and densely granulated histology, suggesting that these mutation may be favorable clinical features. Multivariate survival analyses did not confirm possible prognostic value of mutation in protein deubiquitinases. No BRAF mutations were found. Four TP53 mutations were identified (2 in CD, 2 in silent tumors) in tumors with size >10mm including 3 invasive ones. They were found in Crooke's cell and sparsely granulated tumors. Tumors with missense TP53 mutations had higher TP53 immunoreactivity score than wild-type tumors. Tumor with frameshift TP53 variant had low protein expression. TP53 mutation was a poor prognostic factor in CD according to uni- and multivariate survival analyses in spite of low mutations frequency.

Conclusions

We confirmed high prevalence of USP8 mutations and low incidence of USP48 and TP53 mutations. Changes in protein deubiquitinases genes appear to be favorable prognostic factors in CD. TP53 mutations are rare, occur in both functioning and silent tumors and are related to poor clinical outcome in CD.

A systematic review on idiopathic intracranial hypertension comorbid with polycystic ovarian syndrome and its consequences

BACKGROUND

A few publications have examined the frequency and medical implications of individuals with idiopathic intracranial hypertension (IIH) and polycystic ovarian syndrome (PCOS), but the findings have been inconclusive. IIH and PCOS both mainly affect obese women of reproductive age and have an impact on women's health at various levels. The aim of this systematic review was to compare the prevalence and association between comorbid IIH and PCOS, and their effect on such aspects as metabolism, abnormalities in hormone levels, and reproduction.

METHODS

The criterion for inclusion was a research study of patients suffering from both syndromes. We excluded review articles, case reports, and papers with an inappropriate study design, patient population or outcomes. Electronic databases PubMed, Scopus, Web of Science and gray literature were searched to retrieve studies published from inception to June 10, 2023. The risk of bias assessment was conducted utilizing Covidence software and by discussion between co-authors.

RESULTS

After applying our inclusion/exclusion criteria, we consolidated the initial pool to a final selection of 9 articles, and 2185 patients with comorbidity of these two conditions. The prevalence of PCOS among patients with IIH was observed, with incidence rates ranging from 15.5% to 57%, which is up to 8 times greater, than the 4-10% prevalence of PCOS in the general population. These data may be valuable in clinical practice for both neurologists and gynecologists.

DISCUSSION

PCOS associated with obesity facilitates concurrence of IIH. The diagnosis of concurrence of IIH and PCOS may have significant clinical implications for patients due to the accompanying hormonal disorders, obesity-related consequences, and fertility issues. Other No systematic review was found. We have registered the study in PROSPERO (International prospective register of systematic reviews), and the registration number is CRD42023437485.

Pathologic Characteristics of Somatotroph Pituitary Tumors-An Observational Single-Center Study

The pathologic evaluation of a tumor tissue is an essential part of an acromegaly patient's assessment. This study aimed to analyze the pathologic characteristics of pituitary tumors in patients with acromegaly. The demographic data, in addition to the hormonal, imaging, and pathologic results of 120 patients with acromegaly after pituitary surgery, were extracted from the Polish Acromegaly Registry. We compared sparsely and densely granulated tumors, GH(+), mixed GH(+)/PRL(+) and plurihormonal tumors, α-subunit-positive and α-subunit-negative tumors, and tumors of various Ki-67 indices in terms of the abovementioned features. Sparsely granulated tumors were more frequent in women than in men (p = 0.001) and in younger patients (p = 0.011), and they were larger (p < 0.001) compared to densely granulated tumors. Tumors with positive α-subunit were smaller (p = 0.013), showed extrasellar extension less often (p = 0.039), and were more often densely granulated (p < 0.001) compared to α-subunit-negative tumors. Patients with a higher Ki-67 index were younger (p < 0.001) and more often diagnosed with genetic syndromes (p = 0.02); they had higher GH concentrations (p = 0.007), larger tumors (p = 0.006), and cavernous sinus invasions more frequently (p = 0.022). Conclusions: The pathologic characteristics of somatotroph pituitary tumors are associated with patient's age, sex, hormonal results, tumor size, and the degree of extrasellar expansion.

DNA Methylation Pattern in Somatotroph Pituitary Neuroendocrine Tumors

INTRODUCTION

Growth hormone secretion by sporadic somatotroph neuroendocrine pituitary tumors (PitNETs) is a major cause of acromegaly. These tumors are relatively heterogenous in terms of histopathological and molecular features. Our previous transcriptomic profiling of somatotroph tumors revealed three distinct molecular subtypes. This study aimed to investigate the difference in DNA methylation patterns in subtypes of somatotroph PitNETs and its role in distinctive gene expression.

METHODS

Genome-wide DNA methylation was investigated in 48 somatotroph PitNETs with EPIC microarrays. Gene expression was assessed with RNAseq. Bisulfite pyrosequencing and qRT-PCR were used for verifying the results of DNA methylation and gene expression.

RESULTS

Clustering tumor samples based on methylation data reflected the transcriptome-related classification. Subtype 1 tumors are densely granulated without GNAS mutation, characterized by high expression of NR5A1 (SF-1) and GIPR. The expression of both genes is correlated with specific methylation of the gene body and promoter. This subtype has a lower methylation level of 5' gene regions and CpG islands than the remaining tumors. Subtype 2 PitNETs are densely granulated and frequently GNAS-mutated, while those in subtype 3 are mainly sparsely granulated. Methylation/expression analysis indicates that ∼50% genes located in differentially methylated regions are those differentially expressed between tumor subtypes. Correlation analysis revealed DNA methylation-controlled genes, including CDKN1B, CCND2, EBF3, CDH4, CDH12, MGMT, STAT5A, PLXND1, PTPRE, and MMP16, and genes encoding ion channels and semaphorins.

CONCLUSION

DNA methylation profiling confirmed the existence of three molecular subtypes of somatotroph PitNETs. High expression of NR5A1 and GIPR in subtype 1 tumors is correlated with specific methylation of both genes.

DNA methylation, combined with RNA sequencing, provide novel insight into molecular classification of chordomas and their microenvironment

Chordomas are rare tumors of notochord remnants, occurring mainly in the sacrum and skull base. Despite of their unusually slow growth, chordomas are highly invasive and the involvement of adjacent critical structures causes treatment challenges. Due to the low incidence, the molecular pathogenesis of this entity remains largely unknown. This study aimed to investigate DNA methylation abnormalities and their impact on gene expression profiles in skull base chordomas. 32 tumor and 4 normal nucleus pulposus samples were subjected to DNA methylation and gene expression profiling with methylation microarrays and RNA sequencing. Genome-wide DNA methylation analysis revealed two distinct clusters for chordoma (termed subtypes C and I) with different patterns of aberrant DNA methylation. C Chordomas were characterized by general hypomethylation with hypermethylation of CpG islands, while I chordomas were generally hypermethylated. These differences were reflected by distinct distribution of differentially methylated probes (DMPs). Differentially methylated regions (DMRs) were identified, indicating aberrant methylation in known tumor-related genes in booth chordoma subtypes and regions encoding small RNAs in subtype C chordomas. Correlation between methylation and expression was observed in a minority of genes. Upregulation of TBXT in chordomas appeared to be related to lower methylation of tumor-specific DMR in gene promoter. Gene expression-based clusters of tumor samples did not overlap with DNA methylation-based subtypes. Nevertheless, they differ in transcriptomic profile that shows immune infiltration in I chordomas and up-regulation of cell cycle in C chordomas. Immune enrichment in chordomas I was confirmed with 3 independent deconvolution methods and immunohistochemistry. Copy number analysis showed higher chromosomal instability in C chordomas. Nine out of eight had deletion of CDKN2A/B loci and downregulation of genes encoded in related chromosomal band. No significant difference in patients' survival was observed between tumor subtypes, however, shorter survival was observed in patients with higher number of copy number alterations.

The expression of glucocorticoid and mineralocorticoid receptors in pituitary tumors causing Cushing's disease and silent corticotroph tumors

OBJECTIVE

Pituitary neuroendocrine corticotroph tumors commonly cause Cushing's disease (CD) that results from increased adrenocorticotropic hormone (ACTH) secretion by the pituitary tumor and consequent increase of cortisol levels in blood. However, in some patients, corticotroph tumors remain clinically non-functioning. Cortisol secretion is regulated by the hypothalamic-pituitary-adrenal axis and includes a negative feedback between cortisol and ACTH secretion. Glucocorticoids reduce ACTH level both by hypothalamic regulation and acting on corticotrophs via glucocorticoid (GR) and mineralocorticoid (MR) receptors. The aim of the study was to determine the role of GR and MR expression at mRNA and protein levels in both functioning and silent corticotroph tumors.

METHODS

Ninety-five patients were enrolled, including 70 with CD and 25 with silent corticotroph tumors. Gene expression levels of NR3C1 and NR3C2 coding for GR and MR, respectively, were determined with qRT-PCR in the two tumor types. GR and MR protein abundance was assessed with immunohistochemistry.

RESULTS

Both GR and MR were expressed in corticotroph tumors. Correlation between NR3C1 and NR3C2 expression levels was observed. NR3C1 expression was higher in silent than in functioning tumors. In CD patients NR3C1 and NR3C2 levels were negatively correlated with morning plasma ACTH levels and tumor size. Higher NR3C2 was confirmed in patients with remission after surgery and in densely granulated tumors. Expression of both genes and GR protein was higher in USP8-mutated tumors. Similar relationship between USP8 mutations and expression levels were observed in analysis of silent tumors that also revealed a negative correlation between GR and tumor size and higher NR3C1 expression in densely granulated tumors.

CONCLUSIONS

Although the associations between gene/protein expression and patients clinical features are not strong, they consistently show an evident trend in which higher receptor expression corresponds to more favorable clinical characteristics.

The Expression of Cell Cycle-Related Genes in USP8-Mutated Corticotroph Neuroendocrine Pituitary Tumors and Their Possible Role in Cell Cycle-Targeting Treatment

Protein deubiquitinases USP8 and USP48 are known driver genes in corticotroph pituitary neuroendocrine tumors (PitNETs). USP8 mutations have pleiotropic effects that include notable changes in genes' expression. Genes involved in cell cycle regulation were found differentially expressed in mutated and wild-type tumors. This study aimed to verify difference in the expression level of selected cell cycle-related genes and investigate their potential role in response to cell cycle inhibitors. Analysis of 70 corticotroph PitNETs showed that USP8-mutated tumors have lower CDKN1B, CDK6, CCND2 and higher CDC25A expression. USP48-mutated tumors have lower CDKN1B and CCND1 expression. A lower p27 protein level in mutated than in wild-type tumors was confirmed that may potentially influence the response to small molecule inhibitors targeting the cell cycle. We looked for the role of USP8 mutations or a changed p27 level in the response to palbociclib, flavopiridol and roscovitine in vitro using murine corticotroph AtT-20/D16v-F2 cells. The cells were sensitive to each agent and treatment influenced the expression of genes involved in cell cycle regulation. Overexpression of mutated Usp8 in the cells did not affect the expression of p27 nor the response to the inhibitors. Downregulating or upregulating p27 expression in AtT-20/D16v-F2 cells also did not affect treatment response.

Clinical, hormonal and pathomorphological markers of somatotroph pituitary neuroendocrine tumors predicting the treatment outcome in acromegaly

BACKGROUND

Transsphenoidal adenomectomy (TSS) of somatotroph pituitary neuroendocrine tumor (PitNET) is the first-line treatment of acromegaly. Pharmacological treatment is recommended if surgery is contraindicated or did not lead to disease remission. The choice of treatment best fitting each patient should be based on thorough investigation of patients' characteristics. The current analysis attempts to create a tool for personalized treatment planning.

AIM

This study aimed to assess whether clinical, biochemical, imaging and pathological characteristics can predict surgical remission and response to first-generation somatostatin receptor ligands (SRLs) and pasireotide-LAR in acromegaly.

PATIENTS AND METHODS

A retrospective study of 153 acromegaly patients, treated in the Department of Endocrinology in Bielanski Hospital in Warsaw, Poland was performed. Data on demographics, hormonal and imaging results, pathological evaluation, and treatment outcome was extracted from the Polish Acromegaly Registry collecting information from 11 endocrinology centers in Poland and analyzed.

RESULTS

Patients with surgical remission had lower GH and IGF-1 concentrations at diagnosis (median GH 5.5 µg/L [IQR: 3.1-16.0] vs. 19.9 µg/L [IQR: 9.8-42.4], p=<0.001 and mean IGF-1 3.1xULN ± SD=1.2 vs. 3.7xULN ± SD=1.2, p=0.007, respectively) and smaller tumors (median 12.5mm [IQR: 9-19] vs. 23mm [IQR: 18-30], p<0.001). These tumors were more often densely granulated (DG) (73.2% vs. 40.0%, p=0.001) with positive staining for alpha-subunit (α-SU) (58.3% vs. 35.5%, p=0.021) and lower Ki-67 index (p=0.002). Patients responding well to SRLs were more often male (55.6% vs 44.4%, p=0.026), presented lower GH concentration (median GH 17.2 µg/L [IQR: 6.2-29.0] vs. 23.8 µg/L [IQR: 11.2-49.5], p=0.048) and had more often DG tumors (63.0% vs. 14.3%, p<0.001). No significant differences between good and poor-response to pasireotide-LAR groups were found. In multivariate logistic regression analysis fasting GH concentration <8.63 µg/L, maximal tumor diameter <15.5mm, normoprolactinemia and DG tumor turned out to be independent predictors of surgical remission (OR=0.92, p=0.026; OR=0.87, p=0.069, OR=3.86, p=0.096 and OR=3.05, p=0.181, respectively). Fasting GH concentration <36.6 µg/L and DG tumor turned out to be independent predictors of good response to first-generation SRLs (OR=0.96, p=0.06 and OR=10.68, p=0.002, respectively).

CONCLUSIONS

Younger age at diagnosis, male sex, lower GH, IGF-1 and PRL concentrations, smaller tumor size at diagnosis as well as positive α-SU staining, lower Ki-67 index and DG tumors predicted better treatment outcome in acromegaly patients.

Corticotroph Aggressive Pituitary Tumors and Carcinomas Frequently Harbor ATRX Mutations

CONTEXT

Aggressive pituitary tumors (APTs) are characterized by unusually rapid growth and lack of response to standard treatment. About 1% to 2% develop metastases being classified as pituitary carcinomas (PCs). For unknown reasons, the corticotroph tumors are overrepresented among APTs and PCs. Mutations in the alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene, regulating chromatin remodeling and telomere maintenance, have been implicated in the development of several cancer types, including neuroendocrine tumors.

OBJECTIVE

To study ATRX protein expression and mutational status of the ATRX gene in APTs and PCs.

DESIGN

We investigated ATRX protein expression by using immunohistochemistry in 30 APTs and 18 PCs, mostly of Pit-1 and T-Pit cell lineage. In tumors lacking ATRX immunolabeling, mutational status of the ATRX gene was explored.

RESULTS

Nine of the 48 tumors (19%) demonstrated lack of ATRX immunolabelling with a higher proportion in patients with PCs (5/18; 28%) than in those with APTs (4/30;13%). Lack of ATRX was most common in the corticotroph tumors, 7/22 (32%), versus tumors of the Pit-1 lineage, 2/24 (8%). Loss-of-function ATRX mutations were found in all 9 ATRX immunonegative cases: nonsense mutations (n = 4), frameshift deletions (n = 4), and large deletions affecting 22-28 of the 36 exons (n = 3). More than 1 ATRX gene defect was identified in 2 PCs.

CONCLUSION

ATRX mutations occur in a subset of APTs and are more common in corticotroph tumors. The findings provide a rationale for performing ATRX immunohistochemistry to identify patients at risk of developing aggressive and potentially metastatic pituitary tumors.

Invasive and Noninvasive Nonfunctioning Gonadotroph Pituitary Tumors Differ in DNA Methylation Level of LINE-1 Repetitive Elements

PURPOSE

Epigenetic dysregulation plays a role in pituitary tumor pathogenesis. Some differences in DNA methylation were observed between invasive and noninvasive nonfunctioning gonadotroph tumors. This study sought to determine the role of DNA methylation changes in repetitive LINE-1 elements in nonfunctioning gonadotroph pituitary tumors.

METHODS

We investigated LINE-1 methylation levels in 80 tumors and normal pituitary glands with bisulfite-pyrosequencing. Expression of two LINE-1 open reading frames (L1-ORF1 and L1-ORF2) was analyzed with qRT-PCR in tumor samples and mouse gonadotroph pituitary cells treated with DNA methyltransferase inhibitor. Immunohistochemical staining against L1-ORF1p was also performed in normal pituitary glands and tumors.

RESULTS

Hypomethylation of LINE-1 was observed in pituitary tumors. Tumors characterized by invasive growth revealed lower LINE-1 methylation level than noninvasive ones. LINE-1 methylation correlated with overall DNA methylation assessed with HM450K arrays and negatively correlated with L1-ORF1 and L1-ORF2 expression. Treatment of αT3-1 gonadotroph cells with 5-Azacytidine clearly increased the level of L1-ORF1 and L1-ORF2 mRNA; however, its effect on LβT2 cells was less pronounced. Immunoreactivity against L1-ORF1p was higher in tumors than normal tissue. No difference in L1-ORF1p expression was observed in invasive and noninvasive tumors.

CONCLUSION

Hypomethylation of LINE-1 is related to invasive growth and influences transcriptional activity of transposable elements.

DNA Methylation Influences miRNA Expression in Gonadotroph Pituitary Tumors

microRNAs are involved in pathogenesis of cancer. DNA methylation plays a role in transcription of miRNA-encoding genes and may contribute to changed miRNA expression in tumors. This issue was not investigated in pituitary neuroendocrine tumors (PitNETs) previously. DNA methylation patterns, assessed with HumanMethylation450K arrays in 34 PitNETs and five normal pituitaries, were used to determine differentially methylated CpGs located at miRNA genes. It showed aberrant methylation in regions encoding for 131 miRNAs. DNA methylation data and matched miRNA expression profiles, determined with next-generation sequencing (NGS) of small RNAs, were correlated in 15 PitNETs. This showed relationship between methylation and expression levels for 12 miRNAs. DNA methylation and expression levels of three of them (MIR145, MIR21, and MIR184) were determined in the independent group of 80 tumors with pyrosequencing and qRT-PCR and results confirmed both aberrant methylation in PitNETs and correlation between methylation and expression. Additionally, in silico target prediction was combined with analysis of established miRNA profiles and matched mRNA expression pattern, assessed with amplicon-based NGS to indicate putative target genes of epigenetically deregulated miRNAs. This study reveals aberrant DNA methylation in miRNA-encoding genes in gonadotroph PitNETs. Methylation changes affect expression level of miRNAs that regulate putative target genes with tumorigenesis-relevant functions.

The Search of miRNA Related to Invasive Growth of Nonfunctioning Gonadotropic Pituitary Tumors

PURPOSE

Nonfunctioning gonadotropic pituitary neuroendocrine tumors (PitNETs) are among the most frequent neoplasms of pituitary gland. Although PitNETs are commonly considered benign, a notable part of patients suffer from tumor recurrence after treatment. Invasive growth of pituitary tumor is among the most important prognostic factors. Since molecular features of invasiveness are of potential clinical usefulness, this study was aimed to verify whether invasive and noninvasive nonfunctioning gonadotropic PitNETs differ in the miRNA expression profile and whether the differences could provide a possible molecular classifier.

METHODS

miRNA profiles were determined in 20 patients (11 invasive and 9 noninvasive tumors) using next-generation sequencing. The expression of selected miRNAs was assessed in the independent cohort of 80 patients with qRT-PCR.

RESULTS

When miRNA profiles of invasive and noninvasive tumors were compared, 29 miRNAs were found differentially expressed. Hsa-miR-184, hsa-miR-181a-2-3p, hsa-miR-93-3p, hsa-miR-574-5p, hsa-miR-185-5p, and hsa-miR-3200-5p showed a potential clinical value according to ROC curve analysis. Unfortunately, differential expression of only hsa-miR-185-5p was confirmed in the validation cohort, with AUG at 0.654.

CONCLUSION

Differences in miRNAs expression profiles in invasive and noninvasive gonadotropic PitNETs are slight and the level of miRNA expression seems not to be applicable as useful classifier of tumor invasiveness.

USP8 mutations in corticotroph adenomas determine a distinct gene expression profile irrespective of functional tumour status

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.

The Role of Aberrant DNA Methylation in Misregulation of Gene Expression in Gonadotroph Nonfunctioning Pituitary Tumors

Gonadotroph nonfunctioning pituitary adenomas (NFPAs) are common intracranial tumors, but the role of aberrant epigenetic regulation in their development remains poorly understood. In this study, we investigated the effect of impaired CpG methylation in NFPAs. We determined DNA methylation and transcriptomic profiles in 32 NFPAs and normal pituitary sections using methylation arrays and sequencing, respectively. Ten percent of differentially methylated CpGs were correlated with gene expression, and the affected genes are involved in a variety of tumorigenesis-related pathways. Different proportions of gene body and promoter region localization were observed in CpGs with negative and positive correlations between methylation and gene expression, and different proportions of CpGs were located in 'open sea' and 'shelf/shore' regions. The expression of ~8% of genes differentially expressed in NFPAs was related to aberrant methylation. Methylation levels of seven CpGs located in the regulatory regions of FAM163A, HIF3A and PRSS8 were determined by pyrosequencing, and gene expression was measured by qRT-PCR and immunohistochemistry in 83 independent NFPAs. The results clearly confirmed the negative correlation between methylation and gene expression for these genes. By identifying which aberrantly methylated CpGs affect gene expression in gonadotrophinomas, our data confirm the role of aberrant methylation in pathogenesis of gonadotroph NFPAs.

DNA methylation profiling in nonfunctioning pituitary adenomas

Nonfunctioning pituitary adenomas (NFPAs) are among the most frequent intracranial tumors but their molecular background, including changes in epigenetic regulation, remains poorly understood. We performed genome-wide DNA methylation profiling of 34 NFPAs and normal pituitary samples. Methylation status of the selected genomic regions and expression level of corresponding genes were assessed in a group of 75 patients. NFPAs exhibited distinct global methylation profile as compared to normal pituitary. Aberrant DNA methylation appears to contribute to deregulation of the cancer-related pathways as shown by preliminary functional analysis. Promoter hypermethylation and decreased expression level of SFN, STAT5A, DUSP1, PTPRE and FGFR2 was confirmed in the enlarged group of NFPAs. Difference in the methylation profiles between invasive and non-invasive NFPAs is very slight. Nevertheless, invasiveness-related aberrant epigenetic deregulation of the particular genes was found including upregulation of ITPKB and downregulation CNKSR1 in invasive tumors.

Telomere length and TERT abnormalities in pituitary adenomas

OBJECTIVES

Pituitary adenomas (PAs) are among the most frequent intracranial tumors in humans. Abnormal telomerase activity and telomere lengthening are features of tumor cells. They may result from mutations in TERT promoter region, gene amplification or aberrant DNA methylation pattern. Such changes were found in variety of tumors including those of brain. Aim of the study was to evaluate the incidence of TERT abnormalities and to assess their role in telomere lengthening in PAs.

METHODS

Study involved 101 patients with PA including both nonfunctioning and functioning subtypes. Telomerase length as well as TERT mRNA level and gene amplification were estimated using quantitative PCR (qPCR). Promoter mutations were assessed using Sanger sequencing. The results from genome-wide DNA methylation profiling with HumanMethylation 450K (Illumina) were used for the analysis of TERT locus.

RESULTS

Variable telomere length was observed in patients, however no relationship with clinicopathological features was found. We observed a missense variant in TERT promoter in one patient only whereas increased TERT copy number were identified in 6 patients (5.6%). However no relationship between these results and telomere length or TERT expression was found. DNA methylation at TERT locus was not found to be changed when adenoma samples and normal tissue sections were compared.

CONCLUSION

The results indicate that telomerase abnormalities do not play a role in pathogenesis of pituitary tumors.

AB thymoma with atypical type A component with delayed multiple lung and brain metastases

An atypical type A thymoma is a newly added entity to the last World Health Organization (WHO) histological classification [2015] of uncertain prognosis. The conventional type A and AB thymomas are usually locally aggressive neoplasms that rarely metastasize with distant metastases to the central nervous system (CNS) occurring extremely exceptionally. We present a history of a woman with a mediastinal tumor originally considered to be a Masaoka-Koga stage II "mixed thymoma with well-differentiated thymic carcinoma component" according to the historic Müller-Hermelink nomenclature. By applying the criteria of the new WHO classification the tumor should be reclassified as an AB thymoma with an atypical A component. The patient developed metastases to the lung and brain 10 and 15 years after the original diagnosis, respectively. All metastases morphologically corresponded to an atypical A component of primary thymoma. Molecular study revealed GTF2I mutations in the primary and one of the metastatic tumors. To our knowledge, this is the first description of a GTF2I mutation in AB thymoma with atypical A component and its metastases. The presented case highlights the necessity of an accurate microscopic search for atypical areas in A or AB thymomas because of their potentially negative impact on prognosis.

Microsatellite instability analysis in pituitary adenomas

OBJECTIVE

Mutator phenotypes with microsatellite instability (MSI) are observed in a subset of solid tumors including those localized in the brain. MSI arises from impaired DNA mismatch repair. It can be a potential marker of resistance to radiation and chemotherapy, as demonstrated for several cancer types. Our study aims are to investigate MSI incidence in pituitary adenomas (PA) with a currently recommended methodology.

METHODS

DNA was obtained from 107 patients with PA of which 83 adenomas were nonfunctioning, 13 somatotrophic, 9 lactotrophic and 2 corticotrophic. These were examined for MSI status by PCR and capillary electrophoresis using five quasimonomorphic microsatellite markers: BAT25, BAT26, NR21, NR24 and NR27; in accordance to current Bethesda guidelines.

RESULTS AND CONCLUSION

No microsatellite instability was detected in the tumor samples thus implying the lack of any clinical usefulness of MSI testing in PA cases.

Image-guided dissection of human white matter tracts as a new method of modern neuroanatomical training

Neuronavigation is a kind of image-guided surgery used during neurosurgical procedures. Based on specific equipment which is compatible with the software calculating and processing the patient's data; this method allows the determination of the location of anatomical structures and visualisation of surgical instruments in the operative field. Although standard brain dissection is still the best method of neuroanatomical training, some limitations occur. The most important of these is the inability of conversion from three-dimensional (3D) view to flat pictures of the brain structures, as viewed on computed tomography (CT) and magnetic resonance imaging (MRI), being essential in neuroanatomical training nowadays. The aim of the study was the implementation of a neuronavigating system for brain anatomy training purposes. The study was performed on 10 human brain hemispheres, dissected due to classical methods (standard brain anatomical sections, stepwise ventricular system opening and partial dissection of white matter tracts using Klingler's dissection technique). The material was scanned in a 1.5 T magnetic resonance scanner using a modified neuronavigation protocol. The brains were prepared before dissection as proposed by Klingler. The subsequent steps of the dissection were documented with a digital camera. The progress of the dissection was visualised using the neuronavigation system (Medtronic Stealth Station Treon) with cranial application software. In the course of the study, numerous 3D and 2D images were obtained. The images were related to each other and linked anatomical structures in the specimen with their appearance on CT and MRI scans. The implementation of a neuronavigation system for brain structures dissection facilitates visualization and understanding of their proper location. This new method offers a constant and precise orientation and simplifies understanding of the relation of the 3D view of a specimen to that of the 2D image.

BubR1 is involved in regulation of DNA damage responses

Defective mitotic spindles or an impaired spindle-kinetochore interaction activates the spindle checkpoint. We have previously shown that BubR1 haplo-insufficiency results in enhanced genomic instability and tumorigenesis in mice. Here we report that BubR1 deficiency also leads to a compromised response to DNA damage. Following treatment with doxorubicin, BubR1(+/-) murine fibroblast cells (MEF) were defective in undergoing G(2)/M arrest. Thus, whereas in the presence of DNA damage BubR1(+/+) MEF cells remained arrested in mitosis, BubR1(+/-) MEFs rapidly exited from mitosis and divided. The impaired mitotic arrest of BubR1(+/-) MEFs was associated with low levels of phospho-histone H2AX, p53, and p21 after DNA damage caused by treatment with both doxorubicin and ultraviolet light (UV). The impaired expression of p53 and p21 was also confirmed in human cell lines with BubR1 knockdown via RNA interference. Affinity pull-down coupled with mass spectrometry identified Poly(ADP-ribose) polymerase 1 (PARP-1) as one of the proteins interacting with BubR1. Reciprocal co-immunoprecipitation analysis confirmed the physical interaction between BubR1 and PARP-1. Our further study revealed that the ability of retaining intact PARP-1 or its cleavage product p89 was compromised in BubR1(+/-) MEFs upon treatment with doxorubicin or UV. Given that PARP-1 mediates DNA damage responses and regulates the activity of p53, our studies suggest that there exists a cross-talk between the spindle checkpoint and the DNA damage checkpoint and that BubR1 may play an important role in mediating the cross-talk.

Endoscopic anatomy of the chordae willisii in the superior sagittal sinus

Object. Chordae willisii are structures located in the lumen of the superior sagittal sinus (SSS). It is thought that they act as flow-improving structures within the sinuses. There are few anatomical descriptions of chordae willisii, and all previous observations were performed through standard anatomical dissections. The purpose of this study was to visualize and describe structural and topographical features of the chordae willisii with the aid of rigid endoscopy.

Methods. Twenty-five SSSs obtained from fresh human cadavers during autopsies were the material for this study. Specimens were flushed with tap water to remove clots. Bridging veins emptying into the sinus were ligated, and continuous flow of a saline solution through the sinus in a physiological direction was achieved by connecting the sinus to an irrigating system. Rigid endoscopes of different diameters (2.7–4.5 mm) and optic (0 and 30°) were inserted into the lumen of the sinus. The endoscope was connected to a digital camera and a video system to allow for recording of the observed structures. Finally, the sinuses were opened and the chordae willisii were dissected using standard anatomical methods.

The chordae willisii were observed in all examined specimens. Three different types of the cords were found: lamellar, trabecular, and valvelike types. The most common type was the valvelike (mixed) one, which comprised 45.1% of all cords. The chordae willisii were most commonly observed in the parietooccipital region of the SSS.

Conclusions. Witout disturbing any structural relationships, the use of endoscopy allowed visualization and description of intraluminal structures as they behaved physiologically.

Chlorophyllin protects cells from the cytostatic and cytotoxic effects of quinacrine mustard but not of nitrogen mustard

Chlorophyllin (CHL), the sodium and copper salt of chlorophyll, is capable of inhibiting the mutagenic activity of many chemical compounds. Several mechanisms have been advanced to explain the antimutagenic activity of CHL, including its antioxidant properties and its ability to form complexes with mutagens. The present study was designed to reveal whether the heterocyclic aromatic nature of a potential mutagen is essential to its sensitivity to CHL. Toward this end, the inhibitory effect of CHL on two compounds of similar chemical reactivity (mustards), that either embodied an aromatic structure (quinacrine mustard; QM) or did not (nitrogen mustard; NM), were compared. Human leukemic HL-60 and breast carcinoma MCF-7 cells were treated with QM or NM in the absence or presence of various concentrations of CHL. Both QM and NM when administered for 1-2 h at micromolar concentrations exerted similar effects; both arrested cells in G2 phase of the cell cycle, induced apoptosis and reduced the clonogenicity of MCF-7 cells. The simultaneous addition of 0.22 M CHL to cultures receiving QM virtually abolished the QM-induced inhibition of cell growth and clonogenicity. In contrast, CHL had no effect on reducing the cytostatic or cytotoxic activity of NM. CHL alone, at a concentration of 0.22 M, had minimal effect on growth of HL-60 cells slightly perturbing their progression through G2. The results are consistent with the model that explains the inhibition of the activity of mutagens or antitumor drugs with aromatic structures by CHL as mediated by its ability to sequester these molecules within heterologous mutagen:CHL complexes that are maintained by stacking interactions. Therefore, excess of chlorophyll in the diet, by sequestering aromatic mutagens (or antitumor drugs with a heterocyclic structure, if taken orally), may inhibit their accessibility to cells, thereby reducing their activity.

Translocation of Bax to mitochondria during apoptosis measured by laser scanning cytometry

BACKGROUND

During induction of apoptosis, the pro-apoptotic member of the Bcl-2 protein family (Bax) undergoes translocation to the mitochondria. The translocation, which leads to accumulation of Bax in the mitochondrial intermembrane space, appears to be the critical event determining release of cytochrome c to cytosol: the latter event triggers the irreversible steps of apoptosis, namely, the activation of caspases and the initiation of the degradation of many proteins. The aim of this study was to utilize the morphometric capabilities of the laser scanning cytometer (LSC) and adapt this instrument to detect and measure in situ the process of translocation of Bax to mitochondria.

METHODS

Human breast carcinoma MCF-7 cells growing on microscope slides were treated with the DNA topoisomerase I inhibitor, camptothecin (CPT). CPT is known to induce apoptosis preferentially of S-phase cells. The cells were fixed and permeabilized on the slides, their DNA was stained with propidium iodide (PI), Bax was detected immunocytochemically with the fluoresceinated antibody, and red and green fluorescence emission was measured by the LSC.

RESULTS

Prior to induction of apoptosis, Bax was uniformly and diffusely dispersed in the cell nucleus and cytoplasm. Its translocation and accumulation in mitochondria in cells undergoing apoptosis were detected and measured by the LSC as the increase in intensity of maximal pixel of Bax immunofluorescence. Bivariate analysis of DNA content versus maximal pixel of Bax fluorescence revealed that the CPT-induced Bax translocation into mitochondria was preferential to S-phase cells. Total cellular Bax immunofluorescence measured by flow cytometry, however, was increased in all phases of the cycle without a preference to S-phase cells.

CONCLUSION

Changes in abundance and localization of particular proteins that undergo translocation within the cell, leading to their altered local density, may be conveniently detected by the LSC by taking advantage of its morphometric capabilities. Measurement of total cellular Bax immunofluorescence by flow cytometry combined with analysis of its translocation by LSC revealed that apoptosis of S-phase cells induced by CPT was unrelated to overall Bax abundance per cell but correlated with its accumulation in mitochondria.

Dysfunctional platelet glycoprotein IIb/IIIa associated with a platelet release defect: a family study

We are reporting on a 36-year-old white female with a bleeding history attributed to dysfunctional platelet glycoprotein IIb/IIIa (GPIIb/IIIa) and a coexisting platelet release defect. Platelet aggregation studies (PAS) revealed markedly diminished to absent responses to ADP, epinephrine, collagen and arachidonic acid; the ristocetin response was normal. ATP content was normal with poor release to the agonists as measured by luminescent technique. DDAVP infusion shortened bleeding time from 13.5 min to 8.0 and 12 min (at 1 and 2 hours). Flow cytometry and immunoblotting revealed normal amounts of GPIIb and diminished GPIIIa (50% of control). Using a previously reported ELISA which measures the binding of GPIIb/IIIa to immobilized fibrinogen, the patient's platelet extract showed no binding to fibrinogen. Both the father and mother were found to have decreased PAS responses and normal amounts of GPIIb/IIIa determined by both Western blot and flow cytometry. However, the ELISA showed decreased binding of their GPIIb/IIIa to fibrinogen (71% and 62% as compared to controls, respectively). The patient's dysfunctional fibrinogen receptor was clearly demonstrated by the ELISA. The parents had moderately reduced GPIIb/IIIa function in this assay, but they did not demonstrate a reduced GPIIIa as was noted in the patient. The parents' PAS indicated a platelet release defect. These findings suggest an inherited platelet release defect and a dysfunctional GPIIIa. The partial response to DDAVP would be compatible with the presence of a platelet release defect.

Procurement and identification of HL-A lymphocytotoxic antibodies in sera of nonpregnant, multiparous blood donors

An efficient procedure for large-scale screening of nonpregnant multiparous blood donor sera is described. Yield of useful HL-A reagents in this population compares favorably to yields obtained from screening pregnant women near term. The advantages of screening nonpregnant donors include stable antibody titers, ease of procurement, and the willingness of voluntary blood donors to return for plasmapheresis.