Kristin Astrid Berland Øystese

Non-functioning pituitary adenomas: growth and aggressiveness

Pituitary adenomas (PAs) are common, comprising approximately one third of all intracranial tumors. Non-functioning pituitary adenomas (NFPAs) are the most common PAs. Although usually benign, the NFPAs represent therapeutic challenges because of their location close to the optic chiasm and nerves, and the proximity to the pituitary gland. The therapeutic alternatives are surgery and radiation. To date there is no effective medical treatment. NFPAs are classified according to different modalities, but there are no reliable marker of aggressiveness to guide the clinician in monitoring the patient. More information on growth patterns with constituent biological markers are needed to tailor the care of this patient group. Studies characterizing the membrane receptors of NFPAs have shown promising results, which may give rise to the development of medical treatment.

Estrogen Receptor α, a Sex-Dependent Predictor of Aggressiveness in Nonfunctioning Pituitary Adenomas: SSTR and Sex Hormone Receptor Distribution in NFPA

Context: Nonfunctioning pituitary adenomas (NFPAs) are fairly common and require a multidisciplinary approach. Reliable markers of a clinically aggressive course are lacking. Medical treatment is not available, and transsphenoidal surgery is the preferred primary treatment. Objective: We aimed to characterize the somatostatin, estrogen, and progesterone receptor distribution for NFPAs and compare it with factors of tumor aggressiveness. Design: Tumor samples for immunohistochemistry (n = 145) and quantitative reverse transcription polymerase chain reaction (n = 106) analyses of somatostatin receptor (SSTR) 1, SSTR2, SSTR3, SSTR5, estrogen receptor &agr; (ER&agr;), and progesterone receptor (PR) were measured by immunoreactive score (IRS) and messenger RNA relative quantity and retrospectively compared with variables of aggressiveness. Setting: All patients were operated at the same tertiary referral center. Participants: A total of 164 patients with NFPA and tumor tissue from the primary operation were included. Results: SSTR3 was expressed abundantly by immunohistochemistry in all NFPAs. The IRS of ER&agr; correlated with that of SSTR2 in male patients only (males, P < 0.001; females, P = 0.8). Low ER&agr; level was linked to a higher reintervention rate (P = 0.001) and earlier reintervention (P = 0.004) in male patients only (females, P = 0.95 and P = 0.65, respectively). Absence of ER&agr; together with age provided a good prediction model for reintervention in male patients with gonadotroph adenomas. Conclusions: SSTR3 is expressed abundantly in NFPAs and is therefore a possible target for medical treatment. Absence of ER&agr; together with young age may predict tumor recurrence in groups of NFPAs. Further validation in systematic prospective studies is needed.

A high-throughput analysis of the IDH1(R132H) protein expression in pituitary adenomas

PurposeInactivating mutations of isocitrate dehydrogenase (IDH) 1 and 2, mitochondrial enzymes participating in the Krebs tricarboxylic acid cycle play a role in the tumorigenesis of gliomas and also less frequently in acute myeloid leukemia and other malignancies. Inhibitors of mutant IDH1 and IDH2 may potentially be effective in the treatment of the IDH mutation driven tumors. Mutations in the succinate dehydrogenase, the other enzyme complex participating in the Krebs cycle and electron transfer of oxidative phosphorylation occur in the paragangliomas, gastrointestinal stromal tumors, and occasionally in the pituitary adenomas. We aimed to determine whether the IDH1(R132H) mutation, the most frequent IDH mutation in human malignancies, occurs in pituitary adenomas.MethodsWe performed immunohistochemical analysis by using a monoclonal anti-IDH1(R132H) antibody on the tissue microarrays containing specimens from the pituitary adenomas of different hormonal types from 246 patients. In positive samples, the status of the IDH1 gene was further examined by molecular genetic analyses.ResultsIn all but one patient, there was no expression of mutated IDH1(R132H) protein in the tumor cells by immunohistochemistry. Only one patient with a recurring clinically non-functioning gonadotroph adenoma demonstrated IDH1(R132H)-immunostaining in both the primary tumor and the recurrence. However, no mutation in the IDH1 gene was detected using different molecular genetic analyses.ConclusionIDH1(R132H) mutation occurs only exceptionally in pituitary adenomas and does not play a role in their pathogenesis. Patients with pituitary adenomas do not seem to be candidates for treatment with the inhibitors of mutant IDH1.

Early postoperative growth in non-functioning pituitary adenomas; A tool to tailor safe follow-up

PurposeNon-functioning pituitary adenomas are common, and the treatment and follow-up of these patients represent a multidisciplinary challenge. First line treatment is transphenoidal surgery, with debulking or total removal of tumour. A substantial portion of the tumours relapse after surgery, and there is no consensus of how to follow these patients postoperatively. Our aim was to characterize the postoperative growth of non-functioning pituitary adenomas and correlate it to clinical and paraclinical data.MethodsWe retrospectively registered 52 patients operated for non-functioning pituitary adenomas, with four or more consecutive MR-investigations not interrupted by secondary treatment. Adenoma volumes were estimated by the Cavalieri principle with summation of manually drawn areas multiplied by slice interval. Growth curves were modelled and tumour volume doubling time was calculated for 39 tumours with regrowth after surgery.ResultsA total of 13 tumours showed exponential growth, 10 linear growth and 16 logistic growth after surgery. The remaining 13 did not show regrowth of tumour. Seven of the exponential growing tumours underwent secondary surgery, compared to one and two of linear and logistic growing tumours (p = 0.03), respectively. Initial tumour volume doubling time was significantly lower in logistic growing tumours than in exponential growing tumours (p < 0.01). Men had tumours with lower tumour volume doubling time than women (p = 0.03). None of the tumours demonstrated signs of accelerated growth.ConclusionResidual tumours following surgery frequently grow. The logistic growing tumours had the fastest initial growth in our cohort. We found no indication of accelerated growth, whereby the tumour volume doubling time might be used to predict a “worst-case” scenario when planning follow-up of these patients.

Are volume measurements of non-functioning pituitary adenomas reliable?

PurposePrecise radiological assessment of tumour volume is important in the follow-up of non-functioning pituitary adenomas (NFPAs). We compared the reliability of two methods for tumour volume measurements in the pre- and postoperative setting.MethodsWe assessed the volume of 22 NFPAs at magnetic resonance imaging (MRI) scans before surgery and the first and third postoperative MRI obtained after submission from hospital. Volumetric assessments were performed both by summation of slices (SOS) and by diameter measures. All volumes were calculated independently by two readers.ResultsThe preoperative intra- and inter-rater reliability was good for both the SOS and the diameter method (intraclass correlation coefficient (ICC) 0.996 and 0.990, and ICC: 0.982 and 0.967, respectively). The first postoperative investigation showed poorer intra- and inter-rater reliability for both methods (ICC: 0.872 and 0.791 and ICC: 0.792 and 0.810, respectively). The third postoperative MRI showed good intra-rater reliability (ICC: 0.961 and 0.962, respectively), but poorer inter-rater reliability for both methods (ICC: 0.759 and 0.703, respectively). Volume assessment by SOS presented overall slightly higher reliability than the diametric method. Overall, the reliability between the two methods was good when measured by the same reader (ICC: 0.988, 0.945 and 0.962, for the preoperative, first and third postoperative MRI, respectively).ConclusionThe preoperative intra- and inter-rater reliabilities were satisfactory for both the SOS and diametric method. Postoperative MRI scans showed poorer reliability, suggesting that measurements at these time points should be interpreted with care. For each MRI scan, reliability between methods was satisfactory when investigated by the same reader.

The role of E and N-cadherin in the postoperative course of gonadotroph pituitary tumours

PurposeGonadotroph tumours are the most abundant of the clinically silent pituitary tumours. There is a lack of reliable prognostic markers predicting their clinical course. Our aim was to determine the level of E-cadherin and N-cadherin in a cohort of clinically silent gonadotroph pituitary tumours, and compare them to the rate of reintervention.MethodsTumour tissue from primary surgery was retrospectively investigated and compared with clinical data. Immunohistochemical (N = 105) and real time-qPCR (N = 85) analyses for the levels of N-cadherin and the extra- and intracellular domains of E-cadherin were performed. The immunoreactive scores (IRS) and mRNA relative quantity were compared to the rate of reintervention.ResultsThe tumours presented a high IRS for N-cadherin (Median 12 (IQR 12-12)) and almost no immunoreactivity for the extracellular domain of E-cadherin (Median 0 (IQR 0-0)). The membranous staining for the intracellular domain of E-cadherin varied (Median 6 (IQR 4-6). Reduced membranous expression of the intracellular domain of E-cadherin was associated with nuclear presence of the same domain. Nuclear staining for the intracellular domain of E-cadherin was associated with a lower rate of reintervention (p = 0.01).ConclusionWe found that silent gonadotroph tumours presented high IRS for N-cadherin and low IRS for the extracellular domain of E-cadherin. A substantial proportion of the tumours presented nuclear staining for the intracellular domain of E-cadherin, accompanied by a reduced membranous expression of the intracellular domain of E-cadherin. Absence of nuclear staining for the intracellular domain of E-cadherin served as an independent predictor of reintervention.

Gene expression profiling of fast- and slow- growing gonadotroph non-functioning pituitary adenomas

OBJECTIVE Reliable biomarkers associated with aggressiveness of non-functioning gonadotroph adenomas (GAs) are lacking. As the growth of tumor remnants is highly variable, molecular markers for growth potential prediction are necessary. We hypothesized that fast- and slow-growing GAs present different gene expression profiles and reliable biomarkers for tumor growth potential could be identified, focusing on the specific role of epithelial-mesenchymal transition (EMT). DESIGN AND METHODS Eight GAs selected for RNA sequencing were equally divided into fast- and slow-growing group by the tumor volume doubling time (TVDT) median (27.75 months). Data were analyzed by tophat2, cufflinks and cummeRbund pipeline. 40 genes were selected for RT-qPCR validation in 20 GAs based on significance, fold-change and pathway analyses. The effect of silencing MTDH (metadherin) and EMCN (endomucin) on in vitro migration of human adenoma cells was evaluated. RESULTS 350 genes were significantly differentially expressed (282 genes upregulated and 68 downregulated in the fast group, P-adjusted <0.05). Among 40 selected genes, 11 showed associations with TVDT (-0.669<R<-0.46, P < 0.05). These were PCDH18, UNC5D, EMCN, MYO1B, GPM6A and six EMT-related genes (SPAG9, SKIL, MTDH, HOOK1, CNOT6L and PRKACB). MTDH, but not EMCN, demonstrated involvement in cell migration and association with EMT markers. CONCLUSIONS Fast- and slow-growing GAs present different gene expression profiles, and genes related to EMT have higher expression in fast-growing tumors. In addition to MTDH, identified as an important contributor to aggressiveness, the other genes might represent markers for tumor growth potential and possible targets for drug therapy.