Histopathology and molecular characterisation of intrauterine-diagnosed congenital craniopharyngioma

Phosphorylation of β-catenin at Serine552 correlates with invasion and recurrence of non-functioning pituitary neuroendocrine tumours

Non-functioning pituitary tumours (NF-PitNETs) are common intracranial benign neoplasms that can exhibit aggressive behaviour by invading neighbouring structures and, in some cases, have multiple recurrences. Despite resulting in severe co-morbidities, no predictive biomarkers of recurrence have been identified for NF-PitNETs. In this study we have used high-throughput mass spectrometry-based analysis to examine the phosphorylation pattern of different subsets of NF-PitNETs. Based on histopathological, radiological, surgical and clinical features, we have grouped NF-PitNETs into non-invasive, invasive, and recurrent disease groups. Tumour recurrence was determined based on regular clinical and radiological data of patients for a mean follow-up of 10 years (SD ± 5.4 years). Phosphoproteomic analyses identified a unique phosphopeptide enrichment pattern which correlates with disease recurrence. Candidate phosphorylated proteins were validated in a large cohort of NF-PitNET patients by western blot and immunohistochemistry. We identified a cluster of 22 phosphopeptides upregulated in recurrent NF-PitNETs compared to non-invasive and invasive subgroups. We reveal significant phosphorylation of the β-catenin at Ser552 in recurrent and invasive NF-PitNETs, compared to non-invasive/non-recurrent NF-PitNET subgroup. Moreover, β-catenin pSer552 correlates with the recurrence free survival among 200 patients with NF-PitNET. Together, our results suggest that the phosphorylation status of β-catenin at Ser552 could act as potential biomarker of tumour recurrence in NF-PitNETs.

The epidemiology and management patterns of pediatric pituitary tumors in the United States

PURPOSE

Hypothalamic-pituitary axis dysfunction and mass effect symptoms in the pediatric population can indicate a pituitary region tumor. Herein, we evaluate the epidemiology and management of this rare entity.

METHODS

Pediatric patients (≤ 21yo) who presented from 2004 to 2017 with a pituitary tumor were evaluated from the U.S. National Cancer Database. The distributions and management patterns of pituitary tumors were assessed by patients' tumor type, age, sex, race/ethnicity, tumor size, and insurance status.

RESULTS

19.7% of intracranial tumors in the pediatric population originated in the pituitary region. 7653 pediatric patients with pituitary region tumors were identified, 68.2% of whom were female, with the tumors predominantly occurring in early adolescence (46.9%) and late adolescence (34.8%). The majority of pediatric pituitary region tumors were pituitary adenomas (77.9%), followed by craniopharyngiomas (18.1%) and germ cell tumors (1.6%). Girls demonstrated higher proportions of pituitary adenomas across all ages than boys. Asian/Pacific Islander patients were independently more likely to present at younger ages (mean 13.9yrs) and with germ cell tumors than patients of other races/ethnicities. Only 5.5% of patients were uninsured (referent), but they were independently more likely to present at older ages (mean 17.9yrs) and less likely to undergo surgery than patients with private insurance (OR = 1.93, 95% CI = 1.47-2.52, p < 0.001) or Medicaid (OR = 1.51, 95% CI = 1.14-2.00, p = 0.004).

CONCLUSION

Pituitary region tumors comprise a significant fraction of intracranial pediatric tumors, particularly in adolescent girls. The differential diagnosis of pituitary tumor types differed significantly by patients' age, sex, and race/ethnicity. Uninsured patients were associated with delays in care and less surgical management.

Adamantinomatous craniopharyngioma as a model to understand paracrine and senescence-induced tumourigenesis

Cellular senescence is a process that can prevent tumour development in a cell autonomous manner by imposing a stable cell cycle arrest after oncogene activation. Paradoxically, senescence can also promote tumour growth cell non-autonomously by creating a permissive tumour microenvironment that fuels tumour initiation, progression to malignancy and metastasis. In a pituitary tumour known as adamantinomatous craniopharyngioma (ACP), cells that carry oncogenic β-catenin mutations and overactivate the WNT signalling pathway form cell clusters that become senescent and activate a senescence-associated secretory phenotype (SASP). Research in mouse models of ACP has provided insights into the function of the senescent cell clusters and revealed a critical role for SASP-mediated activities in paracrine tumour initiation. In this review, we first discuss this research on ACP and subsequently explore the theme of paracrine tumourigenesis in other tumour models available in the literature. Evidence is accumulating supporting the notion that paracrine signalling brought about by senescent cells may underlie tumourigenesis across different tumours and cancer models.

From fix to fit into the autoptic human brains

Formalin-fixed, paraffinembedded (FFPE) human brain tissues are very often stored in formalin for long time. Formalin fixation reduces immunostaining, and the DNA/RNA extraction from FFPE brain tissue becomes suboptimal. At present, there are different protocols of fixation and several procedures and kits to extract DNA/RNA from paraffin embedding tissue, but a gold standard protocol remains distant. In this study, we analyzed four types of fixation systems and compared histo and immuno-staining. Based on our results, we propose a modified method of combined fixation in formalin and formic acid for the autoptic adult brain to obtain easy, fast, safe and efficient immunolabelling of long-stored FFPE tissue. In particular, we have achieved an improved preservation of cellular morphology and obtained success in postmortem immunostaining for NeuN. This nuclear antigen is an important marker for mapping neurons, for example, to evaluate the histopathology of temporal lobe epilepsy or to draw the topography of cardiorespiratory brainstem nuclei in sudden infant death syndrome (SIDS). However, NeuN staining is frequently faint or lost in postmortem human brain tissues. In addition, we attained Fluoro Jade C staining, a marker of neurodegeneration, and immunofluorescent staining for stem cell antigens in the postnatal human brain, utilizing custom fit fixation procedures.

Can tissue biomarkers reliably predict the biological behavior of craniopharyngiomas? A comprehensive overview

BACKGROUND

The growing interest in the molecular and genetic alterations of craniopharyngiomas (CPs) is embodied in recent studies revealing insights into the CP tumorigenesis and identifying novel molecular pathways amenable of targeted therapies. The actual impact of this new information, however, remains inconclusive.

METHODS

We present a comprehensive review of the accumulated knowledge on molecular biology of CPs and a critical analysis on the strengths and weaknesses of the studies focused on CP molecular/genetic alterations published to date.

RESULTS

A thorough analysis of the alterations of β-catenin/CTNNB1 and BRAF genes investigated in 1123 CP cases included in 27 studies, showed that, on average, CTNNB1 mutations were present in two-thirds of adamantinomatous CPs and BRAF mutations in 90% of papillary CPs. Their role as oncogenic drivers has not been well established. Although rare, coexistence of both mutations may occur. The involvement of pituitary stem cells in human CP tumorigenesis is still uncertain. Expression of stem markers in human CP samples predominantly occurred along the CP border in contact with brain tissue. Finally, none of the various molecular alterations which have been proposed as markers for CP recurrence can be used today as reliable predictors of the CP behavior.

CONCLUSIONS

The isolated evaluation of CPs' molecular or genetic profiles that do not take into consideration fundamental pathological and therapeutic factors, specifically the tumor topography and the degree of tumor removal, may actually generate confusion regarding the reliability of some biomarkers to predict the CP biological behavior.

Do craniopharyngioma molecular signatures correlate with clinical characteristics?

OBJECTIVE

Exome sequencing studies have recently demonstrated that papillary craniopharyngiomas (PCPs) and adamantinomatous craniopharyngiomas (ACPs) have distinct genetic origins, each primarily driven by mutually exclusive alterations: either BRAF (V600E), observed in 95% of PCPs, or CTNNB1, observed in 75%–96% of ACPs. How the presence of these molecular signatures, or their absence, correlates with clinical, radiographic, and outcome variables is unknown.

METHODS

The pathology records for patients who underwent surgery for craniopharyngiomas between May 2000 and March 2015 at Weill Cornell Medical College were reviewed. Craniopharyngiomas were identified and classified as PCP or ACP. Patients were placed into 1 of 3 groups based on their genomic mutations: BRAF mutation only, CTNNB1 mutation only, and tumors with neither of these mutations detected (not detected [ND]). Demographic, radiological, and clinical variables were collected, and their correlation with each genomic group was tested.

RESULTS

Histology correlated strongly with mutation group. All BRAF tumors with mutations were PCPs, and all CTNNB1 with mutations and ND tumors were ACPs. Preoperative and postoperative clinical symptoms and radiographic features did not correlate with any mutation group. There was a statistically significant relationship (p = 0.0323) between the age group (pediatric vs adult) and the mutation groups. The ND group tumors were more likely to involve the sella (p = 0.0065).

CONCLUSIONS

The mutation signature in craniopharyngioma is highly predictive of histology. The subgroup of tumors in which these 2 mutations are not detected is more likely to occur in children, be located in the sella, and be of ACP histology.

Expression of SRY-related HMG Box Transcription Factors (Sox) 2 and 9 in Craniopharyngioma Subtypes and Surrounding Brain Tissue

Stem cells have been discovered as key players in the genesis of different neoplasms including craniopharyngioma (CP), a rare tumour entity in the sellar region. Sox2 and Sox9 are well-known stem cell markers involved in pituitary development. In this study we analysed the expression of both transcription factors using immunohistochemistry in a large cohort of 64 adamantinomatous (aCP) and 9 papillary CP (pCP) and quantitative PCR in 26 aCP and 7 pCP. Whereas immunohistochemically Sox2+ cells were verifiable in only five aCP (7.8%) and in 39.1% of the respective surrounding cerebral tissue, pCP specimens appeared always negative. In contrast, Sox9 was detectable in all tumours with a significantly higher expression in aCP compared to pCP (protein, p < 0.0001; mRNA p = 0.0484) This was also true for the respective tumour adjacent CNS where 63 aCP (98.4%) and six pCP (66.7%) showed Sox9+ cells. We further confirmed absence of Sox9 expression in nuclear β-catenin accumulating cells of aCP. Our results point to the conclusion that Sox2 and Sox9, seem to play essential roles not only in the specific formation of aCP, but also in processes involving the cerebral tumour environment, which needs to be illuminated in the future.

Recent advances in molecular pathology of craniopharyngioma

Craniopharyngiomas are rare epithelial tumours arising along the path of the craniopharyngeal duct. Two major histological subtypes have been recognised, the papillary and the adamantinomatous. Craniopharyngiomas remain challenging tumours to manage and are associated with significant morbidities and mortality. Recent advances in the molecular pathology of these neoplasms have identified BRAF mutations in the papillary variant, offering promising options for targeted pharmacological treatment. The involvement of β-catenin and the Wnt pathway in the tumorigenesis of the adamantinomatous subtype has been previously established with the identification of stabilising mutations in exon 3 of CTNNB1. Further understanding of the pathogenesis of this subtype has been facilitated with the use of mouse models and xenograft experiments. It has been proposed that the clusters of cells with upregulated Wnt/β-catenin signalling induce tumour formation in a paracrine manner; the complex interactions occurring between different cell populations need to be further clarified for further expansion of this hypothesis. This review outlines recent key advances in our understanding of the molecular pathology of craniopharyngiomas and discusses some of the challenges that need to be overcome for the development of targeted therapies that will hopefully improve the management and the outcomes of these patients.

Pathological and Topographical Classification of Craniopharyngiomas: A Literature Review

Craniopharyngiomas (CPs) are clinically relevant tumors of the sellar region and are associated with high morbidity and occasional mortality. There are two different subtypes of CPs that differ clinically and pathologically: adamantinomatous CP and papillary CP. The differential diagnosis is still challenging even with developments in preoperative imaging as several tumors of the sellar/parasellar region share a continuum of clinical characteristics and imaging similarities. Several topographical classifications of CPs have been mentioned in literature, but to date, there has not been a consensus on a standard reference classification system and there is need to a develop such a model.