Investigating the Protein Signature of Adamantinomatous Craniopharyngioma Pediatric Brain Tumor Tissue: Towards the Comprehension of Its Aggressive Behavior

Proteomics study of primary and recurrent adamantinomatous craniopharyngiomas

BACKGROUND

Adamantinomatous craniopharyngiomas (ACPs) are rare benign epithelial tumours with high recurrence and poor prognosis. Biological differences between recurrent and primary ACPs that may be associated with disease recurrence and treatment have yet to be evaluated at the proteomic level. In this study, we aimed to determine the proteomic profiles of paired recurrent and primary ACP, gain biological insight into ACP recurrence, and identify potential targets for ACP treatment.

METHOD

Patients with ACP (n = 15) or Rathke's cleft cyst (RCC; n = 7) who underwent surgery at Sanbo Brain Hospital, Capital Medical University, Beijing, China and received pathological confirmation of ACP or RCC were enrolled in this study. We conducted a proteomic analysis to investigate the characteristics of primary ACP, paired recurrent ACP, and RCC. Western blotting was used to validate our proteomic results and assess the expression of key tumour-associated proteins in recurrent and primary ACPs. Flow cytometry was performed to evaluate the exhaustion of tumour-infiltrating lymphocytes (TILs) in primary and recurrent ACP tissue samples. Immunohistochemical staining for CD3 and PD-L1 was conducted to determine differences in T-cell infiltration and the expression of immunosuppressive molecules between paired primary and recurrent ACP samples.

RESULTS

The bioinformatics analysis showed that proteins differentially expressed between recurrent and primary ACPs were significantly associated with extracellular matrix organisation and interleukin signalling. Cathepsin K, which was upregulated in recurrent ACP compared with that in primary ACP, may play a role in ACP recurrence. High infiltration of T cells and exhaustion of TILs were revealed by the flow cytometry analysis of ACP.

CONCLUSIONS

This study provides a preliminary description of the proteomic differences between primary ACP, recurrent ACP, and RCC. Our findings serve as a resource for craniopharyngioma researchers and may ultimately expand existing knowledge of recurrent ACP and benefit clinical practice.

Tocilizumab for the fifth progression of cystic childhood craniopharyngioma-a case report

We present the case of a 15-year-old girl, with a fifth cystic progression of an adamantinomatous craniopharyngioma after multiple surgeries and previous local radiotherapy. She had severe visual impairment, panhypopituitarism including diabetes insipidus, and several components of hypothalamic damage, including morbid obesity and severe fatigue. To prevent further late effects hampering her quality of survival, she was treated biweekly with intravenous tocilizumab, an anti-interleukin-6 agent, which stabilized the cyst for a prolonged time. Based on the biology of adamantinomatous craniopharyngioma, this immune-modulating treatment seems promising for the treatment of this cystic tumor in order to reduce surgery and delay or omit radiotherapy.

Proteomic Analysis on Sequential Samples of Cystic Fluid Obtained from Human Brain Tumors

Cystic formation in human primary brain tumors is a relatively rare event whose incidence varies widely according to the histotype of the tumor. Composition of the cystic fluid has mostly been characterized in samples collected at the time of tumor resection and no indications of the evolution of cystic content are available. We characterized the evolution of the proteome of cystic fluid using a bottom-up proteomic approach on sequential samples obtained from secretory meningioma (SM), cystic schwannoma (CS) and cystic high-grade glioma (CG). We identified 1008 different proteins; 74 of these proteins were found at least once in the cystic fluid of all tumors. The most abundant proteins common to all tumors studied derived from plasma, with the exception of prostaglandin D2 synthase, which is a marker of cerebrospinal fluid origin. Overall, the protein composition of cystic fluid obtained at different times from the same tumor remained stable. After the identification of differentially expressed proteins (DEPs) and the protein-protein interaction network analysis, we identified the presence of tumor-specific pathways that may help to characterize tumor-host interactions. Our results suggest that plasma proteins leaking from local blood-brain barrier disruption are important contributors to cyst fluid formation, but cerebrospinal fluid (CSF) and the tumor itself also contribute to the cystic fluid proteome and, in some cases, as with immunoglobulin G, shows tumor-specific variations that cannot be simply explained by differences in vessel permeability or blood contamination.

Contemporary Biological Insights and Clinical Management of Craniopharyngioma

Craniopharyngiomas (CPs) are clinically aggressive tumors because of their invasive behavior and recalcitrant tendency to recur after therapy. There are 2 types based on their distinct histology and molecular features: the papillary craniopharyngioma (PCP), which is associated with BRAF-V600E mutations and the adamantinomatous craniopharyngioma (ACP), characterized by mutations in CTNNB1 (encoding β-catenin). Patients with craniopharyngioma show symptoms linked to the location of the tumor close to the optic pathways, hypothalamus, and pituitary gland, such as increased intracranial pressure, endocrine deficiencies, and visual defects. Treatment is not specific and mostly noncurative, and frequently includes surgery, which may achieve gross total or partial resection, followed by radiotherapy. In cystic tumors, frequent drainage is often required and intracystic instillation of drugs has been used to help manage cyst refilling. More recently targeted therapies have been used, particularly in PCP, but also now in ACP and clinical trials are underway or in development. Although patient survival is high, the consequences of the tumor and its treatment can lead to severe comorbidities resulting in poor quality of life, in particular for those patients who bear tumors with hypothalamic involvement. Accordingly, in these patients at risk for the development of a hypothalamic syndrome, hypothalamus-sparing treatment strategies such as limited resection followed by irradiation are recommended. In this review, we provide an update on various aspects of CP, with emphasis on recent advances in the understanding of tumor pathogenesis, clinical consequences, management, and therapies.

Single-cell RNA sequencing highlights intratumor heterogeneity and intercellular network featured in adamantinomatous craniopharyngioma

Despite improvements in microscopically neurosurgical techniques made in recent years, the prognosis of adamantinomatous craniopharyngioma (ACP) is still unsatisfactory. Little is known about cellular atlas and biological features of ACP. Here, we carried out integrative analysis of 44,038 single-cell transcriptome profiles to characterize the landscape of intratumoral heterogeneity and tumor microenvironment (TME) in ACP. Four major neoplastic cell states with distinctive expression signatures were defined, which further revealed the histopathological features and elucidated unknown cellular atlas of ACP. Pseudotime analyses suggested potential evolutionary trajectories between specific neoplastic cell states. Notably, a distinct oligodendrocyte lineage was identified in ACP, which was associated with immunological infiltration and neural damage. In addition, we described a tumor-centric regulatory network based on intercellular communication in TME. Together, our findings represent a unique resource for deciphering tumor heterogeneity of ACP, which will improve clinical diagnosis and treatment strategies.

Proteomics approaches to characterize the immune responses in cancer

Despite the dynamic development of cancer research, annually millions of people die of cancer. The human immune system is the major 'guard' against tumor development. Unfortunately, cancer cells have the ability to evade the immune system and continue to grow. The proper understanding of the intricate immune response in tumorigenesis remains the holy grail of cancer immunology and designing effective immunotherapy. To decode the immune responses in cancer, in recent years, proteomics studies have received considerable attention. Proteomics studies focus on the detection and quantification of proteins, which are the effectors of biological functions, and as such, are proven to reflect the cell state more accurately, in comparison to genomic or transcriptomic studies. In this review, we discuss the proteomics studies applied to characterize the immune responses in cancer and tumor immune microenvironment heterogeneity. Further, we describe emerging single-cell proteomics approaches that have the potential to be applied in cancer immunity studies.

Pediatric Brain Tumors: Signatures from the Intact Proteome

The present investigation aimed to explore the intact proteome of tissues of pediatric brain tumors of different WHO grades and localizations, including medulloblastoma, pilocytic astrocytoma, and glioblastoma, in comparison with the available data on ependymoma, to contribute to the understanding of the molecular mechanisms underlying the onset and progression of these pathologies. Tissues have been homogenized in acidic water−acetonitrile solutions containing proteases inhibitors and analyzed by LC−high resolution MS for proteomic characterization and label-free relative quantitation. Tandem MS spectra have been analyzed by either manual inspection or software elaboration, followed by experimental/theoretical MS fragmentation data comparison by bioinformatic tools. Statistically significant differences in protein/peptide levels between the different tumor histotypes have been evaluated by ANOVA test and Tukey’s post-hoc test, considering a p-value > 0.05 as significant. Together with intact protein and peptide chains, in the range of molecular mass of 1.3−22.8 kDa, several naturally occurring fragments from major proteins, peptides, and proteoforms have been also identified, some exhibiting proper biological activities. Protein and peptide sequencing allowed for the identification of different post-translational modifications, with acetylations, oxidations, citrullinations, deamidations, and C-terminal truncations being the most frequently characterized. C-terminal truncations, lacking from two to four amino acid residues, particularly characterizing the β-thymosin peptides and ubiquitin, showed a different modulation in the diverse tumors studied. With respect to the other tumors, medulloblastoma, the most frequent malignant brain tumor of the pediatric age, was characterized by higher levels of thymosin β4 and β10 peptides, the latter and its des-IS form particularly marking this histotype. The distribution pattern of the C-terminal truncated forms was also different in glioblastoma, particularly underlying gender differences, according to the definition of male and female glioblastoma as biologically distinct diseases. Glioblastoma was also distinguished for the peculiar identification of the truncated form of the α-hemoglobin chain, lacking the C-terminal arginine, and exhibiting oxygen-binding and vasoconstrictive properties different from the intact form. The proteomic characterization of the undigested proteome, following the top-down approach, was challenging to originally investigate the post-translational events that differently characterize pediatric brain tumors. This study provides a contribution to elucidate the molecular profiles of the solid tumors most frequently affecting the pediatric age, and which are characterized by different grades of aggressiveness and localization.

Treatment of Cystic Craniopharyngiomas: An Update

In spite of the significant technical and technological progress in neurosurgery and the continuous discoveries by the basic research, adamantinomatous craniopharyngioma remains a significant clinical challenge. Actually, the huge size of the tumor, its multiple cystic components, the encasement of Willis' circle and optic pathways, and the invasion of the hypothalamus often prevent its safe surgical resection. Moreover, the local aggressiveness of the tumor accounts for a high risk of recurrence even after a gross total resection. For these reasons, more and more efforts are being dedicated to enhance the knowledge about AC and improve the tools for its treatment.This paper is dedicated to the most recent advances concerning the AC management. Promising, new insights come for the basic research, thanks to the updates on the role of the WNT-β-catenin pathway (important for the tumor genesis and progression, not yet developed enough for a safe target therapy in children but useful for determining the prognosis) and the inflammatory mediators (widely overexpressed, especially by the cyst of the tumor, and for which target therapies are being developed). Moreover, further factors and pathways are under investigation.Also the development of new treatment strategies accounts for the improvement of the prognosis and the quality of life of AC patients. The enhancement of the experience with the endoscopic techniques (both transsphenoidal and transventricular approaches) actually allows to perform a less invasive but effective surgery that can be coupled with new modalities of radiation therapy aiming at obtaining a reliable control of the disease and protecting the endocrinological, ophthalmological, and neurological functions. A special mention is finally deserved by the techniques specifically designed for the intracystic therapy (as cyst fenestration alone or in combination with administration of radionuclides or bleomycin or interferon-α) that are here analyzed together with the aforementioned advances.

Craniopharyngiomas: Challenges and Controversies

Despite its benign histopathology, the treatment of craniopharyngioma remains one of the most formidable challenges faced by skull base surgeons. The technical challenges of tackling these complex central skull base lesions are paralleled by clinical challenges related to their unique tumor biology and the often-complex decision making required. In this article, we critically appraise the most recent literature to explore the challenges and controversies surrounding the management of these lesions. The role of curative resections and the shift in the surgical paradigm toward the multidisciplinary goal-directed management approach are discussed.

Clinical features and prognosis of pediatric infradiaphragmatic craniopharyngioma relative to the tumor inflammatory response

BACKGROUND

The relationship between clinical responses in pediatric infradiaphragmatic craniopharyngioma (Q-CP) and inflammatory response is still unclear. The objective of this study was to investigate the clinical significance of tumor inflammatory response in pediatric Q-CPs.

METHODS

The inflammatory response was evaluated by measuring the number of inflammatory cells in the tumor near adenohypophysis junction. The specimens were classified as mild, moderate, or severe based on the number of inflammatory cells. In addition, the levels of pro-inflammatory cytokines and chemokines in the specimens were measured using a cytokine antibody array. Clinical outcomes were analyzed and compared to the markers of inflammatory response.

RESULTS

IL-6 and IL-8 were highly expressed in pediatric Q-CPs, and the transcription level of IL-6 was the highest in the severe group. Most patients (87.3%) had hypopituitarism; the severe inflammation group had an increased incidence of hypopituitarism, which correlated with significantly lower probability of recurrence-free survival and worsened functional status.

CONCLUSIONS

Inflammatory response is common in craniopharyngiomas and is closely related to their biological behavior and the patients' clinical prognosis. Further studies of the relationship between craniopharyngiomas and the inflammatory response will enable the discovery of potential therapeutic targets, which will reduce morbidity and result in better outcomes for pediatric Q-CP patients.

IMPACT

Pediatric infradiaphragmatic craniopharyngiomas are histologically benign brain tumors that often follow an aggressive clinical course. The inflammatory response in craniopharyngioma is common, which is closely related to the biological behavior and clinical prognosis. Several inflammatory and immune markers have been identified in CP; inflammation is an important role in the pathogenesis of hypopituitarism. The aim was to study the relationship between craniopharyngioma and inflammatory response and find potential therapeutic targets can reduce morbidity and result in better outcomes.

Adamantinomatous craniopharyngioma: advances in proteomic research

BACKGROUND

Many efforts have been performed in the last decade to accomplish the genomic and proteomic characterization of pediatric adamantinomatous craniopharyngioma with the purpose to elucidate the molecular mechanisms underlying the onset and development of this pediatric brain tumor, its high recurrence rate, and, although classified as a histologically benign neoplasm, its aggressive behavior.

METHODS

The focus of this review is to perform the new comparison of the proteomic profiles of the solid component and the intracystic fluid of adamantinomatous craniopharyngioma based on our previous results, obtained by both the top-down and the bottom-up proteomic approaches, to disclose differences and similarities, and to discuss the results in the context of the most recent literature.

RESULTS AND CONCLUSIONS

Proteins and peptides identified in the cyst fluid and in the solid component of adamantinomatous craniopharyngioma (AC) include beyond markers of inflammation (i.e., alpha-defensins), proteins involved in cell migration and protein degradation (i.e., beta-thymosin and ubiquitin peptides), whose main role might be in tumor growth and infiltration of the surrounding neural structures. These last appeared different in the solid components compared with the cyst fluid, missing their terminal part in the solid tissue, a feature generally associated to malignancies, which might represent a distinct molecular site for an aggressive behavior of AC.

Antimicrobial effects of craniopharyngioma cystic fluid

BACKGROUND

Tumours are known to increase the risk of infections, especially those occurring in the central nervous system where insertion of surgical hardware/shunts such as in craniopharyngiomas may be required. However, infections are surprisingly scarce in craniopharyngioma cases. In this study, we explored the possibility of antimicrobial effects of craniopharyngioma cystic fluid.

METHODS

The antibacterial effect of craniopharyngioma cystic fluid samples against selected human pathogens: Escherichia. coli, S. aureus and S. pneumoniae were determined using the agar disc diffusion method. Streptomycin and ampicillin were used as controls. The test organisms were cultured in Mueller-Hinton broth overnight at 37 °C. McFarland standard was used as a reference to adjust the inoculum size of each test organism to a concentration of 1 × 10⁶ CFU/ml using sterile broth.

RESULTS

The craniopharyngioma cystic fluid inhibited growth of Gram-positive bacteria S. aureus and S. pneumoniae, but not the Gram-negative bacteria, E. coli. The samples showed the highest zones of S. pneumoniae growth inhibition of up to 20.0 ± 1.0 mm compared with 18.0 ± 1.0 mm of streptomycin and 9.0 ± 0.0 mm of ampicillin.

CONCLUSION

Craniopharyngioma cystic fluid showed significant antibacterial properties against Gram-positive bacteria. This novel finding has implications in the way we view infections in craniopharyngioma patients. More studies need to be carried out to further elucidate this unique finding and possibly exploit these antimicrobial properties.

Peripheral Blood Occludin Level as a Biomarker for Perioperative Cerebral Edema in Patients with Brain Tumors

Objective

Cerebral edema is a common complication of brain tumors in the perioperative period. However, there is currently no reliable and convenient method to evaluate the extent of brain edema. The objective is to explore the effectiveness of serum occludin on predicting the extent of perioperative brain edema and outcome in patients with brain tumors.

Methods

This prospective study enrolled 55 patients with brain tumors and 24 healthy controls in Sanbo Brain Hospital from June 2019 through November 2019. Serum occludin levels were measured preoperatively and on postoperative day 1. Peritumoral edema was assessed preoperatively using MRI. Pericavity brain edema on postoperative day 1 was evaluated using CT.

Results

Compared with healthy controls, the serum occludin level was higher in patients with brain tumors both preoperatively and postoperatively (P < 0.001). The serum occludin level correlated positively with the degree of brain edema preoperatively (r = 0.78, P < 0.001) and postoperatively (r = 0.59, P < 0.001). At an optimal cutoff of 3.015 ng/mL, the preoperative serum occludin level discriminated between mild and severe preoperative brain edema with a sensitivity of 90.48% and specificity of 84.62%. At an optimal cutoff value of 3.033 ng/mL, the postoperative serum occludin level distinguished between mild and severe postoperative brain edema with a sensitivity of 97.30% and specificity of 55.56%.

Conclusions

The serum occludin level is associated with cerebral edema and could potentially be used as a biomarker for perioperative cerebral edema. This trial is registered with ChiCTR1900023742.

Adamantinomatous craniopharyngioma in the molecular age and the potential of targeted therapies: a review

Pediatric adamantinomatous craniopharyngiomas (ACPs) are histologically benign brain tumors that often follow an aggressive clinical course. Arising in the sellar/suprasellar region, they grow in close proximity to critical neurological and vascular structures and can result in significant neuroendocrine morbidity. First-line treatment often involves surgical resection with or without radiotherapy and has been associated with significant morbidity and poor quality of life outcomes. As a result, the discovery of alternative effective and safe treatments is clearly desirable. In recent years, laboratory studies have harnessed sophisticated techniques to identify the upregulation of several markers that may represent potential therapeutic targets. These targets include IL-6, PD1/PD-L1, MEK, IDO-1, and others. Agents that target these pathways exist, and there is an opportunity to investigate their potential efficacy in the treatment of ACP. Trials investigating some of these agents as monotherapy and in combination for the treatment of pediatric ACP are underway or in development. If positive, these trials may result in a paradigm shift in treatment that will hopefully result in reduced morbidity and better outcomes for patients.

The Inflammatory Milieu of Adamantinomatous Craniopharyngioma and Its Implications for Treatment

Pediatric Adamantinomatous Craniopharyngiomas (ACPs) are histologically benign brain tumors that often follow an aggressive clinical course. Their suprasellar location leaves them in close proximity to critical neurological and vascular structures and often results in significant neuroendocrine morbidity. Current treatment paradigms, involving surgical resection and radiotherapy, confer significant morbidity to patients and there is an obvious need to discover effective and safe alternative treatments. Recent years have witnessed significant efforts to fully detail the genomic, transcriptomic and proteomic make-up of these tumors, in an attempt to identify potential therapeutic targets. These studies have resulted in ever mounting evidence that inflammatory processes and the immune response play a critical role in the pathogenesis of both the solid and cystic portion of ACPs. Several inflammatory and immune markers have been identified in both the cyst fluid and solid tumor tissue of ACP. Due to the existence of effective agents that target them, IL-6 and immune checkpoint inhibitors seem to present the most likely immediate candidates for clinical trials of targeted immune-related therapy in ACP. If effective, such agents may result in a paradigm shift in treatment that ultimately reduces morbidity and results in better outcomes for our patients.