Pediatric Embryonal Brain Tumors Research Articles

Tissue Factor Regulation by miR-520g in Primitive Neuronal Brain Tumor Cells: A Possible Link between Oncomirs and the Vascular Tumor Microenvironment

Pediatric embryonal brain tumors with multilayered rosettes demonstrate a unique oncogenic amplification of the chromosome 19 miRNA cluster, C19MC. Because oncogenic lesions often cause deregulation of vascular effectors, including procoagulant tissue factor (TF), this study explores whether there is a link between C19MC oncogenic miRNAs (oncomirs) and the coagulant properties of cancer cells, a question previously not studied. In a pediatric embryonal brain tumor tissue microarray, we observed an association between C19MC amplification and reduced fibrin content and TF expression, indicative of reduced procoagulant activity. In medulloblastoma cell lines (DAOY and UW228) engineered to express miR-520g, a biologically active constituent of the C19MC cluster, we observed reduced TF expression, procoagulant and TF signaling activities (responses to factor VIIa stimulation), and diminished TF emission as cargo of extracellular vesicles. Antimir and luciferase reporter assays revealed a specific and direct effect of miR-520g on the TF 3' untranslated region. Although the endogenous MIR520G locus is methylated in differentiated cells, exposure of DAOY cells to 5-aza-2'-deoxycytidine or their growth as stem cell-like spheres up-regulated endogenous miR-520g with a coincident reduction in TF expression. We propose that the properties of tumors harboring oncomirs may include unique alterations of the vascular microenvironment, including deregulation of TF, with a possible impact on the biology, therapy, and hemostatic adverse effects of both disease progression and treatment.

Microrna expression signatures predict patient progression and disease outcome in pediatric embryonal central nervous system neoplasms.

BackgroundAlthough, substantial experimental evidence related to diagnosis and treatment of pediatric central nervous system (CNS) neoplasms have been demonstrated, the understanding of the etiology and pathogenesis of the disease remains scarce. Recent microRNA (miRNA)-based research reveals the involvement of miRNAs in various aspects of CNS development and proposes that they might compose key molecules underlying oncogenesis. The current study evaluated miRNA differential expression detected between pediatric embryonal brain tumors and normal controls to characterize candidate biomarkers related to diagnosis, prognosis and therapy.MethodsOverall, 19 embryonal brain tumors; 15 Medulloblastomas (MBs) and 4 Atypical Teratoid/Rabdoid Tumors (AT/RTs) were studied. As controls, 13 samples were used; The First-Choice Human Brain Reference RNA and 12 samples from deceased children who underwent autopsy and were not present with any brain malignancy. RNA extraction was carried out using the Trizol method, whilst miRNA extraction was performed with the mirVANA miRNA isolation kit. The experimental approach included miRNA microarrays covering 1211 miRNAs. Quantitative Real-Time Polymerase Chain Reaction was performed to validate the expression profiles of miR-34a and miR-601 in all 32 samples initially screened with miRNA microarrays and in an additional independent cohort of 30 patients (21MBs and 9 AT/RTs). Moreover, meta-analyses was performed in total 27 embryonal tumor samples; 19 MBs, 8 ATRTs and 121 control samples. Twelve germinomas were also used as an independent validation cohort. All deregulated miRNAs were correlated to patients’ clinical characteristics and pathological measures.ResultsIn several cases, there was a positive correlation between individual miRNA expression levels and laboratory or clinical characteristics. Based on that, miR-601 could serve as a putative tumor suppressor gene, whilst miR-34a as an oncogene. In general, miR-34a demonstrated oncogenic roles in all pediatric embryonal CNS neoplasms studied.ConclusionsDeeper understanding of the aberrant miRNA expression in pediatric embryonal brain tumors might aid in the development of tumor-specific miRNA signatures, which could potentially afford promising biomarkers related to diagnosis, prognosis and patient targeted therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-014-0096-y) contains supplementary material, which is available to authorized users.

Abstract 5082: Whole-exome sequencing of an adult pituitary atypical teratoid rhabdoid tumor (AT/RT) - A not so simple genome as pediatric AT/RT

Abstract Introduction Atypical teratoid rhabdoid tumors (AT/RT) are rare pediatric embryonal brain tumors. AT/RT are genomically characterized by a very simple genomic landscape caused by inactivation of the SMARCB1 tumor suppressor, chromatin remodelling, gene. Adult AT/RT is a super-rare disease with only 33 cases previously reported. For the first time, we report an adult pituitary AT/RT which has undergone whole-exome sequencing (WES) from a patient who subsequently died of intrachemotherapy leptomeningeal progression. Results In combination, the detection of both somatic biallelic SMARCB1 mutations and the loss of INI-1 protein expression confirmed the diagnosis of AT/RT. Trisomy 8 was detected in a minority of AT/RT cells. The overall somatic mutation rate was 1.9 Mb. A total of 98 somatic mutations were detected of which 20/49 non-synonymous coding mutations were predicted to be potentially damaging to protein function. These 20 genes were stratified into 4 functionally discrete groups: Group 1). tubulin / actin dynamics; Group 2). cell adhesion; Group 3). metabolism; Group 4). cytotoxic resistance mechanisms. Molecular pathway analysis predicted that loss of NOTCH1 signalling could be an important cellular node that was perturbed by a combination of LNX1 and POFUT1 mutations. AT/RT cells did not express any endocrine differentiation markers. Furthermore, 90% of AT/RT cells demonstrated intense nuclear p53 expression despite no TP53 mutations or HDM2 amplification being detected. Conclusions This is the first adult AT/RT to have undergone next-generation sequencing using WES. We have shown that the genomic landscape can be relatively complex in comparison to pediatric primary AT/RT(Lee RS et al 2012. J Clin Invest; 122(8):2983-2988). First, we detected a somatic mutation rate which was four times higher (1.9 Mb versus <0.5 Mb) than pediatric primary AT/RT, but which was comparable to the mutation rate of pediatric metastatic AT/RT. Second, we detected a Chr8 CNV in a minority of cells. Given that Chr8 harbors the loci for a variety of pro-metastatic genes, including C-MYC, MT3-MMP and BNIP3, we hypothesize that the intra-chemotherapy tumor progression was possibly caused by a clonal population of trisomy 8 cells which over-expressed the respective proteins of these specific genes. Given the dedifferentiated phenotype of AT/RT cells and that NOTCH1 signalling is known to be essential for maintaining the pituitary stem cell pool, we hypothesize that the combined effects of LNX1 and POFUT1 mutations could have been important events in the generation of an AT/RT cancer-initiating cell, through loss of NOTCH1 signalling. In this regard, we are currently investigating the expression of NOTCH1 signalling proteins, as well as elucidating the cause of the high levels of nuclear p53 expression within this AT/RT, which we also hypothesize was related to perturbations in NOTCH1 signalling. Note: This abstract was not presented at the meeting. Citation Format: Swethajit Biswas, Madeleine Wood, Abhijit Joshi, Nick Bown, Lisa Strain, Philip Kane, Tommy Martinsson, Javier Garrido, James Campbell, Amanda Swain, Alan Ashworth. Whole-exome sequencing of an adult pituitary atypical teratoid rhabdoid tumor (AT/RT) - A not so simple genome as pediatric AT/RT. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5082. doi:10.1158/1538-7445.AM2014-5082

Parent-Reported Social Outcomes After Treatment for Pediatric Embryonal Tumors: A Prospective Longitudinal Study

To examine longitudinal parent-reported social outcomes for children treated for pediatric embryonal brain tumors. Patients (N=220) were enrolled onto a multisite clinical treatment protocol. Parents completed the Child Behavior Checklist/6-18 at the time of their child's diagnosis and yearly thereafter. A generalized linear mixed effects model regression approach was used to examine longitudinal changes in parent ratings of social competence, social problems, and withdrawn/depressed behaviors with demographic and treatment factors as covariates. During the 5-year period following diagnosis and treatment, few patients were reported to have clinically elevated scores on measures of social functioning. Mean scores differed significantly from population norms, yet remained within the average range. Several factors associated with unfavorable patterns of change in social functioning were identified. Patients with high-risk treatment status had a greater increase in parent-reported social problems (P=.001) and withdrawn/depressed behaviors (P=.01) over time compared with average-risk patients. Patients with posterior fossa syndrome had greater parent-reported social problems over time (P=.03). Female patients showed higher withdrawn/depressed scores over time compared with male patients (P<.001). Patient intelligence, age at diagnosis, and parent education level also contributed to parent report of social functioning. Results of this study largely suggest positive social adjustment several years after diagnosis and treatment of a pediatric embryonal tumor. However, several factors, including treatment risk status and posterior fossa syndrome, may be important precursors of long-term social outcomes. Future research is needed to elucidate the trajectory of social functioning as these patients transition into adulthood.

Integrative genomics reveals molecular and clinical heterogeneity in central nervous system primitive neuroectodermal tumors in children.

Through advances in genome science, we are becoming increasingly aware that tumors that appear identical under the pathologist’s microscope can be very different in their genetic composition and clinical behavior. Pediatric embryonal brain tumors share a characteristic histological feature—densely packed sheets of cells with hyperchromatic nuclei and scant cytoplasm.

Concurrent cyclophosphamide and craniospinal radiotherapy for pediatric high-risk embryonal brain tumors

Embryonal tumors are an aggressive subtype of high-grade, pediatric central nervous system (CNS) tumors often with dismal survival rates. The 5-year survival for highest-risk embryonal tumors may be as low as 10 %. We report feasibility and efficacy from our experience using intravenous (IV) cyclophosphamide concurrently with craniospinal radiation (CSI) in high-risk embryonal CNS tumors of childhood. Ten consecutive children (aged: 3.5-15.5 years, median: 10.2 years, six male) with high-risk embryonal tumors, including: large cell/anaplastic medulloblastoma (6), atypical teratoid rhabdoid tumor (1), and leptomeningeal primitive neuroectodermal tumor (3), were treated with IV cyclophosphamide 1 g/M(2) on days 1 and 2 of CSI. Following a median of 36 Gy CSI plus tumor boosts, adjuvant treatment consisted of 21 doses of oral etoposide (7) and alkylator based chemotherapy from five to eight cycles in all. Of the ten patients thus treated, six remain alive with no evidence of disease and four are deceased. Median survival was 3.3 years, with a 3-year progression-free survival of 50 % (5/10). Median follow-up was: 3.3 years (range: 5 months-12.9 years) in the five patients with progression, median time-to-progression was: 1.3 years (range: 1 month-3 years). Median follow-up in the patients without progression is 8.8 years (range: 3-12.9 years). Complications due to adjuvant chemotherapy were typical and included myelosupression (10), necessitating shortened duration of chemotherapy in three, and hemorrhagic cystitis (1). In high-risk embryonal CNS tumors, cyclophosphamide given concurrently with CSI is well tolerated. Early results suggest that a phase II trial is warranted.

Immunohistochemical expression of cell-cycle regulators in pediatric embryonal brain tumors

Embryonal tumors constitute the most common malignant brain tumor group in children. Experimental results indicate that genes involved in cell cycle and signal transduction are deregulated in medulloblastoma (MB) and atypical teratoid/rhabdoid tumors (AT/RT). The cell cycle is regulated by protein complexes composed of a regulatory subunit called Cyclin and a catalytic domain named Cyclin-dependent kinase (CDK). Cyclins and CDKs are in turn regulated by cyclin-dependent kinase inhibitors (CDKI) which inhibit cell-cycle progression. Cyclins D and Cyclin E are important for the passage of cells through G1 to S phase. P-27, a member of the universal CDKI family, is important in regulating the G1/S transition. Thus, the purpose of this study was to investigate the expression of p-27, Cyclin D3, and Cyclin E, and their possible prognostic significance in pediatric embryonal brain tumors. We retrospectively evaluated 51 children with embryonal tumors that were treated surgically in our institute. All patients had regular follow up examinations. The streptavidin-biotin HRP method was performed on paraffin sections for detection of p-27, Cyclin D3, and Cyclin E. There were 42 cases of MB and nine cases of AT/RT. Cyclin D3 expression was detected in 11/42 MB and 3/9 AT/RT patients. Cyclin E expression was detected in 28/42 MB and 8/9 AT/RT patients. High expression of Ki-67 (>50 %) and p-27 (>50 %) was observed in 23.8-73.8 % of MB patients. Combined high Ki-67 and p-27 expression was observed in 21.4 % cases of MB. In these cases there was expression of Cyclin E in 88.8 % and Cyclin D3 in 22.2 % of MB. No significant correlation was found between Ki-67 and p-27, Cyclin D3, and E. No correlation was found between Cyclin D3, Cyclin E, p-27, and overall survival. Increased p-27 and Cyclin E expression was detected in a substantial number of MB patients and in nearly all AT/RT patients. Further studies on a larger number of patients are needed to clarify a possible correlation of p-27 and Cyclin E with tumor behavior.

Loss of INI1 Protein Expression Defines a Subgroup of Aggressive Central Nervous System Primitive Neuroectodermal Tumors

Pediatric embryonal brain tumors can be difficult to classify. Atypical teratoid rhabdoid tumors (ATRT) contain rhabdoid cells, while primitive neuroectodermal tumors (PNETs) are composed of "small round blue cells." Loss of INI1 is a common event in ATRT; therefore, we investigated if the loss of INI1 protein expression was also observed in central nervous system (CNS) PNET and pineoblastoma. A histological review of 42 CNS PNETs and six pineoblastomas was performed. INI1 expression was assessed by immunohistochemistry. Sequencing was performed on the mutational hotspots of INI1. INI1-immunonegative tumors were further investigated using fluorescence in situ hybridization. Epithelial membrane antigen (EMA) protein expression was assessed in six CNS PNETs to further define the phenotype. Five CNS PNETs without rhabdoid cell morphology were immuno-negative for both INI1 and EMA. Of these primary CNS PNET patients, three died <11 months postdiagnosis, which was dissimilar to the INI1-immunopositive primary CNS PNETs where 18/24 (75%) patients were alive 1 year postdiagnosis. We have identified a small subgroup of CNS PNETs which lack INI1 protein expression, but have no evidence of rhabdoid cell morphology. INI1 protein loss may occur through mechanisms other than gene deletion. INI1 immunohistochemistry should be performed for all CNS PNET cases.

How parents cope with their child’s diagnosis and treatment of an embryonal tumor: results of a prospective and longitudinal study

The current study reports longitudinal coping responses among parents of children diagnosed with an embryonal brain tumor. Patients (n = 219) were enrolled on a treatment protocol for a pediatric embryonal brain tumor. Their parents (n = 251) completed the Coping Response Inventory at time of their child's diagnosis and yearly thereafter, resulting in 502 observations. Outcomes were examined with patient and parent age at diagnosis, patient risk, parent gender and education as covariates. At the time of diagnosis, the highest observed coping method was seeking guidance with well above average scores (T = 61.6). Over time, younger parents were found to seek guidance at a significantly higher rate than older parents (P = .016) and the use of acceptance resignation and seeking alternative results by all parents significantly increased (P = .011 and P < .0001 respectively). The use of emotional discharge was also observed above average at time of diagnosis (T = 55.4) with younger fathers being more likely to exhibit emotional discharge than older fathers (P = .002). Differences in coping according to age of the patient and parent education level are also discussed. Results show a high need for guidance, and above average emotional discharge, especially among younger parents. It is imperative for the healthcare team to lead with accurate information so that these parents may make informed decisions about the care of their child. This need remains high years after diagnosis. Therefore it is critical to continue a consistent level of effective communication and support, even following treatment.

Expression of Epidermal Growth Factor Receptor and HER-2 in Pediatric Embryonal Brain Tumors

Background/Aims: Medulloblastomas (MBs), atypical teratoid rhabdoid tumors (AT/RTs) and central nervous system primitive neuroectodermal tumors (PNETs) are aggressive embryonal brain neoplasms in children with overlapping histological features but with different pathogenetic pathways. We set out to evaluate the role of epidermal growth factor receptor (EGFR), HER-2, Ki-67 and p53 in embryonal tumors. Material and Methods: We retrospectively evaluated 36 children with embryonic tumors (27 MBs, 7 AT/RTs and 2 supratentorial PNETs). The immunohistochemical expression of EGFR and HER-2 was correlated to histology, expression of the Ki-67/MIB-1 proliferative index, p53 tumor suppressor oncoprotein and prognosis. Results: High expression of Ki-67 was observed in all MBs being particularly increased (>50%) in 8 cases, while p53 protein was detected in 25/27 MBs showing a high expression in 16 cases. EGFR and HER-2 expression was observed in 10/27 and 17/27 MBs, respectively. High Ki-67/MIB-1 and p53 expression was revealed in all AT/RTs and PNETs, while EGFR and HER-2 were detected in 3/7 and 6/7 AT/RTs, respectively. The 5-year progression-free survival and overall survival were 55.5 and 69.2%, respectively. In MBs, the univariate analysis revealed that the Ki-67 index and male gender were both at a significant level related to the survival of the patient. In multivariate analysis, the Ki-67 index was the only independent predictive variable. Conclusions: The Ki-67 index was identified as a factor with independent prognostic power. EGFR and HER-2 expression is variable in embryonal tumors. HER-2 expression, in a considerable number of MBs and AT/RTs, suggests that HER-2 may be implicated in their pathogenesis representing a potential target for novel therapies.

Clinical outcome in pediatric glial and embryonal brain tumors correlates with in vitro multi‐passageable neurosphere formation

Cultured brain tumors can form neurospheres harboring tumorigenic cells with self renewal and differentiation capacities. Renewable neurosphere formation has clinical predictive value in adult malignant gliomas, yet its prognostic role for pediatric brain tumors is unknown. Established neurosphere conditions were used for culturing samples from glial, embryonal and mixed glioneuronal tumors from 56 pediatric patients. Potential associations between neurosphere formation and clinical outcome were analyzed retrospectively. Thirty-seven percent of all samples formed renewable neurospheres. Analysis of available clinical outcome data from 51 patients demonstrated significantly increased hazard ratios (HR) for both disease progression (HR = 9.9, P < 0.001) and death (HR = 16.6, P < 0.01) in the neurosphere forming group. Furthermore, neurosphere formation correlated with adverse progression free survival (PFS) in glial and embryonal tumors, but not in mixed glioneuronal tumors. Overall survival (OS) was significantly worse for neurosphere-forming patients with embryonal tumors, as a group and amongst the subgroup with medulloblastoma, but not in the glial group. Multivariate analysis showed that neurosphere formation was associated with diminished PFS and OS independent of age, gender, or treatment. Neurosphere formation was an independent predictor of diminished PFS of glial tumors after adjusting for grade. Multivariate analysis, adjusting for both Ki67 staining and neurosphere formation, demonstrated that neurosphere formation remained predictive of progression whereas Ki67 did not. Neurosphere formation is more predictive of pediatric brain tumor progression than semi-quantitative Ki67 staining. Pediatric brain tumor derived neurospheres may provide a predictive model for preclinical explorations.

Metaphase and array comparative genomic hybridization: unique copy number changes and gene amplification of medulloblastomas in South America

Tumors of the central nervous system are the second most frequent malignancy of childhood, accounting for the majority of cancer-related deaths in this age group. Among these tumors, medulloblastomas (MB) remain in need of further genomic characterization toward understanding of pathogenesis and outcome predictors. Eight pediatric embryonal brain tumors were analyzed: five MB (one being desmoplastic), one PNET, one medulloepithelioma, and one ependymoblastoma. Analyses identified genomic imbalances, including the gain of 16p and the nonsyntenic coamplification of MYCN and TERT loci. More detailed FISH analysis showed that coamplification of MYCN and TERT in one of the MBs manifested as dispersed nuclear speckling, consistent with the presence of double minute chromosomes. There was considerable cell-to-cell copy number heterogeneity present, but it was clear that both genes were amplified concordantly. The amplification of oncogenes seems to play an important role in the pathogenesis of MB, and the association between MYCN and TERT amplifications and poor prognosis has not been well recognized. The uncharacteristic pattern of genomic imbalances detected in MB tumors may be a reflection of the characteristics of these tumors occurring in South America.