RESUMO
BACKGROUND: The prognosis for Li-Fraumeni syndrome (LFS) patients with medulloblastoma (MB) is poor. Comprehensive clinical data for this patient group is lacking, challenging the development of novel therapeutic strategies. Here, we present clinical and molecular data on a retrospective cohort of pediatric LFS MB patients. METHODS: In this multinational, multicenter retrospective cohort study, LFS patients under 21 years with MB and class 5 or class 4 constitutional TP53 variants were included. TP53 mutation status, methylation subgroup, treatment, progression free- (PFS) and overall survival (OS), recurrence patterns, and incidence of subsequent neoplasms were evaluated. RESULTS: The study evaluated 47 LFS individuals diagnosed with MB, mainly classified as DNA methylation subgroup "SHH_3" (86%). The majority (74%) of constitutional TP53 variants represented missense variants. The 2- and 5-year (y-) PFS were 36% and 20%, and 2- and 5y-OS were 53% and 23%, respectively. Patients who received postoperative radiotherapy (RT) (2y-PFS: 44%, 2y-OS: 60%) or chemotherapy before RT (2y-PFS: 32%, 2y-OS: 48%) had significantly better clinical outcome then patients who were not treated with RT (2y-PFS: 0%, 2y-OS: 25%). Patients treated according to protocols including high-intensity chemotherapy and patients who received only maintenance-type chemotherapy showed similar outcomes (2y-PFS: 42% and 35%, 2y-OS: 68% and 53%, respectively). CONCLUSIONS: LFS MB patients have a dismal prognosis. In the presented cohort use of RT significantly increased survival rates, whereas chemotherapy intensity did not influence their clinical outcome. Prospective collection of clinical data and development of novel treatments are required to improve the outcome of LFS MB patients.
Assuntos
Neoplasias Cerebelares , Síndrome de Li-Fraumeni , Meduloblastoma , Criança , Humanos , Síndrome de Li-Fraumeni/complicações , Síndrome de Li-Fraumeni/genética , Síndrome de Li-Fraumeni/terapia , Meduloblastoma/terapia , Meduloblastoma/tratamento farmacológico , Estudos Retrospectivos , Estudos Prospectivos , Neoplasias Cerebelares/terapia , Neoplasias Cerebelares/tratamento farmacológico , Mutação em Linhagem Germinativa , Proteína Supressora de Tumor p53/genéticaRESUMO
Epigenetic alterations, including methylation, have been shown to be an important mechanism of gene silencing in cancer. Ependymoma has been well characterized at the DNA copy number and mRNA expression levels. However little is known about DNA methylation changes. To gain a more global view of the methylation profile of ependymoma we conducted an array-based analysis. Our data demonstrated tumors to segregate according to their location in the CNS, which was associated with a difference in the global level of methylation. Supratentorial and spinal tumors displayed significantly more hypermethylated genes than posterior fossa tumors, similar to the 'CpG island methylator phenotype' (CIMP) identified in glioma and colon carcinoma. This hypermethylated profile was associated with an increase in expression of genes encoding for proteins involved in methylating DNA, suggesting an underlying mechanism. An integrated analysis of methylation and mRNA expression array data allowed us to identify methylation-induced expression changes. Most notably genes involved in the control of cell growth and death and the immune system were identified, including members of the JNK pathway and PPARG. In conclusion, we have generated a global view of the methylation profile of ependymoma. The data suggests epigenetic silencing of tumor suppressor genes is an important mechanism in the pathogenesis of supratentorial and spinal, but not posterior fossa ependymomas. Hypermethylation correlated with a decrease in expression of a number of tumor suppressor genes and pathways that could be playing an important role in tumor pathogenesis.
Assuntos
Ependimoma/genética , Ependimoma/fisiopatologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Genes Supressores de Tumor/fisiologia , Neoplasias da Coluna Vertebral/fisiopatologia , Neoplasias Supratentoriais/fisiopatologia , Apoptose/fisiologia , Proliferação de Células , Criança , Análise por Conglomerados , Estudos de Coortes , Metilação de DNA/genética , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Transdução de Sinais/genética , Neoplasias da Coluna Vertebral/genética , Estatística como Assunto , Neoplasias Supratentoriais/genéticaRESUMO
The MYC oncogenes are the most commonly amplified loci in medulloblastoma, and have previously been proposed as biomarkers of adverse disease prognosis by us and others. Here, we report focussed and comprehensive investigations of MYCC, MYCN and MYCL in an extensive medulloblastoma cohort (n = 292), aimed to define more precisely their biological significance and optimal clinical application to direct improved disease risk-stratification and individualisation of therapy. MYCC and MYCN expression elevations were multifactorial, associated with high-risk (gene amplification, large-cell/anaplastic pathology (LCA)) and favourable-risk (WNT/SHH molecular subgroups) disease features. Highly variable cellular gene amplification patterns underlay overall MYC copy number elevations observed in tumour biopsies; we used these alternative measures together to define quantitative methodologies and thresholds for amplification detection in routinely collected tumour material. MYCC and MYCN amplification, but not gain, each had independent prognostic significance in non-infants (≥3.0-16.0 years), but MYCC conferred a greater hazard to survival than MYCN when considered across this treatment group. MYCN's weaker group-wide survival relationship may be explained by its pleiotropic behaviour between clinical disease-risk groups; MYCN predicted poor prognosis in clinical high-risk (metastatic (M+) or LCA), but not standard-risk, patients. Extending these findings, survival decreased in proportion to the total number of independently significant high-risk features present (LCA, M+ or MYCC/MYCN amplification). This cumulative-risk model defines a patient group characterised by ≥2 independent risk-factors and an extremely poor prognosis (<15% survival), which can be identified straightforwardly using the reported MYC amplification detection methodologies alongside clinical assessments, enabling targeting for novel/intensified therapies in future clinical studies.
Assuntos
Neoplasias Cerebelares/genética , Variações do Número de Cópias de DNA/genética , Regulação Neoplásica da Expressão Gênica/genética , Meduloblastoma/genética , Proteínas Proto-Oncogênicas c-myc/genética , Adolescente , Neoplasias Cerebelares/diagnóstico , Neoplasias Cerebelares/mortalidade , Criança , Pré-Escolar , Estudos de Coortes , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Humanos , Masculino , Meduloblastoma/diagnóstico , Meduloblastoma/mortalidade , Proteína Proto-Oncogênica N-Myc , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas Oncogênicas/genética , Proteínas Oncogênicas/metabolismo , Valor Preditivo dos Testes , Proteínas Proto-Oncogênicas c-myc/metabolismo , RNA Mensageiro/metabolismo , Fatores de Risco , Análise de Sobrevida , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoAssuntos
Neoplasias Cerebelares/metabolismo , Metilação de DNA/genética , Meduloblastoma/metabolismo , Mutação/genética , Regiões Promotoras Genéticas/genética , Telomerase/genética , Telomerase/metabolismo , Adolescente , Neoplasias Cerebelares/classificação , Neoplasias Cerebelares/genética , Criança , Pré-Escolar , Estudos de Coortes , DNA de Neoplasias/genética , Epigenômica , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Meduloblastoma/classificação , Meduloblastoma/genéticaRESUMO
PURPOSE: To improve stratification of risk-adapted treatment for non-metastatic (M0), standard-risk medulloblastoma patients by prospective evaluation of biomarkers of reported biological or prognostic significance, alongside clinico-pathological variables, within the multi-center HIT-SIOP-PNET4 trial. METHODS: Formalin-fixed paraffin-embedded tumor tissues were collected from 338 M0 patients (>4.0 years at diagnosis) for pathology review and assessment of the WNT subgroup (MBWNT) and genomic copy-number defects (chromosome 17, MYC/MYCN, 9q22 (PTCH1) and DNA ploidy). Clinical characteristics were reviewed centrally. RESULTS: The favorable prognosis of MBWNT was confirmed, however better outcomes were observed for non-MBWNT tumors in this clinical risk-defined cohort compared to previous disease-wide clinical trials. Chromosome 17p/q defects were heterogeneous when assessed at the cellular copy-number level, and predicted poor prognosis when they occurred against a diploid (ch17(im)/diploid(cen)), but not polyploid, genetic background. These factors, together with post-surgical tumor residuum (R+) and radiotherapy delay, were supported as independent prognostic markers in multivariate testing. Notably, MYC and MYCN amplification were not associated with adverse outcome. In cross-validated survival models derived for the clinical standard-risk (M0/R0) disease group, (ch17(im)/diploid(cen); 14% of patients) predicted high disease-risk, while the outcomes of patients without (ch17(im)/diploid(cen)) did not differ significantly from MBWNT, allowing re-classification of 86% as favorable-risk. CONCLUSIONS: Biomarkers, established previously in disease-wide studies, behave differently in clinically-defined standard-risk disease. Distinct biomarkers are required to assess disease-risk in this group, and define improved risk-stratification models. Routine testing for specific patterns of chromosome 17 imbalance at the cellular level, and MBWNT, provides a strong basis for incorporation into future trials.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias Cerebelares/química , Meduloblastoma/química , Adolescente , Adulto , Biomarcadores Tumorais/genética , Neoplasias Cerebelares/diagnóstico , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/terapia , Criança , Pré-Escolar , Cromossomos Humanos Par 17 , Estudos de Coortes , Feminino , Formaldeído , Humanos , Masculino , Meduloblastoma/diagnóstico , Meduloblastoma/genética , Meduloblastoma/terapia , Inclusão em Parafina , Prognóstico , Fatores de Risco , Fixação de Tecidos , Adulto JovemRESUMO
We undertook a comprehensive clinical and biological investigation of serial medulloblastoma biopsies obtained at diagnosis and relapse. Combined MYC family amplifications and P53 pathway defects commonly emerged at relapse, and all patients in this group died of rapidly progressive disease postrelapse. To study this interaction, we investigated a transgenic model of MYCN-driven medulloblastoma and found spontaneous development of Trp53 inactivating mutations. Abrogation of p53 function in this model produced aggressive tumors that mimicked characteristics of relapsed human tumors with combined P53-MYC dysfunction. Restoration of p53 activity and genetic and therapeutic suppression of MYCN all reduced tumor growth and prolonged survival. Our findings identify P53-MYC interactions at medulloblastoma relapse as biomarkers of clinically aggressive disease that may be targeted therapeutically.
Assuntos
Neoplasias Cerebelares/genética , Meduloblastoma/genética , Recidiva Local de Neoplasia/genética , Proteínas Proto-Oncogênicas c-myc/genética , Proteína Supressora de Tumor p53/genética , Adolescente , Adulto , Animais , Antineoplásicos/uso terapêutico , Neoplasias Cerebelares/tratamento farmacológico , Neoplasias Cerebelares/patologia , Criança , Pré-Escolar , Feminino , Amplificação de Genes , Humanos , Lactente , Masculino , Meduloblastoma/tratamento farmacológico , Meduloblastoma/patologia , Camundongos , Dados de Sequência Molecular , Mutação , Proteína Proto-Oncogênica N-Myc , Recidiva Local de Neoplasia/tratamento farmacológico , Neoplasias Experimentais , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas Oncogênicas/genética , Proteínas Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/metabolismo , Adulto JovemRESUMO
Alternative splicing is an important mechanism for the generation of protein diversity at a post-transcriptional level. Modifications in the splicing patterns of several genes have been shown to contribute to the malignant transformation of different tissue types. In this study, we used the Affymetrix Exon arrays to investigate patterns of differential splicing between pediatric medulloblastomas and normal cerebellum on a genome-wide scale. Of the 1,262 genes identified as potentially generating tumor-associated splice forms, we selected 14 examples of differential splicing of known cassette exons and successfully validated 11 of them by reverse transcriptase PCR. The pattern of differential splicing of three validated events was characteristic for the molecular subset of sonic hedgehog (Shh)-driven medulloblastomas, suggesting that their unique gene signature includes the expression of distinctive transcript variants. Generally, we observed that tumor and normal fetal cerebellar samples shared significantly lower exon inclusion rates than normal adult cerebellum. We investigated whether tumor-associated splice forms were expressed in primary cultures of Shh-dependent mouse cerebellar granule cell precursors (GCP) and found that Shh caused a decrease in the cassette exon inclusion rate of five of the seven tested genes. Furthermore, we observed a significant increase in exon inclusion between postnatal days 7 and 14 of mouse cerebellar development, at the time when GCPs mature into postmitotic neurons. We conclude that inappropriate splicing frequently occurs in human medulloblastomas and may be linked to the activation of developmental signaling pathways and a failure of cerebellar precursor cells to differentiate.
Assuntos
Processamento Alternativo , Neoplasias Cerebelares/genética , Cerebelo/metabolismo , Meduloblastoma/genética , Animais , Linhagem Celular Tumoral , Células Cultivadas , Cerebelo/crescimento & desenvolvimento , Análise por Conglomerados , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação Neoplásica da Expressão Gênica , Genoma/genética , Estudo de Associação Genômica Ampla , Células HEK293 , Humanos , Meduloblastoma/patologia , Camundongos , Camundongos Endogâmicos C57BL , Análise de Sequência com Séries de Oligonucleotídeos , Isoformas de Proteínas/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
PURPOSE: Microarray studies indicate medulloblastoma comprises distinct molecular disease subgroups, which offer potential for improved clinical management. EXPERIMENTAL DESIGN: Minimal mRNA expression signatures diagnostic for the Wnt/Wingless (WNT) and Sonic Hedgehog (SHH) subgroups were developed, validated, and used to assign subgroup affiliation in 173 tumors from four independent cohorts, alongside a systematic investigation of subgroup clinical and molecular characteristics. RESULTS: WNT tumors [12% (21/173)] were diagnosed >5 years of age (peak, 10 years), displayed classic histology, CTNNB1 mutation (19/20), and associated chromosome 6 loss, and have previously been associated with favorable prognosis. SHH cases [24% (42/173)] predominated in infants (<3 years) and showed an age-dependent relationship to desmoplastic/nodular pathology; all infant desmoplastic/nodular cases (previously associated with a good outcome) were SHH-positive, but these relationships broke down in noninfants. PTCH1 mutations were common [34% (11/32)], but PTCH1 exon1c hypermethylation, chromosome 9q and REN (KCTD11) genetic loss were not SHH associated, and SMO or SUFU mutation, PTCH1 exon1a or SUFU hypermethylation did not play a role, indicating novel activating mechanisms in the majority of SHH cases. SHH tumors were associated with an absence of COL1A2 methylation. WNT/SHH-independent medulloblastomas [64% (110/173)] showed all histologies, peaked at 3 and 6 years, and were exclusively associated with chromosome 17p loss. CONCLUSIONS: Medulloblastoma subgroups are characterized by distinct genomic, epigenomic and clinicopathologic features, and clinical outcomes. Validated array-independent gene expression assays for the rapid assessment of subgroup affiliation in small biopsies provide a basis for their routine clinical application, in strategies including molecular disease-risk stratification and delivery of targeted therapeutics.