The present finding indicates that the TP53 p.R337H germline mutation is uncommon in patients with EPN in Brazil and screening of pediatric patients RELA fusion EPN may be informative to better understand the role of TP53 germline mutations in the development and prognosis of these tumors.
By DNA methylation profiling, tumors with MN1 or RELA rearrangement clustered with high-grade neuroepithelial tumor with MN1 alteration (HGNET-MN1) and RELA-fusion ependymoma, respectively.
Ependymoma with RELA fusion has been defined as a novel entity of the revised World Health Organization 2016 classification of tumors of the central nervous system (CNS), characterized by fusion transcripts of the RELA gene and consequent pathological activation of the NFkB pathway.
Molecular characteristics are also important for the diagnosis of several other CNS tumors, such as RELA fusion-positive subtype of ependymoma, atypical teratoid rhabdoid tumor (AT/RT), embryonal tumor with multilayered rosettes, and solitary fibrous tumor/hemangiopericytoma.
We describe a novel RELA-fusion composed by a chimeric transcript C11orf95-LOC-RELA in a supratentorial WHO grade II EPN occurring in a 4-year-old child.
Furthermore, treatment of the RELA-fused EPN cell line with the Notch inhibitors impaired the Notch signaling expression and revealed that Notch axis is not essential for cell proliferation and survival in this setting.
Stable knockdown of LDOC1 in EPN cell lines resulted in a significant increase in gene transcription of v-rel avian reticuloendotheliosis viral oncogene homolog A, which correlated to an increase in NF-κB target genes.
Array-comparative genomic hybridization showed copy number abnormalities consistent with chromosomal instability without evidence of RELA- or YAP1-fusion-features most often seen in posterior fossa ependymoma group B.
Among the p53-positive ependymomas, the vast majority exhibited a RELA fusion leading to the hypothesis that p53 inactivation might be linked to RELA positivity.In order to assess the potential of p53 reactivation through MDM2 inhibition in ependymoma, we evaluated the effects of Actinomycin-D and Nutlin-3 treatment in two preclinical ependymoma models representing the high-risk subtypes PF-EPN-A and ST-EPN-RELA.
We here describe a case of a sarcoma developing in a patient previously treated with chemotherapy and radiation whose original ependymoma and recurrent sarcoma were both shown to carry the type 1 C11orf95-RELA fusion transcript indicating a monoclonal origin for both tumors.
C11orf95-RELA fusion proteins translocated spontaneously to the nucleus to activate NF-κB target genes, and rapidly transformed neural stem cells--the cell of origin of ependymoma--to form these tumours in mice.
The present finding indicates that the TP53p.R337H germline mutation is uncommon in patients with EPN in Brazil and screening of pediatric patients RELA fusion EPN may be informative to better understand the role of TP53 germline mutations in the development and prognosis of these tumors.
Among the p53-positive ependymomas, the vast majority exhibited a RELA fusion leading to the hypothesis that p53 inactivation might be linked to RELA positivity.In order to assess the potential of p53 reactivation through MDM2 inhibition in ependymoma, we evaluated the effects of Actinomycin-D and Nutlin-3 treatment in two preclinical ependymoma models representing the high-risk subtypes PF-EPN-A and ST-EPN-RELA.
Primary ependymomas at diagnosis or relapse from 24 children were analyzed for p53 pathway, using a functional assay in yeast, RT-PCR, Western blot analysis, and/or immunohistochemistry for TP53 mutation, p14(ARF) deletion and promoter hypermethylation, MDM2 and PAX5 expression, respectively. p53-mediated response to radiation-induced DNA damage was evaluated using Western blot and flow cytometry analysis in two ependymoma xenograft models, IGREP37 and IGREP83, derived from primary anaplastic childhood ependymomas.
Chromosomal DNA corresponding to the p53 tumor suppressor gene was amplified by the polymerase chain reaction (PCR) from 31 archival ependymoma specimens.
The molecular groups showed no significant difference in PFS (4-year estimates: posterior fossa ependymoma group A [PF-EPN-A; 42/54], 71.2% ± 8.3%; supratentorial ependymoma positive for v-rel avian reticuloendotheliosis viral oncogene homolog A [ST-EPN-RELA; 8/54], 83.3% ± 17.0%; and supratentorial ependymoma positive for Yes-associated protein [4/54], 100%, P = 0.22).
Location of the primary tumor was supratentorial in four patients (all supratentorial <i>RELA</i>-fused ependymoma [ST-EPN-RELA]) and within the posterior fossa in five patients (posterior fossa ependymoma type A [PF-EPN-A], <i>n</i> = 4; posterior fossa ependymoma not further classifiable, <i>n</i> = 1), and multifocal in one patient.All four patients with ST-EPN-RELA were alive in first or second complete remission (CR) 7.5-12.3 years after diagnosis.