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.
A subgroup of supratentorial ependymomas are characterized by C11orf95-RELA fusions, presumed to be secondary to chromothripsis of chromosome 11, resulting in constitutive activation of the NF-κB signaling pathway and overexpression of cyclin D1, p65, and L1 cell adhesion molecule (L1CAM).
Here, we have used interphase fluorescent in situ hybridization (FISH) for C11orf95 and RELA, immunohistochemistry (IHC) for p65-RelA and the recently developed DNA methylation-based classification besides conventional histopathology, and compared the precision of the methods in 40 supratentorial pediatric brain tumors diagnosed as ependymomas in the past years.
Although most CEs in our group were immunopositive for L1CAM and showed C11orf95-RELA fusion, which have been associated with a poor prognosis in supratentorial ependymomas, all our patients had good outcomes.
Although most CEs in our group were immunopositive for L1CAM and showed C11orf95-RELA fusion, which have been associated with a poor prognosis in supratentorial ependymomas, all our patients had good outcomes.
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.
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.
Here, we have used interphase fluorescent in situ hybridization (FISH) for C11orf95 and RELA, immunohistochemistry (IHC) for p65-RelA and the recently developed DNA methylation-based classification besides conventional histopathology, and compared the precision of the methods in 40 supratentorial pediatric brain tumors diagnosed as ependymomas in the past years.
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.
We used real-time polymerase chain reaction, conventional real-time polymerase chain reaction, and Sanger sequencing to characterize RELA fusion status in formalin-fixed paraffin-embedded samples from 42 ST-EPs (12 adults and 30 pediatric).
Interestingly, almost half of the patients with RELA fusion-positive ependymomas are adults (13/28), and 89.3% (25/28) cases are anaplastic ependymomas, which suggests that RELA fusion testing is necessary in adults with STEEs.
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.
The majority of supratentorial ependymomas (ST-ependymomas) have few mutations but frequently display chromothripsis of chromosome 11q that generates a fusion between C11orf95 and RELA (RELA<sup>FUS</sup>).
RELA fusion proteins activate signaling for tumor proliferation and malignant progression, resulting in poorer prognoses in these patients compared to those in patients with other ST ependymomas.
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.
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.
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.