EPND-08. EPIGENETIC H3K27ME3 DEREGULATION IN PEDIATRIC POSTERIOR FOSSA EPENDYMOMAS
Bibliographic record
Abstract
Ependymomas in children occur most commonly in the posterior fossa of the brain and cause significant morbidity and mortality. The pathogenesis of these tumors remains obscure as recent whole genome and whole exome sequencing efforts have not yielded recurrent genetic mutations. These tumors exhibit abnormal CpG island methylation, suggesting that epigenetic alterations may be a significant driver. To gain insights into the epigenetics of childhood ependymomas, we performed mass spectroscopy for histone modifications to discover that H3K27 trimethylation was globally reduced in these tumors. Despite global reduction in H3K27me3, ChIP-sequencing for H3K27me3 revealed genomic enrichment at several loci important for neurodevelopment. In a cohort of 195 childhood posterior fossa ependymoma samples, reduction in H3K27me3 was associated with worse prognosis (p<0.0001). Comparison of DNA methylation and genome-wide H3K27me3 enrichment from both H3K27M mutant diffuse intrinsic pontine gliomas and childhood ependymomas patient samples showed many similarities and pointed to factors that regulate radial glial (neuronal stem cells) development. Human radial glial cells during development exhibit low H3K27me3. Ependymomas with reduced H3K27me3 corresponded to younger children (p<0.0001), arose mainly from the roof of the forth ventricle, exhibited increased evidence of radiologic and histopathologic invasion and exhibited clinical features consistent with previously described PFA subgroup of ependymomas. Together these data suggest that the epigenetics of the developing posterior fossa are closely related to the pathogenesis of childhood brain tumors and have clinical implications for biomarker development and to inform epigenetic approaches to treat PF ependymomas.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".