CSIG-12. PREX1 LINKS ABERRANT PI 3-KINASE PATHWAY SIGNALING TO MAINTENANCE OF THE NEURAL STEM CELL-LIKE PHENOTYPE OF GLIOBLASTOMA CELLS
Bibliographic record
Abstract
Abstract Virtually all primary glioblastomas have aberrant activation of the PI 3-kinase pathway through mutational inactivation of tumour suppressors such as PTEN and/or mutational activation of oncogenes. Most glioblastomas also overexpress the Rac guanine nucleotide exchange factor PREX1, which is activated by PI 3-kinase pathway signaling. To determine the role of PREX1 in mediating the effects of aberrant PI 3-kinase pathway signaling in glioblastoma, we used CRISPR/Cas9 to knockout PREX1 in patient-derived glioblastoma cells cultured under conditions that maintain their neural stem cell-like characteristics. Multiple PREX1-null glioblastoma cell clones showed reduced motility and an altered morphology, with a smaller cell body and multiple neurite-like extensions. They also had increased expression of doublecortin, a marker of committed neurogenic progenitor cells. Analysis of RNA-seq data for transcription factor usage was consistent with the acquisition of an intermediate progenitor-like phenotype in PREX1-null cells, with loss of neural stem cell-associated polycomb repressive complex 2 and DMRTA2 activity and the expression of an EOMES/TBR2 signature characteristic of intermediate progenitors. The reduced motility, altered morphology and increase in doublecortin protein levels could all be reversed by re-expression of PREX1. PREX1-null cells had a reduced ability to phosphorylate and inactivate Lgl1, which is required for the maintenance of neural stem cell-like glioblastoma cell populations in vivo. These data show that PREX1 links aberrant PI 3-kinase signaling to maintenance of the neural stem cell-like phenotype in glioblastoma cells.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".