Abstract 3438: Hypoxia inhibits BMP4-induced astrocytic differentiation in glioma stem cells
Bibliographic record
Abstract
Abstract The tumor microenvironment is an important contributor to malignancy in glioblastoma (GBM) by influencing stemness properties in glioma stem cells (GSCs) and their capacity for differentiation into various cell types. Tumor hypoxia is a common feature of the GBM microenvironment and can influence cell state through a variety of processes including the inhibition of oxygen-dependent lysine histone demethylases (KDMs) and subsequent epigenetic changes required for differentiation or maintenance of the stem cell state. However, the precise mechanisms underlying hypoxic restriction of differentiation to specific neural lineages is unclear. Here, we show that hypoxia suppresses astrocytic differentiation induced by bone morphogenetic protein 4 (BMP4) in patient-derived GSCs. In 8/10 patient derived GSC lines, BMP4 induced expression of astrocytic markers, such as glial fibrillary acidic protein, and this induction was repressed by hypoxia in 7/10 lines. Interestingly, significant anti-proliferative effects of BMP4 induced differentiation were only observed in 3/10 lines and was rescued in only one GSC line by hypoxia, suggesting that these processes are uncoupled. Although hypoxia may directly limit the activity of oxygen-dependent KDMs important in this process, levels of S-2-hydroxyglutarate (S-2HG), an endogenous KDM inhibitor, were also increased in 5/8 GSC lines under hypoxia. Exogenous treatment with S-2HG or a small molecule KDM6 family inhibitor, phenocopied the repressive effects of hypoxia on BMP4 induced differentiation. In patient tumors, hypoxic areas surrounding pseudopalisading necrosis showed high expression of hypoxia markers, and these hypoxia markers were anti-correlated with markers of astrocytic differentiation. Together, these results demonstrate that the hypoxic tumor microenvironment in GBM, through multiple mechanisms limiting oxygen-dependent KDM activity, promote maintenance of the malignant stemness state by inhibiting astrocytic differentiation. This study implicates tumour hypoxia as a key regulator of stemness and a therapeutic target to promote differentiation in GBM. Treatment strategies that target hypoxic cells are urgently needed to overcome these challenges. Citation Format: Ronald S. Wu, Elisabeth Liedtke, Sheila Mansouri, Samantha Brazier, Paul Guilhamon, Nicole I. Park, Eric Chen, Mathieu Lupien, Daniel D. De Carvalho, Peter G. Dirks, Gelareh Zadeh, Bradley G. Wouters. Hypoxia inhibits BMP4-induced astrocytic differentiation in glioma stem cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3438.
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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 | 0.000 |
| 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".