Hypoxia-induced downregulation of autophagy mediator Beclin-1 reduces the susceptibility of malignant intestinal epithelial cells to hypoxia-dependent apoptosis
Why this work is in the frame
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Bibliographic record
Abstract
Disruption of tumor blood supply causes tumor hypoxia. Hypoxia can induce cell death, but cancer cells that remain viable in the absence of oxygen often possess an increased survival potential, and tumors formed by these cells tend to grow particularly aggressively. Thus, developing approaches aimed at increasing the susceptibility of malignant cells to hypoxia-induced death represents a potentially important avenue for cancer treatment. Molecular mechanisms that control the survival of cancer cells under hypoxia are not well understood. In an effort to understand them we found that hypoxia downregulates Beclin 1, a mediator of autophagy, in malignant intestinal epithelial cells. The reversal of this downregulation promoted autophagosome accumulation, enhanced the activation of a pro-apoptotic protease caspase-9 and subsequent caspase-9-dependent activation of two other pro-apoptotic proteases caspases 3 and 7 in these cells. Furthermore, the reversal of hypoxia-induced downregulation of Beclin 1-stimulated caspase-9-dependent apoptosis of the indicated cells under hypoxia. Interestingly, we found that Beclin 1-dependent caspase-9 activation in hypoxic cells was not associated with an increased release of cytochrome c from the mitochondria to the cytoplasm (such release represents a frequently occurring mechanism for caspase-9 activation). We also observed that Beclin 1-dependent apoptosis of hypoxic malignant cells was independent of FADD, a mediator of death receptor signaling. We conclude that hypoxia triggers a feedback mechanism that delays apoptosis of oxygen-deprived malignant intestinal epithelial cells and is driven by hypoxia-induced Beclin 1 downregulation. Thus, approaches aimed at the disruption of this mechanism can be expected to enhance the susceptibility of such cells to hypoxia-induced apoptosis.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 it