Cancer‐Specific Cell Death in Response to Palmitoylcarnitine is Associated with Increased Mitochondrial Hydrogen Peroxide
Bibliographic record
Abstract
Rationale and Hypothesis A benchmark of cancer cells is the reliance on glycolysis characterized by decreased mitochondrial oxidative phosphorylation (eg. Warburg effect). Recent evidence suggests that fatty acids (palmitoylcarnitine; PCarn) may force a shift to mitochondrial oxidative phosphorylation in HT29 colon cancer causing cell death, yet non‐cancer cells appear to be resistant. These results present the intriguing possibility that ‘lipid‐therapy’ might be well tolerated by healthy cells while retaining potency in cancer. However, the mechanism of lipid‐induced cancer cell death is not known. Glutathione is the main antioxidant found within the cell, we hypothesize that cell survival is determined by heterogeneity of basal intracellular glutathione. We theorize that cells with low basal glutathione will be more susceptible to elevated levels of mitochondrial H 2 O 2 from beta‐oxidation of PCarn, whereas cells with higher glutathione will be more resistant to elevated levels of H 2 O 2 . Experimental approach We developed a live cell kinetic assay to measure H 2 O 2 emission in real time; using this assay we exposed three different cancer lines (HT29 colorectal adenocarcinoma, MCF7 breast adenocarcinoma and HepG2 hepatocellular carcinoma) and one non‐cancerous cell line (CCD841 colon epithelial cells) to increasing amounts of PCarn (25μM, 50μM 100μM) for 2, 24 and 48hrs. As a measure of cell proliferation, we adapted a BCA protein assay to digest adhered cells in‐well as a measure of total cell content. Results After 48hr incubation of 100μM PCarn, H 2 O 2 emission increased in MCF7 (20%) and HT29 (170%), which corresponded to decreased protein contents of 20% and 50% respectively, thereby demonstrating a graded relationship between degree of H 2 O 2 emission and reduction in cell content. HepG2 demonstrated increased H 2 O 2 emission after 48hr incubation with 25μM (150% increase) and 50μM PCarn (218% increase) with a 50% reduction in protein content in both cases. In the non‐cancerous CCD841, we noticed an increase in H 2 O 2 (115%) emission, despite no change in protein content. Collectively, this data suggests that increases in H 2 O 2 production through PCarn oxidation is well tolerated by non‐cancerous cells, however cancer cells are unable to withstand the concomitant increase in mitochondrial H 2 O 2 emission albeit in response to different PCarn concentrations. Future work will determine the manner by which these cancer‐specific redox‐cell death relationships are regulated by glutathione buffering. Support or Funding Information Funding was provided to C.G.R.P. by National Science and Engineering Research Council (#436138‐2013) with infrastructure supported by Canada Foundation for Innovation, Ontario Research Fund and the James H. Cummings Foundation. P. C. T. was supported by an NSERC CGS‐D scholarship.
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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) | 0.001 | 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".