The antitumor anthracyclines doxorubicin and daunorubicin do not inhibit cell growth through the formation of iron-mediated reactive oxygen species
Bibliographic record
Abstract
The use of the anthracycline anticancer drugs doxorubicin and daunorubicin is limited by what is thought to be an iron-based oxygen radical-derived dose-dependent cardiotoxicity. The anthracyclines are also DNA topoisomerase (Topo) II poisons. It is not known if iron-mediated formation of reactive oxygen species (ROS) by the anthracyclines or their Topo II inhibitory effects are responsible for their cell growth-inhibitory effects. Experiments to test these two alternatives were carried out using a CHO-derived cell line (DZR) that was highly resistant to dexrazoxane through a Thr48IIe mutation in Topo IIalpha. The clinically used cardioprotective agent dexrazoxane likely exerts its cardioprotective effects through the chelating ability of its hydrolysis product ADR-925, an analog of EDTA. Dexrazoxane is also a cell growth inhibitor that acts through its ability to inhibit the catalytic activity of Topo II. Thus, the DZR cell line allowed us to examine the cell growth-inhibitory effects of doxorubicin and daunorubicin in the presence of dexrazoxane without the confounding effect of dexrazoxane inhibiting cell growth. The growth-inhibitory effects of neither doxorubicin nor daunorubicin were affected by pretreating DZR cells with dexrazoxane. In contrast, under similar conditions, dexrazoxane strongly protected rat cardiac myocytes from doxorubicin-induced lactate dehydrogenase release. In conclusion, the anthracyclines do not inhibit the growth of DZR cells through the generation of iron-mediated formation of ROS.
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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 | 0.001 |
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".