Role of autophagy in temozolomide‐induced apoptosis in Rhabdomyosarcoma cells
Bibliographic record
Abstract
Rhabdomyosarcoma (RMS) is a muscle‐derived tumor and is the most common pediatric soft tissue sarcoma representing 5% of all childhood cancers. RMS is a major clinical problem in pediatric oncology. Treatment of RMS with the oral alkylating agent temozolomide (TMZ), alone or in combination with other drugs, has recently received considerable interest. However, the mechanism of action of TMZ remains unclear. The aim of this investigation was to determine if autophagy modulates TMZ‐induced cell death in RMS cell lines. MTT assay and Nicoletti flow cytometry analysis were used to measure cell death and apoptosis in SJCRH30 (RH30) human RMS cells and the non‐transformed mouse myoblast cell line C2C12, following TMZ treatment (100 μM). We monitored autophagy using transmission electron microcopy (autophagosome and autophagolysosome formation) and immunoblotting (LC3 lipidation, Atg15‐12 conjugation, p62 degredation). The effect of bafilomycin A1 on TMZ‐induced cytotoxicity was also evaluated. We showed that TMZ decreased the viability of RMS cells in a dose/time‐dependent manner and induced accumulation of sub‐G 1 cell population, representing apoptotic cells. Interestingly, TMZ induced apoptosis by 17‐fold in the RH30 cells, but only increased apoptosis by 2.7‐fold in C2C12 cells. In RH30 cells, TMZ decreased the expression of antiapoptotic proteins Bcl‐XL and Mcl‐1, and increased the expression of the death gene Nix. Moreover, we showed that TMZ altered biochemical markers of autophagy, such as LC3 lipidation, Atg5–12 conjugation, and p62 degradation, and induced morphological evidence autophagy, including accumulation of autophagosomes and autophagolysosome, determined by transmission electron. Finally, treatment of RMS cells with the autophagy flux inhibitor (Bafilomycin A1, 4 and 6 nM) had no significant effect TMZ‐induced cell death in either cell line. In conclusion, our investigation showed that TMZ induced simultaneous autophagy and apoptosis in both RH30 and C2C12 cells; however, cell death induction by TMZ does not appear to be dependent on Bafilomycin A1 inhibited processes, such as autophagosome‐lysosome fusion or autolysosome acidification.
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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".