Combined inhibition of autophagy with mTOR inhibitor to enhance cell death in renal cell carcinoma.
Bibliographic record
Abstract
450 Background: mTOR (mammalian target of rapamycin) and autophagy are increasingly recognized as being a central cellular and pathological process for numerous human diseases, including renal cell carcinoma (RCC). Depending on the cellular context, autophagy may promote cancer cell survival or cell death. However, little is known about the mechanisms of regulating mTOR activity and autophagic function in RCC. We hypothesize that autophagy promotes cell survival via mTOR mediated-phosphatidylinositol 3-kinase (PI3K)/AKT pathway and is regulated by the von Hippel-Lindau (VHL) tumor suppressor. Methods: RCC cells were stably lentiviral transduced with expression of VHL or mCherry-EGFP tandemfluorescent-tagged LC3B for studying autophagic flux. Cell viability was evaluated by cytotoxic XTT and clonogenic assays and flow cytometry. The efficacy of PI3K/AKT/mTOR pathway inhibition by RAD001, PI-103, MK2206, AZD8055, and/or lysosomotropic inhibitors were evaluated by immunoblots and immunofluorescence for autophagy process of autophagosome and lysosome. Results: We show that mTOR is hyperactive in VHL-deficient cells compared to cells with wild-type VHL or VHL-expressing cells. AZD8055-induced toxicity occurs in a VHL-independent manner via cell cycle arrest and clonogenic senescent cell death, but results in significantly increased expression of autophagic marker LC3-II and the formation of autophagic vacuoles. Pharmacologic inhibition or siRNA silencing of autophagy pathway components promotes AZD8055-induced cell death in VHL-deficient cells. Interestingly, defective autophagy marked by the presence of sustained p62 expression in VHL-deficient cells appears to contribute to cell survival via mTOR signaling, which in turn influences autophagosome-lysosome fusion, and thus controls autophagic flux by acting at the termination stage of the process. Conclusions: These results support mTOR and autophagy pathways as potential targets of anticancer drugs and reveal VHL in control of the autophagic program in RCC. Further, this work suggests that combined inhibition of autophagy along with mTOR inhibitors could be a novel therapeutic strategy for the treatment of RCC.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 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 | 0.001 |
| 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".