20<i>S</i>-Protopanaxadiol Inhibits P-Glycoprotein in Multidrug Resistant Cancer Cells
Why this work is in the frame
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Bibliographic record
Abstract
One of the major causes for cancer cells to resist current chemotherapy is attributed to the over-expression of P-glycoprotein (P-gp), resulting in insufficient drug delivery to the tumor sites. Protopanaxadiol ginsenosides Rg3 and Rh2 are known to induce apoptosis and significantly enhance the tumor inhibitory effects of chemotherapeutics in a synergistic fashion. One of the possible mechanisms is by blocking P-gp activity. The final deglycosylation metabolite of protopanaxadiols (PPDs) IN VIVO is 20S-protopapanaxadiol (aglycone PPD, aPPD), which has also shown anticancer activity and synergy with chemotherapy drugs. In the present study, P-gp over-expressing cancer cells were utilized to test whether aPPD also inhibits P-gp activity. We found that aPPD caused similar cytotoxicity in P388adr cells as their parental non-MDR cells, suggesting that aPPD may not be a substrate of P-gp. On the other hand, the calcein AM efflux assay showed that aPPD was able to inhibit P-gp activity as potently as verapamil on MDR cells. The blockage of P-gp activity was highly reversible as wash-out of aPPD resulted in an immediate recovery of P-gp activity. Unlike verapamil, aPPD did not affect ATPase activity of P-gp suggesting a different mechanism of action. The above results indicate that aPPD, unlike its precursor ginsenosides Rg3 and Rh2, is not a substrate of P-gp. It is also the first time that aPPD has showed a reversible nature of its P-gp inhibition. In addition to its pro-apoptotic nature, aPPD may be a potential new P-gp inhibitor for cancer treatment.
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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 | 0.000 | 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) | 0.000 | 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