Antiestrogenic effect of 20S‐protopanaxadiol and its synergy with tamoxifen on breast cancer cells
Bibliographic record
Abstract
BACKGROUND: 20S-protopanaxadiol (aPPD) is a major gastrointestinal metabolic product of ginsenosides. The latter share structural similarity with steroids and are the main pharmacologically active component in ginseng. METHODS: The authors investigated the interaction between aPPD and estrogen receptors (ER) in human breast adenocarcinoma MCF-7 cells through receptor binding assay, ER-induced gene expression, and cell proliferation both in vitro and in vivo. RESULTS: aPPD, but not its close analog ginsenosides, competed with the [(3)H]-17-beta estradiol (E2) for ER with IC(50) at 26.3 microM. aPPD alone weakly induced luciferase reporter-gene expression controlled by an estrogen-regulated element, which was completely blocked by tamoxifen. aPPD alone, or in synergy with tamoxifen, blocked E2-induced transcriptional activation. aPPD also inhibited colony formation of endometrial cancer cells. aPPD potently inhibited estrogen-stimulated MCF-7 cell proliferation and synergistically enhanced the cytotoxicity of tamoxifen on both ER+ MCF-7 and ER- MDA-MB231 cells. Furthermore, aPPD, but not tamoxifen, inhibited Akt phosphorylation. Growth of MCF-7 xenograft tumor supplemented with E2 was completely inhibited in animals treated with aPPD, tamoxifen, or aPPD plus tamoxifen. CONCLUSIONS: These results suggested that aPPD inhibits estrogen-stimulated gene expression and cell proliferation in ER-positive breast cancer cells. In addition, aPPD synergistically enhances cytotoxicity of tamoxifen in an ER-independent fashion, probably by down-regulating Akt activity.
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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".