Dioscin Reverses Drug Resistance via AKT/GSK3β-mediated P-gp Degradation and EMT Inhibition.

Tumor drug resistance and metastasis are leading causes of cancer‑related mortality, both of which are tightly governed by multiple signaling pathways. The AKT‑GSK‑3β axis is a critical regulator of tumor progression, mediating drug resistance and epithelial‑mesenchymal transition (EMT) through its downstream targets. Aberrantly activated AKT‑GSK‑3β signaling modulates the expression and degradation of the drug efflux pump P-gp, which expels chemotherapeutic agents, including paclitaxel (PTX), from cancer cells, resulting in chemotherapy failure and drug resistance. Moreover, hyperactivated AKT‑GSK‑3β signaling drives EMT, a key process closely linked to tumor metastasis and malignant progression. Dioscin (Dio), a natural steroidal saponin, exhibits significant anti‑tumor activity in multiple cancers. However, whether Dio reverses chemoresistance and inhibits tumor growth by targeting the AKT‑GSK‑3β pathway to promote P-gp degradation and suppress EMT remains elusive, which is the central focus of this study. To explore whether Dio enhances the sensitivity of drug-resistant cancer cells to PTX and inhibits cancer metastasis and the EMT process, as well as its potential mechanism(s). Paclitaxel-resistant TE-1/PTX and HeLa/PTX cells were subjected to SRB, colony formation, Rh123 accumulation, wound-healing, and Transwell assays to evaluate Dio's chemosensitizing, anti-EMT, and anti-metastatic effects. Network pharmacology, molecular docking, CETSA, and proteolysis assays verified a direct Dio-AKT1 interaction. Western blotting, Co-IP, and MG132 and MK2206 rescue experiments clarified AKT/GSK3β-dependent P-gp ubiquitin-proteasomal degradation and EMT suppression. HeLa/PTX xenograft models were generated; H&E staining and immunoblotting were used to assess tumor growth, biosafety, and intratumoral protein profiles for in vivo validation. Dio sensitized PTX-resistant cells to paclitaxel, increased intracellular Rh123 accumulation, and inhibited cell migration and invasion. Mechanistically, Dio directly bound AKT1 to suppress AKT/GSK3β signaling, promoted ubiquitin-proteasomal degradation of P-gp, and reversed EMT by upregulating epithelial markers and repressing mesenchymal markers and EMT transcription factors. In vivo, Dio restrained xenograft tumor growth with negligible systemic toxicity, and intratumoral expression patterns of AKT/GSK3β, P-gp, and EMT-related proteins mirrored in vitro findings. Dio has the potential to be a safe and effective agent for drug-resistant cancer therapy.