20(R)-Ginsenoside Rg3

Overexpression of P‐glycoprotein (P‐gp) in non‐small cell lung cancer (NSCLC) cells is one of the primary causes of multidrug resistance (MDR), but the molecular mechanism remains obscure. Murine double minute 2 (MDM2) has been implicated in drug resistance across multiple cancer types. In this study, we investigated the potential mechanism of MDM2 on P‐gp‐mediated MDR of NSCLC and explored the potential therapeutic effects of 20(R)‐ginsenoside Rg3 (Rg3). Western blot, RT‐PCR, and immunohistochemistry (IHC) were applied to analyze the expression of critical signaling markers. The drug accumulation in resistant cells was measured using flow cytometry and confocal microscopy. Bioinformatics analysis, co‐immunoprecipitation (co‐IP), and immunofluorescence were conducted to confirm the protein–protein interactions. MTT, colony formation, EdU, and in vivo cell line derived xenograft (CDX) models were applied to validate therapeutic agents and molecular mechanisms. We demonstrated that MDM2 acted as a positive upstream regulator of P‐gp, and the inhibition of MDM2 by Rg3 increased the sensitivity of resistant cells to taxol treatment both in vivo and in vitro. Mechanistically, we uncovered that MDM2 bound to IκB‐α, facilitating its ubiquitination degradation, which subsequently promoted NF‐κB pathway activation to drive the high expression of P‐gp. Notably, Rg3 blocked this process by inhibiting MDM2. Moreover, interference with the NF‐κB pathway reversed the regulation of P‐gp expression by MDM2. Our findings elucidate the molecular mechanisms of Rg3 in the treatment of P‐gp‐mediated MDR in NSCLC. This study also provides a new strategy to overcome P‐gp‐mediated MDR by inhibiting the MDM2‐IκB‐α signaling axis.