Abstract

We have previously demonstrated that ginsenoside 20(S)-Rh2 is a potent ABCB1 inhibitor and explored the cellular pharmacokinetic mechanisms for its synergistic effect on the cytotoxicity of adriamycin. The present studies were conducted to elucidate the key factors that influenced ABCB1 expression which could further alter adriamycin cellular pharmacokinetics. Meanwhile, the influence of 20(S)-Rh2 on the above factors was revealed for explaining its synergistic effect from the view of ABCB1 expression. The results indicated that 20(S)-Rh2 inhibited adriamycin-induced ABCB1 expression in MCF-7/Adr cells. Subsequent analyses indicated that 20(S)-Rh2 markedly inhibited adriamycin-induced activation of the MAPK/Nf-κB pathway, Nf-κB translocation to the nucleus and Nf-κB binding activity. Furthermore, 20(S)-Rh2 repressed the adriamycin-enhanced ability of Nf-κB to bind to the human MDR1 promoter, and MAPK/Nf-κB inhibitors and Nf-κB siRNA reversed the adriamycin-induced expression of ABCB1. Moreover, the cellular pharmacokinetics of adriamycin was also significantly altered by inhibiting Nf-κB. In conclusion, the MAPK/Nf-κB pathway mediates adriamycin-induced ABCB1 expression and subsequently alters the cellular pharmacokinetics of adriamycin. It was speculated that 20(S)-Rh2 acted on this pathway to lower adriamycin-induced ABCB1 expression in MCF-7/Adr cells, which provided mechanism-based support to the development of 20(S)-Rh2 as a multi-drug resistance (MDR) reversal agent.