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Oroxylin A reverses P-glycoprotein-mediated multidrug resistance of MCF7/ADR cells by G2/M arrest.

Toxicol Lett. 2013 Mar 4;

Authors: Zhu L, Zhao L, Wang H, Wang Y, Pan D, Yao J, Li Z, Wu G, Guo Q


Oroxylin A is a naturally occurring monoflavonoid isolated from the root of Scutellaria baicalensis Georgi, which has been used in traditional Chinese medicine for its anti-tumor, anti-inflammatory and anti-bacterial properties. The purpose of this study is to investigate the reversal effect and the fundamental mechanisms of oroxylin A in MCF7/ADR cells. Data indicated that oroxylin A showed strong reversal potency in MCF7/ADR cells and the reversal fold (RF) reached 4.68. After treatment with oroxylin A, MCF7/ADR cells displayed reduced functional activity and expression of MDR1 at both the protein and mRNA levels. Meanwhile, oroxylin A induced cells G2/M arrest in a concentration-dependent manner by increasing the expression of p-Chk2 (Thr68). Moreover, western blot and EMSA assays were used to reveal the inhibition of NF-κB in nucleus and the suppression of NF-κB binding activity by oroxylin A. NSC 109555 ditosylate-Chk2 inhibitor partly dismissed G2/M arrest induced by oroxylin A, reversed the increased trend of p-Chk2 and p-P53 (Ser20), inhibited the decreasing effect of oroxylin A on the expression of P-gp and decreased the reversal fold of 90μM oroxylin A from 4.68 fold to 1.73 fold. In conclusion, we suggested that oroxylin A reversed MDR by G2/M arrest and the underlying mechanism attributed to the suppression of P-gp expression via Chk2/P53/NF-κB signaling pathway.

PMID: 23470866 [PubMed - as supplied by publisher]