The in vitro and in vivo anti-tumor effect of decursin in estrogen receptor-negative human breast cancer cells occurs via downregulation of Akt signaling pathway

Abstract

Background Hormonal therapies are widely used to treat breast cancer, but extrogen receptor (ER)-negative forms are resistant to such therapies. Therefore, an effective therapeutic agent is needed. Recent studies suggest decursin, a pyranocoumarin, to possess cytotoxic and anti-tumor effects on various cancers. Therefore, we examined the effect of decursin in ER-negative breast cancer. Methods ER-negative MDA-MB-231 and SK-BR-3 cells were used. Cell growth and cell cycle progression was analyzed by MTT assay and flow cytometry. Apoptosis as assessed by DAPI staining and quantification of Bcl-2 family gene expression. Akt-mediated signaling was examined by immunoblotting. Subcellular localization of b-catenin and p27kip were visualized by immunofluorescence and biochemically assessed by nuclear/cytoplasmic fractionation. Gene expression at the mRNA level was measured by RT-PCR and reporter assay. The in vivo anti-tumor effect of decursin was seen in the mouse xenograft model. Results Cell growth was attenuated by decursin. Apoptosis was induced as evidenced by increased sub G1 population, enhanced nuclear fragmentation, up-regulation of Bax and Bad, and down-regulation of Bcl-2 protein. The expression of EGFR and c-ErbB2 were reduced and Akt and Erk were downregulated. Suppressed Akt activity was seen by reduced phosphorylation of its substrates, GSK-3 and p27kip. The expression and nuclear localization of -catenin, TCF-LEF promoter activity, and cyclin D1 mRNA level were reduced by decursin. Moreover, augmented nuclear localization of p27kip was observed. Finally, xenograft tumor growth of MDA-MB-231 was significantly reduced in decursin-administered mice. Conclusion By showing the anti-cancer effect of decursin and suggest cell cycle arrest and apoptosis as a molecular mechanism, our novel findings provide decursin as a potential preventive and/or therapeutic agent against ER-negative breast cancers.