Background and purpose: Elephantopus scaber L. (Asteraceae) is a traditional herbal medicine with anti-cancer effects. We evaluated the in vitro and in vivo efficacy of a major sesquiterpene lactone constituent of E. scaber, deoxyelephantopin (DET), against mammary adenocarcinoma and the underlying molecular mechanism.
Experimental approach: A variety of cellular assays, immunoblotting and immunohistochemistry, as well as both orthotopic and metastatic TS/A tumour models in BALB/c mice, were used. Test mice were pretreated and post-treated with DET or paclitaxel and mammary tumour growth evaluated.
Key results: DET (< or =2 microg x mL(-1)) significantly inhibited colony formation, cell proliferation, migration and invasion of TS/A cells and induced G(2)/M arrest and apoptosis in TS/A cells. c-Jun N-terminal kinase-mediated p21(Waf1/Cip1) expression and caspase activation cascades were up-regulated by DET, effects suppressed by N-acetyl-L-cysteine. Moreover, tumour necrosis factor alpha-induced matrix metalloproteinase-9 enzyme activity and expression and nuclear factor-kappa B activation were abolished by DET. Pretreatment with DET was more effective than paclitaxel, for profound suppression of orthotopic tumour growth (99% vs. 68% reduction in tumour size) and lung metastasis of TS/A cells (82% vs. 63% reduction in metastatic pulmonary foci) and prolonged median survival time (56 vs. 37 days, P < 0.01) in mice. The levels of cyclooxygenase-2 and vascular endothelial growth factor in metastatic lung tissues of TS/A-bearing mice were attenuated by DET.
Conclusions and implications: Our data provide evidence for the suppression of mammary adenocarcinoma by DET with several mechanisms and suggest that DET has potential as a chemopreventive agent for breast cancer.