Quercetin is a flavonoid found in many fruits, vegetables and tea and exerts anti-tumor activity in several tumor models. In this study, we have examined the tumor growth inhibitory effect of quercetin in MCF-7 xenograft models using female and male mice and observed alteration of signaling molecules involved in cell survival and apoptosis. Our results showed that administration of 50Ռg/g quercetin daily significantly inhibited tumor growth in both female and male MCF-7 xenograft models. It has shown that quercetin increases the activation of AMP-activated protein kinase (AMPK) along with tumor regression. AMPK is a major signaling molecule for the regulation of energy metabolism. Recent studies indicated that AMPK acts as a master controller in cancer cells through regulating several survival-related pathways. Phosphorylated Akt and Cycloxygenase-2 (COX-2) levels were found to be related to anti-tumor activities of quercetin. The results suggested that quercetin has a potential anti-tumor activity against breast cancer and it may be related to suppression of oncogenic molecules such as Akt and COX-2, and activation of pro-apoptotic molecules such as AMPK. (Cancer Prev Res 14, 54-59, 2009)

Keywords: Quercetin, AMP-activated protein kinase, Akt, Cyclooxygenase-2, MCF-7 xenograft