Samy Mohamed

Despite tamoxifen (TAM) is beneficial in treating a significant proportion of patients with breast cancer, many women still relapse after long-term therapy. Caffeic acid phenethyl ester (CAPE) is a component of honeybee propolis, with a plethora of important biological actions including anticancer activity. This study aimed to explore the cytotoxicity, the type of drugs interaction as well as the apoptotic and autophagic pathways of the combined treatment of TAM and CAPE in MCF-7 cells. Their antitumor activity and effect on survival of mice bearing Ehrlich tumor were also analyzed. The results showed synergistic cytotoxic effects, manifested by significant activation of apoptotic machinery, along with downregulation of protein levels of Bcl-2 and beclin-1, upon using the combination regimen. However, the ratio between microtubule-associated protein light chain 3-II and -I was not altered. Moreover, a decrease in vascular endothelial growth factor level was detected. Similarly, TAM + CAPE increased the life span of tumor-bearing animals and caused a marked regression in their tumor size and weight compared with those treated with either TAM or CAPE alone. In conclusion, CAPE relatively improved the anticancer activity of TAM in both in vitro and in vivo models via its apoptotic and angiostatic potentials.

Although Tamoxifen (TAM) is one of the most widely used drugs in managing breast cancer, many women still relapse after long-term therapy. Caffeic acid phenethyl ester (CAPE) is a polyphenolic compound present in many medicinal plants and in propolis. The present study examined the effect of CAPE on TAM cytotoxicity in MCF-7 cells. MCF-7 cells were treated with different concentrations of TAM and/or CAPE for 48 h. This novel combination exerted synergistic cytotoxic effects against MCF-7 cells via induction of apoptotic machinery with activation of caspases and DNA fragmentation, along with downregulation of Bcl-2 and Beclin 1 expression levels. However, the mammalian microtubule-associated protein light chain LC 3-II level was unchanged. Vascular endothelial growth factor level was also decreased, whereas levels of glutathione and nitric oxide were increased. In conclusion, CAPE augmented TAM cytotoxicity via multiple mechanisms, providing a novel therapeutic approach for breast cancer treatment that can overcome resistance and lower toxicity. This effect provides a rationale for further investigation of this combination.