Kwon et al. BMC Cancer 2010, 10:392 http://www.biomedcentral.com/1471-2407/10/392 Page 8 of 10 Figure 5 Cinnamon extract treatment induces tumor apoptosis by decreasing the levels of NF B and AP1 and their target genes. (A) Genomic DNA was isolated from tumor tissues from each treatment group and DNA fragmentation was confirmed by staining with ethidium bromide in 2% agarose gel. (B) The protein levels of pro-caspase and active caspases 3 in tumor tissues from each group were determined by immunoblotting. (C) To check the structural changes of nucleus, tumor tissues from each group were sectioned and then stained with Hoechst. Round areas and arrows indicate apoptotic cells (bigger size of this picture was included in Additional file 4, Figure S3). (D) The levels of NF B and AP1 in tumor tissues from each group were compared by immunoblotting between the treatment groups. The gene expression (E) and protein (F) level of Bcl-2, BcL-xL and survivin in tumor tissues were measured by quantitative real-time PCR or immunoblotting, respectively. Two (**) asterisk indicates p < 0.005. Not significant (NS). Data are representative of three individual experiments with similar results. medicine and CAMs [30]. However, it is still unclear about the exact action mechanisms of cinnamon and its active components related with diverse biological func- tion. Although various beneficial effects of cinnamon extract have been reported, most studies were per- formed in vitro culture system without elucidation of mechanism of action in vivo. In our previous work [22], we have shown that anti- tumoral effects of cinnamon extract in mouse melanoma is mediated by modulation of angiogenesis and cytotoxic activity of CD8+ T cells. In the present study, we further demonstrated that anti-tumoral effects of cinnamon extract are also linked with the induction of apoptosis in a cancer specific manner. In addition, treatment of cin- namon extract reduced the levels and activities of NF B and AP1 and their target genes such as Bcl-2 and Bcl- xL. These findings strongly suggest that potent anti- tumoral effects of cinnamon extract are mediated by multiple action mechanisms. Active induction of apoptosis in a cancer specific manner is an attractive way to cure many types of can- cers [31,32]. Cancers have various strategies to escape from the recognition and elimination by the surveillance of host immune system. These include altered expres- sion of genes and proteins involved in cell survival, death and transformation [33]. Among them, one of common survival strategy of cancer cells is to escape from apoptosis by deregulation of apoptotic genes [32] or hyper-activation of anti-apoptotic genes [34]. There- fore, cancer specific induction of apoptosis is thought to be a good strategy for cancer treatment. In this study, we demonstrated that treatment of cinnamon extract suppressed melanoma progression in vivo (Figure 4 and 5) and inhibition of tumor cell growth in vitro (Figure 1 and Figure 2) through apoptosis induction. Compared with known anti-cancer drugs (for example, Doxorubi- cin) [35], potential benefit of cinnamon extract as a complementary and alternative medicine may contribute