Quercetin inhibits the invasion and mobility of murine melanoma B16-BL6 cells through inducing apoptosis via decreasing Bcl-2 expression

Quercetin has been known to have anti-tumor and anti-oxidation activities. In the present study, we have investigated its in vitro anti-metastatic act ivity. Quercetin inhibited the invasion and mobility of murine melanoma B16 -BL6 cells in a dose-dependent manner but did not affect their adhesion to either laminin, fibronectin, or type VI collagen. Moreover, quercetin signi ficantly inhibited the proliferation of B16-BL6 cells only in the case of t ime incubation longer than 48 h. Quercetin dose-dependently decreased the c ell rates in S and G2-M phases of cell cycle. The effect of quercetin to ca use a remarkable apoptosis of B16-BL6 cells was also demonstrated by flow c ytometric assay as well as DNA fragmentation with a typical 180-bp ladder b and in agarose electrophoresis and a quantitative analysis. Furthermore, qu ercetin markedly inhibited the expression of anti-apoptotic protein Bcl-2 b ut hardly influenced Bcl-X-L. These results suggest that the inhibition of quercetin on invasiveness and migration of B16-BL6 cells are closely associ ated with the arrest of cell cycle as well as the induction of apoptosis by decreasing the Bcl-2 expression.