Modulation of cell cycle regulatory protein expression and suppression of tumor growth by mimosine in nude mice

Our previous results demonstrated that the plant amino acid mimosine blocke d cell cycle progression and suppressed proliferation of human lung cancer cells in vitro by multiple mechanisms. Inhibition of cyclin D1 expression o r induction of cyclin-dependent kinase inhibitor p21(WAF1) expression was f ound in mimosine-treated lung cancer cells. However, whether mimosine may m odulate the expression of these cell cycle regulatory proteins and suppress tumor growth in vivo is unknown. In this study, we examined the anticancer effect of mimosine on human H226 lung cancer cells grown in nude mice. Our results demonstrated that mimosine inhibits cyclin D1 and induces p21(WAF1 ) expression in vivo. Furthermore, results of TUNEL analysis indicated that mimosine may induce apoptosis to suppress tumor growth in nude mice. Colle ctively, these results suggest that mimosine exerts anti-cancer effect in v ivo and might be useful in the therapy of lung cancer.