Mimosine induces apoptosis in the HL60 human tumor cell line

Mimosine, a plant amino acid not found in proteins, has been widely used as a synchronizing agent, blocking the progression of cell cycle on the G1/S phase border. The mechanism by which this block is achieved is still unclea r. We report that in HL60 cells the synchronization is related to an increa se in apoptosis. Another human tumor cell line, K562, is insensitive to bot h phenomena thereby demonstrating that apoptosis observed in HL60 is line-s pecific. We hypothesize that the mimosine-induced apoptosis and alteration of the cell cycle is due to the inhibition of hypusine generation.