[Growth inhibition of human myeloid leukemia cells in vitro by harringtonine].

Harringtonine was discovered as an anticancer agent in China. It has been shown to be effective against myeloid leukemia. In this report, we have demonstrated that harringtonine inhibited the growth of human myeloid leukemia cells in vitro at low concentrations. Together with the clinical data in which 28% of the patients could be induced into complete remission only by harringtonine, this agent may be used as a first choice of antileukemia agents in the treatment of myeloid leukemia. The mechanism of the antitumor action of harringtonine is considered to be an effect on protein synthesis and is characterized by breakdown of polysomes to monosomes. The mechanism of action appears to be different from those of the other antileukemia agents, such as cyclophosphamide, daunorubicin, vincristine, or cytosine arabinoside. Harringtonine could be added to the other anti-leukemia agents used routinely in treatment of leukemia, and the combination of harringtonine with the other agents is expected to improve the therapy of myeloid leukemia.