ANTITUMOR ACTIVITY OF HOWIINOL(GHM10) ON L1210 CELLS IN VITRO

Howiinol(GHM10) is a new compound isolated from Goniothalamus howii. Previous studies showed that GHM10 significantly inhibited the growth of cancer cells both in vitro and in vivo. In the present study, the characteristics of the inhibitory effect of GHM10 on L1210 cells was investigated. The results showed that the IC50 of L1210 cells treated with GHM10 for 1　h, 24　h, and 7　d was 685, 332 and 159 μg·ml-1, respectively. This outcome is in compliance with the hypothesis that GHM10 is a cell cycle nonspecific cytotoxic drug. When L1210 cells were treated with 1～2 μg·ml-1 of GHM10 for 24 h, the growth rate and mitotic index were decreased and the morphology of cell nuclei changed, but the cell viability remained at the level of 96% or more, indicating that GHM10 mainly inhibited cell proliferation. The cell cycle kinetics of L1210 cells were studied by using a flow cytometer. The results showed that the transition of cells from G1 phase to S phase was blocked to certain extent by the treatment of GHM10 4 μg·ml-1 for 12 h. The fluidity of cell membrane was also increased when the L1210 cells were exposed to 2～3 μg·ml-1 of GHM10 for 24 h.