Effects of synthetic isoharringtonine on DNA, RNA, ATP, protein and nucleoprotein of transplanted tumour cells in mice

Synthetic isoharringtonine (His 20 microg/ml) inhibited the incoporations of [3H]thymidine, [3H]uridine and [3H]leucine into DNA, RNA and protein syntheses of leukemia 7712 cells during the period o f12-48 h after exposure in vitro. The degree of inhibition increased with the incubation time. After the L7712 cells were treated with His 20 microg/ml for 12, 24,36, and 48 h, the incorporations of [32P]Na2HPO4 into nucleoprotein were inhibited by 75%, 92%, 96%, and 98%, and those into ATP were inhibited by 70%, 78%, 88%, 92%, respectively. ID50 of stereoisomers of synthetic isoharringtonine-IHs,IH1, IH2, and IHn on DNA synthesis in L7712 cells incubated for 48 h were 4, 62, 46 and 0.9 microg/ml, respectively. After S180 and ascetic hepatoma cells were treated with His 99 microg/ml for 48 h, the incorporations of [3H]thymidine into DNA were inhibited by 70% and 83%, respectively.