Inhibition of cell proliferation by lithium is associated with interference in cdc2 activation.

Lithium can interfere with embryonal development in a variety of organisms. We investigated the effect of lithium on the proliferation of early embryonal cells. [3H]Thymidine incorporation of non-committed mouse P19 embryonal carcinoma cells was inhibited by lithium treatment. Similar effects were seen in a variety of other cells. This growth inhibition occurred in the G2 phase, since cells accumulated with a 4N DNA content, but the appearance of mitotic cells was blocked. Lithium could also prevent the activation of cdc2, thereby inhibiting cyclin B/cdc2 kinase activity. These data indicate that lithium might disturb embryonal development through interference in embryonal cell cycle regulation.