Abstract

Neocarzinostatin, an antineoplastic agent which consists of a chromophore noncovalently bound to a protein of approximately 10,000D MW, induces the morphological differentiation of cells of the C1300 murine neuroblastoma line in vitro. It also has antimitotic activity, ascribed previously in other cell lines to the action of the chromophore upon DNA. The chromophore is antimitotic for neuroblastoma cells, as well. The morphology-altering effect of neocarzinostatin can also be mimicked by chromophore alone. The morphology-altering effect becomes apparent at doses of the agent which decrease the culture growth rate to approximately 50% of control values. It appears that induction of morphological neural differentiation of neuroblastoma cells requires an increase in the doubling time above a critical value.