Effects of cesalin on the ultrastructure and biological properties of cultured mammalian cells.

Cesalin rapidly inhibits the incorporation of uridine and thymidine into KB, MCF-7, HBL-100, and HTC cells but has no measurable effect on AlAb cells. Protein syntheiss is inhibited only after the effect on DNA and RNA is observed. After 12 to 48 hr, the cells in cultures containing cesalin increasingly lose adhesion to the flask surface and float in the medium. Both the inhibition of nucleotide incorporation and the inhibition of the cell growth, used as assays for cytotoxicity, show a varying sensitivity of these cell lines to cesalin, with AlAb cells being the most resistant and KB cells being the most sensitive. The ultrastructural changes induced by cesalin in KB cells demonstrate alteration in the nucleolus, increase in rough endoplasmic reticulum, extensive blebbing of the plasma membrane, and invagination of the nuclear membrane. The blebbing of the plasma membrane decreases after 24 hr with the appearance of a highly disorganized nuclear structure and numerous vacuoles containing insoluble fragments.