Effect of retinoic acid on the proliferation and tumorigenicity of mouse mastocytoma cells : Effect of retinoic acid on mastocytoma cells.

Retinoic acid (RA) inhibited the in vitro growth of the mouse mast cell tumor line P(815) in a dose- and time-dependent manner. The inhibition was accompanied by an increase in the amount of neutral intracellular mucopolysaccharides. Study of cell cycle kinetics showed that exposure to retinoic acid led to a slowing-down of the cell-cycle progression possibly related to a more differentiated cell population disclosed by microscopy with a lower proliferative capacity. In vivo, delays in both tumor appearance and mouse mortality were observed after injecting RA into mice bearing mastocytomas. These results suggest that RA could be of interest in the treatment of human malignant systemic mastocytosis with proliferation of immature mast cells.