Effects of arotinoids upon murine embryonal carcinoma cells

Five arotinoids have been compared with all-trans- and 13-cisretinoic acids for their ability to promote differentiation of cells from murine embryonal carcinoma line Nulli-SCC1. Ro-13-7410, which contains a terminal carboxylic acid residue, and Ro-14-9572, the sodium sulfinate derivative, are potent inducers of differentiation. The sodium sulfonate derivative, Ro-14-3899, is somewhat less active, whereas the ethyl sulfone (Ro-15-1570) and Ro-15-0778, an arotinoid lacking a terminal group, have little or no effect on embryonal carcinoma cell differentiation. Competition by the arotinoids with all-trans-retinoic acid for sites on the cellular retinoic acid-binding protein is qualitatively consistent with their capacity for promoting differentiation. This relationship and the response of differentiation-defective embryonal carcinoma cells to Ro-13-7410 support the view that arotinoids and retinoids promote differentiation of embryonal carcinoma cells via the same mechanism.