Lethal effect of cis- but not trans-22-dehydrocholesterol on mouse fibroblast cells.

cis- and trans-22-dehydrocholesterol were incorporated into the culture medium for mouse fibroblasts cells. Although neither isomer had an effect on sterol biosynthesis, the cis isomer inhibited cell growth and viability and increased Rb+ efflux from the cells. The trans isomer had no effect on growth and could replace exogenous cholesterol for growth of cells for which sterol biosynthesis was blocked by 25-hydroxycholesterol.