Suramin, a polycyclic and polyanionic
drug, has been successfully used in the
therapy of inoperable
adrenocortical cancer. The present study was undertaken to investigate the effects of
suramin on normal human adrenocortical cells in primary monolayer cultures. The proliferation and the basal, as well as the
adrenocorticotropin (
ACTH)-stimulated,
cortisol secretion of these cells were studied. The data show that
suramin decreases basal, as well as
ACTH-stimulated,
cortisol secretion in a dose-dependent manner (P less than .05 from 300 mumol/L upward). At a
suramin concentration of 3 mmol/L,
cortisol secretion was inhibited by 70% +/- 4% in
ACTH-stimulated cells and by 42% +/- 6% in unstimulated cells. The proliferation of adrenocortical cells in response to
fetal calf serum was also inhibited by
suramin at concentrations from 300 mumol/L upward, maximal suppression (71% +/- 6%, P less than .01) being observed at a concentration of 10 mmol/L. Both inhibition of
cortisol secretion and inhibition of adrenocortical cell proliferation were not due to toxicity of the compound, as could be shown by restimulation of
cortisol secretion in
suramin-treated cells with
ACTH. Our results indicate that
suramin exerts an inhibitory influence on the
cortisol secretion and on the proliferation of normal human adrenocortical cells.
Suramin may not only be useful in the treatment of
adrenocortical cancer, but may also have an ameliorative effect on other malignant conditions with augmented
steroid hormone production, resistant to conventional forms of
therapy.