Effect of bursal anti-steroidogenic peptide (BASP) on cortisol biosynthesis in ACTH-stimulated canine adrenocortical carcinoma cells in vitro.

Previous studies from our laboratory have demonstrated that bursal anti-steroidogenic peptide (BASP) inhibits progesterone biosynthesis from ovine luteinizing hormone-stimulated chicken ovarian granulosa cells. In the present investigation, we evaluated the efficacy of BASP for reducing cortisol secretion from normal canine adrenocortical cells and neoplastic adrenocortical cells from a dog with Cushing's syndrome. Treatment of adrenocortical cells derived from either normal healthy dogs or a cushingoid dog with adrenocorticotropic hormone (ACTH; 0-10 nM) caused an approximately two-fold increase in cortisol production from both normal or tumor derived adrenocortical cells. Small but significant decreases (up to 34%) in cortisol production were observed from normal and tumor derived canine adrenocortical cells when exposed to increasing concentrations of BASP (0.0-0.15 bursal equivalents; BEQ). Incubation of adrenocortical carcinoma cells or normal adrenocortical cells with ACTH (0-10 nM) and BASP (0.0-0.15 BEQ) increased cyclic AMP formation up to 2.5-fold. Interestingly, BASP suppressed basal cortisol production from tumor derived adrenocortical cells to normal levels when compared to the basal cortisol levels from normal derived adrenocortisol cells. Data from the present studies indicate that BASP is capable of suppressing basal and ACTH-stimulated cortisol production from normal or tumor derived adrenocortical cells in vitro. The possible clinical efficacy of homologous canine BASP on canine adrenal function or chicken BASP in other species of animals remains to be evaluated.