Lack of steroidogenic response to cyclic AMP and ACTH in adrenal cells from rats bearing the MtTF4 tumor.

Adrenal cell suspensions prepared from rats bearing the MtTF4 tumor failed to increase corticosterone production when exposed to adenosine 3', 5'-cyclic monophosphate (cyclic AMP) or ACTH, placing the defect in these adrenals beyond the ACTH receptor site. Adrenal cells from normal rats responded well to these stimuli. Adrenal cyclic AMP phosphodiesterase prepared from the tumor bearing rats appeared normal both with respect to its specific activity and inhibition profile with theophylline. Exposure of the MtTF4 adrenal cells to 1,2-3H-cholesterol in the presence of either cyclic AMP or ACTH did not result in an increase in radioactively labeled corticosterone, whereas increased label could be demonstrated in adrenal cells from normal rats similarly treated.