Expression of steroidogenic factor 1 in canine cortisol-secreting adrenocortical tumors and normal adrenals.

We report on a screening for the relative messenger RNA (mRNA) and protein expression of steroidogenic factor 1 (SF-1) in normal canine adrenals (n = 10) and cortisol-secreting adrenocortical tumors (11 adenomas and 26 carcinomas). The relative mRNA expression of SF-1 was determined by quantitative real-time polymerase chain reaction analysis and revealed no differences between normal adrenals, adenomas, and carcinomas. Immunohistochemistry demonstrated SF-1 protein expression in a nuclear pattern throughout the normal adrenal cortex and a predominantly nuclear staining pattern in adrenocortical tumors. Of the 15 dogs available for follow up, 7 dogs developed hypercortisolism within 2.5 yr after adrenalectomy, with metastatic disease in 6 dogs and adrenocortical tumor regrowth in 1 dog. The relative SF-1 mRNA expression in dogs with early recurrence was greater (2.46-fold, P = 0.020) than in dogs in remission for at least 2.5 yr after adrenalectomy. In conclusion, we demonstrated the presence of SF-1 expression in normal canine adrenals and adrenocortical tumors. The high SF-1 mRNA expression in carcinomas with early recurrence might indicate its value as a prognostic marker, as well as its potential for therapeutic development.