EXPRESSION OF STEROIDOGENIC ENZYME MESSENGER RIBONUCLEIC-ACIDS AND CORTICOSTEROID PRODUCTION IN ALDOSTERONE-PRODUCING AND NONFUNCTIONING ADRENAL ADENOMAS

''Nonfunctioning'' adrenal adenomas are often diagnosed in patients wi thout recognizable clinical symptoms of adrenocortical hyperfunction. The objective of this study was to determine directly the steroidogeni c activity of such adenomas (n = 12) and compare them histologically a nd functionally to normal human adrenals (n = 6) and aldosterone-produ cing adenomas (n = 15). The histological appearances of nonfunctioning and aldosterone-producing adenomas were surprisingly similar. Nonfunc tioning adrenal adenomas expressed all mRNAs of P450scc, P450c17, P450 c21, adrenodoxin, and adrenodoxin reductase with relative levels compa rable to those found in normal adrenals. Consistent with their hormone -producing nature, these adenomas had cortisol and aldosterone content s as high as those in normal adrenal tissues, a significantly (P < 0.0 5) increased 17-hydroxyprogesterone content, and a disproportionally l ow expression of P450c21 mRNA compared to aldosterone-producing adenom as. Cells isolated from both aldosterone-producing and nonfunctioning adrenal adenomas exhibited highly ACTH sensitive cortisol and aldoster one production, suggesting again the presence of both zona glomerulosa -like and zona fasciculata-like steroidogeneses in these adenoma tissu es. These results indicate that so-called nonfunctioning adrenal adeno mas are not without steroidogenic activity. Therefore, the assumption that adrenal adenomas are entirely nonfunctioning in the absence of re cognizable hormonal hyperfunction may not be correct.