In vitro release of aldosterone and cortisol in human adrenal adenomas correlates to mRNA expression of steroidogenic enzymes for genes CYP11B2 and CYP17

Adenomas of the adrenal cortex cause different disorders depending on the m ain steroid synthesized and released. The aim of this research is to increa se our understanding of the pathophysiology of steroidogenesis in adrenocor tical disorders by comparing the release of steroids from adrenocortical ad enomas in vitro with the messenger RNA (mRNA) expression of steroid synthes izing enzymes. Fourteen patients with adrenal tumors were included in the p resent study; nine were diagnosed with primary aldosteronism and three with Gushing's syndrome. Two patients had an adrenal tumor discovered on comput ed tomography (GT) during workup for an unrelated disease. Serum cortisol, plasma aldosterone, and urinary catecholamines were normal. Tissue was take n for in vitro steroid release, and aldosterone and cortisol in the medium after a 1-hour incubation were determined. Oligonucleotide probes with sequ ences complementary to mRNAs encoding for the steroid synthesizing enzymes 11 beta -hydroxylase (CYP11B1), 18-hydroxylase (CYP11B2), 17 alpha -hydroxy lase (CYP17), and 21-hydroxylase (CYP21) were synthesized (Genset, Paris, F rance) and in situ hybridization was performed. Moderate expression of CYP1 1B2 and low expression of CYP11B1 were seen in the zona glomerulosa. The zo na fasciculata of the control adrenals expressed a high signal of CYP11B1, whereas the expression of CYP11B2 was very low. There was considerable vari ation in aldosterone release from the aldosteronomas, whereas the tumors fr om the Gushing patients showed no detectable release of aldosterone. In con trast, tumors from patients with primary aldosteronism, Gushing's syndrome, and no hyperfunction all had the ability to synthesize and release cortiso l in vitro. The highest cortisol release was found in tumors from patients with Gushing's syndrome, but also the nonhyperfunctioning tumors and some o f the aldosteronomas released significant amounts of cortisol. The two pati ents with highest release of aldosterone in vitro showed the highest expres sion of CYP11B2 and the lowest expression of CYP11B1 and CYP17. The remaini ng aldosteronomas had low expression of CYP11B2, similar to the two other g roups. Expression of CYP11B1 was high as expected in the Gushing adenomas, but also the two nonhyperfunctioning tumors and some of the aldosteronomas showed a moderate expression. Adenomas from Gushing's syndrome, nonhyperfun ctioning adenomas, and some of the aldosterone- producing adenomas had mode rate to high expression of CYP17. This paper presents new means for functio nal characterization of adrenocortical tumors. Diagnosis of an aldosteronom a is often difficult, and with the advent of these methods it is possible t o determine the functional capacity of a tumor, once it is removed. This is of special interest if the patient remains hypertensive postoperatively, a nd it is not clear whether the patient indeed had a functioning tumor.