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CLINICAL STUDY |
1 INRA USC 2006, 14032 Caen, France2 Université de Caen, EA 2608, 14032 Caen, France3 Hopital Civil, Service d'Endocrinologie et Maladies Métaboliques, 67091 Strasbourg, France4 CHU Côte de Nacre,, Département de Génétique et Reproduction, 14033 Caen, France5 Service d'Endocrinologie et Maladies Métaboliques, AP-HP Cochin, Paris, France6 CHU Côte de Nacre,, Service d'Endocrinologie et Maladies Métaboliques, 14033 Caen, France
(Correspondence should be addressed to Y Reznik at Department of Endocrinology, CHU Côte de Nacre, 14033 Caen Cedex, France; Email: reznik-y{at}chu-caen.fr)
Objective: The aromatase enzyme catalyzes the final stage of estrogen biosynthesis pathway from androgens. Its expression in the adrenal is poorly studied except for the rare estrogen-producing adrenocortical tumors. In order to further characterize aromatase expression in the adrenal, we evaluated the aromatase enzyme activity, Cyp19a1 gene expression level, and promoter utilization in normal adrenal tissues and in adrenocortical secreting tumors.
Design and methods: Six normal adult adrenals (NA), 2 feminizing adrenal tumors (FT), 10 cortisol-producing adenomas with overt (CS, n=4) or sub-clinical Cushing syndrome (SCS, n=6) and 3 aldosterone-producing adenomas (APA) were studied. Tissue aromatase activity was determined by the tritiated (3H)-water method. Total aromatase mRNA were measured by a competitive RT-PCR. Promoter regions PII and PI.4-derived transcripts were also studied in NA, FT, and other steroid-producing tumors by a semi-quantitative comparative RT-PCR. Immunofluorescence analysis was performed in normal human adrenal tissues.
Results: Aromatase activity was detected in NA tissues and in all tumor subtypes, at high levels in both FT. In NA, aromatase immunofluorescence was detected in the cytoplasm of steroidogenic cells, mainly from zona reticularis. Compared with NA, aromatase transcript levels were similar in CS and APA, lower in SCS and similar or higher in FT. Promoter analysis suggested predominant PII utilization in NA, APA, and SCS, but similar PII and PI.4 utilization in CS tumors.
Conclusion: Aromatase is expressed at similar levels in normal adrenal and in adrenocortical tumors, but at variably high levels in FT. Different promoter utilization patterns are found among tumor subtypes.
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