ZONE-SPECIFIC LOCALIZATION OF CYTOCHROME P45011B1 IN HUMAN ADRENAL-TISSUE BY PCR-DERIVED RIBOPROBES

Cytochrome P45011B1 (11 beta-hydroxylase) was detected in the human ad renal cortex and in human adenomas by in situ hybridization methods. S pecific riboprobes were generated by in vitro transcription of 11 beta -hydroxylase - specific synthetic oligonucleotides with attached T7 an d SP6 polymerase promoters. [S-35]- and digoxigenin-labeled riboprobes were hybridized to sections of an aldosterone-producing adenoma (APA) , the non-tumour portion of the corresponding adrenal gland, and two a denomas not related to hyperaldosteronism using standard protocols and varying washing conditions. After exposure of the radiolabeled sectio ns to X-ray film, the signals were quantified and compared by statisti cal tests. Following autoradiography or immunohistochemical detection of the digoxigenin cytochrome P45011B1 mRNA was clearly localized in t he zona fasciculata/reticularis of non-tumour portion of an human adre nal with an APA. Zona glomerulosa, medulla and connective tissue were free of label. As revealed by the semi-quantitative analysis, 11 beta- hydroxylase mRNA signals in the APA were significantly lower than thos e in the attached non-tumour portion and the other two adenomas. The r esults confirm known observations on the occurrence of cytochrome P450 11B1 in the adrenal cortex of other species, but show, contrary to sev eral immunohistochemical studies, that the enzyme is obviously not exp ressed in the zona glomerulosa.