Characterization of immunoreactive beta-endorphin secreted from cultured human corticotropin-secreting adenomas.
Seven human corticotropin-secreting adenomas causing Cushing's disease or Nelson's syndrome were maintained in long-term culture. Pooled media from the individual adenomas were analyzed for the composition of their secretory products. From a radioimmunoassay (RIA) with 100% cross-reactivity for human beta-endorphin (beta h-EP) and beta-lipotropin (beta h-LPH), immunoreactive beta h-EP (IR X beta h-EP) was found to be the predominant secretory product after Sephadex G-50 analysis in 4 cases (40-80% of total IR), immunoreactive beta h-LPH (IR X beta h-LPH) predominated in 1 case, and both were equipresent in 2-cases. IR X beta h-EP was further purified by high-performance liquid chromatography (HPLC) and analyzed in 4 cases with ion-exchange chromatography on SP-Sephadex C-25 and a RIA which completely cross-reacts with beta h-EP, [N alpha-Ac]-beta h-EP, beta h-EP-(1-27) and [N alpha-Ac]-beta h-EP-(1-27). In all cases, the IR X beta h-EP was the main component (40-70%); the remaining IR material was attributable partially to [N alpha-Ac]-beta h-EP or other, less defined immunoreactive material. In 3 cases, enough IR X beta h-EP material was available for HPLC and to perform a radioreceptor assay using tritiated beta h-EP as primary ligand. The displacing potency of these preparations relative to synthetic beta h-EP was related to the content of the immunoreactive component eluting in the position of synthetic beta h-EP.
Westphal
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M
Li
C H
CH
Wilson
C B
CB
D000236:Adenoma / Q000032:analysis*; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004723:Endorphins / Q000032:analysis*; D006801:Humans; D010911:Pituitary Neoplasms / Q000032:analysis*; D011333:Pro-Opiomelanocortin / Q000378:metabolism; D011863:Radioimmunoassay; D011869:Radioligand Assay; D001615:beta-Endorphin
D004723:Endorphins; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone