title: Comparison of ACTH and ACTH precursor peptides secreted by human pituitary and lung tumour cells in vitro.
abstract: The molecular forms of ACTH secreted by established human small cell lung cancer (SCLC) cells and primary cultures derived from a bronchial carcinoid tumour, a pituitary adenoma and hyperplastic pituitary tissue have been characterized by Sephadex G-75 chromatography and quantified with two novel immunoradiometric assays for ACTH and ACTH precursor peptides. Pro-opiomelanocortin (POMC; Mr 31,000) and pro-ACTH (Mr 22,000) were secreted by all cell types. No smaller peptides were identified in the culture media from SCLC and bronchial carcinoid cells, implying a deficiency in the enzymes and/or intracellular organelles required for extensive POMC processing. A more heterogeneous profile of ACTH-containing peptides was produced by cells of pituitary origin, indicating more extensive proteolytic processing of POMC. However, the major peptide secreted by cells from a large aggressive pituitary adenoma was unprocessed POMC (Mr 31,000). These results suggest that both lung and pituitary cells in vitro retain their in-vivo pattern of POMC processing and provide valuable models in which to study the regulation of ACTH synthesis and secretion.
authors.affiliation: Department of Clinical Biochemistry, University of Manchester, Hope Hospital, Salford.
authors.forename: S R
authors.initials: SR
authors.lastname: Crosby
authors.forename: M F
authors.initials: MF
authors.lastname: Stewart
authors.forename: W E
authors.initials: WE
authors.lastname: Farrell
authors.forename: S
authors.initials: S
authors.lastname: Gibson
authors.forename: A
authors.initials: A
authors.lastname: White
mesh_terms: D000236:Adenoma / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000302:isolation & purification*; D002276:Carcinoid Tumor / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000378:metabolism; D006801:Humans; D006965:Hyperplasia; D008175:Lung Neoplasms / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism / Q000473:pathology; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000302:isolation & purification; D011498:Protein Precursors / Q000302:isolation & purification*; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D011498:Protein Precursors; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone