Further characterization of corticotrophin releasing factor activity from a bronchial tumour

The nature of corticotrophin releasing factor (CRF) activity secreted by a human bronchial carcinoid cell line was investigated. The CRF activity in incubation media exposed to bronchial tumour cells was concentrated by preparative high pressure liquid chromatography (HPLC). Analytical HPLC resolved the CRF activity into several different forms. The incorporation of [3H]leucine and other [3H]amino acids into materials which co-eluted with CRF activity when fractionated by analytical HPLC suggested that the bronchial carcinoid cells were secreting peptide CRF(s). The most abundant radioactive material was shown to have a molecular weight of 12 000 by sodium dodecyl sulphate gel electrophoresis. This radioactive fraction also stimulated ACTH secretion by rat pituitary cell cultures in a dose-responsive manner.