Ectopic hormone production by bronchial carcinomas in culture

Monolayer tissue culture has been used as a system in which to study aspects of ectopic hormone secretion. Of a series of twenty-four human bronchial carcinomas, nineteen were successfully established in culture and the supernatant medium from each tested for peptide hormones by radioimmunoassay. Six tumours were found to produce adrenocorticotrophin (ACTH), four to release calcitonin (CT) and one to release both of these hormones. No growth hormone or insulin was detected throughout the series. Net in vitro synthesis of both ACTH and CT was demonstrated by recovery of more hormone during culture than was originally contained in the explanted tumour tissue. The production of hormone by four out of six proliferative cultures established, and its persistence through many subculture passages, confirms ectopic hormone production as a stable heritable characteristic of some lung tumours. The ability of hormone-producing bronchial tumour cells to respond to factors known to influence hormone output from normal endocrine cells was tested. ACTH release was stimulated in one tumour by Pitressin and CT in another by gastrin. In addition, the release of CT from the same tumour cell line was shown to be inhibited by the accumulation of high external concentrations of CT as has been reported for normal C-cells.