ABSTRACT
We have developed three human cloned cell lines that produce immunoreactive human calcitonin (ihCT) and ACTH (iACTH) as well as exhibit characteristics of cultured neural cells. Clones HMS-41/I, -78/2, and -98/2 were developed from cell lines HeLa AV3, MBA 9812 (bronchogenic carcinoma), and SW 267 (pheochromocytoma), respectively. Karyological analysis of both the parent and the cloned cell lines confirmed the identity of HeLa AV3 and MBA 9812. When grown in serum-free media designed for culturing neural cells, the patterns of production for both ihCT and iACTH varied among the clones. The multiple patterns of hormone production suggest that the mechanisms involved in the biosynthesis, processing, and secretion of these hormones differ among the clones. The clones contain neuron-specific enolase and the putative neurotransmitters beta-alanine and gamma-amino butyric acid, and they respond to cAMP analogs by differentiating, as noted by the extension of neurites (except the HeLa-derived HMS-41/I). The iACTH extracted from cells and synthetic ACTH exhibited equivalent profiles upon isoelectric focusing. The forms of ihCT noted in cell extracts were similar to those observed in extracts of human tumor tissue. Our rabbit antiserum to hCT failed to detect ihCT in those cell extracts prepared for ACTH determination or in extracts of rat pituitaries, but it did detect CT in rat thyroids by both RIA and immunofluorescent procedures. We concluded that our antisera to hCT do not detect the precursor form of ACTH. The availability of these cloned cell lines provides model systems for examining the production of these peptide hormones and the concomitant expression of neural and endocrine characteristics.
