ECTOPIC PRODUCTION OF HIGH MOLECULAR WEIGHT CALCITONIN AND CORTICOTROPIN BY HUMAN SMALL CELL CARCINOMA CELLS IN TISSUE CULTURE: EVIDENCE FOR SEPARATE PRECURSORS

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Abstract
The DMS-79 continuous line of human small cell lung carcinoma cells, which produces immunoreactive (IR)-corticotropin ( ACTH ), -lipotropin ( LPH ), and -β-endorphin (βEND), was found to produce IR-calcitonin (CT). Two major high molecular weight (HMW) forms of IR-CT were observed after gel exclusion chromatography under denaturing conditions ( mol. wt. ~7,000 and ~14,000), as well as a minor HMW IR-CT component (mol. wt. ~70,000). None of these IR-CT materials was extracted from DMS-79 medium by affinity chromatography using an ACTH antibody covalently bound to agarose. These results demonstrate ectopic production of HMW forms of CT and ACTH/LPH/βEND by human lung tumor cells in tissue culture, but do not support the existence of a common CT/ACTH/LPH/βEND precursor molecule.