Henry Ford Hospital Medical Journal


Using recombinant DNA techniques, we analyzed the structure of human calcitonin (CT)-encoding DNA. The sequence of nucleotides derived from the messenger RNA (mRNA) predict the amino acid sequence of the entire human CT precursor protein. The complete CT gene could be isolated from a DNA library of the human genome. The CT precursor encoding sequences (exons) as well as the noncoding intervening sequences (introns) could be identified. Another sequence, called human calcitonin gene-related peptide (hCCRP), could be located near this CT-encoding DNA. A genomic fragment encoding hCCRP was used as a probe to detect and isolate the corresponding mRNA in medullary thyroid carcinoma (MTC). The results of these investigations provide strong indication for the existence of a second (pseudo) CT gene in the human genome which also is expressed in human MTC. Besides the production of CT, the expression of the proopiomelanocortin (POMC) gene in human MTC was proved by hybridization analysis.