Detection of mRNA encoding calcitonin, calcitonin gene related peptide and proopiomelanocortin in human tumors

Expression of the calcitonin (CT)/calcitonin gene related peptide (CGRP) gene and the proopiomelanocortin (POMC) gene has been demonstrated by Northern blot hybridization analysis of RNA extracted from human medullary thyroid carcinoma (MTC), pheochromocytoma and lung carcinoma. CT mRNA in these tumors could not be distinguished in size from CT mRNA isolated from normal human thyroid tissue. CGRP mRNA (previously demonstrated in 12 out of 12 lung tumor cell lines investigated) could not be detected in 13 primary lung tumors or 10 metastases thereof. The length of POMC mRNA in MTCs (present in all 4 metastases investigated but not in 7 primary tumors) and pheochromocytomas is about 100 nucleotides more than pituitary POMC RNA. In lung tumors 2 POMC RNA species can be detected, one of the same size as in pituitary tissue and one about 100 nucleotides larger.