Molecular markers of neuroendocrine development and evidence of environmental regulation

We constructed a human pheochromocytoma cDNA library and used differential hybridization to human pheochromocytoma and human neuroblastoma cDNA probes to isolate genes that are highly expressed in the adrenal medullary neuroendocrine tumor, pheochromocytoma, but not in the more immature embryonal tumor of adrenal medulla, neuroblastoma. Two cDNA clones, pG8 and pG2, were more highly expressed in normal and neoplastic chromaffin tissue than they are in neuroblastoma. Furthermore, they are expressed in a remarkably limited number of other human tumors or normal tissues. pG8 is highly expressed in medullary thyroid carcinoma, another tumor of neural crest origin, which can occur in association with pheochromocytoma in the multiple endocrine neoplasia type II syndrome. pG2 is highly expressed in the adrenal cortex, an endocrine gland thought to be embryologically unrelated to the neural crest-derived adrenal medulla. The expression of both pG8 and pG2 can be induced in human neuroblastoma cells with dexamethasone, suggesting a mechanism by which glucocorticoids may influence development of a neuroendocrine phenotype.