Nestin as a valuable marker in the classification of adrenocortical tumors

Abstract

Nestin is a newly identified intermediate filament protein that belongs to the sixth class of intermediate filaments. Previous studies have demonstrated that nestin is abundantly expressed in neuroectodermal stem cells and is extinguished from differentiated cells of the central nervous system. Nestin is also expressed in skeletal muscle progenitor cells, but down-regulated on cellular differentiation. In addition, nestin is shown to be predominantly expressed in tumors that are thought to arise from immature cells, such as primitive neuroectodermal tumors, medulloblastomas, pediatric rhabdomyosarcomas, and gastrointestinal stromal tumors. Expression of the intermediate filament nestin was long believed to be restricted to neuroectodermal stem cells. However, expression of nestin could recently be detected in seral tumors. Since adrenocortical carcinomas, a tumor entity which is still very difficult to classify, may gain the ability to aberrantly express neuroectodermal peptides, including chromogranin A and synaptophysin, we asked whether nestin can also be detected in adrenocortical carcinomas and if so whether it is a valuable tool for the clinical pathologist. Therefore, we studied expression of nestin by normal adrenal glands, adrenocortical adenomas, and andrenocortical cancers. We found positve immunostaining in sections of 1 out of 6 normal adrenal glands (17%), 1 out of 9 adrenocortical adenomas (11%), and 10 out of 13 andrenocortical carcinomas (77%). Expression of nestin mRNA could be detected in all tissues, independently of their grade of dedifferentiation. We conclude that nestin is a valuable marker in the characterization of adrenocortical tumors. In addition, this study once more brings up the question whether nestin is specific for stem cells.