[Neuron-specific enolase as a new tumor marker].

Enolase is a glycolytic enzyme widely distributed in each mammalian tissue and consists of three distinct subunits alpha, beta, and gamma. In the brain enolase exhibits three dimetric isozymic forms: alpha alpha, alpha gamma and gamma gamma. The gamma protein subunit has recently been found to be identical with the nervous system-specific and species-nonspecific protein, 14-3-2; therefore, alpha gamma and gamma gamma types of enolase were characterized as neuron-specific enolase (NSE). NSE has been also detected in the pituitary gland, thyroid gland, adrenal medulla and pancreas, all of which contain neuroendocrine cells. Recently NSE was observed by immunostaining or radioimmunoassay in neuroendocrine tumor such as glucagonomas, insulinomas, gut carcinoids, medullary thyroid carcinomas or neuroblastomas. Furthermore, small cell carcinoma of the lung which has been known to frequently exhibit neuroendocrine properties was found to produce NSE. In this paper NSE as a tumor marker in various cancers was evaluated by immunostaining or enzyme immunoassay which was developed by a co-worker Kato. The data revealed that serum NSE was clinically useful as a tumor marker, especially a monitoring marker of disease extent. NSE productions were also observed in adenocarcinoma of the colon or the lung and large cell carcinoma of the lung as well as small cell carcinoma of the lung and the esophagus, all of which were considered to share the biochemical features of neuroendocrine tumor. The evidence challenges a speculation that small cell carcinoma of the lung has an origin separated from the other histological types of lung carcinoma. In this meaning NSE is an important tumor marker for both clinical medicine and basic research.