Expression of gamma-subunit of enolase, neuron-specific enolase, in human non-neuroendocrine tumors and derived cell lines.

The gamma-subunit of 2-phospho-D-glycerate hydrolyase, E.C. 4.2.1.11 (enolase), neuron-specific enolase (NSE), is present at high concentrations in neurons and neuroendocrine cells and has therefore recently been introduced as a marker for neuroendocrine tumors. By the indirect methods, immunocytochemistry and radioimmunoassay, NSE has been detected also in some nonneuroendocrine tumors, a finding that could reflect technical artifacts or the capacity for NSE expression in nonneuroendocrine tumor cells. This paper reports on the expression of NSE in human neuroendocrine and nonneuroendocrine tumor specimens and in a panel of permanent human cell lines, by using a direct (enzymatic) and an indirect (radioimmunoassay) method for determination of NSE. We detected NSE in all tested tumor specimens and neuroendocrine tumor cell lines and in a majority (21 of 24) of the nonneuroendocrine tumor cell lines. In general, neuroendocrine tumor specimens and derived tumor cell lines contained more NSE than the nonneuroendocrine tumor specimens and cell lines. However, some of the cultured hematopoietic cell lines (T leukemia and Epstein-Barr virus immortalized B lymphoblastoid cell lines) had NSE levels comparable to those found in some neuroblastoma and small-cell lung carcinoma cell lines. We conclude that NSE is not exclusively expressed in neuroendocrine tumor cells.