IA-2, a transmembrane protein tyrosine phosphatase, is expressed in human lung cancer cell lines with neuroendocrine phenotype.

IA-2 is a transmembrane protein tyrosine phosphatase isolated recently from a human insulinoma subtraction library. Its expression in normal human tissues is restricted primarily to the pancreatic islets and brain. In this report, we describe the expression of IA-2 mRNA in a panel consisting of 20 lung tumor cell lines with neuroendocrine and non-neuroendocrine phenotype and 17 non-lung tumor cell lines. IA-2 mRNA was detected in 8 of 11 neuroendocrine small cell lung carcinomas, 4 of 4 non-small cell lung carcinomas with neuroendocrine phenotype, and 11 of 12 non-lung neuroendocrine tumor cell lines. In contrast, IA-2 mRNA was not detected in five non-neuroendocrine lung carcinomas, nor in a panel of other non-neuroendocrine tumor cell lines. The expression pattern of IA-2 mRNA suggests that IA-2 may represent a new marker for neuroendocrine differentiation In human lung cancer cells and perhaps other neuroendocrine tumors.