PRODUCTS OF VASOPRESSIN GENE-EXPRESSION IN SMALL-CELL CARCINOMA OF THE LUNG

Small-cell neuroendocrine carcinoma of the lung is known to express pr oducts related to the vasopressin gene, although these products have b een reported to sometimes differ from those generated by neurones of t he hypothalamo-neurohypophyseal system. To further investigate vasopre ssin gene expression in neuroendocrine carcinomas, we performed immuno histochemistry on 24 histologically classified small-cell carcinomas u sing antibodies directed against different regions of the vasopressin precursor. All of the tumours examined contained at least two parts of the vasopressin precursor, suggesting that vasopressin might have a b iological role in these tumours and indicating a role for these produc ts in tumour diagnosis and treatment. Sixty-seven per cent of the tumo urs contained immunoreactivity for all major regions of the precursor: vasopressin, vasopressin-associated human neurophysin, the bridging r egion between the hormone and the neurophysin, and vasopressin-associa ted human glycopeptide. However, 33% of the tumours examined appeared to express only part of the vasopressin precursor, as evidenced by the absence of immunoreactivity for the neurophysin and/or the glycopepti de. These results support the proposition that both normal and abnorma l vasopressin gene expression occurs in small-cell carcinoma of the lu ng.