Abstract
Small-cell neuroendocrine carcinoma of the lung is known to express products related to the vasopressin gene, although these products have been reported to sometimes differ from those generated by neurones of the hypothalamo-neurohypophyseal system. To further investigate vasopressin gene expression in neuroendocrine carcinomas, we performed immunohistochemistry on 24 histologically classified small-cell carcinomas using 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 biological role in these tumours and indicating a role for these products in tumour diagnosis and treatment. Sixty-seven per cent of the tumours contained immunoreactivity for all major regions of the precursor: vasopressin, vasopressin-associated human neurophysin, the bridging region between the hormone and the neurophysin, and vasopressin-associated 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 glycopeptide. These results support the proposition that both normal and abnormal vasopressin gene expression occurs in small-cell carcinoma of the lung.
Highlights
Paraffin-embedded surgical specimens were obtained from a library of SCCL tumours at Dartmouth Hitchcock Medical Center
The specificity of the antibodies in immunohistochemistry was demonstrated by the positive identification of neuronal cell bodies and axon terminals in b paraffin-embedded sections of human hypothalamus and posterior pituitary, and by a lack of staining in sections incubated with normal serum in place of primary antibody
Staining was located throughout the tumour (Figure la and b) and was not observed in sections incubated with normal serum instead of primary antibody
Summary
Paraffin-embedded surgical specimens were obtained from a library of SCCL tumours at Dartmouth Hitchcock Medical Center. The specimens were fixed in acetone within 90 min of tumour resection and processed according to the AMeX (acetone, methylbenzoate, xylene) method (Sato et al, 1986). Diagnosis for SCCL was confirmed at the light microscopic level on haematoxylin and eosin-stained sections according to Correspondence: A.S. Friedmann, Department of Physiology, Dartmouth Medical Schol, 1 Medical Center Drive, Lebanon, NH 03756, USA. Received 9 August 1993; and in revised form 27 September 1993. Of the 24 SCCL tumours selected, eight were removed from the lung, while 16 were biopsies of metastases to either the lymph nodes or other organs. Paraffin-embedded sections of 4 gm were transferred to microscope slides
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