SOMATOSTATIN RECEPTORS ARE PRESENT IN SMALL-CELL BUT NOT IN NON-SMALL-CELL PRIMARY LUNG CARCINOMAS - RELATIONSHIP TO EGF-RECEPTORS

Sixteen primary human lung tumours were analysed for their content of somatostatin receptors using receptor autoradiography with somatostatin‐28 and somatostatin octapeptide analogues as radio‐ligands. Two out of 4 small‐cell lung carcinomas were somatostatin receptor‐positive, with a high density of homogeneously distributed receptors on tumour tissue only. Somatostatin receptors were characterized in one of the tumours in homogenate binding assay as saturable, high‐affinity binding sites (KD =0.53 nM) with a number of sites (Bmax) equivalent to 189 fmoles/mg protein. These sites were specific for somatostatin, since only biologically active somatostatin analogues but not unrelated peptides showed high‐affinity binding. Both receptor‐positive patients had limited disease; furthermore, the small‐cell lung carcinoma patient with the longest survival was receptor‐positive, while the one with the shortest survival was receptor‐negative. None of the 12 non‐small‐cell lung carcinomas (5 squamous carcinomas, 7 adenocarcinomas) contained somatostatin receptors. For comparison, epidermal growth factor receptors were found in all non‐small‐cell lung carcinomas. Neuroendocrine features (synaptophysin, chromogranin, neuronspecific enolase, protein gene product 9.5) were present in all small‐cell lung carcinomas but absent in non‐small‐cell lung carcinomas. Given the receptor‐mediated action of somatostatin in other neuroendocrine tumours, these data may have a bearing on the clinical application of somatostatin analogues in patients with small‐cell lung carcinomas. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company