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, neuron-specific 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.
Reubi
J C
JC
Sandoz Research Institute Berne, Switzerland.
Waser
B
B
Sheppard
M
M
Macaulay
V
V
D000328:Adult; D000368:Aged; D001345:Autoradiography; D002289:Carcinoma, Non-Small-Cell Lung / Q000032:analysis*; D018288:Carcinoma, Small Cell / Q000032:analysis*; D066246:ErbB Receptors / Q000032:analysis*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D017981:Receptors, Neurotransmitter / Q000032:analysis*; D017481:Receptors, Somatostatin; D013004:Somatostatin / Q000378:metabolism*
D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin; D013004:Somatostatin; D066246:ErbB Receptors