Characterization of VIP- and helodermin-preferring receptors on human small cell lung carcinoma cell lines.

We investigated the molecular and pharmacologic characteristics of VIP receptors on two human SCLC cell lines: NCI-N592 and NCI-H345. With NCI-N592 cell, the order of potency of VIP-related peptides in inhibiting 125I-VIP binding and in stimulating cAMP production was typical of the human VIP receptor. By covalent cross-linking, a polypeptide of Mr 62,300 was obtained. Conversely, the behavior of NCI-H345 cell line was totally different: helodermin was the most potent peptide, VIP and PHI were equipotent, while hGRF and secretin were totally ineffective. These results suggest that NCI-N592 cells possess a typical VIP receptor while NCI-H345 cells possess a helodermin-preferring receptor, and that the natural target of helodermin might not be the VIP receptor.