Physalaemin-Like Immunoreactivity from Human Lung Small Cell Carcinoma: Isocratic Reversed-Phase HPLC Analysis of the Chemically Modified Peptide

Abstract

The metastatic human lung tumor, small cell carcinoma (SCC), exhibits ectopic (inappropriate) synthesis of numerous peptide hormones, such as ACTH, [Arg⁸]-vasopressin, hCGβ, calcitonin, oxytocin, prolactin, and growth hormone (Rees et al. 1974; Rees 1976; Baylin and Mendelsohn 1980). Furthermore, tumors resected from patients (Wood et al. 1981), or passaged in nude (athymic) mice (Erisman et al. 1982), or cultured into numerous cell lines (Moody et al. 1981, 1983 a, b; Sorenson et al. 1982) were found to contain immunoreactivity to the amphibian peptide bombesin and more recently to physalaemin (Erisman et al. 1982; Lazarus et al. 1983), which is the prototype of the tachykinin family of peptides discovered by Erspamer et al. (1964). The presence of immunoreactivity to bombesin was detected in human fetal and neonatal lungs (Wharton et al. 1978) and in the lungs of children (Cutz et al. 1981; Track and Cutz 1982) and appears to be associated with a mammalian form of bombesin similar to porcine gastrin-releasing peptide, a 27 amino acid residue peptide (Iwanago 1983; Price et al. 1983; Tsutsumi et al. 1983). On the other hand, the physalaemin-like immunoreactive material (PLIM), initially discovered in the gastrointestinal tract (Lazarus and DiAugustine 1980; Lazarus et al. 1980), was also present in neuronal (Lazarus et al. 1980) and pulmonary tissue from diverse mammlian species (Lazarus et al. 1982). Further studies showed however, that PLIM differed from the amphibian peptide (Lazarus et al. 1982) and the purified immunoreactive material was in fact an octapeptide with homology to the N-terminal region of physalaemin (Wilson et al. 1984).