BOMBESIN-LIKE PEPTIDE RECEPTORS IN HUMAN BRONCHIAL EPITHELIAL-CELLS

Northern blot and RNAse protection assays previously failed to detect bombesin-like peptide (BLP) receptors in normal human lung tissue, but by RT/PCR cultured human bronchial epithelial (HBE) cells expressed a ll three BLP receptor subtypes, predominantly neuromedin B (NMB) recep tor. By RT/PCR, we found expression of all three BLP receptor subtypes by human lung tissue and confirmed NMB receptor expression in six out of six HBE samples. However, transformed HBE BEAS B2B cells expressed only gastrin-releasing peptide (GRP) receptors; saturable, high-affin ity (K-d = 3.5 nM) specific [I-125]GRP binding confirmed functional GR P receptor, with M(r) = 75 kDa and immunologic cross-reactivity with G RP receptor from human small-cell lung carcinoma (SCLC) NCI-H345 cells . Altered regulation of BLP receptors may accompany transformation of normal lung cells to cancer.