SIGMA-RECEPTORS ARE EXPRESSED IN HUMAN NONSMALL CELL LUNG-CARCINOMA

N-(2-piperidinoethyl)4-iodobenzamide), IPAB, was used to characterize sigma receptors in non-small cell lung cancer (NSCLC) cell lines. (125 )IPAB bound with high affinity to large cell carcinoma (NCI-H1299), ad enocarcinoma (NCI-H838), and lung carcinoid (NCI-H727) cell lines. Spe cific IPAB binding was inhibited with high affinity by haloperidol (Ki 0.6 nM), IPAB (Ki = 14 nM) and 1,3-ditolyl guanidine (DTG) (Ki = 40 n M). Relative to other receptor ligands, IPAB was not readily internali zed at 37 degrees C. IPAB had little effect on the growth of NSCLC cel ls. Scintigraphic imaging studies using (131)IPAB in nude mice bearing NCI-H838 xenografts visualized the tumor at 24 or 30 hours after inje ction. These results suggest that sigma receptors which are present on NSCLC cells may be used as external markers for imaging tumors in viv o.