Neurotensin is produced by and secreted from classic small cell lung cancer cells

The presence of neurotensin in various human tumor cell lines was investigated by radioimmunoassay. High concentrations (0.06-5.1 pmol/mg protein) were detected in 50% of the classic but not variant small cell lung cancer or other human tumor cell lines examined. Biochemical studies indicated that the main peak of immunoreactivity coeluted with synthetic neurotensin using gel filtration and high pressure liquid chromatography techniques. Also, the rate of neurotensin secretion increased approximately 2-fold when theophylline was added which elevated intracellular levels of cAMP 4-fold. Because neurotensin is present in and secreted from many classic small cell lung cancer cells, it may function as a regulatory peptide in this disease.