Nonconstitutive expression of the gastrin-releasing peptide autocrine growth system in human small cell lung carcinoma NCI-H345 cells.

Constitutive, unregulated autocrine growth is thought to be an important mechanism whereby cancer cells gain a proliferative advantage over nonmalignant cells. The question addressed here was whether the autocrine growth system for gastrin-releasing peptide (GRP) in human small cell lung carcinoma cells is, in fact, always expressed in a constitutive, unregulated fashion. Lag, rapid, and plateau growth states were defined for small cell lung carcinoma NCI-H345 cells based on periods during which they expressed different growth rates after plating as single cell suspensions.

Novel soluble, high-affinity gastrin-releasing peptide binding proteins in Swiss 3T3 fibroblasts.

Swiss 3T3 cells contained substantial amounts of soluble and specific [125I]GRP binders. Like the membrane-associated GRP receptor, they were of high affinity, saturable, bound to GRP(14-27) affinity gels, and exhibited specificity for GRP(14-27) binding. They differed in that acid or freezing destroyed specific binding, specific binding exhibited different time and temperature effects, no detergent was required for their solubilization, ammonium sulfate fractionation yielded different profiles, the M(rs) were lower, GRP(1-16) also blocked binding, and a polyclonal anti-GRP receptor antiserum did not bind on Western blots.

Isolation of the bombesin/gastrin-releasing peptide receptor from human small cell lung carcinoma NCI-H345 cells.

Purification of the gastrin-releasing peptide (GRP) or bombesin receptor has proved elusive in part due to technical difficulties. In the present studies, the problem of oxidized radioligand was avoided by the use of 125I-GRP, which was verified to be not oxidized by high performance liquid chromatography. Specific 125I-GRP binding (at 0 degrees C) to intact human small cell lung carcinoma NCI-H345 cells which had been subjected to a dilute acid wash was 6 fmol/10(6) cells.

Isolation of a gastrin releasing peptide receptor from normal rat pancreas.

The presence of a putative GRP receptor on rat pancreatic particulate membranes was demonstrated by covalent cross-linking to 125I-gastrin releasing peptide (GRP), which revealed a radioactive band with Mr = 80-90 kDa on reduced SDS-PAGE. Fresh rat pancreatic membranes contained a GRP receptor which was solubilized with Triton X-100 as assessed by its failure to sediment at 100,000 x g for one hour and its ability to pass through a 0.22 mu filter.