l-365260 and Stomach-Neoplasms

Gastrin contributes to the growth and proliferation of gastric cancer cells and it is related to the effect of tyrosine kinase. This study was to investigate the effect of gastrin on tyrosine phosphorylation of focal adhesion kinase (FAK) in human gastric cancer cell line SGC7901.. The vector pCR3.1/GR, that expresses human gastrin receptor (GR) stably, was transfected into SGC7901 cells (SGC7901-GR). The expression of GR was tested by reverse transcription-polymerase chain reaction (RT-PCR). SGC7901-GR and SGC7901 cells were treated with L-365260, an antagonist of GR, and stimulated with gastrin at different concentrations for different time. The tyrosine phosphorylation level of FAK was detected by immunoprecipitation and Western blot.. When treated with different concentrations of gastrin for 1 min, the tyrosine phosphorylation levels of FAK were significantly higher in SGC7901-GR cells than in SGC7901 cells (0.64+/-0.06 vs. 0.40+/-0.05 at 0.1 nmol/L, 0.91+/-0.10 vs. 0.52+/-0.07 at 1 nmol/L, and 1.00+/-0.10 vs. 0.62+/-0.06 at 10 nmol/L, P<0.01). When treated with 10 nmol/L gastrin for different time, the tyrosine phosphorylation levels of FAK were also significantly higher in SGC7901-GR cells than in SGC7901 cells (0.72+/-0.08 vs. 0.59+/-0.05 at 1 min, 0.83+/-0.05 vs. 0.65+/-0.07 at 5 min, 0.88+/-0.06 vs. 0.58+/-0.03 at 10 min, and 1.00+/-0.08 vs. 0.47+/-0.10 at 20 min, P<0.05). L-365260 decreased the tyrosine phosphorylation levels of FAK from 1.00+/-0.07 to 0.72+/-0.07 in SGC7901-GR cells (P<0.01), and from 0.62+/-0.06 to 0.45+/-0.05 in SGC7901 cells (P<0.01). The protein levels of FAK in different cells remained unchanged during these experiments (P>0.05).. FAK is a pivotal signal transducer in downstream of gastrin with GR. Tyrosine phosphorylation is the symbol of FAK activation.

Topics: Benzodiazepinones; Cell Line, Tumor; Focal Adhesion Kinase 1; Gastrins; Genetic Vectors; Humans; Phenylurea Compounds; Phosphorylation; Receptor, Cholecystokinin B; Signal Transduction; Stomach Neoplasms; Transfection

In this study we identified and characterized the receptor related to the modulation of growth of human gastric cancer by gastrin. By performing receptor binding assays on human AGS gastric cancer cells with the selective CCK-B/gastrin receptor antagonist [3H]L-365,260, specific and saturable binding were determined. Binding was dependent on protein concentration, time, temperature, and the presence of protease inhibitors, and was located in the membrane fraction. Gastrin, as well as CCK, stimulated gastric cancer cell growth in a receptor-mediated fashion at a concentration consistent with the binding affinity. Receptor gene expression for the CCK-B/gastrin receptor, but not for the CCK-A receptor, was found by reverse transcription polymerase chain reaction. Receptor binding assays as well as transcriptional and growth studies provide evidence that gastrin-stimulated growth of human gastric cancer is mediated by CCK-B/gastrin-like receptors.

Topics: Benzodiazepinones; Cholecystokinin; Gastric Mucosa; Gastrins; Gene Expression; Growth Substances; Humans; In Vitro Techniques; Molecular Sequence Data; Phenylurea Compounds; Receptors, Cholecystokinin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stomach Neoplasms; Transcription, Genetic; Tumor Cells, Cultured

Gastrin has been shown to promote the growth of some colonic tumor cell lines. To evaluate the involvement of this hormone in the proliferation of gastric tumors, we studied the effects of gastrin/CCK-receptor antagonists (L365,260 and L364,718), proglumide and C terminal-specific gastrin antibodies on the human gastric adenocarcinoma cell line HGT-1. L365,260, but not L364,718, dose-dependently inhibited cell proliferation (72% after 4 days at 10 nM) and [3H]thymidine incorporation (68% after 2 days at 10 nM) in serum-free medium. No cytotoxic effects of proglumide or L365,260 on this cell line were detected. Proglumide inhibited cell proliferation in serum-free medium (40% and 66.5% after 2 and 4 days of treatment; IC50 = 1.4 mM) and in 5% fetal calf serum (FCS)-supplemented medium (30% and 22% after 2 and 4 days of treatment; IC50 = 3.25 mM). [3H]Thymidine incorporation was also inhibited by proglumide in serum-free medium (IC50 = 2.3 mM) and 5% FCS-supplemented medium (IC50 = 3.35 mM). Gastrin did not induce cell proliferation or increase [3H]thymidine incorporation and no high-affinity gastrin binding sites were observed. However, C terminal-specific gastrin antibodies, even at low concentration, caused a dramatic decrease in both cell number (IC50 = 1:4000 antiserum dilution) and [3H]thymidine incorporation (IC50 = 1:400 antiserum dilution) in the HGT-1 cell line. In addition, immunofluorescence analysis revealed that these antibodies specifically bind HGT-1 cells and radioimmunoassay analysis confirms the presence of gastrin/CCK-like peptide in cell extracts.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenocarcinoma; Antibodies; Benzodiazepinones; Cell Division; Devazepide; Gastrins; Growth Substances; Humans; Neoplasm Proteins; Phenylurea Compounds; Proglumide; Receptors, Cholecystokinin; RNA, Messenger; RNA, Neoplasm; Stomach Neoplasms; Tumor Cells, Cultured