inositol-1-4-5-trisphosphate and Stomach-Neoplasms

Our previous study using a cDNA microarray demonstrated that positive identification of differently expressed genes among gastric cancer cells involved in peritoneal dissemination could be accomplished. One of these genes with overexpression is inositol 1, 4, 5-trisphosphate receptor type 3 (IP3R3). IP3R3 is an intracellular Ca2+ release channel responsible for mobilizing stored Ca2+. Three different receptor types have been molecularly cloned, and their genes have been classified into a family. But the role of the IP3 signaling pathway in the peritoneal dissemination of gastric cancers is still unclear. In this study, IP3R3 is overexpressed in gastric cancer cell lines established from malignant ascites, but weakly expressed in gastric cancer cell lines established from primary tumor as well as in normal gastric epithelial cells. IP3R1 and 2 are expressed only weakly or not at all in these cells. The antagonist of IP3R, 2-APB, inhibited cell proliferation and induced apoptosis of gastric cancer cells from malignant ascites at concentrations of 100 nM to 100 microM in a dose dependent manner. Conversely, 2-APB showed a weak effect on other gastric cancer cells established from primary tumors (SNU1), lymph node metastases or liver metastases (MKN1 or 74), methothelial cell lines Met5A and myeloid leukemia cell HL60 cells. This suggests that this inhibitory effect depends on the level of IP3R3 expression. As cells that express IP3R3 mRNA (i.e., pancreatic aciner cells) are known to have a secretory function in which IP3/Ca2+ signaling has been shown to be involved, IP3R3 may be a prerequisite for secretion in gastric cancer cells. These results indicate that IP3R3 may be specifically involved in gastric cancer peritoneal dissemination and that IP3R3 may be a molecular target of the peritoneal dissemination of gastric cancer. Its antagonist, 2-APB, may thus be useful for the treatment of gastric cancer, especially for peritoneal dissemination.

Topics: Apoptosis; Boron Compounds; Cell Division; Humans; Inositol 1,4,5-Trisphosphate; Oligonucleotide Array Sequence Analysis; Peritoneal Neoplasms; Signal Transduction; Stomach Neoplasms; Tumor Cells, Cultured

To study the change and significance of intracellular-free calcium levels ([Ca2+]i) and inositol 1, 4, 5-trisphosphate (IP3) levels in the process of gastric carcinoma cell apoptosis induced by cisplatin.. Apoptosis induced by cisplatin in gastric carcinoma BGC823 cell was investigated by light and electronmicroscopy, agarose gel electrophoresis and flow cytometry. [Ca2+]i was determined by Fura-2 fluorescin load technic, IP3 was determined by competitive protein binding method.. When BGC823 cells were treated with cisplatin (2 micrograms/ml) for 24 hours changes appeared typical of apoptosis. [Ca2+]i and IP3 were significantly increased, especially at the initial stage of apoptosis. However, from 2 to 24 hours after cisplatin treatment, IP3 levels progressively decreased, being significantly lower than those of the untreated controls.. In the process of cisplatin induced apoptosis of gastric carcinoma cells, [Ca2+]i and IP3 levels are up-regulated at the very initial stage but down-regulated from 2 hours afterwards.

Topics: Antineoplastic Agents; Apoptosis; Calcium; Cisplatin; Humans; Inositol 1,4,5-Trisphosphate; Stomach Neoplasms; Tumor Cells, Cultured

To understand the role of NM23/NDPK in the transmembrane signal transduction proccess in tumor metastasis.. The NDPK activity, IP3 contents, the invasive potentials of the cells of mouse forestomach carcinoma(MFC) substrains with different metastatic potentials and the effect of LN and EGF were observed.. Both the NDPK activity and the contents of IP3 of the cells of the subclone with lower metastatic potential was higher than that with higher metastatic potential. Also, the cells with lower metastatic potential had lower invasive potential and higher responsibility to the challenge of EGF compared with that higher metastatic potential. However, no different effect of LN on the cells of those subclones was found.. NDPK might regulate the metastasis of FMC cells by impacting the G protein efficacy with the selection of exotic signal ligands.

Topics: Animals; Epidermal Growth Factor; Inositol 1,4,5-Trisphosphate; Mice; Neoplasm Metastasis; Neoplasm Transplantation; Nucleoside-Diphosphate Kinase; Signal Transduction; Stomach Neoplasms; Tumor Cells, Cultured

To examine the IP3 amounts, invasive potentials, and response to LN and EGF of the substrains with high or low metastatic ability from two kinds of carcinoma cell lines (MFC and CNZ-2Z).. Radio-ligand binding assay and matrigel invasive assay.. The low metastatic substrains from the two lines had higher amounts of IP3 and stronger response to EGF than their responsive high ones, but high metastatic substrains from CNZ-2Z had stronger response to LN than the low ones while MFC substrains had not significant difference in response to LN.. There is internal difference in signal transduction between the high and low metastatic cancer cells, and it is significant to study the difference in detail.

Topics: Animals; Epidermal Growth Factor; Humans; Inositol 1,4,5-Trisphosphate; Laminin; Mice; Nasopharyngeal Neoplasms; Neoplasm Metastasis; Signal Transduction; Stomach Neoplasms; Tumor Cells, Cultured

The histamine H3 receptor agonist (R)alpha-methylhistamine (MeHA) inhibited, in a nanomolar range, basal and carbachol-stimulated inositol phosphate formation in the human gastric tumoral cell line HGT1-clone 6. The inhibition was reversed by micromolar concentrations of the histamine H3 receptor antagonist thioperamide and was sensitive to cholera or pertussis toxin treatment. Using [3H]N alpha-MeHA as specific tracer, high affinity binding sites were demonstrated with a Bmax of 54 +/- 3 fmol/mg of protein and a KD of either 0.61 +/- 0.04 or 2.2 +/- 0.4 nM, in the absence or presence of 50 microM GTP[gamma]S, respectively. The binding sites were solubilized by Triton X-100 and prepurified by gel chromatography. They were separated from the histamine H2 receptor sites by filtration through Sepharose-famotidine and finally retained on Sepharose-thioperamide. The purified sites concentrated in one single silver-stained protein band of 70 kDa in SDS-polyacrylamide gel electrophoresis. They specifically bound [3H]N alpha-MeHA with a KD of 1.6 +/- 0.1 nM and a Bmax of 12,000 +/- 750 pmol/mg of protein. This corresponds to a 90,225-fold purification over cell lysate and a purity degree of 84%. Binding was competitively displaced by N alpha-MeHA (IC50 = 5.8 +/- 0.7 nM), (R) alpha-MeHA (IC50 = 9 +/- 1 nM), and thioperamide (IC50 = 85 +/- 10 nM), but not by famotidine (H2 antagonist) or by mepyramine (H1 antagonist). These findings provide the first evidence for solubilization, purification, and molecular mass characterization of the histamine H3 receptor protein and for the negative coupling of this receptor phosphatidylinositol turnover through a so far unidentified G protein.

Topics: Binding Sites; Carbachol; Cholera Toxin; Chromatography, Affinity; Chromatography, Gel; Guanosine 5'-O-(3-Thiotriphosphate); Histamine Antagonists; Humans; Inositol 1,4,5-Trisphosphate; Inositol Phosphates; Kinetics; Methylhistamines; Molecular Weight; Phosphatidylinositols; Piperidines; Receptors, Histamine; Receptors, Histamine H3; Stomach Neoplasms; Tumor Cells, Cultured