Human Gastric Cancer MGC-803 Cells Research Articles

Characterization and anti-tumor activity of a polysaccharide from Hedysarum polybotrys Hand.-Mazz

A water-soluble polysaccharide named as HPS-1 was isolated from the roots of Hedysarum polybotrys Hand.-Mazz by hot water extraction, anion-exchange and gel-permeation chromatography and tested for its anti-tumor activity. Its structural characteristics were investigated by FTIR, HPLC, NMR spectroscopy, GLC–MS, methylation analysis, periodate oxidation and Smith degradation. Based on the data obtained, HPS-1 was found to be an α-(1 → 4)- d-glucan, with a single α- d-glucose at the C-6 position every nine residue, on average, along the main chain. The glucan has a weight-average molecular weight of about 9.4 × 10 4 Da. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that HPS-1 significantly inhibited the proliferation of human hepatocellular carcinoma HEP-G2 cells and human gastric cancer MGC-803 cells in vitro, indicating HPS-1 could have a possible cancer therapeutic potential.

Erk is involved in the differentiation induced by diallyl disulfide in the human gastric cancer cell line MGC803

Diallyl disulfide (DADS) is a major constituent of garlic. Previously, we found that DADS both inhibited proliferation in human gastric cancer cells in vitro and in vivo, and induced G2/M arrest. In this study, we investigated whether this differentiation effect was induced by DADS in human gastric cancer MGC803 cells, and whether it was related to an alteration in ERK activity. The results showed that the growth of MGC803 cells was inhibited by DADS. Cells treated with DADS displayed a lower nucleocytoplasmic ratio and tended to form gland and intercellular conjunction structures. The ConA-mediated cell agglutination ratio and cells' ALP specific activity decreased. In MGC803 cells, dye transfer was limited to a few cells neighbouring the dye-injected cell and to a depth of 1-2 layers beneath the scrape site. However, after treatment with DADS, the LY (Lucifer Yellow) was transferred to several cells immediately neighbouring the microinjected cell and to a depth of 2-4 cell layers from the scrape site. This indicated that DADS induced differentiation in MGC803 cells. Western blot analysis revealed that although DADS did not influence the quantity of ERK1/2 protein expressed, it did decrease its phosphorylation in a concentration-dependent manner, compared with the controls. At 30 mg x L(-1), DADS inhibited the activation of ERK1/2 in 15-30 min. These results suggested that the DADS-induced differentiation of MGC803 cells involved an alteration of the ERK1/2 signaling pathway.

Up-regulation of telomere-binding TRF1, TRF2 related to reactive oxygen species induced by As 2O 3 in MGC-803 cells

In this work, our study focused on As 2O 3 action in view point of telomere. Results showed that treatment of human gastric cancer MGC-803 cells with arsenic trioxide could cause up-regulation of telomeric repeat binding factor TRF1 and TRF2 mRNA and protein levels, and induced G2/M phase arrest and cell apoptosis. At the same time, telomere length shortening and telomerase inhibitory were not obvious. Flow cytometry measurements indicated that the increase of TRF1 and TRF2 proteins is related to oxidative stress by arsenic trioxide. Results also indicate that after arsenic trioxide treatment, p53 protein levels increased significantly and also could bind directly at the telomere t-loop junction. These findings demonstrate arsenic trioxide-induced cell cycle arrest and apoptosis might involve a novel pathway related to TRF1, TRF2 protein.

Diallyl disulfide-induced G2/M arrest of human gastric cancer MGC803 cells involves activation of p38 MAP kinase pathways.

To determine the role of p38 MAP kinase signal transduction pathways in diallyl disulfide (DADS)-induced G2/M arrest in human gastric cancer MGC803 cells. MGC803 cell growth inhibition was measured by MTT assay. Phase distribution of cell cycle was analyzed by flow cytometry. Expression of Cdc25C, p38, phosphorylation of p38 (pp38) were determined by Western blotting. MTT assay showed that SB203580, a specific p38 MAPK inhibitor blocked DADS-induced growth inhibition. Flow cytometry analysis revealed that treatment of MGC803 cells with 30 mg/L DADS increased the percentage of cells in the G2/M phase from 9.3% to 39.4% (P<0.05), whereas inhibition of p38 activity by SB203580 abolished induction of G2/M arrest by DADS. Western blotting showed that phosphorylation of p38 was increased 3.52-fold following treatment of MGC803 cells with 30 mg/L DADS for 20 min (P<0.05), whereas Cdc25C was decreased 68% following treatment of MGC803 cells with 30 mg/L DADS for 24 h (P<0.05). Decreased Cdc25C protein expression by DADS was attenuated by SB203580 (P<0.05). DADS-induced G2/M arrest of MGC803 cells involves activation of p38 MAP kinase pathways. Decreased Cdc25C protein expression by p38 MAPK played a crucial role in G2/M arrest after treatment with DADS.

P53-induced gene 11 (PIG11) involved in arsenic trioxide-induced apoptosis in human gastric cancer MGC-803 cells

Arsenic trioxide (As2O3) has been used as an effective chemotherapy agent for some human cancer, such as acute promyelocytic leukemia. We have demonstrated that low level of As2O3 relatively selectively inhibited growth of the solid tumor MGC-803 cells by triggering apoptosis. In this study, we found PIG11, a p53-induced gene, was upregulated markedly by As2O3 using the technique of differential display reverse transcriptase PCR (DDRT-PCR). Addition of anti-PIG11 phosphorothioated oligonucleotide (5'-GGC CGC CAT CTT CTC CTC-3') before As2O3 treatment, abolished the transient increase in PIG11 gene expression. Furthermore, it significantly inhibited the As2O3-induced apoptosis of MGC-803 cells, but had no effect in addition of missense (5'-GAG GAG AAG ATG GCG GCC-3') phosphorothioated oligonucleotides. These results suggest that PIG11, as a downstream target of p53, is involved in apoptosis of MGC-803 cells.

Role of calcium in phototoxicity of 2-butylamino-2-demethoxy-hypocrellin A to human gastric cancer MGC-803 cells

After incubation with 2-butylamino-2-demethoxy-hypocrellin A (2-BA-2-DMHA), photodynamically induced change in the cytoplasmic free calcium concentration ([Ca 2+] i) and its effect on cell damage were investigated in human gastric cancer (MGC-803). Fluorescence spectrophotometry measurement indicated that the photosensitization of MGC-803 by 2-BA-2-DMHA caused an increase in intracellular calcium [Ca 2+] i, and this increase in [Ca 2+] i showed a dependence on the concentration of 2-BA-2-DMHA, light dose and extracellular [Ca 2+] e. This phenomenon of intracellular calcium accumulation was further confirmed by using laser scanning confocal microscopy (LSCM). Furthermore, the results from MTT assay and flow cytometry analysis suggested that chelation of extracellular calcium by EGTA or intracellular calcium by BAPTA could inhibit photodynamically induced cell killing, while increase of [Ca 2+] i by thapsigargin (TG), a highly specific inhibitor of the Ca 2+-ATPase, or by A23187, a calcium ionophore could enhance this action. Meanwhile, the nucleus morphology was also investigated by fluorescence microscopy. The results indicated that the increase in intracellular Ca 2+ concentration was responsible for 2-BA-2-DMHA photodynamically induced damage to MGC-803.

Arsenite-induced reactive oxygen species and the repression of α-tocopherol in the MGC-803 cells

We have investigated the action of oxidative stress in arsenite-induced apoptosis of human gastric cancer MGC-803 cells. Cells exhibited obvious characteristic of apoptosis following the treatment with 1.0 μM arsenite for 24 h. During the process, low concentration of arsenite significantly increased superoxide formation and lipid peroxidation, which was dose-dependent and was related to cell apoptosis induced by arsenite. The oxidant-dependent increase in intracellular [Ca 2+] level and p53 gene expression were also observed at the same time. A phospholipase C inhibitor, 1-[6-([(17β)-3-methoxyestra-1,3,5,(10)-trien-17-yl]-amino)hexyl]-2,5-dione (U73122), could block the rapid transient increase in intracellular Ca 2+ levels, as well as the subsequent fragmentation of nuclear DNA. Addition of α-tocopherol before arsenite treatment abolished the transient increase in superoxide formation, lipid peroxidation, intracellular [Ca 2+] levels and p53 gene expression, and furthermore could significantly inhibited the arsenite-induced apoptosis of MGC-803 cells. These results indicate that arsenite-induced oxidative stress, which stimulate cellular signaling systems, are involved in apoptosis of MGC-803 cells.

Apoptosis induced by isoliquiritigenin in human gastric cancer MGC-803 cells.

Isoliquiritigenin, which is possibly a principal anti-tumor constituent of licorice, a traditional Chinese herb, was examined for apoptosis-inducing activity in human gastric cancer MGC-803 cells. Typical morphological and biochemical features of apoptosis including cell shrinkage, chromatin condensation, DNA ladder formation, and appearance of apoptotic peaks (subG(1)) were observed in MGC-803 cells with isoliquiritigenin treatment. Using Fluo-3 and Rh123 as fluorescent probes, respectively, it was found that the intracellular free calcium concentration increased and the mitochondrial transmembrane potential (Deltapsi(m)) decreased in a dose-dependent manner in apoptotic cells. These results suggest that isoliquiritigenin induced apoptosis of MGC-803 cells through calcium- and Deltapsi(m)-dependent pathways, indicating that it is potentially useful as a natural anti-cancer agent.

Induction of apoptosis and inhibition of human gastric cancer MGC-803 cell growth by arsenic trioxide

Arsenic trioxide (As2O3), used to treat human diseases for centuries in traditional Chinese medicine, has been identified as a very effective antileukaemic agent, but its effect on solid tumours which could be more suitable for clinical treatment with arsenic compounds is still unknown. In this study, we investigated the in vitro effect of As2O3 at concentrations of 0.01–1μM against six human malignant cell lines, MGC-803, HIC, MCF-7, HeLa, BEL-7402 and A549 cells. As2O3 inhibited growth and induced apoptosis in these malignant cells at varying degrees, in a time dose-dependent manner. The most marked effects were seen in the gastric cancer cell line, MGC-803. In contrast, minimal growth inhibition and induction of apoptosis occurred in human embryonic pulmonary cells following treatment with As2O3 found at the same concentrations. Changes in intracellular Ca2+, following As2O3 treatment were measured by Ca2+ sensitive fluorescent probe Indo-1/AM in flow cytometric assays. The increase in intracellular Ca2+ correlated with the sensitivity of these cells to As2O3, possibly indicating that a critical intracellular Ca2+ signal transduction pathway could be involved in As2O3-mediated cell-death and its selectivity. The marked sensitivity of MGC-803 cells in vitro suggests that As2O3 may be a potential antigastric cancer agent.