This study aimed to explore the molecular mechanism of rubioncolin C(RuC) in inhibiting gastric cancer(GC). AGS and MGC803 cell lines were selected as cellular models. After treating the cells with RuC at different concentrations, the effects of RuC on the proliferation ability of GC cells were assessed using the CCK-8 method, real-time cellular analysis(RTCA), and colony formation assays. Transmission electron microscopy was used to observe subcellular structural changes. Immunofluorescence was applied to detect LC3 fluorescent foci. Acridine orange staining was used to evaluate the state of intracellular lysosomes. Western blot was employed to detect the expression of autophagy-related proteins LC3Ⅱ, P62, and lysosomal cathepsin D(CTSD). The SuperPred online tool was used to predict the target proteins that bound to RuC, and molecular docking analysis was conducted to identify the interaction sites between RuC and CTSD. The drug affinity responsive target stability(DARTS) assay was performed to detect the direct binding interaction between RuC and CTSD. The results showed that RuC significantly inhibited the proliferation and colony formation of GC cells at low concentrations, with 24-hour half-maximal inhibitory concentrations(IC_(50)) of 3.422 and 2.697 μmol·L~(-1) for AGS and MGC803 cells, respectively. After 24 hours of treatment with RuC at concentrations of 1, 2, and 3 μmol·L~(-1), the colony formation rates for AGS cells were 61.0%±1.5%, 28.0%±0.5%, and 18.2%±0.5%, respectively, while the rates for MGC803 cells were 56.0%±0.5%, 23.3%±1.0%, and 11.8%±1.0%, all of which were significantly reduced. Transmission electron microscopy revealed that RuC promoted an increase in autophagosome formation in GC cells. Immunofluorescence detection showed that LC3 fluorescent foci of GC cells increased with the increase in RuC dose. RuC up-regulated the expression of autophagy-related proteins LC3Ⅱ and P62 in GC cells. Acridine orange staining indicated that RuC altered the acidic environment of lysosomes. SuperPred online prediction identified CTSD as a potential target protein of RuC. Western blot analysis revealed that RuC induced the up-regulation of the inactive precursor of CTSD in GC cells. CTSD activity assays indicated that RuC reduced the activity of CTSD. Molecular docking simulations found that RuC bound to the substrate-binding region of CTSD, forming hydrogen bonds with the Tyr205 and Asp231 residues. Microscale thermophoresis and DARTS assays further confirmed that RuC directly bound to CTSD. In summary, RuC inhibits lysosomal activity by targeting and down-regulating the expression of CTSD, thereby inducing autophagosome accumulation in GC cells.
Humans ; Stomach Neoplasms/enzymology* ; Cathepsin D/chemistry* ; Cell Line, Tumor ; Molecular Docking Simulation ; Cell Proliferation/drug effects* ; Autophagosomes/metabolism* ; Autophagy/drug effects*

The aim of the study was to investigate the anti-proliferation and apoptosis-inducing effects of S1, a novel tetrandrine derivative, in human gastric cancer BGC-823 cells and explore the possible mechanism of action. The anti-proliferative activity was determined by MTT assay; the induction of cell cycle arrest and apoptosis were detected by flow cytometry. Quantitative real time RT-PCR and Western blotting were used to evaluate the mRNA and protein expression levels in mitochondrial pathway. S1 significantly reduced cell viability and induced a G2/M phase arrest and apoptosis in dose- and time-dependent manner. Further studies showed that S1 increased mRNA and protein expression of Bax and the Bax/Bcl-2 ratio. Moreover, S1 decreased the protein expression of procaspase-9 and procaspase-3, suggesting that the induction of apoptosis may be related to the alteration of the ratio of Bax/Bcl-2 and the activation of caspases. These findings suggested that S1 merits further investigation as a novel therapeutic agent for the treatment of human gastric cancer.
Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Benzylisoquinolines ; chemistry ; pharmacology ; Caspase 3 ; genetics ; metabolism ; Caspase 9 ; genetics ; metabolism ; Cell Cycle Checkpoints ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Humans ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; Stomach Neoplasms ; drug therapy ; enzymology ; genetics ; physiopathology ; bcl-2-Associated X Protein ; genetics ; metabolism

Although medical treatment has been shown to improve quality of life and prolong survival, no significant progress has been made in the treatment of advanced gastric cancer (AGC) within the last two decades. Thus, the optimum standard first-line chemotherapy regimen for AGC remains debatable, and most responses to chemotherapy are partial and of short duration; the median survival is approximately 7 to 11 months, and survival at 2 years is exceptionally > 10%. Recently, remarkable progress in tumor biology has led to the development of new agents that target critical aspects of oncogenic pathways. For AGC, many molecular targeting agents have been evaluated in international randomized studies, and trastuzumab, an anti-HER-2 monoclonal antibody, has shown antitumor activity against HER-2-positive AGC. However, this benefit is limited to only ~20% of patients with AGC (patients with HER-2-positive AGC). Therefore, there remains a critical need for both the development of more effective agents and the identification of molecular predictive and prognostic markers to select those patients who will benefit most from specific chemotherapeutic regimens and targeted therapies.
Angiogenesis Inhibitors/therapeutic use ; Animals ; Antineoplastic Agents/*therapeutic use ; Humans ; *Molecular Targeted Therapy ; Protein Kinase Inhibitors/therapeutic use ; Receptor, Epidermal Growth Factor/antagonists & inhibitors/metabolism ; Receptor, erbB-2/antagonists & inhibitors/metabolism ; Signal Transduction/drug effects ; Stomach Neoplasms/*drug therapy/enzymology/genetics/pathology ; Treatment Outcome

OBJECTIVETo study the effects of lysyl oxidase (LOX) on the migration and adhesion of the human gastric cancer cell line HGC-27 cells in vitro.

METHODSThe human gastric cancer cell line HGC-27 cells were cultured in vitro, and treated with different concentration of β-aminopropionitrile (BAPN). The ability of migration was assessed by wound-healing assay. The ability of adhesion was detected by homogenous and heterogeneous adhesion experiments.

RESULTSCompared that with 0 mmol/L BAPN, the ability of migration of the cells after treatment with 0.2 mmol/L BAPN was descended at 8, 24, 32 and 48 h; the number of cells with homogeneous adhesion was increased from (6.97 ± 0.07) × 10(3)/ml to (7.78 ± 0.11) × 10(3)/ml; and the number of cells with heterogeneous adhesion was decreased from (8.98 ± 0.15) × 10(3)/ml to (8.35 ± 0.10) × 10(3)/ml, both < 0.05. Compared with that of cells treated with 0 mmol/L and 0.2 mmol/L BAPN, the migration ability of cells after treatment with 0.3 mmol/L BAPN was descended at 8, 24, 32 and 48 h; the number of cells with homogeneous adhesion was raised to (8.02 ± 0.11) × 10(3)/ml and the number of cells with heterogeneous adhesion was down to (7.93 ± 0.07) × 10(3)/ml (P < 0.05).

CONCLUSIONLOX may promote the metastasis of cancer cells by enhancing invasion, increasing heterogeneous adhesion and decreasing homogeneous adhesion.

Aminopropionitrile ; administration & dosage ; pharmacology ; Cell Adhesion ; drug effects ; Cell Line, Tumor ; Cell Movement ; drug effects ; Dose-Response Relationship, Drug ; Humans ; Neoplasm Invasiveness ; Protein-Lysine 6-Oxidase ; antagonists & inhibitors ; metabolism ; physiology ; Stomach Neoplasms ; enzymology ; pathology

Rebamipide a gastroprotective drug, is clinically used for the treatment of gastric ulcers and gastritis, but its actions on gastric cancer are not clearly understood. Phospholipase D (PLD) is overexpressed in various types of cancer tissues and has been implicated as a critical factor in inflammation and carcinogenesis. However, whether rebamipide is involved in the regulation of PLD in gastric cancer cells is not known. In this study, we showed that rebamipide significantly suppressed the expression of both PLD1 and PLD2 at a transcriptional level in AGS and MKN-1 gastric cancer cells. Downregulation of PLD expression by rebamipide inhibited its enzymatic activity. In addition, rebamipide inhibited the transactivation of nuclear factor kappa B (NFkappaB), which increased PLD1 expression. Rebamipide or PLD knockdown significantly suppressed the expression of genes involved in inflammation and proliferation and inhibited the proliferation of gastric cancer cells. In conclusion, rebamipide-induced downregulation of PLD may contribute to the inhibition of inflammation and proliferation in gastric cancer.
Alanine/*analogs & derivatives/pharmacology ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Down-Regulation/*drug effects ; Gene Expression Regulation, Neoplastic/*drug effects ; Humans ; Inflammation/*enzymology/genetics/pathology ; Isoenzymes/genetics/metabolism ; NF-kappa B/metabolism ; Phospholipase D/*genetics/metabolism ; Promoter Regions, Genetic/genetics ; Quinolones/*pharmacology ; Stomach Neoplasms/*enzymology/genetics/*pathology ; Transcription, Genetic/drug effects

BACKGROUND: Up-regulation of the hepatocyte growth factor (HGF), its transmembrane tyrosine kinase receptor (c-Met), and urokinase type plasminogen activator (uPA), is associated with the development and metastasis of various types of cancers. However, the mechanisms by which HGF/c-Met signaling mediates cancer progression and metastasis are unclear. METHODS: We investigated the roles of HGF/c-Met in tumor progression and metastasis in NUGC-3 and MKN-28 stomach cancer cell lines. RESULTS: Treatment with HGF increased c-Met phosphorylation in a dose-dependent manner, as well as increasing cell proliferation. HGF treatment also increased the protein level and the activity of uPA in NUGC-3 and MKN-28 cells. A monoclonal antibody against human uPA receptor (uPAR), mAb 3936, inhibited HGF-mediated tumor cell invasion in a dose-dependent manner. Down-regulation of uPA using uPA-shRNA induced a decrease in in vitro cell invasion in NUGC-3 cells. CONCLUSIONS: These results suggest that NUGC-3 and MKN-28 cells express functional c-Met, which may provide a therapeutic target for interfering with metastases of cancer cells by inhibiting uPA and uPAR-mediated proteolysis.
Urinary Plasminogen Activator/antagonists & inhibitors/*metabolism ; Stomach Neoplasms/drug therapy/*enzymology ; Signal Transduction/*drug effects ; Receptors, Growth Factor/*drug effects ; Receptor Protein-Tyrosine Kinases/*drug effects ; Proto-Oncogene Proteins c-met/*drug effects ; Neoplasm Metastasis ; Humans ; Hepatocyte Growth Factor/*metabolism ; Disease Progression ; Adenocarcinoma/drug therapy/enzymology

The regulatory mechanisms for the proliferation and the particular invasive phenotypes of stomach cancers are not still fully understood. Up-regulations of hepatocytes growth factor (HGF), its receptor (c-Met), and urokinase-type plasminogen activator (uPA) are correlated with the development and metastasis of cancers. In order to investigate roles of HGF/c-Met signaling in tumor progression and metastasis in stomach cancers, we determined effects of a specific MEK1 inhibitor (PD098059) and a p38 kinase inhibitor (SB203580) on HGF-mediated cell proliferation and uPA expression in stomach cancer cell lines (NUGC-3 and MKN-28). HGF treatment induced the phosphorylations of ERK and p38 kinase in time- and dose- dependent manners. Pre-treatment with PD098059 reduced HGF-mediated cell proliferation and uPA secretion. In contrast, SB203580 pre-treatment enhanced cell proliferation and uPA secretion due to induction of ERK phosphorylation. Stable expression of dominant negative-MEK1 in NUGC-3 cells showed a decrease in HGF-mediated uPA secretion. These results suggest that interaction of a MEK/ERK and a p38 kinase might play an important role in proliferation and invasiveness of stomach cancer cells.
Cell Line, Tumor ; Cell Proliferation/drug effects ; Culture Media, Serum-Free ; Dose-Response Relationship, Drug ; Enzyme Activation/drug effects ; Enzyme Inhibitors/pharmacology ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Flavonoids/pharmacology ; Hepatocyte Growth Factor/*pharmacology ; Humans ; Imidazoles/pharmacology ; Kinetics ; MAP Kinase Kinase 1/metabolism ; Mitogen-Activated Protein Kinases/antagonists & inhibitors/*metabolism ; Neoplasm Metastasis ; Phosphorylation/drug effects ; Pyridines/pharmacology ; Research Support, Non-U.S. Gov't ; Stomach Neoplasms/*enzymology/*pathology ; Urinary Plasminogen Activator/*secretion ; p38 Mitogen-Activated Protein Kinases/metabolism

OBJECTIVETo observe the effect of polo like kinase 1 (plk1) gene depletion on the growth of gastric cancer cell line-MKN45 cells in vitro and vivo and discuss the feasibility and effectiveness of arranging plk1 as gene therapeutic target for gastric cancer.

METHODSThe plk1 expression of MKN45 cells was inhibited by RNA interference (RNAi). The plk1 mRNA and protein level were measured by real-time quantitative PCR and western blotting, and the change of cell cycle distribution and apoptosis rate were detected by flow-cytometry, and the MKN45 cells proliferation was measured by MTT method. MKN45 cells treated with plk1 siRNA were transplanted subcutaneously in nude mice and their tumorgenesis ability were observed, the plk1 protein levels of the samples from nude mice in different groups were compared.

RESULTSAfter treatment with plk1 siRNA, plk1 mRNA and protein level decreased obviously in certain time, more MKN45 cells accumulated at G(2)/M (P < 0.05). Apoptosis rate of MKN45 cells treated with plk1 siRNA was higher than that of control cells at 48 h and 72 h (P < 0.05), and MKN45 cells proliferated slowly than control groups (P < 0.05), while the tumorgenesis ability obviously decreased, but the plk1 protein levels of the samples from nude mice in different groups were not different.

CONCLUSIONSsiRNA targeting plk1 can inhibit the proliferation of MKN45 cells in vitro and vivo. Plk1 may be a novel therapeutic target for gastric cancer.

Animals ; Apoptosis ; drug effects ; Cell Cycle Proteins ; drug effects ; genetics ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Male ; Mice ; Mice, Nude ; Protein-Serine-Threonine Kinases ; drug effects ; genetics ; Proto-Oncogene Proteins ; drug effects ; genetics ; RNA Interference ; RNA, Small Interfering ; genetics ; pharmacology ; Stomach Neoplasms ; drug therapy ; enzymology ; pathology ; Transfection

OBJECTIVETo observe the effect of polo-like kinase 1 (PLK1) gene depletion on mitosis phenotype and elucidate its vital role in gastric cancer cell line (MKN45) mitosis.

METHODSThe PLK1 expression in MKN45 cells was blocked by RNA interference (RNAi), the expression level of PLK1 mRNA and protein were measured by real-time quantitative PCR and Western blot, respectively. The morphological change of microtubules and mitosis phenotype in MKN45 cells were observed by immunofluorescence staining and laser confocal microscopy, the morphological changes of cells were observed by reverse microscopy, the variation of cell cycle distribution was detected by flow-cytometry.

RESULTSAfter RNAi targeting PLK1, PLK1 mRNA and protein level decreased obviously, the cell microtubules became obscure and lost cohesiveness, the mitosis phenotype also varied substantially (P < 0.05), more gastric cancer cells became rounded and showed G(2) phase cell DNA content (P < 0.05).

CONCLUSIONPLK1 gene plays a key role in mitosis and its inhibition can lead to mitosis arrest in MKN45 cells.

Adenocarcinoma ; enzymology ; metabolism ; pathology ; Cell Cycle Proteins ; biosynthesis ; genetics ; Cell Line, Tumor ; G2 Phase ; drug effects ; Humans ; Mitosis ; drug effects ; Protein-Serine-Threonine Kinases ; biosynthesis ; genetics ; Proto-Oncogene Proteins ; biosynthesis ; genetics ; RNA Interference ; RNA, Messenger ; biosynthesis ; genetics ; RNA, Small Interfering ; genetics ; pharmacology ; Stomach Neoplasms ; enzymology ; metabolism ; pathology ; Transfection

OBJECTIVETo observe the effect of drug-containing serum of Chinese traditional herbal decoction Weikangning (WKN) on growth of gastric cancer cell, expression of vascular endothelial growth factor (VEGF) and its receptors including KDR and Flt-1.

METHODSA total of 120 male Wistar rats were given high, medium and low-dose WKN. After the drug-containing serum was prepared, the gastric cancer cells MGC-803 of different dose groups were cultured with the drug-containing serum, respectively. The gastric cell growth was observed by using light microscope and flow cytometer,the expression of VEGF and its receptor Flt-1 was detected with SABC immunohistochemistry method and the mRNA expression levels of VEGF and its receptors including KDR and Flt-1 of different groups were detected with reverse transcription-polymerase chain reaction (RT-PCR), respectively.

RESULTSThe gastric cancer cell growth and cell cycle of the three medicated groups were significantly improved as compared with those of the control group (P <0. 01) ,the proportion of cells in G0 - G1 phase was increased,while the cells in S phase were decreased. It was shown that the apoptotic rates were increased in the medicated groups in a dose-dependent manner. The gray scales ( microm(2) ) of VEGF and Flt-1 in high, medium and low dose groups was 182. 44 +/-0. 54,178. 65 +/-0. 56,174. 80 +/-0. 81 and 168. 51 +/- 0. 81,162. 01 +/-0. 52,148. 20 +/-0. 69, respectively vs 147.82 +/-0. 15(P <0.01) and 144.31 +/-0.71 (P <0.01) in the control group. The mRNA expression of VEGF and its receptors significantly decreased in gastric cancer cells after cultured with WKN contained serum (P < 0. 01 ).

CONCLUSIONWKN has inhibitory effects on gastric cancer cell growth and mRNA expression of VEGF as well as its receptors KDR and Flt-1.

Animals ; Antineoplastic Agents, Phytogenic ; pharmacology ; therapeutic use ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Male ; Rats ; Rats, Wistar ; Stomach Neoplasms ; drug therapy ; enzymology ; metabolism ; Vascular Endothelial Growth Factor A ; metabolism ; Vascular Endothelial Growth Factor Receptor-1 ; metabolism ; Vascular Endothelial Growth Factor Receptor-2 ; metabolism