Human Gastric Cancer SGC-7901 Cells Research Articles

Raltitrexed induces mitochondrial‑mediated apoptosis in SGC7901 human gastric cancer cells.

Raltitrexed is a specific inhibitor of thymidylate synthase (TS), which has been considered as a potential chemotherapeutic agent for the treatment of advanced gastric cancer. In the present study, the apoptosis mechanisms of raltitrexed in SGC7901 human gastric cancer cells were investigated. The cytotoxic activity of raltitrexed on SGC7901 cells was determined by cell counting kit-8 (CCK-8) assay. The CCK‑8 assay indicated that raltitrexed inhibits SGC7901 cell growth in a dose- and time-dependent manner. The morphological changes were observed by fluorescent microscopy, and characteristic morphological changes, including nuclear shrinkage and apoptotic bodies, were observed following Hoechst 33258 staining. The effects on apoptosis, cell cycle, mitochondrial transmembrane potential and reactive oxygen species (ROS) were measured by flow cytometry. The analysis revealed that raltitrexed exerted a growth inhibitory effect by inducing time-dependent apoptosis and cell-cycle arrest at the G0/G1 phase. In addition, a compromised mitochondrial membrane potential and overproduction of ROS demonstrated the involvement of the mitochondrial signaling pathway. Raltitrexed‑induced caspase‑3‑dependent apoptosis was identified using a caspase-3 activity assay and pretreatment with the caspase-3 inhibitor, Ac‑DEVD‑CHO (sequence, Ac-Asp-Glu-Val-Asp-CHO). The activity of caspase-3 was analyzed with a spectrometer. The protein expression levels of Bax, Bcl-2, cytochrome c, cleaved caspase-3 and TS were examined by western blot and the mRNA expression level of TS was detected by quantitative polymerase chain reaction. The analysis revealed that the protein levels of Bax, cytochrome c and cleaved caspase‑3 were significantly increased by raltitrexed, while Bcl-2 expression levels were reduced. Furthermore, raltitrexed increased the expression of the TS protein and mRNA in a time‑dependent manner. These results indicate that raltitrexed induces the apoptosis of SGC7901 cells through the caspase‑3‑dependent mitochondrial signaling pathway and upregulates the expression of the TS protein and mRNA.

Anti-apoptotic and apoptotic pathway analysis of arsenic trioxide‑induced apoptosis in human gastric cancer SGC-7901 cells.

The present study aimed to investigate the effect of arsenic trioxide (As2O3) on human gastric cancer SGC-7901 cells. SGC-7901 cells were treated with different concentrations of As2O3 in the cell growth media for 24, 48 and 72h, and the growth rates were determined by WST-1 cell proliferation assays. Analyses of nuclear morphological changes were performed with DAPI fluorescence staining. Cell apoptosis rates as assessed by flow cytometry were determined after cells were grown in media for 48h containing different As2O3 concentrations. The protein expression patterns of the apoptosis factors, Bax, Fas and caspase-8, and anti-apoptosis factors, Akt, p-Akt, mTOR and p-mTOR, were evaluated by western blot analysis following treatment of the cells with different As2O3 concentrations in the cell growth media for 48h. As a result, As2O3 inhibited the growth of human gastric cancer SGC-7901 cells in concentrations >5µmol/l for longer than 24h. Flow cytometric analysis revealed that the apoptosis of SGC-7901 cells occurred in an As2O3 concentration-dependent manner after 48h (P<0.001). Expression levels of Bax, Fas and caspase-8 were increased, whereas expression levels of Akt, p-Akt, mTOR and p-mTOR were decreased in the SGC-7901 cells after a 48-h incubation with different As2O3 concentrations. In conclusion, As2O3 induced human gastric cancer SGC-7901 cell apoptosis in a time- and concentration dependent manner by inhibiting the activity of anti-apoptosis-related factors.

Effects of damage-regulated autophagy regulator gene on the SGC7901 human gastric cancer cell line.

The aim of this study was to investigate the effects of the adenoviral-mediated autophagy gene, damage-regulated autophagy regulator (DRAM), on the proliferation and autophagy of SGC7901 human gastric cancer cells in vitro. The recombinant adenovirus, AdMax-pDC315-DRAM-EGFP, working as a virus vector of DRAM was constructed and infected into the SGC7901 human gastric cancer cell line. The MTT assay was used to determine the growth rate of the SGC7901 cells. Activation of autophagy was monitored with monodansylcadaverin (MDC) staining following AdMax-pDC315-DRAM-EGFP treatment. Immunofluorescent staining was used to examine the expression of microtubule-associated protein 1 light chain 3 (LC3), and western blotting was used to examine the expression of apoptosis- and autophagy-associated proteins, including Beclin1, p53, p21 and B-cell lymphoma 2 (Bcl-2), in the culture supernatant. The viability of the SGC7901 cells was activated by AdMax-pDC315-DRAM-EGFP treatment. The AdMax-pDC315-DRAM-EGFP-treated cells exhibited positive LC3 expression detected by immunoreactivity and MDC staining. Inductions in the expression of the apoptosis-related proteins, p53 and p21, and the autophagic protein, Beclin1, were revealed by western blot analysis. By contrast, downregulation of the apoptosis-related protein, Bcl-2, following AdMax-pDC315-DRAM-EGFP treatment was identified. In conclusion, the present study demonstrated that AdMax-pDC315-DRAM-EGFP treatment resulted in upregulation of the level of autophagy and induction of cell proliferation in the SGC7901 human gastric cancer cell line in vitro.

Celecoxib regulates apoptosis and autophagy via the PI3K/Akt signaling pathway in SGC-7901 gastric cancer cells

Gastric cancer, one of the most common malignancies worldwide, typically has a poor prognosis and poor survival rate. Previous studies have investigated the chemopreventive effect of celecoxib. In the present study, the SGC-7901 human gastric cancer cell line was utilized to examine the chemopreventive mechanisms of celecoxib. The inhibition of cell proliferation was determined using MTT assay, cell apoptosis was monitored by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) and flow cytometry, and cell ultrastructural changes were assessed via transmission electron microscopy. The mRNA expression of Akt, caspase-8 and -9 was examined using quantitative reverse-transcription-polymerase chain reaction (qRT-PCR) and p-Akt, procaspase-8 and -9 were analyzed via western blotting. The results showed that celecoxib inhibited the proliferation of SGC-7901 cells in a time- and dose-dependent manner. Additionally, celecoxib induced apoptosis as substantiated by typical apoptotic bodies, autophagosomes and an increased apoptotic rate. It was found that following celecoxib treatment, Akt mRNA expression was not significantly altered, and that p-Akt protein levels decreased in a time- and dose-dependent manner. Additionally, caspase-8 and -9 mRNA expression was significantly increased, while procaspase-8 and -9 protein expression decreased relative to the time- and dose-dependent effects. These results demonstrated that celecoxib induced apoptosis and autophagy of gastric cancer cells in vitro through the PI3K/Akt signaling pathway. Moreover, our findings suggested that celecoxib induces apoptosis in gastric cancer cells through the mitochondrial and death receptor pathways, providing additional understanding regarding the chemopreventive behaviors of celecoxib and its uses in cancer therapy.

Autophagy promotes the survival and development of tumors by participating in the formation of vasculogenic mimicry

Autophagy, type II nonapoptotic cell death, is characterized by the formation of double-membrane cytosolic vesicles, the recycling of damaged cytoplasmic content and the maintenance of genetic stability and cellular homeostasis, under conditions of nutrient starvation, hypoxia or other therapeutic stress. In the present study, we comprehensively discuss its indispensable role in the formation of vasculogenic mimicry (VM), capillary-like tubes consisting of cells from the tumor itself instead of vascular endothelial cells. A short hairpin RNA (shRNA) to silence beclin1, an autophagy-specific gene, was designed, synthesized and subcloned into a vector to establish an autophagy-inhibited group, while negative control and blank groups were also established using human gastric cancer SGC7901 cells. We then investigated the VM formation ability of these three groups and detected changes in gene expression, survival and invasion correspondingly. The results showed that, following the formation of VM, the expression of pluripotent genes (c-myc, oct3/4, sox-2) and autophagy-specific genes (beclin1, ATG5, ATG7) were increased, which was consistent with the negative control cell group. However, the autophagy inhibited cell group did not form VM, and the expression of pluripotent genes was decreased. Moreover, the inhibition of autophagy reduced the survival and invasive ability of cancer cells under stress. We suggest that during the formation of VM, the stable expression of genes and the maintenance of survival and invasion are indispensable. Under a stress environment, autophagy is activated to maintain the stability of gene expression, maintain survival and invasive ability and facilitate VM formation, which can provide nutrients, oxygen and invasive channels to tumors, facilitating survival and development under stress.

Apoptosis of human gastric cancer SGC-7901 cells induced by podophyllotoxin.

Numerous studies have demonstrated that podophyllotoxin and its derivatives exhibit antitumor effects. The aim of the present study was to investigate SGC-7901 cell apoptosis and the underlying mechanism induced by podophyllotoxin. SGC-7901 cells were treated with varying concentrations of podophyllotoxin. MTT assays and flow cytometry were used to evaluate the effects of podophyllotoxin on the proliferation and apoptosis of SGC-7901 cells, while fluorescence inverted microscopy was used to observe the morphology of SGC-7901 cells that had been dyed with Hoechst 33258. In addition, laser scanning confocal microscopy was used to analyze the mitochondrial membrane potential (MMP) of SGC-7901 cells dyed with Rhodamine 123. Western blotting was performed to analyze the expression levels of cytochrome c (cyt-c), caspase-9 and caspase-3 in the SGC-7901 cells. The results indicated that podophyllotoxin was capable of inhibiting growth and inducing the apoptosis of SGC-7901 cells in a dose-dependent manner, causing cell cycle arrest at the G2/M phase. After 48 h of treatment, the apoptotic morphology of SGC-7901 cells was clear, exhibiting cell protuberance, concentrated cytoplasms and apoptotic bodies. Following 24 h of treatment, the MMP of the SGC-7901 cells decreased. In addition, after 48 h, the expression of cyt-c was shown to be upregulated, while the expression levels of pro-caspase-9 and pro-caspase-3 in the SGC-7901 cells were shown to be downregulated. In conclusion, apoptosis can be induced in SGC-7901 cells by podophyllotoxin, potentially via a mitochondrial pathway, indicating that podophyllotoxin may be a potent agent for cancer treatment.

Inhibiting Enhancer of Zeste Homolog 2 Promotes Cellular Senescence in Gastric Cancer Cells SGC-7901 by Activation of p21 and p16

Cellular senescence, which can be defined as a stress response preventing the propagation of cells that have accumulated potentially oncogenic alterations, is invariably associated with a permanent cell cycle arrest. Enhancer of zeste homolog 2 (EZH2) as a member of polycomb group proteins and its targets include cell cycle regulatory proteins, which govern cell cycle progression and cellular senescence. In this study, we report that EZH2 depletion promotes the senescent state in human gastric cancer cells SGC-7901. We found that EZH2 functionally suppressed the senescent state in human gastric cancer cells SGC-7901. EZH2 depletion inhibited cell proliferation, arrested cellular cycle, restored features of a cellular senescence phenotype, and promoted doxorubicin-induced senescence. To prove that EZH2 expression contributes substantially to the change of key cell cycle regulators, we showed that p21 and p16 were activated to a certain extent upon EZH2 depletion and activation of p21 was in a p53-independent manner. Taken together, our data suggest that EZH2 depletion promotes the progression of senescence by mediating the activation of tumor suppressor genes p21 and p16, and could serve as a potential epigenetic target for gastric cancer therapy.

Flap endonuclease 1 is a promising candidate biomarker in gastric cancer and is involved in cell proliferation and apoptosis

As a DNA repair protein, flap endonuclease 1 (FEN1), a structure-specific 5' nuclease, plays pivotal roles in the maturation of Okazaki fragments, long-patch base excision repair, restarting of stalled replication forks and telomere maintenance. FEN1 possesses 5' endonuclease, 5' exonuclease and gap-endonuclease activities, which render it an essential node in maintaining genome fidelity. The aim of this study was to investigate the association between the expression level of FEN1 and gastric cancer and to explore the role of FEN1 in carcinogenesis and the progression of gastric cancer. The mRNA and protein expression of FEN1 in 42 matched pairs of human gastric tumor tissues and corresponding normal tissues were measured by semiquantitative reverse transcription-PCR and immunohistochemical staining. FEN1 expression was downregulated in the SGC-7901 gastric cancer cells following transfection with siRNA targeting the FEN1 gene. Western blot analysis was used to evaluate the protein expression of FEN1 in SGC-7901 human gastric cancer cells in order to verify the transfection efficiency of FEN1 siRNA. Moreover, cell proliferation was analyzed by MTS assay. The apoptosis of the cells was determined by flow cytometry. Our results revealed that FEN1 was overexpressed in gastric cancer in comparison to the corresponding normal gastric tissues (P<0.01). We further confirmed that FEN1 expression has a positive correlation with the degree of differentiation (P=0.027), lymphatic metastasis (P=0.001), tumor size (P=0.026) and TNM stage (P=0.020) of gastric cancer. A high FEN1 expression in SGC-7901 cells can be effectively downregulated by siRNA constructed to target the FEN1 gene. Moreover, the inhibition of FEN1 expression suppressed the proliferation and induced the apoptosis of SGC-7901 cells. Taken together, our results indicate that FEN1 may be a promising biomarker for the diagnosis of gastric cancer and individual therapy.

Unprecedented High‐Nuclear Transition‐Metal‐Cluster‐Substituted Heteropolyoxoniobates: Synthesis by {V8} Ring Insertion into the POM Matrix and Antitumor Activities

Reactions of hexaniobate with vanadate in the presence of Ni(2+) , Zn(2+) , or Cu(2+) have furnished three high-nuclear vanadium cluster-substituted heteropolyoxoniobates (HPNs): {Ni(en)3 }5 H{V(V) Nb8 V(IV) 8 O44 }⋅9 H2 O (1), (H2 en)Na2 [{Zn(en)2 (Hen)}{Zn(en)2 (H2 O)}2 {PNb8 V(IV) 8 O44 }]⋅11 H2 O (2), and Na{Cu(en)2 }3 {[Cu(en)2 ]2 [PNb8 V(IV) 8 O44 ]}⋅11 H2 O (3) (en=1,2-diaminoethane). Their structures have been determined and characterized by single-crystal X-ray diffraction analysis, thermogravimetric analysis (TGA), and elemental analysis. Structural analysis has revealed that compounds 1-3 contain similar {V8 }-substituted [X(V) Nb8 V(IV) 8 O44 ](11-) (X=P, V) clusters, obtained by inserting a {V8 } ring into tetravacant HPN [XNb8 O36 ](27-) . To the best of our knowledge, compounds 1-3 represent the first high-nuclear vanadium cluster-substituted HPNs, and compound 1 is the largest vanadoniobate cluster yet obtained in HPN chemistry. Nickel and zinc cations have been introduced into HPNs for the first time, which might promise a more diverse set of structures in this family. Antitumor studies have indicated that compounds 1 and 2 exhibit high activity against human gastric cancer SGC-7901 cells, SC-1680 cells, and MG-63 cells.

Effect of antisense miR-224 on gastric cancer cell proliferation and apoptosis

To observe the effects of miR-224 antisense oligonucleotide (ASO) on the proliferation and apoptosis of gastric cancer cells in vitro and vivo. The expression of miR-224 in the cancer tissues and their adjacent tissues in 120 gastric cancer patients were detected by real-time quantitative PCR. The biological effects of miR-224 ASO on human gastric cancer SGC7901 cells was assessed by MTT assay, clone formation assay, flow cytometry and in vivo experiment in nude mice. Compared with the control group (0.50 ± 0.07), miR-224 ASO significantly reduced the miR-224 mRNA expression in the cancer patients (0.09 ± 0.01, P < 0.05). MTT assay results showed that the survival rate of gastric cells at 24 h, 48 h and 72 h was 53.6%, 59.1% and 70.1% in the miR-224 ASO group, and 12.3%, 17.4% and 24.7%, respectively, in the control group (P < 0.05 for all). Clone formation assay revealed that clone formation rate in the miR-224 ASO group was (5.33 ± 0.74)%, significantly lower than the (33.33 ± 8.38)% in the control group (P < 0.05). Flow cytometry indicated that the apoptotic index was (15.68 ± 1.46)% in the miR-224 ASO group and (3.36 ± 0.88)% in the control group (P < 0.01). In addition, the expressions of Bcl2 mRNA and protein were 1.05 ± 0.04 and 0.21 ± 0.03 in the miR-224 ASO group, significantly lower than that in the control group (4.87 ± 0.96 and 0.88 ± 0.09, P < 0.01). The in vivo study further showed that the tumor volume in the experimental group is significantly smaller than that in the control group (P = 0.01). MiR-224 is overexpressed in human gastric cancer. Reducing the expression of miR-224 can effectively inhibit the growth and promote apoptosis of gastric cancer cells. miR-224 may become a new target for the regulation of gene expression in gastric cancer.

Inhibitory Effects of Water Caltrop Pericarps on the Growth of Human Gastric Cancer Cells In Vitro

Water caltrop is a popular traditional vegetable in China, and its pericarps are always wasted. In the present work reported here, pericarps from three different Chinese water caltrop cultivars were collected and extracted using 70% methanol and hot water. All the extracts contained significant amounts of polyphenols (183.7-201.7 mg GAE/g), flavonoids (34.3-54.6 mg RE/g) and saponins (23.2- 36.3 mg GRE/g). These extracts exhibited strong antioxidant capacity as assessed by DPPH, ABTS and FRAP methods. High correlations were found in DPPH, ABTS and polyphenols, FRAP and saponins. All the three extracts inhibited proliferation of SGC7901 human gastric cancer cells and HepG2 human hepatocarcinoma cells in a dose dependent manner without detectable cytotoxicity on HUVEC normal cells. Flow cytometry showed that apoptosis of SGC7901 and HepG2 cells was induced by water caltrop extracts while HUVEC cells were relatively resistant to apoptosis. Hot water extracts showed similar bioactivities as methanol extracts, which indicated that hot water could be used to extract bioactive compounds instead of organic solvents. These results suggest that water caltrop pericarps could be explored for their potential as anti-cancer drugs in future studies.

Growth inhibition and induction of apoptosis in SGC-7901 human gastric cancer cells by evodiamine

Evodiamine is one of the major bioactive compounds isolated and purified from the fruit of Fructus Evodiae. Numerous studies have indicated that evodiamine exhibits activity against human tumor cells. In the present study, the effect of evodiamine on the proliferation and apoptosis of SGC-7901 human gastric cancer cells and the correlative mechanisms were investigated. This may provide further experimental evidence of the pharmacological actions of evodiamine and a strategy for its use as a novel chemotherapeutic drug. Following treatment with evodiamine, the typical morphological changes of apoptosis were observed in human SGC-7901 cells. Cell cycle analysis indicated that evodiamine induced G2/M phase arrest in SGC-7901 cells and flow cytometry revealed that evodiamine induced apoptosis. Analysis of the enzymatic activity demonstrated that evodiamine increased the activity of caspase-3, -8 and -9 in SGC-7901 cells. The protein expression of caspase-3, -8 and -9 and Bax increased, and the expression of Bcl-2 decreased following treatment with evodiamine. These results suggest that evodiamine is able to inhibit the proliferation of SGC-7901 cells by inhibiting the cell cycle at G2/M phase and inducing apoptosis in SGC-7901 cells by activating caspase-3, -8 and -9, and altering the expression of caspase-3, Bax and Bcl-2.

Inactivation of Akt by arsenic trioxide induces cell death via mitochondrial-mediated apoptotic signaling in SGC-7901 human gastric cancer cells

Arsenic trioxide (As2O3) has been recognized as a potential chemotherapeutic agent, yet the details concerning its mechanism of action in solid cancers remain undetermined. The present study assessed the role of Akt in the cell death induced by As2O3. The MTT assay showed that As2O3 suppressed the proliferation of SGC-7901 cells in a dose- and time-dependent manner. Characteristic apoptotic changes were observed in the As2O3‑treated cells by Hoechst33342 staining, and FACS analysis showed that As2O3 caused dose-dependent apoptotic cell death. As2O3 activated caspase-3 and-9, and PARP cleavage in a dose-dependent manner. Compromised mitochondrial membrane potential and an increased protein level of Bax indicated involvement of mitochondia. As2O3 decreased the levels of p-Akt(Ser473), p-Akt(Thr308) and p-GSK-3β (Ser9), suggesting that As2O3 inactivated Akt kinase. In addition, LY294002 (a PI3 kinase inhibitor) augmented the apoptosis induced by As2O3. These results demonstrated that inhibition of PI3K/Akt signaling was involved in As2O3-induced apoptosis of gastric cancer SGC-7901 cells.

Antibacterial Activities of Six Medicinal Plants Used Traditionally by Saudi People to Treat Common Diseases

Antibiotic resistance is increasing and dangerous problem resulting in a decrease in the used number and fully active antimicrobial agents available to treat infections with multidrug resistant (MDR) bacteria. Herbal medicines may be an alternative treatment options. This study aimed to evaluate the antibacterial activities of some medicinal plants used traditionally in Saudi Arabia against some pathogenic and MDR bacteria. The antimicrobial activities of water and organic crude extracts were prepared. Out of the 6 plants tested, 5 showed antimicrobial activities against one or more of the tested genera using paper disc diffusion assay. The most active antimicrobial plants were the extract of Azadirachta indica (neem), Zingiber officinale (ginger) Eucalptus globules , Rosmarinus officinalis and Lawsonia inermis with minimal inhibitory concentration (MICs) values ranged from 50-150µg/ml. Lepidium sativium have very weak activity with MIC of ≥200 µg/ml. At 600µg/ml, no toxicity was recorded for all tested extracts except of A. indica extract that showed toxicity (% of mortality ≥50). No antitumor activities for the different plant extracts were recorded against Human gastric cancer SGC-7901 cells. The

4,5-Dihydropyrazole derivatives containing oxygen-bearing heterocycles as potential telomerase inhibitors with anticancer activity

Telomere and telomerase were closely related to the occurrence and development of some cancers. After the key active site of telomerase was identified, to enhance the ability of dihydropyrazole derivatives to inhibit telomerase, we designed a series of novel 4,5-dihydropyrazole derivatives containing heterocyclic oxygen moiety based on previous studies. The telomerase inhibition assay showed that compound 10a displayed the most potent inhibitory activity with an IC50 value of 0.6 μM for telomerase. The antiproliferative assay showed that 10a exhibited high activity against human gastric cancer cell SGC-7901 with an IC50 value of 10.95 ± 0.60 μM. Flow cytometric analysis and western blot results showed that 10a induced both apoptosis and autophagy. A docking simulation showed that 10a could bind well to the active site of telomerase and act as a telomerase inhibitor. The 3D-QSAR model was also built to provide a more pharmacological understanding that could be used to design new agents with more potent telomerase inhibitory activity.

Facile Preparation of Paclitaxel Loaded Silk Fibroin Nanoparticles for Enhanced Antitumor Efficacy by Locoregional Drug Delivery

Non-toxic, safe materials and preparation methods are among the most important factors when designing nanoparticles (NPs) for future clinical application. Here we report a novel and facile method encapsulating anticancer drug paclitaxel (PTX) into silk fibroin (SF), a biocompatible and biodegradable natural polymer, without adding any toxic organic solvents, surfactants or other toxic agents. The paclitaxel loaded silk fibroin nanoparticles (PTX-SF-NPs) with a diameter of 130 nm were formed in an aqueous solution at room temperature by self-assembling of SF protein, which demonstrated mainly silk I conformation in the NPs. In cellular uptake experiments, coumarin-6 loaded SF NPs were taken up efficiently by two human gastric cancer cell lines BGC-823 and SGC-7901. In vitro cytotoxicity studies demonstrated that PTX kept its pharmacological activity when incorporating into PTX-SF-NPs, while SF showed no cytotoxicity to cells. The in vivo antitumor effects of PTX-SF-NPs were evaluated on gastric cancer nude mice exnograft model. We found that locoregional delivery of PTX-SF-NPs demonstrated superior antitumor efficacy by delaying tumor growth and reducing tumor weights compared with systemic administration. Furthermore, the organs of mice in NP treated groups didn't show obvious toxicity, indicating the in vivo safety of SF NPs. These results suggest that SF NPs are promising drug delivery carriers, and locoregional delivery of SF NPs could be a potential future clinical cancer treatment regimen.

S-benzyl-cysteine-mediated Cell Cycle Arrest and Apoptosis Involving Activation of Mitochondrial-dependent Caspase Cascade through the p53 Pathway in Human Gastric Cancer SGC-7901 Cells

S-benzyl-cysteine (SBC) is a structural analog of S-allylcysteine (SAC), which is one of the major water- soluble compounds in aged garlic extract. In this study, anticancer activities and the underlying mechanisms of SBC action were investigated and compared these with those of SAC using human gastric cancer SGC-7901 cells. SBC significantly suppressed the survival rate of SGC-7901 cells in a concentration- and time-dependent manner, and the inhibitory activities of SBC were stronger than those of SAC. Flow cytometry revealed that SBC induced G2-phase arrest and apoptosis in SGC-7901 cells. Typical apoptotic morphological changes were observed by Hoechst 33258 dye assay. SBC-treatment dramatically induced the dissipation of mitochondrial membrane potential (Δψm), and enhanced the enzymatic activities of caspase-9 and caspase-3 whilst hardly affecting caspase-8 activity. Furthermore, Western blotting indicated that SBC-induced apoptosis was accompanied by up-regulation of the expression of p53, Bax and the down-regulation of Bcl-2. Taken together, this study suggested that SBC exerts cytotoxic activity involving activation of mitochondrial-dependent apoptosis through p53 and Bax/Bcl-2 pathways in human gastric cancer SGC-7901 cells.

Induction of Cytotoxicity and Apoptosis in Human Gastric Cancer Cell SGC-7901 by Isovaltrate Acetoxyhydrin Isolated from Patrinia heterophylla Bunge Involves a Mitochondrial Pathway and G2/M Phase Cell Cycle Arrest

Our previous study demonstrated cytotoxicity of a crude extract from Patrinia heterophylla Bunge (PHEB). In the present study, we aimed to investigate the effects of isovaltrate acetoxyhydrin (IA) isolated from PHEB on the gastric cancer cell SGC-7901, in order to explore a potential treatment for gastric cancer. MTT assays were employed to determine the effects of IA on cell vitality and proliferation, with monitoring of cell morphology changes and examination of apoptosis with Annexin V-PI staining. Flow cytometry was used to assess cell cycle progression and mitochondrial membrane potential. The activity of caspase 3, 9 was evaluated by spectrophotometry, and the protein levels of Bax, Bcl2 and Cyclin B1 were analyzed with Western blotting of total proteins extracted from cultured cells. The results demonstrated direct toxicity of IA towards SGC-7901 cells. Evidence of apoptosis included blebbing and chromatin condensation. Annexin V-PI assays revealed early apoptosis, involving rapid depolarization of mitochondrial membranes and activity of caspase 3, 9 signaling pathways. Western blotting showed that Bcl2 and Bax proteins was down- and up-regulated, respectively, and cyclin B1 was up-regulated. Cell cycle analysis further indicated that IA could induce G2/M phase arrest in SGC-7901 cells. In conclusion, we believe that IA induces apoptosis of SGC-7901 cells, therefore providing a potential therapeutic agent for treatment of gastric cancer.

Knockdown of RAGE inhibits growth and invasion of gastric cancer cells

The receptor for advanced glycation end-products (RAGE) is an oncogenic trans-membranous receptor, which is overexpressed in multiple human cancers. However, the role of RAGE in gastric cancer is still elusive. In this study, we investigated the expression and molecular mechanisms of RAGE in gastric cancer cells. Forty cases of gastric cancer and corresponding adjacent non-cancerous tissues (ANCT) were collected, and the expression of RAGE was assessed using immunohistochemistry (IHC) in biopsy samples. Furthermore, RAGE signaling was blocked by constructed recombinant small hairpin RNA lentiviral vector (Lv-shRAGE) used to transfect into human gastric cancer SGC-7901 cells. The expression of AKT, proliferating cell nuclear antigen (PCNA) and matrix metallopeptidase-2 (MMP-2) was detected by Real-time PCR and Western blot assays. Cell proliferative activities and invasive capability were respectively determined by MTT and Transwell assays. Cell apoptosis and cycle distribution were analyzed by flow cytometry. As a consequence, RAGE was found highly expressed in cancer tissues compared with the ANCT (70.0% vs 45.0%, P=0.039), and correlated with lymph node metastases (P=0.026). Knockdown of RAGE reduced cell proliferation and invasion of gastric cancer with decreased expression of AKT, PCNA and MMP-2, and induced cell apoptosis and cycle arrest. Altogether, upregulation of RAGE expression is associated with lymph node metastases of gastric cancer, and blockade of RAGE signaling suppresses growth and invasion of gastric cancer cells through AKT pathway, suggesting that RAGE may represent a potential therapeutic target for this aggressive malignancy.

Enhancement of expression of survivin promoter-driven CD/TK double suicide genes by the nuclear matrix attachment region in transgenic gastric cancer cells

This work aimed to study a novel transgenic expression system of the CD/TK double suicide genes enhanced by the nuclear matrix attachment region (MAR) for gene therapy. The recombinant vector pMS-CD/TK containing the MAR–survivin promoter–CD/TK cassette was developed and transfected into human gastric cancer SGC-7901 cells. Expression of the CD/TK genes was detected by quantitative real-time PCR (qPCR) and Western blot. Cell viability and apoptosis were measured using the methyl thiazolyl tetrazolium (MTT) assay and flow cytometry. When the MAR fragment was inserted into the upstream of the survivin promoter, the qPCR result showed that the expression of the CD/TK genes significantly increased 7.7-fold in the transgenic SGC-7901 cells with plasmid pMS-CD/TK compared with that without MAR. MTT and flow cytometry analyses indicated that treatment with the prodrugs (5-FC+GCV) significantly decreased the cellular survival rate and enhanced the cellular apoptosis in the SGC-7901 cells. The expression of the CD/TK double suicide genes driven by the survivin promoter can be enhanced by the MAR fragment in human gastric cancer cells.