Effects of simulated carbon dioxide and helium peumoperitoneum on proliferation and apoptosis of gastric cancer cells

AIM:To investigate the effects of carbon dioxide (CO2) and helium insufflation administered at different pressures on the growth and apoptosis of cultured human gastric cancer cells. METHODS:The gastric cancer cells MKN-45 were exposed to a CO2 and helium environment maintained at different pressures (0, 5, 10 and 15 mmHg). The cells were exposed to simulated pneumoperitoneum environment for 4 h, and pH of the culture media was measured after it was moved to normal conditions for 0, 2, 4, 6 and 8 h. Proliferation viability of MKN-45 was examined by 3-4,5Dimethylthiazol-2-yl,5-diphenyltetrazolium bromide or triazolyl blue (MTT) assay after it was moved to normal conditions. Apoptotic ratio was measured by Annexin V-FITC/PI double labelled staining. RESULTS:The pH of media was acid and recovered to normal after 4 h in the CO2 group while it was basic in the helium group. There was no difference between CO2 groups (under 10 mmHg ) and control group (P > 0.05) in the proliferative viability of the cells. The cultured cells exposed to 15 mmHg CO2 environment grew more slowly than control group from 4 to 7 d (P < 0.01 ) while there was no difference from 1 to 3 d (P > 0.05). The proliferative viability in helium group was not obviously different from the control group (P > 0.05). The apoptotic ratio of the cultured cells was markedly higher than that of the control group (P < 0.01) at 10 and 15 mmHg CO2 insufflation pressure. In helium group, the apoptotic ratio was not obviously different from the control group (P > 0.05). CONCLUSION:There is no obvious effect in the proliferation and apoptosis of MKN-45 cells under 10 mmHg CO2 insufflation pressure and helium in any pressure. Fifteen mmHg CO2 insufflation pressure can inhibit the proliferation of the cells and improve apoptosis.

Inhibitory effect of Polo-like kinase 1 depletion on mitosis and apoptosis of gastric cancer cells

AIM： Polo-like kinase 1 （PLK1） serine/threonine kinase plays a vital role in multiple phases of mitosis in gastric cancer cells. To investigate the effect of PLK1 depletion on mitosis and apoptosis of gastric cancer cells. METHODS： PLK1 expression was blocked by small RNA interference（siRNA）. The expression levels of PLK1, cdc2, cyclin B and caspase 3 were detected by Western blotting. Then, PLK1 depletion, cdc2 activity, cell proliferation, cell cycle phase distribution, mitotic spindle structure, and the rate of apoptosis of the PLK1 knockdown cells were observed. RESULTS： PLK1 gene knockdown was associated with increased cyclin B expression, increased cdc2 activity （but not with the expression levels）, accumulation of gastric cancer cells at G2/M, improper mitotic spindle formation, delayed chromosome separation and delayed or arrested cytokinesis. Moreover, PLK1 depletion in gastric cancer cells was associated with decreased proliferation, attenuated pro-caspase 3 levels and increased apoptosis. CONCLUSION： Blockage of to decreased mitosis or even PLK1 expression may lead apoptosis in gastric cancer cells, indicating that PLK1 may be a valuable therapeutic target for gastric cancer.

Effects of small interfering RNA inhibit Class Ⅰ phosphoinositide 3-kinase on human gastric cancer cells

AIM: To investigate the effects of small interfering RNA (siRNA)-mediated inhibition of Class?I?phosphoinositide 3-kinase (Class?I?PI3K) signal transduction on the proliferation, apoptosis, and autophagy of gastric cancer SGC7901 and MGC803 cells.METHODS: We constructed the recombinant replication adenovirus PI3K(I)-RNA interference (RNAi)-green fluorescent protein (GFP) and control adenovirus NC-RNAi-GFP, and infected it into human gastric cancer cells. MTT assay was used to determine the growth rate of the gastric cancer cells. Activation of autophagy was monitored with monodansylcadaverine (MDC) staining after adenovirus PI3K(I)-RNAi-GFP and control adenovirus NC-RNAi-GFP treatment. Immunofluorescence staining was used to detect the expression of microtubule-associated protein 1 light chain 3 (LC3). Mitochondrial membrane potential was measured using the fluorescent probe JC-1. The expression of autophagy was monitored with MDC, LC3 staining, and transmission electron microscopy. Western blotting was used to detect p53, Beclin-1, Bcl-2, and LC3 protein expression in the culture supernatant.RESULTS: The viability of gastric cancer cells was inhibited after siRNA targeting to the Class?I?PI3K blocked Class?I?PI3K signal pathway. MTT assays revealed that, after SGC7901 cancer cells were treated with adenovirus PI3K(I)-RNAi-GFP, the rate of inhibition reached 27.48% ± 2.71% at 24 h, 41.92% ± 2.02% at 48 h, and 50.85% ± 0.91% at 72 h. After MGC803 cancer cells were treated with adenovirus PI3K(I)-RNAi-GFP, the rate of inhibition reached 24.39% ± 0.93% at 24 h, 47.00% ± 0.87% at 48 h, and 70.30% ± 0.86% at 72 h (P < 0.05 compared to control group). It was determined that when 50 MOI, the transfection efficiency was 95% ± 2.4%. Adenovirus PI3K(I)-RNAi-GFP (50 MOI) induced mitochondrial dysfunction and activated cell apoptosis in SGC7901 cells, and the results described here prove that RNAi of Class?I?PI3K induced apoptosis in SGC7901 cells. The results showed that adenovirus PI3K(I)-RNAi-GFP transfection induced punctate distribution of LC3 immunoreactivity, indicating increased formation of autophagosomes. The results showed that the basal level of Beclin-1 and LC3 protein in SGC7901 cells was low. After incubating with adenovirus PI3K(I)-RNAi-GFP (50 MOI), Beclin-1, LC3, and p53 protein expression was significantly increased from 24 to 72 h. We also found that Bcl-2 protein expression down-regulated with the treatment of adenovirus PI3K(I)-RNAi-GFP (50 MOI). A number of isolated membranes, possibly derived from ribosome-free endoplasmic reticulum, were seen. These isolated membranes were elongated and curved to engulf a cytoplasmic fraction and organelles. We used transmission electron microscopy to identify ultrastructural changes in SGC7901 cells after adenovirus PI3K(I)-RNAi-GFP (50 MOI) treatment. Control cells showed a round shape and contained normal-looking organelles, nucleus, and chromatin, while adenovirus PI3K(I)-RNAi-GFP (50 MOI)-treated cells exhibited the typical signs of autophagy.CONCLUSION: After the Class?I?PI3K signaling pathway has been blocked by siRNA, the proliferation of cells was inhibited and the apoptosis of gastric cancer cells was enhanced.

H pylori stimulates proliferation of gastric cancer cells through activating mitogen-activated protein kinase cascade

AIM: To explore the mechanism by which H pylori causes activation of gastric epithelial cells. METHODS: A VacA (+) and CagA (+) standard H pylori line NCTC 11637 and a human gastric adenocarcinoma derived gastric epithelial cell line BGC-823 were applied in the study. MTT assay and 3H-TdR incorporation test were used to detect the proliferation of BGC-823 cells and Western blotting was used to detect the activity and existence of related proteins. RESULTS: Incubation with H pylori extract increased the proliferation of gastric epithelial cells, reflected by both live cell number and DNA synthesis rate. The activity of extracellular signal-regulated protein kinase (ERK) signal transduction cascade increased within 20 min after in- cubation with H pylori extract and appeared to be a sus- tained event. MAPK/ERK kinase (MEK) inhibitor PD98059 abolished the action of H pylori extract on both ERK activity and cell proliferation. Incubation with H pylori extract increased c-Fos expression and SRE-dependent gene expression. H pylori extract caused phosphorylation of several proteins including a protein with molecular size of 97.4 kDa and tyrosine kinase inhibitor genistein inhibited the activation of ERK and the proliferation of cells caused by H pylori extract. CONCLUSION: Biologically active elements in H pylori extract cause proliferation of gastric epithelial cells through activating tyrosine kinase and ERK signal trans- duction cascade.

Effects of allitridi on cell cycle arrest of human gastric cancer cells

AIM： To determine the effect of allitridi on cell cycle of human gastric cancer （HGC） cell lines MGC803 and SGC7901 and its possible mechanism. METHODS： Trypan blue dye exclusion was used to evaluate the proliferation, inhibition of cells and damages of these ceils were detected with electron microscope, Flow cytometry and cell mitotic index were used to analyze the change of cell cycle, immunohistochemistry, and RT- PCR was used to examine expression of the p21^WAF1 gene, RESULTS： MGC803 cell growth was inhibited by allitridi with 24 h ICso being 6.4μg/mL, SGC7901 cell growth was also inhibited by allitridi with 24 h IC50 being 7.3μg/mL, After being treated with allitridi at the concentration of 12μg/mL for 24 h, cells were found to have direct cytotoxic effects, including broken cellular membrane, swollen and vesiculated mitochondria and rough endoplasmic reticula, and mass lipid droplet, When cells were treated with allitridi at the concentration of 3, 6, and 9μg/mL for 24 h, the percentage of Go/G1 phase cells was decreased and that of G2/M phase cells was significantly increased （P = 0.002） compared with those in the group, When cells were treated with allitridi at the concentration of 6μg/mL, cell mitotic index was much higher （P = 0.003） than that of control group, indicating that allitridi could cause gastric cancer cell arrest in M phase, Besides, the expression levels of p21^WAF1 gene of MGC803 cells and p21^WAF1 gene of SGC7901 cells were remarkably upregulated after treatment, CONCLUSION： Allitridi can cause gastric cancer cell arrest in M phase, and this may be one of the mechanisms for inhibiting cell proliferation, Effect of allitridi on cells in M phase may be associated with the upregulation of p21^WAF1 genes. This study provides experimental data for clinical use of allitridi in the treatment of gastric carcinoma.

Relationship between VEGF,EGF and Invasion,Metastasis of Gastric Cancer Cells

Objective： To investigate the relationship between expression of vascular endothelial growth factor （VEGF）, epidermal growth factor （EGF） and the biological properties of gastric cancer cells such as invasion and metastasis. Methods： RT-PCR was performed to semi-quantitatively detect the mRNA expressions of EGF, EGFR, VEGF and VEGFR in four kinds of gastric cancer cell lines BGC823, MGCS03, HGC27 and SGC7901, which were classified by their differentiation degree in our experiment. We obtained cell line growth curves from MTT assays. The migration of gastric cancer cells was observed under inverted phase contrast microscope. The changes of invasion and adhesion were detected by a Transwell assay. Results： The growth rates slowed down sequentially in MGC803, HGC27, BGC823 and SGC7901（P〈 0.05）. The ability of migration, invasion and adhesion were reduced sequentially, and the difference was significant. The expressions of EGF, EGFR, VEGF and VEGFR were significantly stronger in MGCS03 and HGC27 than in BGC823 and SGC7901 cells, and the difference was statistically significant（P〈0.05）. Conclusion： The expressions of VEGF and EGF had close relationship with the properties of migration, adhesion and invasion of gastric cancer cells in vitro. Thus, targeting VEGF and EGF may be a potential therapeutic strategy for inhibiting peritoneal metastasis of gastric cancer.

IMMUNOELECTRON MICROSCOPIC STUDY ON THE LOCALIZATION OF MONOCLONAL ANTIBODIES ON GASTRIC CANCER CELLS

The localization of three monoclonal antibodies (MAb) against gastric cancer was studied on two human gastric cancer cell lines by immunoelectron microscopic technique. It has shown that the corresponding antigens of MAb 3G9 and 3H11 were distributed on the microvilli (M) and non-microvillus (NM) plasma membrane of target cells, with various M to NM ratios depending on the MAbs and target cells used. However, the corresponding antigens of MAb PD4 was only localized on the surface of round or finger-like bulges of target cells and never on the microvilli and non-microvillous plasma membrane. Since the nature and function of these tumor antigens have not been identified yet, the implication of the different distributions of these antigens remians to be clarifated.

SELECTIVE KILLING OF GASTRIC CANCER CELLS BY MONOCLONAL ANTIBODY CONJUGATED WITH A CHAIN OF RICIN

A specific cytotoxic agent against gastric cancer was constructed by covalently coupling the ricin A chain to monoclonal artibody, MGb2. MGb2 was modified by SPDP to introduce the 3-(2-pyridylthio) propionyl radical and then treated with a reduced A chain to give a disulfide linked conjugate that retained the original binding specificity of the antibody moiety. The conjugate obtained retained the activity of the antibody and the biological activity of the A chain well.

miRNA-195:The New Target of Inhibiting the Proliferation,Migration and Invasion of Gastric Cancer Cells via Propofol

Objective:To explore the effect of propofol(Prof)on the proliferation,migration and invasion of human gastric cancer cell MGC-803 and its molecular mechanism.Methods:The MTT method was used to study the effects of Prof with different doses and durations on the viability of MGC-803 cells.Hoechst 33258 staining and electron microscopy were used to detect the effects of Prof on MGC-803 cell apoptosis.Transwell experiments were used to detect the effects of Prof on the migration and invasion of MGC-803 cells.RT-PCR detects the effect of Prof on the expression of miR-195 in MGC-803 cells,and Western Blot detects the effect of Prof on the protein expression of JAK/STAT signaling pathway.Results:Compared with 0μg/ml Prof,5μg/ml,10μg/ml and 20μg/ml Prof treatment with 24h,48h and 72h can significantly reduce cell viability(P<0.05).Compared with the Control group,the percentage of Hoechst 33258 staining positive cells in the Prof group and the apoptosis rate under the electron microscope were significantly increased(P<0.05).Compared with the Control group,the cell migration rate and invasion rate of the Prof group were significantly reduced(P<0.05).Compared with the Control group,the expression of miRNA-195 in the Prof group cells was increased significantly(P<0.05).Compared with the Control group,the activity of p-Jak1 and p-STAT3 proteins in the Prof group were significantly reduced(P<0.05).Conclusion:Prof can reduce the cell viability,migration and invasion of gastric cancer cell MGC-803,and promote its apoptosis.Its mechanism may be related to the promotion of miR-195 expression and inhibition of JAK/STAT signal pathway activity.

PEI-PEG as a siRNA Genetic Vector Demonstrating Interference in the Expression of CD44v6 Protein in Gastric Cancer Cells

OBJECTIVE To investigate the effect of polyethylene imine glycol （PEI-PEG）/siRNA nanocomposites in the in vitro transfection of human gastric cancer SGC7901 cell lines and the down-regulation of gene expression of the adherence factor CD44v6. METHODS PEI-PEG/siRNA nanoparticles, in different N/P ratios, were synthesized and transfected into gastric cancer cells. Lipo2000/siRNA was used in the control group. The transfection efficiencies were observed under fluorescence microscope. The cytotoxicity of the nanoparticles was measured using the MTT assay （mononuclear cell direct cytotoxicity assay）, and the down-regulation effect of siRNA on CD44v6 gene was evaluated by Western blot. Based on the different N/P ratios, PEI-PEG/siRNA composites were synthesized and transfected into gastric cancer cells. Lipo2000/siRNA was used in the controls. The transfection efficiency was observed under fluorescence microscope. The cytotoxicity of the nanoparticles was measured using the MTT assay and the down-regulation effect of siRNA on CD44v6 gene was evaluated by Western blot. RESULTS After transfection, the transfection efficiency of the PEI-PEG/siRNA nanocomposites increased incrementally in N/P ratio value. The transfection efficiency improved with an increase in N/P ratio. When the N/P value was 15, fluorescence became more intense in the PEI-PEG/siRNA group than in the Lipo2000/siRNA group. At the same time, cell viability was （80.4 ± 5.6）% in the MTT reduction assay, which was similar to that in the Lipo2000/siRNA group. The results of Western blot analysis showed that the expression level of CD44v6 protein decreased to （59.7 ± 3.0）% after siRNA-CD44v6 was inhibited. CONCLUSION PEI-PEG could effectively form the nanocomposite in combination with siRNA, be transfected into the SGC7901 gastric cancer cell lines and inhibit CD44v6 protein expression. Moreover, as a genetic carrier, PEI-PEG copolymer has greater advantages, including high transfection e. ciency, less cytotoxicity and an easily alterable vector structure.

Prostaglandin D2 regulation of autophagy affects stemness of gastric cancer stem cells

Objective:To explore the effect and mechanism of prostaglandins D2(PGD2)on the stemness of gastric cancer stem cells(GCSCs).Methods:7901-GCSCs were enriched by serum-free culture method;then the positivity rate of CD44,a stemness marker,was detected by flow cytometry in serum-free cultured 7901-GCSCs;the sphere-forming ability was detected by the sphere-forming assay after stimulation with different concentrations of PGD2(2.5,5,10)μg/mL,and the expression of stemness-related indicators(OCT4,CD44)and autophagyrelated proteins(LC3,Beclin-1)after PGD2 stimulation was detected by the western blot assay in different concentrations.The expression of stemness-related indexes(OCT4,CD44)and autophagy-related proteins(LC3,Beclin-1)were detected by Western blot assay after stimulation with different concentrations of PGD2.The expression of autophagy-related proteins after stimulation with different concentrations of CQ(2.5,5,10)μM was detected by Western blot experiment.The protein expression of autophagy-related proteins(LC3,Beclin-1)and stemness-related indexes(OCT4,CD44)was detected by Western blot experiment after PGD2 as well as PGD2+CQ treatment.Results:Flow cytometry results showed that the expression of CD44 positivity was increased in serum-free cultured 7901-GCSCs compared with gastric cancer cells SGC-7901(P<0.05),which fulfilled the needs of subsequent experiments.The results of stem cell spheroid formation assay showed that the spheroid formation ability of 7901-GCSCs in the PGD2 group was significantly weakened compared with that of the DMSO group(P<0.05).Western blot results showed that the protein expression of stemness-related indexes(OCT4,CD44)was down-regulated in the 7901-GCSCs in the PGD2 group compared with that of the DMSO group(P<0.05),and the expression of autophagy-related proteins(LC3,Beclin-1)expression increased(P<0.05).Compared with the DMSO group,the expression of autophagy-related proteins(LC3,Beclin-1)was decreased in the CQ group(P<0.05).Western blot results also showed that the expression of cellular autophagy-related proteins and stemness-related indexes in the PGD2+CQ group was not significantly changed compared with that of the DMSO group(ns:the difference was not significant),suggesting that the CQ could block the effect of PGD2 on the expression of stemness markers in 7901-GCSCs.7901-GCSCs stemness inhibition.Conclusion:PGD2 may affect the stemness of 7901-GCSCs by regulating autophagy.

Multifaceted role of microRNAs in gastric cancer stem cells: Mechanisms and potential biomarkers

MicroRNAs(miRNAs)have received much attention in the past decade as potential key epigenomic regulators of tumors and cancer stem cells(CSCs).The abnormal expression of miRNAs is responsible for different phenotypes of gastric cancer stem cells(GCSCs).Some specific miRNAs could be used as promising biomarkers and therapeutic targets for the identification of GCSCs.This review summarizes the coding process and biological functions of miRNAs and demon-strates their role and efficacy in gastric cancer(GC)metastasis,drug resistance,and apoptosis,especially in the regulatory mechanism of GCSCs.It shows that the overexpression of onco-miRNAs and silencing of tumor-suppressor miRNAs can play a role in promoting or inhibiting tumor metastasis,apart from the initial formation of GC.It also discusses the epigenetic regulation and potential clinical applications of miRNAs as well as the role of CSCs in the pathogenesis of GC.We believe that this review may help in designing novel therapeutic approaches for GC.

Growth inhibition of gastric cancer cells by all-trans retinoic acid through arresting cell cycle progression

Objective To investigate the mechanism of all-trans retinoic acid (ATRA) on the regulation of the cell cycle in gastric cancer cells. Methods The protein level was detected by Western blot. Immunoprecipitation was used in protein kinase activity determination. Cell growth and cell cycle phase were examined by MTT assay and flow-cytometric analysis, respectively.Results ATRA could effectively induce G0/G1 arrest and inhibit cell growth in certain human gastric cancer cell lines. ATRA might induce p21WAF1/CIP1 expression in ATRA-sensitive cell lines through p53-dependent and p53-independent pathways. Induction of p21WAF1/CIP1 caused decrease in CDK4 and CDK2 activities independent of CDK4 and CDK2 protein expression levels. In addition, the dephosphorylated form of Rb protein increased because of the down-regulation of CDK4 and CDK2 activities by ATRA. Conclusions Growth inhibition on gastric cancer cells by ATRA occurs through the regulation of relevant proteins leading to the arrest of cell cycle progression.

Mechanism of inhibition on activator protein 1 activity by all trans retinoic acid in gastric cancer cells

To determine the mechanism of all trans retinoic acid (ATRA) on growth inhibition in human gastric cancer cells Methods Gastric cancer cell lines: MGC80 3, BGC 823, SGC 7901 and MKN 45 CAT assay, Northern blot, Western blot, gene transfection and MTT assay Results ATRA can inhibit the activator protein 1 (AP 1) activity in ATRA sensitive cell lines, but not in ATRA resistant cell line, and the anti AP 1 activity of ATRA is mediated by its receptor, retinoic acid receptor α (RARα) ATRA can also inhibit the expression of cJun and cFos One of the mechanisms for ATRA to inhibit the growth of gastric cancer cells may be through its inhibitory effect on the AP 1 activity and its influence on up regulation of RARα expression The inhibition of cJun and cFos expressions by ATRA may also contribute to the anti AP 1 activity Conclusions ATRA inhibits the growth of gastric cancer cells through the regulation of AP 1 activity This action is mediated by RARα

Extract from Zanthoxylum piperitum Induces Apoptosis of AGS Gastric Cancer Cells through Akt/MDM2/p53 Signaling Pathway

Objective:To determine the effect of Zanthoxylum piperitum extracet(ZPE)on apoptosis and analyze anticancer substances in ZPE,changes in proteins related to apoptosis,and pathological changes in tumors in mouse.Methods:Fifteen 4-week-old female BALB/c nu/nu mice were divided into 3 groups depending on ZPE dose,with 5 in each group.AGS gastric carcinoma cells(1 x 10^(6) cells/200 jxL)were subcutaneously injected into the flank of each mouse.One week after the injection of AGS cells,ZPE was administered to the skin tissue[10 or 50 mg/(kg-d)]in the low-and high-dose groups,respectively for 20 days.Control animals were injected with vehicle only.After 3 weeks,the tumor was extracted and carried out for immunohistochemistry,the tendency of apoptosis and p53 in the body was checked using TdT-mediated dUTP nick-end labeling(TUNEL)assay.For 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay,annexin V dead cell staining,cell cycle arrest and Western blotting,AGS gastric carcinoma cells were incubated with various concentrations of ZPE for 24 h.Cell survival rates were analyzed by MTT assays.Apoptosis was analyzed using annexin V dead cell staining and cell cycle arrest and measured using Muse cell analyzer.Results:High performance liquid chromatography(HPLC)analysis showed that ZPE contained organic sulfur compounds such as alliin and S-allylcysteine.MTT assay results revealed that ZPE(10-85»xg/mL)could effectively inhibit the growth of AGS gastric cancer cells at higher concentrations(P<0.05,P<0.01).The annexin V&dead cell staining assay and cell cycle arrest assay confirmed a dose-dependent increase in the apoptosis rate and G!phase in ZPE(10-70 jig/mL)groups.ZPE decreased the expression of anti-apoptotic proteins(p-Akt,p-MDM2,Bcl-2),while increased pro-apoptotic proteins(cleaved PARP,p53,pro-Caspase 3,Bax).TUNEL assays revealed an increase in cell apoptosis.Immunohistochemistry staining confirmed the involvement of p53.Conclusion:ZPE decreases AGS cell proliferation and induces apoptosis by inhibiting Akt and MDM2 expression.

Retinoic acid receptor β is required for anti-activator protein-1 activity by retinoic acid in gastric cancer cells

Objective To investigate the role of retinoic acid receptor β (RARβ) in mediating inhibitory effect of all-trans retinoic acid (ATRA) on activator protein-1 (AP-1) activity in gastric cancer cells. Methods Transient transfection and chloramphenicol acetyltransferase (CAT) assay, Northern blot, gene transfection, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and anchorage-independent growth assay were used.Results Transient transfection of RARβ expression vector into MKN-45 cells resulted in the RARβ concentration-dependent repression of AP-1 activity induced by 12-o-tetradecanoylphorbol-13-acetate (TPA), regardless of the presence of ATRA. When the c-jun and c-fos expression vectors were cotransfected with the RARβ expression vector into MKN-45 cells, AP-1 activity was also obviously repressed. The inhibitory effect, again, was RARβ-concentration-dependent. The stable transfection of the RARβ gene into MKN-45 cells led to cell growth inhibition and colony formation inhibition by ATRA. Furthermore, Cotransfection of both RARβ/DNA binding domain (DBD) and reporter gene could not alter AP-1 activity, even in the presence of ATRA. However, when the cotransfection was substituted with the RARβ/ligand binding domain (LBD), the inhibition was significantly enhanced by ATRA. Conclusion RARβ might be required for anti-AP-1 activity, and contribute to growth inhibition of gastric cancer cells by ATRA.

Effects of human microRNA-181a-5p on proliferation and migration of gastric cancer cells

Objective To preliminarily explore the effects of human microRNA-181a on migration of gastric cancer cells and its mechanism.Methods The expression of miRNA-181a-5p in gastric cancer cell line GC9811 and peritoneal high metastasis gastric cancer cell line GC9811-P were tested by quantitative real-time polymerase chain reaction(qRT-PCR).GC9811 cell line was

Xiaotan Sanjie decoction attenuates tumor angiogenesis by manipulating Notch-1-regulated proliferation of gastric cancer stem-like cells

AIM: To determine the underlying mechanisms of action and influence of Xiaotan Sanjie (XTSJ) decoction on gastric cancer stem-like cells (GCSCs).

Sox2 enhances the tumorigenicity and chemoresistance of cancer stem-like cells derived from gastric cancer

Gastric cancer stem-like cells（GCSCs） have been identified to possess the ability of self-renewal and tumor initi-ation.However,the mechanisms involved remain largely unknown.Here,we isolated and characterized the GCSCs by side population（SP） sorting procedure and cultured sphere cells（SC） from human gastric cancer cell lines SGC-7901,BGC-823,MGC-803,HGC-27 and MKN-28.The sorting and culture assay revealed that SP cells proliferated in an asymmetric division manner.In addition,SP cells exhibited a higher potential of spheroid colony formation and greater drug resistance than non-SP cells（NSP）.Moreover,the SC were found with enhanced capabilities of drug resistance in vitro and tumorigenicity in vivo.Sox2 mRNA and protein was highly and significantly overex-pressed in the SP cells and SC.Importantly,downregulation of Sox2 with siRNA obviously reduced spheroid colony formation and doxorubicin efflux,as well as increased apoptosis rate in sphere cells in vitro and suppressed tumori-genicity in vivo.These results suggest that both SP cells and cultured SC enrich with GCSCs and that Sox2 plays a pivotal role in sustaining stem cell properties and might be a potential target for gastric cancer therapy.

Side population cells isolated from KATO Ⅲ human gastric cancer cell line have cancer stem cell-like characteristics

AIM: To investigate whether the side population (SP) cells possess cancer stem cell-like characteristics in vitro and the role of SP cells in tumorigenic process in gastric cancer. METHODS: We analyzed the presence of SP cells indifferent human gastric carcinoma cell lines, and then isolated and identified the SP cells from the KATO Ⅲ human gastric cancer cell line by flow cytometry. The clonogenic ability and self-renewal were evaluated by clone and sphere formation assays. The related genes were determined by reverse transcription polymerase chain reaction. To compare tumorigenic ability, SP and non-side population (NSP) cells from the KATO Ⅲ human gastric cancer cell line were subcutaneously injected into nude mice. RESULTS: SP cells from the total population accounted for 0.57% in KATO Ⅲ, 1.04% in Hs-746T, and 0.02% in AGS (CRL-1739). SP cells could grow clonally and have self-renewal capability in conditioned media. The expression of ABCG2, MDRI, Bmi-1 and Oct-4 was different between SP and NSP cells. However, there was no apparent difference between SP and NSP cells when they were injected into nude mice. CONCLUSION: SP cells have some cancer stem celllike characteristics in vitro and can be used for studying the tumorigenic process in gastric cancer.