Gastric Carcinoma Cell Line SGC-7901 Research Articles

Silencing of Yap Gene Inhibits Metastasis in a Severe Combined Immune Deficiency Mice Orthotopic Implantation Gastric Cancer Model

YAP signaling has been proved to be involved in cell growth, invasion and metastasis in multiple malignancies. But little has been reported about the effects of YAP transduction on gastric cancer metastases. The present study was aimed to explore the effects of shRNA-mediated targeting of YAP gene on human gastric cancer metastases in severe combined immune deficiency (SCID) mice. Human gastric carcinoma cell line SGC7901 was implanted into the stomach of SCID mice, which were randomly divided into 3 groups (n=10). Via intraperitoneal injection, mice received YAP-shRNA, negative control, or normal saline respectively. The results of TUNEL and FQ-PCR showed an obvious induction of apoptosis in the YAP-shRNA group. Intratumoral vascular density and lymphatic density were suppressed in the YAP-shRNA group. In conclusion, silencing of YAP gene effectively induces the cell apoptosis and inhibits microvascular angiogenesis and lymphagiogenesis of gastric cancer cells in vivo, suggesting that YAP may serve as a promising therapeutic target for treatment of cancer.

Anti-proliferation effects and molecular mechanisms of action of tetramethypyrazine on human SGC-7901 gastric carcinoma cells.

To investigate the effects of tetramethypyrazine (TMP) on proliferation and apoptosis of the human gastric carcinoma cell line 7901 and its possible mechanism of action. The viability of TMP-treated 7901 cells was measured with a 3-(4, 5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) and cell apoptosis was analyzed by flow cytometry. The distribution of cells in different phases of cell cycle after exposure of TMPs was analyzed with flow cytometry. To investigate the molecular mechanisms of TMP-mediated apoptosis, the expression of NF-xBp65, cyclinD1 and p16 in SGC-7901 cells was analyzed by reverse transcription- polymerase chain reaction (RT-PCR) and western blotting. TMP inhibited the proliferation of human gastric carcinoma cell line 7901 in dose and time dependent manners. Cell growth was suppressed by TMP at different concentrations (0.25, 0.5, 1.0, 2.0 mg/ml), the inhibition rate is 0.46%, 4.36%, 14.8%, 76.1% (48h) and 15.5%, 18.5%, 41.2%, 89.8% (72h) respectively. When the concentration of TMPs was 2.0mg/ml, G1-phase arrest in the SGC-7901 cells was significant based on the data for cell cycle distribution. RT-PCR demonstrated that NF-xBp65 and cyclin D1 mRNA expression was significantly down-regulated in 7901 cells treated with 2.0 mg/ml TMP for 72h (p<0.05), while the p16 mRNA level was up-regulated (p<0.05). The protein expression of NF-xBp65 and cyclin D1 decreased gradually with the increase in TMP concentration, compared with control cells (p<0.05), while expression of protein p16 was up-regulated (p<0.01). TMP exhibits significant anti-proliferative and pro-apoptotic effects on the human gastric carcinoma cell line SGC-7901. NF-xBp65, cyclinD1 and p16 may also play important roles in the regulation mechanisms.

Effects of simulated weightlessness on cellular morphology and biological characteristics of cell lines SGC-7901 and HFE-145.

We investigated the effects of simulated weightlessness on cellular morphology, proliferation, cell cycle, and apoptosis of the human gastric carcinoma cell line SGC-7901 and the human gastric normal cell line HFE-145. A rotating clinostat was used to simulate weightlessness. The Image-Pro4.5 image analysis system was used for morphometric analysis. Proliferating cell nuclear antigen expression was examined by immunohistochemical staining. Changes in the cell cycle were examined using a cytometer. Apoptosis was measured using the terminal dUTP nick-end labeling (TUNEL) method. When subjected to simulated weightlessness, the cellular morphology of SGC-7901 cells was changed at 12, 24, 48, and 72 h, cell conversion from the G1 to S phase was blocked, proliferation was inhibited at 48 and 72 h, and the apoptosis index was increased at 72 h. The same changes were observed for HFE-145 cells at 12 h when subjected to simulated weightlessness, but no significant changes were found afterward compared with controls. SGC-7901 cells change their cellular morphology and biological characteristics during clinostat-simulated weightlessness at 72 h, but HFE-145 cells only change at 12 h and adapt to simulated weightlessness after that point.

Tumor suppressor ING4 overexpression contributes to proliferation and invasion inhibition in gastric carcinoma by suppressing the NF-κB signaling pathway

There is growing evidence that inhibitor of growth 4 (ING4) plays a pivotal role in development and progression of multiple different tumors; however, its precise function in gastric carcinoma remains to be elucidated. In the present study, we investigated ING4 level in gastric carcinoma tissues and cells, and preliminarily elucidated the role of ING4 in the proliferation and invasion of gastric carcinoma. The results demonstrated that expressions of ING4 mRNA and protein in gastric carcinoma tissues and cells were significantly lower than those in normal tissues and cells (P < 0.05). ING4 level in gastric carcinoma cells stably expressing ING4 was markedly higher than those in untreated group and empty vector pcDNA3.1 group (P < 0.05). Elevated ING4 level resulted in the inhibition of proliferation and invasion in three of gastric carcinoma cell lines MKN-28, SGC-7901 and MKN-45. Most notably, increased ING4 level evidently evoked the down-regulation of p65, p-IκBα, MMP-9 and uPA proteins and the up-regulation of IκBα protein. Our results presented herein suggest that ING4 level elevation mediated proliferation and invasion inhibition may be tightly associated with the suppression of NF-κB signaling pathway.

Construction of the human miRNA-451 expression vector and its expression in gastric carcinoma cell line SGC-7901

Objective The aim of the study was to construct miRNA-451 expression vector pLMP-miRNA-451 which could help identify the functions of miRNA-451 in SGC-7901 cell.

Ghrelin induces gastric cancer cell proliferation, migration, and invasion through GHS-R/NF-κB signaling pathway

This study aims to investigate the roles of ghrelin signaling in human gastric carcinoma cell lines AGS and SGC7901. Effects of ghrelin signaling on CDK6, P53, NF-κB/P65 and MMP2 mRNA and/or protein expression were determined by real-time PCR and western blot. MTT method and flow cytometry were performed to assess the gastric cancer cell proliferation. The SGC7901 cells overexpressing ghrelin were inoculated into nude mice to produce tumors which were measured later. The wound-healing assay and cell invasion assay were used to test the cell migration and invasive ability of gastric cancer. Ghrelin signaling promotes the oncogene CDK6 gene expression and represses the tumor suppressor gene P53 gene expression in gastric cancer. Ghrelin activates NF-κB/P65 signaling pathway through GHS-R in gastric cancer. Ghrelin upregulates the metastasis factor MMP2 expression via GHS-R/NF-κB signaling pathway in gastric cancer cells and promotes tumor cells migration and invasion, suggesting that ghrelin signaling is a critical pathway in cancer metastasis. Ghrelin induces cell proliferation, migration and invasion via GHS-R/NF-κB signaling pathway in gastric cancer cells. Ghrelin treatment must be avoided for gastric cancer patients.

Effect of down-regulated S100A7 expression on proliferation and migration of gastric carcinoma cell line SGC-7901

Effect of down-regulated S100A7 expression on proliferation and migration of gastric carcinoma cell line SGC-7901

Aquaporin 5 promotes the proliferation and migration of human gastric carcinoma cells

Aquaporin 5 (AQP5) promotes the progression and invasion of several cancers, but its role in the tumorigenesis of human gastric carcinoma (GC) has not been clearly defined. Here, we investigated the potential functions of AQP5 in the proliferation and migration of human GC. RT-PCR and western blotting were used to detect the expression of AQP5 in human GC cell lines. Immunohistochemistry was applied to evaluate the expression of AQP5 in human GC tissues and corresponding normal tissues. Following ectopic overexpression of AQP5 or inhibition of AQP5 by its inhibitor, acetazolamide (AZA), cell proliferation and migration of AGS cells were analyzed by MTT assay, colony formation assay, and wound healing assay. Heterogeneous expression of AQP5 mRNA and protein was observed in human GC cell lines MKN45, MKN28, AGS, and SGC7901. AQP5 was up-regulated in GC tissues in comparison to corresponding normal tissues. AQP5 protein was mainly localized in the cell membrane. Overexpression of AQP5 was correlated with enhanced lymph node metastasis. In vitro, overexpression of AQP5 notably enhanced, while inhibition of AQP5 by AZA significantly attenuated the proliferation and migration of AGS cells. Our data indicate that AQP5 may play an important role in the tumorigenesis and progression of human GC and suggest that AQP5 is a potential therapeutic target against GC.

Characterization of polyethylene glycol-grafted polyethylenimine and superparamagnetic iron oxide nanoparticles (PEG-g-PEI-SPION) as an MRI-visible vector for siRNA delivery in gastric cancer in vitro and in vivo

Gene therapy is a promising therapeutic method but is severely hampered due to its lack of an ideal delivery system. Therefore, in this study, a nonviral and magnetic resonance imaging (MRI) visible vector, polyethylene glycol-grafted polyethylenimine and superparamagnetic iron oxide nanoparticles (PEG-g-PEI-SPION) was used as a nanocarrier for small interfering RNA (siRNA) delivery in gastric cancer. Biophysical characterization of PEG-g-PEI-SPION was systematically analyzed, including size, zeta potential, siRNA condensation capacity, cell viability, transfection efficiency, cellular uptake, and MRI-visible function in vivo. Besides, CD44 variant isoform 6 (CD44v6), a protein marker for metastatic behavior in gastric cancer, and was chose as the target gene to further analyze the siRNA delivery function of PEG-g-PEI-SPION. Under comprehensive analysis, the appropriate N/P ratio of PEG-g-PEI-SPION/siRNA was 10, and siRNA targeting at human CD44v6 (siCD44v6) transferred by PEG-g-PEI-SPION was effective at downregulating the CD44v6 expression of gastric carcinoma cell line SGC-7901 in vitro. Moreover, knockdown of CD44v6 impaired migrating and invasive abilities of SGC-7901 cells. Furthermore, PEG-g-PEI-SPION was a highly efficient contrast agent for MRI scan in vivo. PEG-g-PEI-SPION was a promising nonviral vector with molecular image tracing capacity for cancer gene therapy. And CD44v6 was a potential target gene for the prevention and detection of metastatic behavior in gastric cancer.

Effects of proliferation and apoptosis of gastric carcinoma cell line SGC-7901 by Cetuximab

Objective To investigate the anti-tumor effect and its mechanisms of Cetuximab on human gastric carcinoma cell line SGC-7901 in vitro.Methods In vitro,human gastric carcinoma cell line SGC-7901 was treated by Cetuximab in different concentrations.The inhibitory effect of cell growth was assayed by methyl thiazol tetrazolium (MTT) assay,cell cycles and apoptosis were analyzed by flow cytometry (FCM) ; the mRNA expressions of cysteinyl aspartate-specific protease-3 ( Caspase-3 ) were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) ; Immunohistochemistry was used to detect B lymphocytes/leukemia-2 (bcl-2) and p-27 protein expression.Results (1) MTT assay indicated that as the concentration of the Cetuximab on the proliferation of SGC-7901 cell increased,the inhibition ratio increased from (9.76 ± 1.41 )％ to (78.12 ± 3.88)％.the inhibition ratio was also found in time dependent manner.There was great statistical signification between varies medicated group and control group (P ＜0.05 ),and there also were great statistical signification between medicated group each other ( P ＜ 0.05 ).(2) Comparing with control group,the cell apoptosis was induced by Cetuximab at 48 hours,meanwhile,the ratio of G0/G1 phase was increased and the ratio of S phase was decreased,in dose-dependent manner ( P ＜ 0.05 ).(3) RT-PCR assay and Immunocytochemistry showed that the expression of Caspase-3,p-27 mRNA and protein were upregulated and bcl-2 mRNA and protein was downregulated by Cetuximab at 48hours with concentration increased ( P ＜ 0.05 ).Conclusion The growth of SGC-7901 cell in vitro is inhibited by Cetuximab and in dose-and-time dependent manner. Cetuximab also can arrest cell cycle at G0/G1 phase,induce cell apoptosis. Maybe its mechanism is through upregulating the expressions of Caspase-3,p-27 mRNA and protein,downreglating the espression of bcl-2mRNA and protein. Key words: Gastric carcinoma cell SGC-7901; Cetuximab; Apoptosis; B lymphocytes/leukemia-2; Cysteinyl aspartate-specific protease-3; p-27

ABT-737 Synergizes with Arsenic Trioxide to Induce Apoptosis of Gastric Carcinoma Cells In Vitro and In Vivo

This study investigated the potential synergistic effects of two inducers of apoptosis: the small molecule ABT-737 and arsenic trioxide (ATO). Human gastric carcinoma cell lines SGC-7901 and MGC-803 were used to determine the effects of ABT-737 and ATO (alone or in combination) on cell proliferation and apoptosis in vitro. In vivo effects of these drugs were investigated in SGC-7901 solid tumours, grown in immunodeficient mice. ABT-737 and ATO inhibited proliferation and induced apoptosis in SGC-7901 and MGC-803 cells in concentration- and time-dependent manners, and showed a synergistic effect. ABT-737 disturbed the binding of B cell lymphoma (Bcl)-2 homologous antagonist killer and Bcl-extra large; ATO downregulated myeloid cell leukaemia (Mcl)-1 protein and upregulated Mcl-1short, the short splicing variant. ABT-737 and ATO significantly suppressed SGC-7901 xenograft growth, synergistically inhibited tumour growth and induced apoptosis in vivo. This study provides preclinical evidence that ABT-737 and ATO synergize to induce apoptosis of gastric carcinoma cells, suggesting that further investigation of these agents (as potential treatments for gastric cancer) is warranted.

P-0030 CypA Plays Roles in the Proliferation of Gastric Carcinoma Cells

ABSTRACT Introduction Cyclophilin A (CypA) is a member of the peptidyl-prolyl isomerases, the primary intracellular receptor of the immunosuppressant cyclosporin A (CsA). CypA plays an important role in life activities and participate in a variety of disease processes. Recent evidence points to possible roles for CypA overexpression in tumorigenesis. However gastric carcinoma was rarely involved in CypA research so far. Methods In this research, using immunohistochemistry assay we confirmed the overexpression of CypA in gastric carcinoma tissues at protein level. The mRNA level of CypA in gastric carcinoma cell lines are also detected by Real-Time PCR. Results Compared with normal gastric epithelial cell line GES-1, the mRNA levels of CypA in gastric carcinoma cell lines SGC-7901, MKN-45, BGC-823 and MGC-803 were 1.29, 1.46, 1.54 and 1.55 fold high respectively (Fig.1). To investigate the roles CypA plays in the occurrence and development of gastric carcinoma, we constructed 4 RNA interference vectors: pRNA-CypA shRNA 1-4 and confirmed the positive clone by PCR with pRNA primer, then sequenced the plasmid DNA for additional verification. BGC-823 cells were grown to 70% confluency in 24-well plates and transfected with 0.5ug pRNA-CypA shRNAs using Lipofectamine LTX (Invitrogen). At 48 and 96 hours following transfection the mRNA level of CypA in these cells were detected by Real-Time PCR. The results showed us that after transfection with pRNA-CypA shRNA3, BGC-823 cells yielded ∼80% and ∼30% CypA knockdown at 48h and 96h respectively compared with untreated BGC-823 cells; with pRNA-CypA shRNA2 yielded ∼27% and ∼35% CypA knockdown at 48h and 96h respectively; pRNA-CypA shRNA1 and pRNA-CypA shRNA4 had little RNA interference effects. A transient increase of CypA mRNA level occurred in transfection, and reduced to the normal level at 96h after transfection. We collected the BGC-823 cells at 48h with the best RNAi efficiency by pRNA-CypA shRNA3 plasmid to perform flow cytometric analysis of cell cycle. From the cell cycle distribution, cell populations of S & G2/M phase (M2 & M3) in untreated BGC-823cells, BGC-823cell transfected with pRNA plasmid and CypA knockdown (transfected with pRNA-CypA-shRNA3 plasmid) BGC-823cell were 45.3%, 49.7% and 33.0% respectively. CypA knockdown resulted in an augmentation of cell populations in G0/G1 phase (M1) accompanied with a decrease in S & G2/M phase (M2 & M3). Cell proliferation decreased obviously in CypA knockdown BGC-823 cells, and cell cycle arrested in G0/G1 phase (M1). These results establish the relevance of CypA to gastric carcinoma proliferation in vitro. Conclusion Our results establish the relevance of CypA to gastric carcinoma proliferation in vitro. In further study we will do more experiments to reveal mechanisms how CypA plays roles in occurrence and development of gastric carcinoma and the pathways though which the signals of CypA transfer.

Establishment of the cultured model of microencapsulated human gastric carcinoma cells SGC-7901

Objective To establish the cultured model of microencapsulated human gastric carcinoma (HGC) cell line SGC-7901.Methods The SGC-7901 cells were cultured and encapsulated in APA microcapsules using the prepared electrostatic droplet generator for 21 days.The level of proliferation and metabolism of the microencapsulated HGC cells were detected by using methyl thiazol tetrazolium ( MTT),and glucose and lactic acid concentrations were determined in the supernatant.Microencapsulated HGC cells were stained with hematoxylin and eosin (HE),and the expression of bromodeoxyuridine ( BrdU),vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) gene was detected by using immunocytochemistry on the 7th,14th and 21st day.Monolayer cultured cells served as controls.Results On the 14th day,the relative number of the microencapsulated cells was no longer increased and decreased slightly on the next few days.Glucose was consumed and its concentration was decreased to 10 mmol/L,and lactic acid was generated and its concentration was increased to 100 mol/L in microencapsulated HGC cells on the 20th day.The expression of PCNA and VEGF gene could be detected in SGC7901 cells.The expression of BrdU,PCNA and VEGF was still detected in the microencapsulated SGC9701 cells on the 7th and 14th day.On the 21st day,the expression of Brdu and PCNA was found on the outer layer of spheroid,and that of VEGF gene was detected within the whole spheroid.Conclusion The cultured model of microencapsulated HGC SGC9701 had been established,and gene expression was stable. Key words: Gastric carcinoma; Microencapsulation; Bromodeoxyuridine; Proliferating cell nuclear antigen; Vascular endothelial growth factor

Galectin-1 is up-regulated by RASSF1A gene in human gastric carcinoma cell line SGC7901

We have previously shown that overexpression of RASSF1A inhibits the growth of human gastric cancer SGC7901 cells, but the underlying mechanism remains unknown. In this study, the differential protein expression by RASSF1A gene in human gastric cancer cell line SGC7901 was determined by 2-D gel electrophoresis combined with matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and bioinformatics. Differential expression analysis of the protein profiles by RASSF1A gene identified a total of 35 protein spots, of which 10 were up-regulated and 25 were down-regulated. Eight proteins were identified by MALDI-TOF MS: Galectin-1, TRP-14, ACBP, PSMB5, PSMB4, TIM, vimentin, CD79α. RASSF1A up-regulated the mRNA expression of Galectin-1, TRP-14, ABCP in SGC7901. RASSF1A also led to an increased expression of Galectin-1 protein in SGC7901 confirmed by western blotting and immunocytochemistry analysis. RASSF1A inhibited the activity of NF-κB in SGC7901 cells. These data indicated that Galectin-1 may be playing a role in RASSF1A signaling in SGC7901.

Intestinal metabolite compound K of panaxoside inhibits the growth of gastric carcinoma by augmenting apoptosis via Bid‐mediated mitochondrial pathway

Compound K (20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol, CK), an intestinal bacterial metabolite of panaxoside, has been shown to inhibit tumour growth in a variety of tumours. However, the mechanisms involved are largely unknown. We use human gastric carcinoma cell lines BGC823, SGC7901 and human gastric carcinoma xenograft in nude mice as models to study the mechanisms of CK in gastric cancers. We found that CK significantly inhibits the viabilities of BGC823 and SGC7901 cells in dose- and time-dependent manners. CK-induced BGC823 and SGC7901 cells apoptosis and cell cycle arrest in G2 phase by up-regulation of p21 and down-regulation of cdc2 and cyclin B1. Further studies show that CK induces apoptosis in BGC823 and SGC7901 cells mainly through mitochondria-mediated internal pathway, and that CK induces the translocation of nuclear Bid to mitochondria. Finally, we found that CK effectively inhibited the tumour formation of SGC7901 cells in nude mice. Our studies show that CK can inhibit the viabilities and induce apoptosis of human gastric carcinoma cells via Bid-mediated mitochondrial pathway.

Identification of Proteins Associated With let-7a in Gastric Carcinoma Cell Line SGC-7901 by Proteomics*

In order to elucidate the mechanisms of let-7a down-regulation in pathogenesy of gastric carcinoma,proteins associated with the function of let-7a were detected in high throughout screening.The cell line of SGC-7901 stablely overexpressing let-7a was successfully established by gene clone.Two-dimensional gel electrophoresis(2-DE) was used to separate the total proteins of SGC-7901/let-7a,SGC-7901/EV and SGC-7901,and PDQuest software was applied to analyze 2-DE images.Ten differential protein spots were identified by MALDI-TOF-MS,and they may be the proteins associated with let-7a function.The overexpressed proteins included antioxidant protein 2,insulin-like growth factor binding protein 2,protein disulfide isomerase A2,C-1-tetrahydrofolate synthase,cyclin-dependent kinase inhibitor1 and Rho-GTPase activating protein 4.The underexpressed proteins were consisted of S-phase kinase-associated protein 2,platelet membrane glycoprotein,fibronectin and Cks1 protein.Furthermore,the differential expression levels of the partial proteins(CDKN1,Spk2 and fibronectin) were confirmed by Western blot analysis.The 10 differentially expressed proteins could be divided into groups based on their functions: signal transduction,chaperone,transcription and translation,metabolism and cytoskeleton,which were involved in cell cycle,the transcription regulation,cell adherence,cellular metabolism and so on.The data suggest that these differential proteins may be associated with the function of let-7a in gastric carcinoma,and will be valuable for further to study the mechanisms of let-7a down-regulation in pathogenesy of gastric carcinoma.

Effects of transfected gut-enriched Kriippel-like factor on growth of human gastric carcinoma cell line SGC-7901 and its xenograft in nude mice

Objective To investigate the antitumour effects of transfected gut-enriched Kruppellike factor(GKLF) on human gastric carcinoma cell line SGC-7901 in vitro and in vivo. Methods The expression of GKLF mRNA and protein in human gastric carcinoma cell line SGC-7901 were detected before and after transfection by real-time fluorescence quantitative PCR and Western blot,respectively. Proliferation and invasion in SGC-7901 were measured respectively by MTT assay, flow cytometry, colony formation assay and cell invasion assay after transfected with GKLF. The growth of xenograft was observed, the microvessel density(MVD) of xenograft tissue was determined by immunohistochemistry. Results The GKLF mRNA and protein in SGC-7901 were overexpressed after transfected with GKLF(P＜0.05). The proliferative speed of SGC7901-pcDNA3.1-GKLF group was markedly lower than that of SGC-7901 and SGC7901-pcDNA3.1 groups (P＜0.05). Transfected with GKLF caused part of the G0/G1 arrest, decreased clone formation rate and the invasion ability (P＜0.05). The growth speed of xenograft in SGC7901-pcDNA3.1-GKLF group was lower, the weight and MVD of xenograft tissue in SGC7901-pcDNA3. 1-GKLF group were less (P＜ 0. 05).Conclusion Transfected with GKLF maysuppress proliferation and invasion in human gastric carcinoma cell line SGC-7901, inhibit the growth and the angiogenesis of xenograft in nude mice. Key words: Gut-enriched Kruppel-like transcription factors; Transfection; Stomach neoplasms; Cell line, tumor; Mice, nude; Neoplasm transplantation

Genistein Induced Apotosis in Human Gastric Carcinoma Cells

The apoptosis in gastric cancer cells induced by genistein and the relationship between this apoptosis and expression of NF-κB and Caspase-3 were studied. In vitro experiments, MTT assay was used to determine the cell growth inhibitory rate. Transmission fluorescence microscope, transmission electron microscopy, DNA-fragment assay were used to qualitively detect the apoptosis status of gastric cancer line SGC-7901 before and after the genistein treatment. Immunohistochemical staining and Western Blotting were performed to detect the expression of gene NF-κB and Caspase-3. The results showed that genistein inhibited the growth of gastric carcinoma cell line SGC-7901 in a dose-and time-dependent manner. Genistein induced SGC-7901 cells to undergo apoptosis with typically apoptotic characteristics, including morphological changes of chromatin condensation, chromatin crescent formation, nucleus fragmentation and apoptotic body formation. Genistein could reduce the expression of gene NF-κB, and improve the expression of gene Caspase-3.

The G1 phase arrest and apoptosis by intrinsic pathway induced by valproic acid inhibit proliferation of BGC-823 gastric carcinoma cells

Recent studies have demonstrated that the histone deacetylation level was closely related to the genesis and development of tumors. Thus, activating histone acetyltransferases and/or suppressing histone deacetylases (HDACs) can become an approach for tumor chemotherapy. The histone acetylation regulation often results in the inhibition of cell proliferation, induction of cell apoptosis or differentiation, and cell cycle arrest in G1 phase. It has been demonstrated recently that the traditional anticonvulsant valproic acid was an efficient class I HDAC inhibitor (HDACI); however, its antitumor effect and mechanisms on gastric cancers so far has not been elucidated clearly. In the present study, gastric carcinoma cell lines BGC-823, HGC-27, and SGC-7901 were cultured with valproic acid (VPA) in vitro. The cell morphology was observed by invert microscope, the proliferation was detected by MTT assay, the apoptosis and cell cycle were analyzed by flow cytometry assay with Annexin V/PI and PI, the activities and protein expressions of Caspase 3, Caspase 8, Caspase 9 of BGC-823 cells were detected by spectrophotometry and indirect immunofluorescence technique, respectively. The protein expressions of Cyclin A, Cyclin D1, Cyclin E, P21(Waf/cip1) of BGC-823 cells were analyzed by indirect immunofluorescence assay, and messenger ribonucleic acid (mRNA) expressions were detected by RT-PCR assay. The results showed that the proliferation of three kinds of gastric carcinoma cells could be inhibited obviously by VPA, which was related to the apoptosis induction and cell cycle arrest in G1 phase. The intrinsic pathway (cytochrome C pathway) was chiefly involved in the mechanism of apoptosis, which was indicated by activation of Caspase 9 and Caspase 3. The extrinsic pathway was partially involved, with slight activation of Caspase 8. The mechanism underlying its effect on cell cycle arrest in G1 phase induction was due to the upregulation of P21(Waf/cip1), Mad1 expression and downregulation of Cyclin A, c-Myc expression.

Blocking of PI3K/AKT induces apoptosis by its effect on NF-κB activity in gastric carcinoma cell line SGC7901

NF-κB plays an important role in many aspects of tumorigenesis and tumor progression by its antiapoptosis effect. Hence, NF-κB has been regarded as a therapeutic target in cancer, because inhibition of NF-κB not only induces enhancing apoptosis but also causes increasing sensitivity to radiation or chemotherapy in several tumor cells. The activation of NF-κB is presumed to be associated with PI3K/Akt signal pathway in gastric carcinoma, but the underlying molecular mechanism remains unclear. Our work demonstrates that blocking PI3K/Akt by LY294002 inhibits the NF-κB activity with significantly increased apoptosis in gastric cancer cell. Furthermore, when the cells were pretreated with IKK siRNA and/or IκB siRNA then exposed to LY294002, the results suggest that the regulatory significantly increased apoptosis in gastric cancer cell. Furthermore, when the cells were pretreated, effect of PI3K/AKT on NF-κB activity is associated with the influence of PI3K/AKT on IKK/IκB. The apoptosis induced by blocking PI3K/AKT might be ascribed to inhibition of NF-κB activity through IKK/IκB at least in part.