Human Gastric Cancer SGC-7901 Cells Research Articles

Grifola frondosa Glycoprotein GFG-3a Arrests S phase, Alters Proteome, and Induces Apoptosis in Human Gastric Cancer Cells

ABSTRACTGFG-3a is a novel glycoprotein previously purified from the fermented mycelia of Grifola frondosa with novel sugar compositions and protein sequencing. The present study aims to investigate its effects on the cell cycle, differential proteins expression, and apoptosis of human gastric cancer SGC-7901 cells. Our findings revealed that GFG-3a induced the cell apoptosis and arrested cell cycle at S phase. GFG-3a treatment resulted in the differential expression of 21 proteins in SGC-7901 cells by upregulating 10 proteins including RBBP4 associated with cell cycle arrest and downregulating 11 proteins including RUVBL1, NPM, HSP90AB1, and GRP78 involved in apoptosis and stress response. qRT-PCR and Western blot analysis also suggested that GFG-3a could increase the expressions of Caspase-8/-3, p53, Bax, and Bad while decrease the expressions of Bcl2, Bcl-xl, PI3K, and Akt1. These results indicated that the stress response, p53-dependent mitochondrial-mediated, Caspase-8/-3-dependent, and PI3k/Akt pathways were involved in the GFG-3a-induced apoptosis process in SGC-7901 cells. These findings might provide a basis to prevent or treat human gastric cancer with GFG-3a and understand the tumor-inhibitory molecular mechanisms of mushroom glycoproteins.

Construction of a RNAi lentiviral vector targeting ARK5 gene and its effect on the biological behavior of gastric cancer SGC7901 cells

To construct a RNA interference lentiviral vector aimed at human ARK5 (AMPK-related protein kinase 5) gene and explore its effect on the biologic behavior of human gastric cancer SGC7901 cells. Targeting human ARK5 mRNA coding sequence, we designed three specific short hairpin RNAs (shRNAs) and constructed the lentiviral vector, then infected human gastric cancer SGC7901 cells with this vector. Afterwards, we used qPCR and Western blot for detecting the silencing effect on ARK5 gene, MTT colorimetric assay to measure the cell proliferation, cell scratch test for cell migration and Transwell for cell invasion, and flow cytometry analysis for apoptosis in cells treated with glucose starvation and TNF-α. Sequencing proved that the recombinant lentiviral vector containing ARK5-shRNA-3 was constructed successfully. Real time fluorescent quantitative PCR assay showed that the expression abundance of ARK5 gene in the normal control group, negative control group and ARK5-shRNA-3 infected group were 1.002+ 0.082, 1.001+ 0.050 and 0.140+ 0.003, respectively, showing a statistically significant difference (P<0.01). Cell scratch test showed that the cell migration rate of ARK5-shRNA-3 infected group was (38.5+ 4.3)%, significantly lower than that of the normal control group [(72.4+ 6.4)%] and negative control group [(75.1+ 7.1)%, P<0.01]. The results of Transwell test showed that the number of penetrating cells in the normal control group, negative control group and ARK5-shRNA-3 transfection group were 257.4±12.3, 245.7±11.6, 112.5±7.8, with a significant difference (P<0.01). After glucose starvation and TNF-α-treatment for 24 h, the cell death rate of the normal control group, negative control group and ARK5-shRNA-3 group were (11.7±3.2)%, (12.3±2.6)% and (30.8±4.3)%, respectively, showing that the cell apoptosis rate of ARK5-shRNA-3 transfected group was significantly higher than that of the normal control and negative control groups (P<0.01). We have successfully constructed a recombinant lentiviral vector which can efficiently silence ARK5 gene. Using it we can inhibit the proliferation, migration, invasion of tumor cells, and promote cell apoptosis under the condition of TNF-α treatment and glucose starvation.

MicroRNA-524-5p suppresses the growth and invasive abilities of gastric cancer cells.

Previous studies have demonstrated that microRNAs (miRNAs) are associated with tumor development and progression. miRNA-524-5p (miR-524-5p) has been reported to be involved in the development and progression of several types of cancer, but its role in gastric cancer has not been fully elucidated to date. Therefore, the aim of the present study was to investigate the expression levels and function of miR-524-5p in human gastric cancer. The expression levels of miR-524-5p were assessed in gastric cancer specimens and cell lines, including MKN-45, SGC-7901 and MGC-803 cell lines and gastric epithelial mucosa GES-1 cells, using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell proliferation and cell apoptosis assays and invasion analysis in gastric cancer cell lines were performed to evaluate the effects of miR-524-5p on gastric cancer cells in vitro. The expression levels of matrix metallopeptidase (MMP)-2 and MMP-9 were determined by RT-qPCR and western blot analysis. The expression of miR-524-5p was significantly decreased in gastric cancer tissues and cell lines. Additionally, the results of the in vitro experiments demonstrated that overexpression of miR-524-5p inhibited cell proliferation and invasion, and promoted cell apoptosis in gastric cancer cells. Human gastric cancer SGC-7901 and MGC-803 cell lines transfected with miR-524-5p exhibited reduced expression levels of MMP-2 and MMP-9. Taken together, the results of the present study indicated that miR-524-5p may function as a novel tumor suppressor gene in gastric cancer, and may serve as a biomarker and therapeutic target for the treatment of gastric cancer.

Upregulation of microRNA-31 targeting integrin α5 suppresses tumor cell invasion and metastasis by indirectly regulating PI3K/AKT pathway in human gastric cancer SGC7901 cells.

To verify the hypothesis that upregulation of microRNA-31 (miR-31) targeting integrin α5 (ITGA5) suppresses tumor cell invasion and metastasis by indirectly regulating phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway in human SGC7901 gastric cancer (GC) cells. The miRTarBase was used to predict whether ITGA5 is the target gene of miR-31, which was further confirmed by luciferase reporter gene assay. The SGC7901 GC cells were divided into five groups including the blank, miR-31 mimic, miR-31 mimic control, miR-31 inhibitor, and miR-31 inhibitor control groups. Reverse transcriptase-polymerase chain reaction (RT-PCR), western blotting, cell scratch test, and transwell assays were respectively performed in our study. TGA5 was found as the target gene of miR-31. The RT-PCR detection revealed that, compared with the blank group, ITGA5 messenger RNA (mRNA) expression decreased in the miR-31 mimic group, but increased in the miR-31 inhibitor group. The western blotting examination suggested that the expressions of ITGA5, PI3K, and AKT proteins reduced in the miR-31 mimic group, but enhanced in the miR-31 inhibitor group when compared to the blank group, respectively. The cell scratch and transwell assays indicated that the miR-31 expressions were negatively associated with GC cell migration and invasion. Besides, RT-PCR combined with western blotting demonstrated that the miR-31 expressions were higher in the normal tissues than those in the GC tissues, while the ITGA5 mRNA and protein showed lower expression in the normal tissues than they did in the GC tissues. Our study concluded that upregulation of miR-31 targeting ITGA5 may suppress tumor cell invasion and metastasis by indirectly regulating PI3K/AKT signaling pathway in human SGC7901 GC cells.

ITRAQ-Based Proteomic Analysis of Ginsenoside F2 on Human Gastric Carcinoma Cells SGC7901.

Ginsenoside F2 (F2), a protopanaxdiol type of saponin, was reported to inhibit human gastric cancer cells SGC7901. To better understand the molecular mechanisms of F2, an iTRAQ-based proteomics approach was applied to define protein expression profiles in SGC7901 cells in response to lower dose (20 μM) and shorter duration (12 hour) of F2 treatment, compared with previous study. 205 proteins were screened in terms of the change in their expression level which met our predefined criteria. Further bioinformatics and experiments demonstrated that F2 treatment downregulated PRR5 and RPS15 and upregulated RPL26, which are implicated in ribosomal protein-p53 signaling pathway. F2 also inhibited CISD2, Bcl-xl, and NLRX1, which are associated with autophagic pathway. Furthermore, it was demonstrated that F2 treatment increased Atg5, Atg7, Atg10, and PUMA, the critical downstream effectors of ribosomal protein-p53 signaling pathway, and Beclin-1, UVRAG, and AMBRA-1, the important molecules in Bcl-xl/Beclin-1 pathway. The 6 differentially abundant proteins, PRR5, CISD2, Bcl-xl, NLRX1, RPS15, and RPL26, were confirmed by western blot. Taken together, ribosomal protein-p53 signaling pathway and Bcl-xl/Beclin-1 pathway might be the most significantly regulated biological process by F2 treatment in SGC7901 cells, which provided valuable insights into the deep understanding of the molecular mechanisms of F2 for gastric cancer treatment.

Autophagy Protects from Raddeanin A-Induced Apoptosis in SGC-7901 Human Gastric Cancer Cells.

Raddeanin A (RA) is an extractive from Anemone raddeana Regel, a traditional Chinese medicine. The aim of this study is to assess the efficacy of RA against human gastric cancer (GC) cells (SGC-7901) and explore its mechanism. MTT assay showed that RA inhibition of proliferation of SGC-7901 cells increased in a dose-dependent manner. Flow cytometry analysis and Hoechst 33258 staining showed that RA induced apoptosis on SGC-7901 cells. Meanwhile, it induced autophagy. Western blotting analysis showed that the RA induces apoptosis and autophagy by activating p38 MAPK pathway and inhibiting mTOR pathway. Further studies showed that autophagy inhibition could protect from RA-induced apoptosis in SGC-7901 cells. In conclusion, RA can induce SGC-7901 cell apoptosis and autophagy by activating p38 MAPK pathway. And autophagy can protect SGC-7901 cells from apoptosis induced by RA.

Sodium Selenite Inhibits Proliferation of Gastric Cancer Cells by Inducing SBP1 Expression.

Selenium is an essential trace element with an inhibitory effect on many types of human cancers, including gastric cancer. Selenium-binding protein 1 (SBP1) has been shown as a possible mediator of selenium's anti-cancer functions. Indeed, SBP1 was downregulated in gastric cancer, which is related with poor prognosis. However, the molecular mechanisms underlying the anti-tumor effects of SBP1 remain poorly understood. In this study, we aimed to assess the effects of selenium and/or SBP1 on the proliferation of gastric cancer cells. We used SGC7901 and N87 human gastric cancer cell lines and nude mice carrying subcutaneously implanted SGC7901 cells. Treatment with sodium selenite for 48 h caused the inhibition of cell proliferation and the increase in apoptosis of SGC7901 and N87 cells. Furthermore, sodium selenite increased the expression level of SBP1 and decreased the levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and the Wnt pathway components and its downstream targets, including β-catenin, GSK-3β, c-myc and cyclinD1 in these cell lines. However, these effects of sodium selenite were attenuated in SGC7901 and N87 cells by knockdown of SBP1 expression. Thus, the sodium selenite-induced SBP1 expression is associated with the inhibition of cell proliferation and with the induced apoptosis. Importantly, sodium selenite treatment retarded the growth of the transplanted SGC7901 cells in nude mice, with the induction of SBP1 expression, which was associated with the decrease of Nrf2 expression and the inactivation of the Wnt/β-catenin signaling pathway. We suggest that sodium selenite may have a potential application in gastric cancer treatment.

Interleukin-8: A potent promoter of angiogenesis in gastric cancer.

Angiogenesis is a critical process in the development of tumor malignancy and occurs at various stages of tumor progression. Interleukin-8 (IL-8) is a pro-angiogenic factor produced by tumor-infiltrating macrophages that has been revealed to facilitate the development of angiogenesis in various cancers. However, whether IL-8 activates angiogenesis in gastric cancer remains unclear. The present study investigated the effect of IL-8 on the migration and canalization capacities of human umbilical vein endothelial cells (HUVECs). In addition, the protein and messenger RNA (mRNA) expression of selected angiogenesis markers, consisting of vascular endothelial growth factor (VEGF)-A, VEGF receptor (VEGFR)-1 and VEGFR-2, were assessed in the HUVECs. The HUVECs were co-cultured with human gastric cancer SGC7901 cells and exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1.0 ng/ml). The migration and canalization abilities of the cells were detected by Transwell chamber and tube formation assays. Protein expression was detected using immunofluorescence and western blot analysis, and mRNA levels were assessed using reverse transcription quantitative polymerase chain reaction. The protein and mRNA levels of VEGF-A, VEGFR-1 and VEGFR-2 were measured in HUVECs cultured for 24 h. IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly promoted HUVEC cell migration (P=0.005, P=0.001 and P<0.001, respectively) and tube formation (P=0.039, P=0.003 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-A (P<0.001) and VEGFR-2 (P=0.034, P<0.001, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-1 (P=0.037 and P=0.002, respectively). Similarly, IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGF-A (P=0.046, P=0.001 and P<0.001, respectively) and VEGFR-1 (P=0.042, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGFR-2 (P=0.003, P=0.005, P<0.001 and P<0.001, respectively). In conclusion, IL-8 may be a potent promoter of angiogenesis in gastric cancer.

Chelidonine induces mitotic slippage and apoptotic-like death in SGC-7901 human gastric carcinoma cells.

The aim of the present study was to investigate the effect of chelidonine on mitotic slippage and apoptotic-like death in SGC-7901 human gastric cancer cells. The MTT assay was performed to detect the antiproliferative effect of chelidonine. Following treatment with chelidonine (10 µmol/l), the ultrastructure changes in SGC-7901, MCF-7 and HepG2 cells were observed by transmission electron microscopy. The effects of chelidonine on G2/M phase arrest and apoptosis of SGC-7901 cells were determined by flow cytometry. Indirect immunofluorescence assay and laser scanning confocal microscopy (LSCM) were used to detect the phosphorylation level of histone H3 (Ser10) and microtubule formation was detected using LSCM following immunofluorescent labeling. Subsequent to treatment with chelidonine (10 µmol/l), expression levels of mitotic slippage-associated proteins, including BUB1 mitotic checkpoint serine/threonine kinase B (BubR1), cyclin-dependent kinase 1 (Cdk1) and cyclin B1, and apoptosis-associated protein, caspase-3 were examined by western blotting at 24, 48 and 72 h. The half maximal inhibitory concentration of chelidonine was 23.13 µmol/l over 48 h and chelidonine induced G2/M phase arrest of cells. The phosphorylation of histone H3 at Ser10 was significantly increased following treatment with chelidonine for 24 h, indicating that chelidonine arrested the SGC-7901 cells in the M phase. Chelidonine inhibited microtubule polymerization, destroyed microtubule structures and induced cell cycle arrest in the M phase. Giant cells were observed with multiple micronuclei of varying sizes, which indicated that following a prolonged arrest in the M phase, the cells underwent mitotic catastrophe. Western blotting demonstrated that the protein expression levels of BubR1, cyclin B1 and Cdk1 decreased significantly between 48 and 72 h. Low expression levels of BubR1 and inactivation of the cyclin B1-Cdk1 complex results in the cells being arrested at mitosis and leads to mitotic slippage. In addition, apoptotic morphological changes in multinucleated cells were observed, the apoptosis rates increased gradually with administration of chelidonine in a time-dependent manner and the protein levels of caspase-3 increased significantly between 24 and 72 h. Thus, chelidonine induces mitotic slippage, and apoptotic-like death occurs in SGC-7901 cells undergoing mitotic catastrophe. Gastric cancer is a common malignancy, and ranks second in overall cancer-associated mortalities worldwide. The present study demonstrated that chelidonine induces M phase arrest and mitotic slippage of SGC-7901 human gastric carcinoma cells via downregulating the expression of BubR1, Cdk1 and cyclin B1 proteins. With the prolongation of chelidonine treatment, the giant cells with multiple micronuclei underwent mitotic slippage and were maintained in the G1 phase and did not survive. A number of multinucleated cells underwent apoptosis via a caspase-dependent signaling pathway. The current study proposes that chelidonine induces mitotic slippage and apoptotic-like death of SGC-7901 cells.

A ruthenium(II) complex binds protein and inhibits proliferation and induces apoptosis in human gastric cancer SGC-7901 cells

A new Ru(II) complex, [Ru(ttbpy)2(NMIP)](ClO4)2 (ttbpy=4,4′-di-tert butyl-2,2′-bipyridine, NMIP=2′-(2″-nitro-3″,4″-methylenedioxyphenyl)imidazo[4′,5′-f][1,10]-phenanthroline), has been synthesized and characterized by elemental analysis, ESI-MS and 1H NMR spectroscopy. The complex induces a decrease in fluorescent intensity upon binding to protein bovine serum albumin (BSA). The cytotoxic activity of the ligand and the complex against A549, BEL-7402, HeLa, PC-12, SGC-7901, SiHa and LO2 (normal) cell lines was investigated by the MTT method. The complex show high cytotoxicity toward BEL-7402 (IC50=5.0±1.2μM), HeLa (IC50=5.7±1.8μM) and SGC-7901 (IC50=4.9±0.2μM) cell lines. The cellular uptake indicates that the complex can enter into the cytoplasm and accumulate in the cell nuclei. In addition, the complex can increase the reactive oxygen species levels and induce a decrease in the mitochondrial membrane potential in SGC-7901 cells. The cell cycle arrest shows that the complex inhibited the cell growth in SGC-7901 cells at the G2/M phase.

Upregulation of microRNA-375 increases the cisplatin-sensitivity of human gastric cancer cells by regulating ERBB2.

Resistance to chemotherapy is a major challenge in the effective treatment of patients with gastric cancer; however, the mechanisms underlying chemoresistance in gastric cancer cells are yet to be elucidated. MicroRNAs (miRNAs) have previously been associated with cancer progression and sensitivity to chemotherapy; therefore, the present study aimed to identify miRNAs that may influence the sensitivity of human gastric cancer cells to cisplatin (DDP) treatment. Initially, miRNAs that were differentially expressed between the DDP-sensitive SGC7901 human gastric cancer cell line and DDP-resistant SGC7901/DDP cell line were identified using high-throughput sequencing technology. miRNA-375 (miR-375), which was shown to be downregulated in the SGC7901/DDP cells, has previously been associated with numerous types of cancer; however, to the best of our knowledge, a role for miR-375 in the DDP-sensitivity of gastric cancer cells has yet to be explored. In the present study, the expression levels of miR-375 were significantly downregulated in the SGC7901/DDP cells, as compared with the SGC7901 cells, as demonstrated by reverse transcription-quantitative polymerase chain reaction. In addition, upregulation of miR-375 significantly enhanced the anti-proliferative and apoptosis-inducing effects of DDP, whereas downregulation of miR-375 decreased these effects. Subsequently, western blot analysis demonstrated that upregulation of miR-375 in the SGC7901/DDP cells increased their sensitivity to DDP treatment via regulating the protein expression levels of erb-b2 receptor tyrosine kinase 2 and phosphorylated-Akt. The results of the present study indicate that the expression levels of miR-375 may influence the sensitivity of human gastric cancer cells to the effects of DDP; thus suggesting that a combination of miR-375 regulation and DDP may be considered a novel strategy in the treatment of patients with chemoresistant gastric cancer.

Purification and characterization of a novel polysaccharide–peptide complex from Clinacanthus nutans Lindau leaves

A novel polysaccharide–peptide complex CNP-1-2 with molecular weight of 9.17×104Da was obtained from Clinacanthus nutans Lindau leaves by hot water extraction, ethanol precipitation, and purification with Superdex 200 and DEAE-Sepharose Fast Flow column chromatography. CNP-1-2 exhibited the highest growth inhibitory effect on human gastric cancer cells SGC-7901 with inhibition ratio of 92.34% and stimulated activation of macrophages with NO secretion level of 47.53μmol/L among the polysaccharide fractions. CNP-1-2 comprised approximately 87.25% carbohydrate and 9.37% protein. Monosaccharide analysis suggested that CNP-1-2 was composed of l-rhamnose, l-arabinose, d-mannose, d-glucose and d-galactose with a molar ratio of 1.30:1.00:2.56:4.95:5.09. Methylation analysis, FT-IR, and 1H NMR spectroscopy analysis revealed that CNP-1-2 might have a backbone consisting of 1,4-linked Glcp, 1,3-linked Glcp, 1,3-linked Manp, 1,4-linked Galp, 1,2,6-linked Galp and 1,2,6-linked Galp. Its side chain might be composed of 1-linked Araf, 1,6-linked Galp and 1-linked Rhap residues. AFM (atomic force micrograph) analysis revealed that CNP-1-2 had the molecular aggregation along with branched and entangled structure.

TIPE2 functions as a metastasis suppressor via negatively regulating β-catenin through activating GSK3β in gastric cancer.

Tumor necrosis factor (TNF)-α-induced protein 8-like 2 (TNFAIP8L2, TIPE2) is a novel anti-inflammatory factor involved in maintaining immune homeostasis. Accumulating evidence has also shown that TIPE2 displays tumor-suppressive effects in several tumor types. Previous studies revealed that TIPE2 inhibits hepatocellular carcinoma metastasis by repressing Ral and Rac1 GTPases. However, its antimetastatic activity and underlying mechanism in other human cancers is largely unknown. We investigated TIPE2 in AGS, HGC-27 and SGC-7901 human gastric cancer cells compared with GES-1 normal human gastric mucous epithelial cells. We demonstrated that TIPE2 was expressed in GES-1 gastric mucous epithelial cells but lost in all three types of gastric cancer cells. We then performed a gain-of-function study by adenovirus-mediated TIPE2 overexpression (AdVTIPE2) and investigated the effects of TIPE2 on migration and invasion of AGS human gastric cancer cells. Wound healing and Transwell invasion assays showed that forced expression of TIPE2 markedly suppressed the gastric cancer cell migration and invasion in vitro. Mechanistically, TIPE2 remarkably reduced the total levels of pAKT, pGSK3β and β-catenin as well as the nuclear level of β-catenin in gastric cancer cells. The TIPE2-elicited antimetastatic effect in gastric cancer was closely associated with the inhibition of AKT signaling and enhancement of GSK3β activity followed by the degradation and decreased translocation to nucleus of β-catenin. These results provide the first compelling evidence that TIPE2 suppresses gastric cancer metastasis via downregulating β-catenin signaling through inhibiting AKT and activating GSK3β, indicating that TIPE2 is a promising therapeutic target for human gastric cancer metastasis.

Geldanamycin induces apoptosis in human gastric carcinomas by affecting multiple oncogenic kinases that have synergic effects with TNF-related apoptosis-inducing ligand.

The aim of the present study was to evaluate the effect of geldanamycin (GA) on the treatment of human gastric carcinomas and to investigate the molecular mechanism that provides the basis for the combination of GA with the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induction strategy. The expression of target proteins at the mRNA level was determined using reverse transcription-polymerase chain reaction (RT-PCR), and apoptosis was evaluated with the terminal deoxynucleotidyl transferase mediated digoxigenin-dUTP nick-end labeling and Annexin V/propidium iodide (PI) staining methods. Phosphorylation of targeted kinases was studied using immunocytochemistry methods, and malignant phenotypes were studied using in vitro assays. GA treatment inhibits proliferation, migration and invasion, and induces apoptosis in human gastric cancer SGC-7901 cells, most likely by decreasing the expression of B-RAF and by phosphorylation of protein kinase B (AKT) and ERK. The inhibitory role of AKT in TRAIL regulation holds considerable potential for achieving a synergic effect in clinical therapy, using a combination of GA treatment and TRAIL induction. The present study provides a basis for the future application of heat shock protein 90 (Hsp90) inhibitors, such as GA, in the clinical treatment of gastric cancer, particularly in combination therapies with TRAIL inducers.

In vitro analysis of the role of the mitochondrial apoptosis pathway in CSBE therapy against human gastric cancer.

The caper plant (Capparis spinosa L.) was a common Uyghur folk medicine, and is a member of the Capparidaceae family. In a previous study, the n-butanol extract of C. spinosa L. (CSBE) was demonstrated to exert anti-tumor activity; however, the underlying mechanism is currently not understood. The present study aimed to elucidate the mechanism underlying the CSBE-induced mitochondrial apoptotic pathway, in order to investigate the anti-tumor effects of this plant extract. CSBE-induced apoptosis of the SGC-7901 human gastric cancer cell line was observed, and alterations in the expression levels and localization of initiators, markers, and executors of the mitochondrial apoptosis pathway were analyzed. Following treatment of SGC-7901 cells with CBSE, proliferation was inhibited and apoptosis was induced; and these effects were associated with mitochondrial membrane potential disruption, cytochrome c release into the cytoplasm, and caspase-9 and caspase-3 activation. CSBE may have induced SGC-7901 cell apoptosis by upregulating the expression of B-cell lymphoma-2 (BCL-2)-associated X protein, and downregulating the expression of BCL-2. The results of the present study suggested that CSBE may induce SGC-7901 cell apoptosis via activation of the mitochondrial apoptosis pathway.

Involvement of nuclear receptor RZR/RORγ in melatonin-induced HIF-1α inactivation in SGC-7901 human gastric cancer cells.

The melatonin nuclear receptor is an orphan member of the nuclear receptor superfamily RZR/ROR, which consists of three subtypes (α, β and γ), suggesting that immunomodulatory and antitumor effects through the intracellular action of melatonin depend on nuclear signaling. In the present study, the biological mechanisms of melatonin were elucidated in association with the RZR/RORγ pathway in SGC-7901 human gastric cancer cells under hypoxia. Melatonin suppressed the activity of RZR/RORγ and SUMO-specific protease 1 (SENP1) signaling pathway, which is essential for stabilization of hypoxia‑inducible factor-1α (HIF‑1α) during hypoxia. Furthermore, melatonin inhibited the stability of HIF-1α in a time-and conce-ntration-dependent manner in SGC-7901 human gastric cancer cells during hypoxia. Consistently, siRNA-RZR/RORγ effectively blocked the expression of SENP1, HIF-1α and vascular endothelial growth factor (VEGF) production in SGC-7901cells under hypoxia, suggesting the role of nuclear receptor RZR/RORγ in melatonin-inhibited HIF-1α and VEGF accumulation. Moreover, siRNA RZR/RORγ obviously antagonized to inhibit the action of the gastric cancer cell proliferation by melatonin. Our findings suggest that melatonin suppresses HIF-1α accumulation and VEGF generation via inhibition of melatonin nuclear receptor RZR/RORγ in SGC-7901cells under hypoxia.

Apoptosis induced by farrerol in human gastric cancer SGC-7901 cells through the mitochondrial-mediated pathway.

Farrerol, a typical flavanone isolated from the Chinese medicinal plant Rhododendron dauricum L., has been found to show various biological activities. However, to the best of our knowledge, its inhibitory actions against cancer cells have not been reported as yet. Therefore, the present study aimed to investigate the cytotoxic and apoptotic effects of farrerol on human gastric cancer SGC-7901 cells. Farrerol showed a 50% inhibition of SGC-7901 cell growth at a concentration of 40.4 μmol/l for 24 h according to MTT assays. The cell morphology results indicated that SGC-7901 cells treated with farrerol showed several features of apoptotic cell death, which was also confirmed by the Annexin-V FITC/PI double-staining assay. Further studies showed that farrerol treatment induced the attenuation of mitochondrial membrane potential, accompanied by the release of Cyt-c and the activation of caspase-9 and caspase-3. Furthermore, farrerol decreased the gene expression of Bcl-2, whereas the gene expression level of Bax was found to increase after farrerol treatment. These combined results indicated that farrerol can induce apoptosis through a mitochondrial-mediated pathway.

Low-dose interleukin-8 induces the adhesion, migration and invasion of the gastric cancer SGC-7901 cell line.

Interleukin-8 (IL-8), an important inflammatory cytokine, is strongly associated with gastric cancer development and metastasis. High-dose (>1 ng/ml) IL-8 has been revealed to promote the adhesion, migration and invasion of human gastric cancer SGC-7901 cells in a dose-dependent manner. However, the IL-8 level produced by gastric cells is marginal, at even less than 1 ng/ml. It is unclear whether low-dose IL-8 also induces these capacities. In the present study, the effect of low-dose IL-8 on the adhesion, migration and invasion of the SGC-7901 cell line and the underlying molecular mechanism with regard to cluster of differentiation 44 (CD44) were investigated. The SGC-7901 cells were exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1 ng/ml) in vitro. The adhesion of the SGC-7901 cells to fibronectin, an extracellular matrix component, was then detected by cell counting kit 8 assay. Migration and invasion abilities were evaluated by wound scratch and Transwell chamber assays. In addition, protein and mRNA levels of CD44 were measured using immunofluorescence and western blotting, and quantitative polymerase chain reaction, respectively, in cells cultured for 72 h. Following the exposure of the SGC-7901 cells to the various low doses of IL-8, the cell adhesion, migration and invasion capacities were promoted by IL-8, but not in a significant dose-dependent manner. Low-dose IL-8 upregulated the protein and mRNA expression of CD44. In conclusion, low-dose IL-8 potently induces the adhesion, migration and invasion of SGC-7901 cells, and the regulation of CD44 expression is one of the potential molecular mechanisms involved.

Paclitaxel combined with harmine inhibits the migration and invasion of gastric cancer cells through downregulation of cyclooxygenase-2 expression.

Cyclooxygenase-2 (COX-2) has a critical role in the invasiveness and metastasis of gastric cancer. In addition, paclitaxel (PTX) and harmine (HM) were reported to be potential therapeutic drug candidates for cancer therapy; however, the synergistic antitumor effect of PTX and HM combined treatment on the human gastric cancer cells remains to be elucidated. The aim of the present study was to evaluate the effects of PTX and/or HM on the cell migration and invasion in two human gastric cancer cell lines, SGC-7901 and MKN-45. MTT assay was used to detect the growth inhibition induced by PTX and HM. The Transwell assay was employed to assess the effects of PTX and HM on the cell migration and invasion. The expression levels of COX-2 and matrix metalloproteinase-9 (MMP-9) were analyzed by western blot analysis. The results demonstrated that PTX and HM inhibited cell proliferation in a dose-dependent manner. Individually PTX and HM were able to inhibit the migration and invasion of two human gastric cancer cells; however, the combination of PTX and HM exerted synergistic effects on migration and invasion inhibition, with downregulation of COX-2 and matrix metalloproteinase (MMP)-9. In conclusion, the results of the present study indicated that combination chemotherapy using PTX with HM exerted an antitumor effect, which may be implicated for the treatment of gastric cancer. Of note, the combination of the two drugs inhibited migration and invasion more effectively compared with each drug alone, the mechanism of which proceeded via the downregulation of COX-2 expression.

Anti-proliferative Effect of Physcion on Human Gastric Cell Line via Inducing ROS-Dependent Apoptosis.

In this study, the anti-proliferative effect of physcion, an anthraquinone derivative isolated and characterized from both terrestrial and marine sources, against human gastric cancer SGC-7901 cells was investigated and the underlying mechanisms were explored. Physcion reduced SGC-7901 cell viability in a dose- and time-dependent manner, as demonstrated by MTT assay. It triggered the mitochondrial/caspase apoptotic pathway indicated by loss of mitochondrial membrane potential and cytochrome c release. Moreover, physcion induced a sustained activation of the phosphorylation of AMPK, and compound C (an inhibitor of AMPK) significantly reversed physcion-induced apoptosis in SGC-7901 cells. In addition, physcion provoked the generation of reactive oxygen species (ROS) in SGC-7901 cells, while the antioxidant N-acetyl cysteine almost completely blocked physcion-induced AMPK activation and apoptosis. Taken together, these findings suggest that physcion induces apoptosis through a ROS/AMPK-dependent mitochondrial pathway.