Gastric Cell Line SGC-7901 Research Articles

The effects of miRNA-577 on the function of human gastric cancer cells

Objective To investigate the effects of miRNA-577 on the cell proliferation and migration of human gastric cancer cell line SGC-7901, and to explore its mechanism. Methods The expression levels of miRNA-577 in human gastric mucosal epithelial cells GES (gastric epithelial cells) and human gastric cancer cell line SGC-7901 were detected by real-time polymerase chain reaction (RT-PCR). Gastric cancer SGC-7901 cells were infected with transfected with miRNA-577 or control miRNA vector. Transwell assay, methyl thiazolyl tetrazolium (MTT) test, and flow cytometry were used in both groups. Western blot was used to detect the level of cyclin dependent kinase 4 (CDK4) protein. Results Compared to GES, the expression level of miRNA-577 was decreased significantly in gastric cancer cell lines (P<0.01). The ratio of proliferation inhibition, and cells arrested at G1/G0 phase were increased significantly in miRNA-577 lentiviral infected group compared to the negative control group (P<0.05). CDK4 protein expression was lower in the miRNA-577 lentiviral infected group(P<0.01). Conclusions miRNA-577 has lower expression level in gastric caner cell line SGC-7901. miRNA-577 can inhibit proliferation, induce cell cycle arrest of gastric caner cell line SGC-7901, maybe through downregulating expression of CDK4. Key words: MicroRNAs/ME/PD; Stomach neoplasms/ME/DT; Cyclin-dependent kinase 4/ME

Andrographolide Inhibits Proliferation and Metastasis of SGC7901 Gastric Cancer Cells.

To explore the mechanisms by which andrographolide inhibits gastric cancer cell proliferation and metastasis, we employed the gastric cell line SGC7901 to investigate the anticancer effects of andrographolide. The cell survival ratio, cell migration and invasion, cell cycle, apoptosis, and matrix metalloproteinase activity were assessed. Moreover, western blotting and real-time PCR were used to examine the protein expression levels and the mRNA expression levels, respectively. The survival ratio of cells decreased with an increasing concentration of andrographolide in a dose-dependent manner. Consistent results were also obtained using an apoptosis assay, as detected by flow cytometry. The cell cycle was blocked at the G2/M2 phase by andrographolide treatment, and the proportion of cells arrested at G1/M was enhanced as the dose increased. Similarly, wound healing and Transwell assays showed reduced migration and invasion of the gastric cancer cells at various concentrations of andrographolide. Andrographolide can inhibit cell proliferation, invasion, and migration, block the cell cycle, and promote apoptosis in SGC7901 cells. The mechanisms may include upregulated expression of Timp-1/2, cyclin B1, p-Cdc2, Bax, and Bik and downregulated expression of MMP-2/9 and antiapoptosis protein Bcl-2.

Hypoxia regulates CD44 expression via hypoxia-inducible factor-1α in human gastric cancer cells.

Hypoxia induces proliferation and invasion in cancer cells via hypoxia-inducible factor (HIF)-1α. The cell adhesion molecule cluster of differentiation (CD) 44 has been associated with increased cell invasion and metastasis. Whether hypoxia regulates the expression of CD44 in gastric cancer cells remains to be established. In the current study, the effects of hypoxia on HIF-1α and CD44 expression levels in human gastric cell lines SGC-7901 and BGC-823 were evaluated. The cells were cultured in 1% O2 for 1 week and then treated with 20 nM rapamycin for 72 h. Cell viability was evaluated using the Cell Counting kit-8 assay, and cell invasion was detected by the Transwell invasion assay. The protein and messenger (m) RNA expression levels of HIF-1α and CD44 were detected using western blotting and reverse transcription-quantitative polymerase chain reaction, respectively. The results revealed that cell viability and invasion increased under hypoxic conditions, but decreased following rapamycin treatment in SGC-7901 and BGC-823 cells. Hypoxia also increased the protein and mRNA expression levels of HIF-1α and CD44 in these two cell lines. However, this hypoxia-induced increase in HIF-1α and CD44 protein and mRNA expression levels was inhibited by rapamycin. These findings suggest that hypoxia induced the proliferation and invasion of SGC-7901 and BGC-823 cells. Furthermore, CD44 expression levels were potentially associated with HIF-1α expression levels. Therefore, in gastric cancer cells, hypoxia may regulate CD44 expression via HIF-1α in order to promote cell proliferation and invasion.

Role and mechanism research on reversal of 5-fluorouracil resistance by epigallocatechin gallate in gastric cancer drug-resistance cells lines SGC-7901/5-FU

Drug-resistance gastric cancer cell line (SGC-7901/5-FU) was established by high doses of repeated impact joint drug concentration increment methods. The cell viability of the parent cell line and the drug-resistance cell line were determined by standard MTT assay. Cell survival rate of drug-resistance was calculated by the formula [(A490 of the treatment group / A490 of the control group) × 100%]. Cell half inhibitory concentration (IC50) and resistance index (RI) were calculated by the Graphpad prime 6.0 software(RI=IC50 value of drug-resistance cells / IC50 value of parent cells). The apoptosis rate of SGC-7901/5-FU cells was quantified by flow cytometry after staining with annexin-V and PI. Western blot was used to detect the protein expression of drug-resistance-related proteins (ABCG2, P-gp, MDR-1 and GST-π) and apoptosis-related proteins (PARP, Survivin, Bax and bcl-2). IC50 value was significantly increased in drug-resistant cells compared with parental cells [(64.7±3.9) mg/L and (4.1±0.3) mg/L, respectively, t=26.46, P=0.000], and the RI was 15.6. Proliferation activity in the drug-resistant cells was higher than that in parental cells at different 5-FU concentrations (all P<0.05). In drug-resistant cells, the IC50 value of 5-FU combined with EGCG group obviously decreased compared with 5-FU group [(7.3±0.1) mg/L and (63.1±1.4) mg/L respectively, t=40.84, P=0.000], and the RI was 0.12. Proliferation activity in drug-resistant cells was significantly decreased after EGCG treatment at different 5-FU concentrations (all P<0.05). Cell apoptosis rates in control group, 5-FU group, EGCG group and 5-FU combined with EGCG group were (3.0±1.0)%, (7.0±1.3)%, (6.0±1.2)% and (18.0±1.4)%, while apoptosis rate in 5-FU combined with EGCG group was significantly higher than those of other 3 groups(F=129.5, P=0.000). Western blot revealed that after EGCG treatment, the expression levels of drug-resistance-related proteins (ABCG2, P-gp, MDR-1 and GST-π) in the drug-resistant cell line SGC-7901/5-FU decreased significantly; the expression levels of apoptosis marker protein PARP and pro-apoptotic protein Bax increased significantly; and the expression levels of anti-apoptotic protein Survivin and Bcl-2 decreased significantly (all P<0.05). EGCG can reduce the resistance of gastric cancer resistant cell line SGC-7901/5-FU, whose role may be via the inhibition of the expression of drug-resistance-related proteins, and the elevation of the protein expression ratio of PARP/Survivin and Bax/Bcl-2.

In vitro and in vivo study on the regulation of microRNA-101 in human gastric cancer proliferation, migration and invasion

Objective To investigate the expression of microRNA-101 (miRNA-101) in human gastric cancer, and to explore its effects on proliferation, migration and invasion of gastric cancer cell. Methods The expression of miRNA-101 in 28 human gastric cancer tissues, human gastric cell lines BGC-823, SGC-7901, MKN-45, AGS and human normal gastric epithelial cell line GES-1 were determined by real time polymerase chain reaction (PCR). Recombinant miRNA-101 adenovirus vector was constructed. The effects of miRNA-101 on gastric cancer proliferation was detected with cell proliferation assay. The ability of gastric cancer cell migration and invasion was assessed with Transwell assay. Gastric xenograft cancer model was established in BALB/c nude mice and the tumor size was compared. The t test was used for the statistical analysis. Results The expression of miRNA-101 in gastric cancer tissues was 0.661±0.396, which was lower than that of corresponding para carcinoma tissues (1.128±0.697), and the difference was statistically significant (t=10.091, P<0.01). The expression of miRNA-101 in normal gastric epithelial cell line GES-1 was higher than those of gastric cancer cell lines BGC-823, SGC-7901, MKN-45 and AGS. There was significant suppression role of miRNA-101 on MKN-45 cells proliferation, and which also had inhibition role on cell migration and invasion of gastric cancer cell lines BGC-823, SGC-7901, MKN-45 and AGS. At five weeks after MKN-45 gastric xenograft cancer nude mice model established, the tumor size of Ad-miRNA-101 group ((333.56±46.71) mm3) was smaller than that of Ad-enhanced green fluorescent protein (EGFP) group (806.41±51.83) mm3, and the difference was statistically significant (t=21.431, P<0.01). Conclusion In gastric tissues and cells, miRNA-101 is a tumor suppressive miRNA and its downregulated expression involved in the genesis and development of gastric cancer, which may be a new target of biological target therapy in gastric cancer. Key words: microRNAs; Stomach neoplasms; miRNA-101

MicroRNA‑197 reverses the drug resistance of fluorouracil‑induced SGC7901 cells by targeting mitogen‑activated protein kinase 1.

MicroRNAs (miRNAs) are a group of small non-coding RNA molecules, which serve an important function in the development of multidrug resistance in cancer through the post-transcriptional regulation of gene expression and RNA silencing. In the present study, the functional effects of miR-197 were analyzed in chemo-resistant gastric cancer cells. Low expression levels of miR-197 were observed in the fluorouracil (5-FU)-resistant gastric cell line SGC7901/5-FU when compared with those in the parental gastric cell line SGC7901. Overexpression of miR-197 in SGC7901/5-FU cells was identified to partially restore 5-FU sensitivity. miRNA target prediction algorithms suggested that mitogen-activated protein kinase 1 (MAPK1) is a candidate target gene for miR-197. A luciferase reporter assay confirmed that miR-197 led to silencing of the MAPK1 gene by recognizing and then specifically binding to the predicted site of the MAPK1 mRNA 3′-untranslated region. When miR-197 was overexpressed in SGC7901 cells, the protein levels of MAPK1 were downregulated. Furthermore, MAPK1 knockdown significantly increased the growth inhibition rate of the SGC7901/5-FU cells compared with those in the control group. These results indicated that miR-197 may influence the sensitivity of 5-FU treatment in a gastric cancer cell line by targeting MAPK1.

Protease-activated ratiometric fluorescent probe for pH mapping of malignant tumors.

A protease-activated ratiometric fluorescent probe based on fluorescence resonance energy transfer between a pH-sensitive fluorescent dye and biocompatible Fe3O4 nanocrystals was constructed. A peptide substrate of MMP-9 served as a linker between the particle quencher and the chromophore that was covalently attached to the antitumor antibody. The optical response of the probe to activated MMP-9 and gastric cell line SGC7901 tumor cells was investigated, followed by in vivo tumor imaging. Based on the ratiometric pH response to the tumor microenvironment, the resulting probe was successfully used to image the pH of subcutaneous tumor xenografts.

The downregulation of miR-200c/141 promotes ZEB1/2 expression and gastric cancer progression.

Gastric cancer is the fourth most common malignancy in the world. Although microRNA-200 (miR-200) family members are thought to play roles in tumorigenesis, their functions in carcinogenesis are tumor specific, and the underlying mechanism of action still remains elusive. Few studies to date have addressed the dysregulation and function of miR-200 family members in gastric cancer progression. Here, we report that the miR-200 family members, miR-200c and miR-141, were significantly downregulated in gastric cancer specimens and gastric cancer cell lines. Importantly, on clinical samples, the expression of miR-200c and miR-141 was inversely correlated with TNM stage, tumor invasion depth (T), tumor embolus and disease-free survival. Wound-healing assay results showed that co-transfected miR-200c/141 could inhibit the migration and invasion capability of the gastric cell line SGC-7901. We also found that miR-200c and miR-141 directly targeted zinc finger E-box-binding homeobox 1/2 (ZEB1/2) and upregulated E-cadherin expression. In specimens from gastric cancer patients, reduced expression of miR-200c/141 was associated with increased expression of ZEB1 and/or ZEB2. In addition, the downregulation of miR-200c and miR-141 was found to be due to a highly methylated CpG island located upstream of their genomic sequence and/or upregulated TGF-β signaling. Treatment with the chemotherapeutic agent decitabine, a known DNA methyltransferase inhibitor, increased miR-200c/141 expression and ameliorated decreased expression of miR-200c/141 induced by TGF-β in SGC-7901 cells. Our study revealed that miR-200c/141 was downregulated by CpG island methylation and TGF-β signaling, which decreased ZEB1/2 expression and increased E-cadherin expression to inhibit migration and invasion of gastric cancer cells and provides powerful evidence for the application of decitabine in gastric cancer treatment.

α-Mangostin suppresses human gastric adenocarcinoma cells in vitro via blockade of Stat3 signaling pathway.

To investigate the anti-tumor effects of α-mangostin, a major xanthone identified in the pericarp of mangosteen (Garcinia mangostana Linn), against human gastric adenocarcinoma cells in vitro, and the mechanisms of the effects. Human gastric adenocarcinoma cell lines BGC-823 and SGC-7901 were treated with α-mangostin. The cell viability was measured with MTT assay, and cell apoptosis was examined using flow cytometry and TUNEL assay. The expression of the relevant proteins was detected using Western blot. Treatment with α-mangostin (3-10 μg/mL) inhibited the viability of both BGC-823 and SGC-7901 cells in dose- and time-manners. Furthermore, α-mangostin (7 μg/mL) time-dependently increased the apoptosis index of the cancer cells, reduced the mitochondrial membrane potential of the cancer cells, and significantly increased the release of cytochrome c and AIF into cytoplasm. Moreover, the α-mangostin treatment markedly suppressed the constitutive Stat3 protein activation, and Stat3-regulated Bcl-xL and Mcl-1 protein levels in the cancer cells. The anti-tumor effects of α-mangostin against human gastric adenocarcinoma cells in vitro can be partly attributed to blockade of Stat3 signaling pathway.

Establishment of stable SGC-7901 gastric cancer cell line with cortactin down-regulation

Objective To establish a stable SGC-7901 gastric cancer cell line with cortactin downregulation.Methods Three pairs of primers specific to knockdown cortactin and a pair of control primers were designed and synthesized.The primers were annealed and inserted into PLKO.1 plasmids.The plasmids,psPAX2,and PCMV-VSVG were transfected into HEK293T cells simultaneously,and then lentiviral particles were produced and collected.The lentiviral particles were used to infect SGC-7901 cells and puromycin was used to select stable cell lines.Three stable cell lines were selected at last.Real-time quantitative polymerase chain reaction (Real-time PCR) and Western blotting were conducted to detect the expression level of cortactin mRNA and protein respectively.Results The expression levels of cortactin mRNA and protein were significantly down-regulated.The mRNA and protein levels of cortactin in PLKO.1 + short hairpin RNA (shRNA)3 cell line were significantly decreased,about 10％ of the control stable cell line.Conclusion The stable SGC-7901 gastric cell lines with cortactin down-regulation were established successfully. Key words: Cortactin; Short hairpin RNA ; Gastric

Decreased expression of CCNG2 is significantly linked to the malignant transformation of gastric carcinoma

This study aimed to analyze the expression, clinical significance of cyclin G2 (CCNG2) in gastric carcinoma, and the biological effect in its cell line by CCNG2 overexpression. Immunohistochemistry and western blot were used to analyze CCNG2 protein expression in 87 cases of gastric cancer and normal tissues to study on the relationship between CCNG2 expression and clinical factors. CCNG2 lentiviral vector was transfected into gastric SGC-7901 cell line. RT-PCR and western blot were used to detect the mRNA level and protein of CCNG2. MTT assay and cell cycle were also conducted as to the influence of the upregulated expression of CCNG2 that might be found on SGC-7901 cell biological effect. Immunohistochemically, the level of CCNG2 protein expression was found to be significantly lower in gastric cancer tissue than in normal tissues (P < 0.05). Western blot shows that the relative amount of CCNG2 protein in gastric cancer tissue was found to be significantly lower than in normal tissues (P < 0.05). The level of CCNG2 protein expression was correlated with T stages, lymph node metastasis, clinical stage, and histological grade (P < 0.05). Loss of CCNG2 expression correlated significantly with poor overall survival time by Kaplan-Meier analysis (P < 0.05). The result of biological function showed that SGC-7901 cell-transfected CCNG2 had a lower survival fraction, higher percentage of the G0/G1 phases, and lower CDK2 protein expression compared with SGC-7901 cell untransfected CCNG2 (P < 0.05). CCNG2 expression decreased in gastric cancer and correlated significantly T stages, lymph node metastasis, clinical stage, histological grade, and poor overall survival, suggesting that CCNG2 may play important roles as a negative regulator to gastric cancer cell by promoting degradation of CDK2.

Pyruvate Kinase M2 Plays a Dual Role on Regulation of the EGF/EGFR Signaling via E-Cadherin-Dependent Manner in Gastric Cancer Cells

Background and AimsEGFR activation and PKM2 expression are instrumental in tumorigenesis. EGFR activation regulates PKM2 functions in a subcellular compartment-dependent manner and promotes gene transcription and tumor growth. In addition, PKM2 is upregulated in EGFR-induced pathways in glioma malignancies. However, we found that PKM2 could also regulate the activity of the EGF/EGFR signaling pathway in gastric cancer cells. We aimed to define the biological mechanisms for PKM2 in regulating the cell motility and invasion.MethodsWe employed stable transfection with short hairpin RNA to stably silence the expression of PKM2 in the BGC823, SGC7901 and AGS gastric cancer cell lines. The effects of PKM2 in vitro were determined by assessing cell migration and invasion. Immunohistochemical analysis was used to explore the relationship among PKM2 and other proteins.ResultsOur results indicate that the knockdown of PKM2 decreased the activity of E-cadherin and enhanced the EGF/EGFR signaling pathway in the gastric cell lines BGC823 and SGC7901 that were positive for E-cadherin expression. However, in the undifferentiated gastric carcinoma cell line AGS, which lacks E-cadherin expression, PKM2 promoted cell migration and invasion. Immunohistochemical analyses showed that the levels of E-cadherin expression, ERK1/2 phosphorylation, and cytoplasmic PKM2 expression were correlated with each other.Conclusion:PKM2 may play different roles in differently differentiated gastric cancer cell types, and this finding would be consistent with the previous clinical research. The results of our study reveal an important link between PKM2 and E-cadherin during EGFR-stimulated gastric cancer cell motility and invasion.

ZNRF3 acts as a tumour suppressor by the Wnt signalling pathway in human gastric adenocarcinoma

E3 ubiquitin ligases regulate a variety of biological processes through the ubiquitin-proteasome system, together with ubiquitin activating enzyme E1 and ubiquitin-conjugating enzyme E2. Previous studies have demonstrated that zinc and ring finger 3 (ZNRF3), which belongs to the E3 ubiquitin ligases family is involved in the Wnt signalling pathway, which plays an important role in causing cancer. However, the expression and function of ZNRF3 in human gastric adenocarcinoma still remains unclear. Immunohistochemical and western blot analysis showed a significant down-regulation of ZNRF3 protein in gastric adenocarcinoma tissues compared with adjacent normal gastric tissues. In addition, there was a correlation between the down-regulation of ZNRF3 and poor tissue differentiation in gastric adenocarcinoma. To investigate the potential function of ZNRF3 in cell proliferation and apoptosis, a gastric cell line SGC7901 was employed. The over-expression of wild-type ZNRF3, which was accomplished by the transient transfection of recombinant pEGFP-ZNRF3 (or empty plasmids as control) into the cell line SGC7901, was confirmed by western blot analysis. Flow-cytometry-based and Cell Counting Kit-8 assays showed that over-expression of wt ZNRF3 induced apoptosis and suppressed proliferation. ZNRF3-overexpressing gastric cells displayed partly attenuated protein levels of beta-catenin and TCF-4 compared with those transfected with the empty plasmid. Our study demonstrates a novel gastric adenocarcinoma suppressor and reveals that ZNRF3 inhibits gastric cancer cell growth and promotes the cell apoptosis by affecting the Wnt/beta-catenin/TCF signalling pathway.

Identification of CD44+ cancer stem cells in human gastric cancer.

The cancer stem cell hypothesis suggests that tumors are initiated and maintained by cancer stem cells capable of self-renewal and differentiation into mature tumor cells. Recent studies have demonstrated the existence of cancer initiating cells in different solid tumors. In this study, we identified a subpopulation of CD44+ cells within the tumor of gastric cancer patients, which, upon treatment by chemotherapeutic agent 5-fluorouracil (5-FU), were markedly enriched. In vitro culture of isolated CD44+ subpopulation from gastric tumors by magnetic beads sorting led to formation of gastric spheroid colonies. These colonies retained CD44+ surface marker expression during culture, and were undifferentiated in nature. Subcutaneous injections of CD44+ gastric cancer cells conferred tumorigenicity in SCID mice. Moreover, implantation of CD44+ cells from these established tumors remained tumorigenic in successive passages. Using CD44+ cells isolated from the gastric cell lines AGS and SGC7901, similar results were obtained. Upon enrichment by 5-FU, CD44+ cells harbored increased ALDH expression as compared with CD44- cells. Our results demonstrated for the first time the existence of CD44+ cells within the tumors of gastric cancer patients that are endowed with stem cells properties, and also provide a plausible explanation for chemo-resistance frequently observed in gastric cancer patients. Such findings provide a basis for further studies on targeting this tumorigenic subpopulation for better treatment of gastric cancer patients.

Biological effects of zoledronic acid on gastric cancer drug-resistant cell line SGC-7901/ADR

Objective To detect effects of zoledronic acid on the invasion and adhesion of adria- mycin resistant gastric cancer cell line SGC-7901/ADR, and to investigate whether zoledronic acid could restore sensitivity to adriamycin and possible mechanism. Methods Methyl thiazol tetrazolium （MTT） as- say was used to investigate the effect of 1 x 10-4 tool/L zoledronic acid and 0. 5 mg/L doxorubicin on the adhesion of SGC7901/ADR cells. Transwell was used to investigate cellular invasive ability. Enzyme linked immunosorbent assay （ELISA） was used to quantify supernatant matrix metalloproteinase （MMP）-2 and intercellular adhesion molecule-1 （ICAM-1）. MMP-2, tissue inhibitorof metalloproteinase （TIMP）-2, MMP-9, ICAM-1 and CD44 levels were quantified by using real-time polymerase chain reaction （PCR）. Results （ 1 ） After SGC-7901/ADR cells were incubated with 1 x 10 4 mol/L zoledronie acid （Z） alone or in combined with O. 5 mg/L adriamycin （ Z ＋ A） for 6 h, the adhesion rate was 44. 32% for control （ C ） group, 34.73% for Z group, and 31.30% for Z ＋ A group. The adhesion rate was reduced in treated groups as compared with untreated group （ P 〈 0. 05 ） ; （ 2 ） The number of invasive cells per high power field in C group, Z group and Z ＋ A group was 103.73 ±7.84, 97.64 ±9. 62, and 71.58_＋10.57 re- spectively. As compared with control group, the invasive ability was reduced significantly in Z ＋ A group （P 〈 0. 05 ） ; （3） ELISA results indicated that as compared with control group, the MMP-2 and ICAM-1 in the supernatant of Z group and Z ＋ A group were significantly reduced （P 〈0. 05 or P 〈0. 01 ）. As corn-pared with Z group, both MMP-2 and /CAM-1 were significantly reduced in Z ＋ A group （ P 〈 0. 01 ） ; （4） CIM4 mRNA expression in C group, Z group, and Z ＋ A group was 1. 0000 ＋ 0. 1083, 0. 2601 -＋ 0. 0041,0. 4681 -＋ 0. 0314, and 0. 0950 ＋- 0. 0052 respectively. Similar results were observed in the ex- pression of ICAM-1, MMP-2 and MMP-9. Conclusion Zoledronie acid could inhibit the adhesion and in- vasion of SGC-7901/ADR cells, and restore the sensitivity of SGC-7901/ADR cells to doxorubicin. These effects may be related to the decreased expression of ICAM-1, MMP-2, MMP-9 and CD44, and the in- creased TIMP-2 expression. Key words: Zoledronic acid; Gastric cancer; Invasion; Adhesion

Biological role of β-arrestin1 in human gastric cancer BGC-823 cells

Objective To investigate the effects of β-arrestinl on proliferation, migration, invasion and apoptosis of human gastric cancer BGC-823 cell line. Methods The expression of β- arrestinl in human gastric epithelial cell line GES, human gastric cancer cell line BGC-823, MKN-28 and SGC-7901 was detected by realtime-polymerase chain reaction （PCR） and Western blot. The stable β-arrestinl and negative control interfered BGC-823 cell line were established by RNA interference technology. The cell proliferation, migration, invasion and cell apoptosis of β-arrestinl stable interfered BGC-823 cell line was examined by cell counting, scratch test, Transwell chamber test and flow cytometry assays. The data were analyzed by t test. Results The expression of β- arrestinl in cell line GES, MKN-28, SGC-7901 and BGC-823 was 0. 001 ± 0. 001, 0. 002±0. 000, 0. 003± 0. 002 and 0. 005 ± 0. 000 respectively. The inhibition ratio of proliferation in β-arrestinl interfered BGC-823 cells and negative control cells were -30.2% and 100.0%. The invasion ability was also inhibited, the number of migratory cells was 126. 25±3.24 and 213. 50±6.27 （t=0. 000, P〈0.01）, and the apoptosis rate was （41. 350±1. 053）% and （11. 497±0. 589）% （t=0. 015, P〈0.05）. Conclusions β-arrestinl is highly expressed in gastric carcinoma, and the expression increased along with the malignancy degree. The cell proliferation, migration and invasion is inhibited by interference of β-arrestinl in BGC-823 cells, while the cell apoptosis is promoted. Key words: β-arrestinl; Stomach neoplasms; RNA interference; Tumor cells, cultured

Effect of Tissue Factor on Invasion Inhibition and Apoptosis Inducing Effect of Oxaliplatin in Human Gastric Cancer Cell

Tissue factor (TF) is expressed abnormally in certain types of tumor cells, closely related to invasion and metastasis. The aim of this study was to construct a human gastric cancer cell line SGC7901 stably-transfected with human TF, and observe effects on oxaliplatin-dependent inhibition of invasion and the apoptosis induction. The target gene TF was obtained from human placenta by nested PCR and introduced into the human gastric cell line SGC7901 through transfection mediated by lipofectamine. Stably-transfected cells were screened using G418. Examples successfully transfected with TF-pcDNA3 recombinant (experimental group), and empty vector pcDNA3 (control group) were incubated with oxaliplatin. Transwell chambers were used to show change in invasive ability. Caspase-3 activity was detected using a colorimetric method and annexin-V/PI double- staining was applied to detect apoptosis. We generated the human gastric cancer cell line SGC7901/TF successfully, expressing TF stably and efficiently. Compared with the control group, invasion increased, whereas caspase-3 activity and apoptosis rate were decreased in the experimental group. TF can enhance the invasive capacity of gastric cancer cells in vitro. Its increased expression may reduce invasion inhibition and apoptosis-inducing effects of oxaliplatin and therefore may warrant targeting for improved chemotherapy.

Floating cells with stem cell properties in gastric cell line SGC-7901

To obtain floating spheres from the adherent gastric cancer cell line SGC-7901 and to analyze the properties of the spheres. Serum-free medium was applied to cultured SGC-7901 cells. Limiting dilution assay, tumor formation assay, microarray analysis, and real-time fluorescent quantitative PCR were used to test the stem cell properties of the spheres. A subpopulation of SGC-7901 cells formed floating spheres in serum-free medium. These cells showed enhanced tumorigenic ability and also highly expressed certain stem-cell-associated proteins. We successfully propagated floating spheres with stem cell properties in the SGC-7901 gastric cell line.

Effect of RNA interference targeting HIF-1α gene on biological behavior of human esophageal squamous cell carcinoma and gastric adenocarcinoma cells in vitro

To investigate the effect of hypoxia inducible factor-1α (HIF-1α) on the proliferation, migration and vasculogenic mimicry(VM) in human esophageal squamous cell carcinoma cell line Eca-109 and gastric adenocarcinoma cell line SGC-7901 in vitro. The recombinant plasmid pGCsi-shHIF-1α was transfected into Eca-109 and SGC-7901 cells by Lipofectamine(TM) 2000. The inhibitory effect of HIF-1α was measured at protein level by Western blot under normoxia and hypoxia. The cell proliferation was detected by colony formation and MTT assays. The migration of transfected cells was assayed using Transwell chambers. Whether Eca-109 and SGC-7901 cells could form the capillary tube-like structures (TLSs) was observed by 3-dimensional culture, and the tube formation of transfected cells was detected by tube-like structure formation assay. The expression of HIF-1α protein in each group of transfected cells was significantly suppressed under normoxia and hypoxia (Eca-109: 0.00, 0.74 ± 0.05; 0.00, 1.11 ± 0.06; SGC-7901: 0.00, 0.60 ± 0.05; 0.00, 0.96 ± 0.07, P < 0.01). Colony formation and MTT assays showed that the cell proliferation of the pGCsi-shHIF-1α transfected cells was slower than that of the control groups (104.7 ± 9.6, 151.7 ± 4.5; 88.3 ± 5.1, 128.3 ± 6.7, P < 0.05). The migration of the recombinant plasmid-transfected cells was significantly suppressed compared with that of cells transfected with empty vector (55.5 ± 11.2, 121.9 ± 17.3; 64.7 ± 10.8, 132.3 ± 16.0, P < 0.01). Both the Eca-109 and SGC-7901 cells could form TLSs when cultured on matrigel, and the number of tubules was significantly increased under hypoxia (30.8 ± 3.9, 34.3 ± 3.4; 26.2 ± 3.4, 30.1 ± 4.1, P < 0.05), the tubule-forming ability of transfected groups was significantly inhibited under normoxia and hypoxia (Eca-109: 3.7 ± 2.8, 30.8 ± 3.9; 3.9 ± 2.7, 34.3 ± 3.4; SGC-7901: 4.9 ± 3.5, 26.2 ± 3.4; 5.3 ± 3.6, 30.1 ± 4.1, P < 0.01). Both the esophageal squamous cell carcinoma cell line Eca-109 and gastric adenocarcinoma cell line SGC-7901 are capable of forming vasculogenic mimicry structures in vitro. The recombinant plasmid pGCsi-shHIF-1α can efficiently suppress their proliferation, migration and vasculogenic mimicry formation.

RNA interference-mediated knockdown of JAK2 and ERK1 inhibitsHelicobacter pyloriCagA-induced gastrin up-regulation in gastric cancer cell lines AGS and SGC-7901

RNA interference-mediated knockdown of JAK2 and ERK1 inhibits<i>Helicobacter pylori</i>CagA-induced gastrin up-regulation in gastric cancer cell lines AGS and SGC-7901