Gastric Mucosal Epithelial Cell Line Research Articles

PDLIM1 Inhibits Chemoresistance by Blocking DNA Damage Repair in Gastric Cancer.

Current cisplatin (CDDP) resistance remains a major challenge in the treatment of advanced gastric cancer. To address the issue of drug resistance, we explored the regulatory functions of PDZ and LIM structural domain protein 1 (PDLIM1) in CDDP chemotherapy for gastric cancer. In this study, we analyzed PDLIM1 expression and prognosis using bioinformatics on publicly available data. PDLIM1 expression in a gastric mucosal epithelial cell line (GSE-1), CDDP- sensitive (SGC7901, BGC823) and CDDP-resistant gastric cancer cells was detected by RTqPCR and Western blotting. Cell proliferative capacity was assessed by knockdown of PDLIM1 and overexpression of PDLIM1 in cells administered in combination with cisplatin, and apoptotic levels were measured by CCK-8 and colony formation assay and by flow cytometry. Expression of breast cancer susceptibility gene 1 (BRCA1) and γH2AX was determined by Western blotting or immunofluorescence staining. Downregulation of PDLIM1 was found in tumor tissues and cells, which was associated with poor clinical outcomes. Knockdown of PDLIM1 enhanced proliferation and attenuated apoptosis in gastric cancer cells. In addition, the therapeutic effects of CDDP on proliferation, apoptosis, and DNA damage repair were attenuated by PDLIM1 deletion.PDLIM1 expression was downregulated in CDDP-resistant tumor cells. Overexpression of PDLIM1 overcomes CDDP resistance in tumor cells as BRCA1 expression decreases and γH2AX expression increases. Our findings demonstrate that PDLIM1 enables to alleviate gastric cancer progression and resistance to cisplatin via impeding DNA damage repair.

Forkhead Box M1 Regulates the Proliferation,Invasion,and Drug Resistance of Gastric Cancer Cells via circ_NOTCH1

Objective To investigate the impacts of forkhead box M1(FOXM1)on the proliferation,invasion,and drug resistance of gastric cancer cells by regulating the circular RNA circ_NOTCH1.Methods Western blotting and real-time quantitative PCR were performed to determine the expression of FOXM1 protein and circ_NOTCH1,respectively,in the gastric cancer tissue,para-carcinoma tissue,human normal gastric mucosa epithelial cell line GES-1 and gastric cancer cell lines MGC-803,HGC-27,and BGC-823.BGC-823 cells were classified into the following groups:control,short hairpin RNA FOXM1(sh-FOXM1)and negative control(sh-NC),small interfering RNA circ_NOTCH1(si-circ_NOTCH1)and negative control(si-NC),and sh-FOXM1+circ_NOTCH1 overexpression plasmid(sh-FOXM1+pcDNA-circ_NOTCH1)and sh-FOXM1+negative control(sh-FOXM1+pcDNA).CCK-8 assay and clone formation assay were employed to measure the cell proliferation,and Transwell assay to measure cell invasion.After treatment with 1.0 mg/L adriamycin for 48 h,the cell resistance in each group was analyzed.Western blotting was employed to determine the expression levels of FOXM1,proliferating cell nuclear antigen(PCNA),Bax,multi-drug resistance-associated protein 1(MRP1),and multi-drug resistance gene 1(MDR1).RNA pull-down and RNA immunoprecipitation were employed to examine the binding of circ_NOTCH1 to FOXM1 protein.Results Compared with those in the para-carcinoma tissue,the expression levels of FOXM1 protein and circ_NOTCH1 in the gastric cancer tissue were up-regulated(all P<0.001).Compared with GES-1 cells,MGC-803,HGC-27,and BGC-823 cells showed up-regulated expression levels of FOXM1 protein and circ_NOTCH1(all P<0.001).Compared with the control group and sh-NC group,the sh-FOXM1 group with down-regulated expression of FOXM1 protein and circ_NOTCH1 showed decreased optical density value,clone formation rate,cell invasion number,and cell viability,down-regulated expression of PCNA,MRP1,and MDR1,and up-regulated expression of Bax protein in BGC-823 cells(all P<0.001).Compared with the control group and the si-NC group,the si-circ_NOTCH1 group with down-regulated expression of circ_NOTCH1 showed decreased optical density value,clone formation rate,cell invasion number,and cell viability,down-regulated expression of PCNA,MRP1,and MDR1,and up-regulated expression of Bax protein in BGC-823 cells(all P<0.001).Compared with sh-FOXM1 group and sh-FOXM1+pcDNA group,the sh-FOXM1+pcDNA-circ_NOTCH1 group with up-regulated expression of circ_NOTCH1 showed increased optical density value,clone formation rate,cell invasion number,and cell viability,up-regulated expression of PCNA,MRP1,and MDR1,and down-regulated expression of Bax protein(all P<0.001).FOXM1 protein was able to interact with circ_NOTCH1.Conclusion Interference with FOXM1 may inhibit the proliferation,invasion,and drug resistance of gastric cancer cells by silencing circ_NOTCH1 expression.

Efficiency and Mechanism Evaluation of Magnolia officinalis Water Extract in Preventing Gastric Ulcer.

In this study we aimed at demonstrating the ability of Magnolia officinalis water extract to ameliorate gastric ulcers in in vitro and in vivo experiments. The gastric mucosa epithelial cell line, RGM 1, was pretreated with Magnolia officinalis water extract (0, 0.1, 1, 2, 5, or 10 mg/ml) and cultured in DMEM/F12 medium (pH 7.4) for 2 h and then in DMEM/F12 medium (pH 4.0) for 10 min. Magnolia officinalis water extract protected the cell viability and decreased reactive oxygen species formation by the acidic medium. In the in vivo experiment, Magnolia officinalis water extract (100 mg/kg) was administrated daily for 28 days in ICR mice via oral gavage, and then Shay's ulcer surgical method was performed to induce gastric ulcers. We analyzed the pH value of stomach acid and the pathological section, inflammation, and cannabinoid receptor type 2 (CB2) cDNA levels of the stomach. Magnolia officinalis water extract not only enhanced the pH value of stomach acid but also ameliorated the ulcer index and inflammation and increased CB2 expression effectively. These results suggest that Magnolia officinalis water extract might be used to decrease the incidence of gastric ulcer.

Immobilized short-chain dehydrogenase/reductase on Fe3O4 particles acts as a magnetically recoverable biocatalyst component in patulin bio-detoxification system

Patulin is one of the most important mycotoxins that contaminates fruit-derived products and causes acute or chronic toxicity in humans. In the present study, a novel patulin-degrading enzyme preparation was developed by taking a short-chain dehydrogenase/reductase and covalently linking it to dopamine/polyethyleneimine co-deposited magnetic Fe3O4 particles. Optimum immobilization provided 63% immobilization efficiency and 62% activity recovery. Moreover, the immobilization protocol substantially improved thermal and storage stabilities, proteolysis resistance, and reusability. Using reduced nicotinamide adenine dinucleotide phosphate as a cofactor, the immobilized enzyme exhibited a detoxification rate of 100% in phosphate-buffered saline and a detoxification rate of more than 80% in apple juice. The immobilized enzyme did not cause adverse effects on juice quality and could be magnetically separated quickly after detoxification to ensure convenient recycling. Moreover, it did not exhibit cytotoxicity against a human gastric mucosal epithelial cell line at a concentration of 100 mg/L. Consequently, the immobilized enzyme as a biocatalyst had the characteristics of high efficiency, stability, safety, and easy separation, establishing the first step in building a bio-detoxification system to control patulin contamination in juice and beverage products.

Quercetin exerts anti-inflammatory effects via inhibiting tumor necrosis factor-α-induced matrix metalloproteinase-9 expression in normal human gastric epithelial cells.

BACKGROUNDGastric injury is the most common digestive system disease worldwide and involves inflammation, which can lead to gastric ulcer or gastric cancer (GC). Matrix metallopeptidase-9 [MMP-9 (gelatinase-B)] plays an important role in inflammation and GC progression. Quercetin and quercetin-rich diets represent potential food supplements and a source of medications for treating gastric injury given their anti-inflammatory activities. However, the effects and mechanisms of action of quercetin on human chronic gastritis and whether quercetin can relieve symptoms remain unclear.AIMTo assess whether tumor necrosis factor-α (TNF-α)-induced MMP-9 expression mediates the anti-inflammatory effects of quercetin in normal human gastric mucosal epithelial cells.METHODSThe normal human gastric mucosa epithelial cell line GES-1 was used to establish a normal human gastric epithelial cell model of TNF-α-induced MMP-9 protein overexpression to evaluate the anti-inflammatory effects of quercetin. The cell counting Kit-8 assay was used to evaluate the effects of varying quercetin doses on cell viability in the normal GES-1 cell line. Cell migration was measured using Transwell assay. The expression of proto-oncogene tyrosine-protein kinase Src (c-Src), phospho (p)-c-Src, extracellular-signal-regulated kinase 2 (ERK2), p-ERK1/2, c-Fos, p-c-Fos, nuclear factor kappa B (NF-κB/p65), and p-p65 and the effects of their inhibitors were examined using Western blot analysis and measurement of luciferase activity. p65 expression was detected by immunofluorescence. MMP-9 mRNA and protein levels were measured by quantitative reverse transcription polymerase chain reaction (qRT–PCR) and gelatin zymography, respectively.RESULTSqRT-PCR and gelatin zymography showed that TNF-α induced MMP-9 mRNA and protein expression in a dose- and time-dependent manner. These effects were reduced by the pretreatment of GES-1 cells with quercetin or a TNF-α antagonist (TNFR inhibitor) in a dose- and time-dependent manner. Quercetin and TNF-α antagonists decreased the TNF-α-induced phosphorylation of c-Src, ERK1/2, c-Fos, and p65 in a dose- and time-dependent manner. Quercetin, TNF-α antagonist, PP1, U0126, and tanshinone IIA (TSIIA) reduced TNF-α-induced c-Fos phosphorylation and AP-1–Luciferase (Luc) activity in a dose- and time-dependent manner. Pretreatment with quercetin, TNF-α antagonist, PP1, U0126, or Bay 11-7082 reduced TNF-α-induced p65 phosphorylation and translocation and p65–Luc activity in a dose- and time-dependent manner. TNF-α significantly increased GES-1 cell migration, and these results were reduced by pretreatment with quercetin or a TNF-α antagonist.CONCLUSIONQuercetin significantly downregulates TNF-α-induced MMP-9 expression in GES-1 cells via the TNFR-c-Src–ERK1/2 and c-Fos or NF-κB pathways.

Quercetin Improves Mitochondrial Function and Inflammation in H2O2-Induced Oxidative Stress Damage in the Gastric Mucosal Epithelial Cell by Regulating the PI3K/AKT Signaling Pathway.

Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders, the therapeutic strategy of which it is limited due to its complex pathogenesis. Oxidative stress-induced damage in gastric mucosal epithelial cells is related to the pathogenesis and development of FD. Quercetin (Que) is one of the active ingredients of Zhishi that showed antioxidant, antiapoptotic, and anti-inflammatory effects. The aim of this study is to investigate the effect of Que on oxidative stress-induced gastric mucosal epithelial cells damage and its underlying molecular mechanism. The gastric mucosal epithelial cell line GES-1 was treated with 200 μM of H2O2 to construct an oxidative stress-induced damage model. The H2O2 cells were then administrated with different concentrations of Que. The results indicated that high concentration of Que (100 μM) showed cytotoxicity in H2O2-induced GES-1 cells. However, appropriate concentration of Que (25 and 50 μM) alleviated the oxidative stress damage induced by H2O2, as demonstrated by the increase of proliferation, decrease of ROS generation, apoptosis, inflammation, and alleviation of mitochondrial function and cell barrier. In addition, Que increased the activation of phosphorylation of PI3K and AKT decreased by H2O2. To investigate whether Que alleviated the oxidative stress damage in GES-1 cells by the PI3K/AKT signaling pathway, the GES-1 cells were treated with Que (25 μM) combined with and without LY294002, the PI3K inhibitor. The results showed that LY294002 suppressed the alleviation effect on Que in H2O2-induced GES-1 cells. In conclusion, the current study demonstrates that Que alleviates oxidative stress damage in GES-1 cells by improving mitochondrial function and mucosal barrier and suppressing inflammation through regulating the PI3K/AKT signaling pathway, indicating the potential therapeutic effects of Que on FD.

The expression and clinical significance of the tRNA aspartic acid methyltransferase 1 protein in gastric cancer.

This study aimed to investigate the role of the tRNA aspartic acid methyltransferase 1 (TRDMT1) protein in thedevelopment and progression of gastric cancer (GC). The 90 GC tissues and 35 paracancerous tissues (gastric mucosa) were collected from patients (31 males and 59 females; average age 66), who were pathologically diagnosed as GC. The expression of TRDMT1 in three GC cell lines (MKN28, BGC823, and MGC803) and tissues from GC patients were detected by western blotting and immunological staining, respectively. The relationship between TRDMT1 expression and clinicopathological parameters in GC patients was explored.TRDMT1 was knocked down by RNAi lentivirus in GC cells. GC cell migration and invasion were analyzed using scratch and transwell assays. TRDMT1 expression in the GC cell lines was higher than that in the normal gastric mucosal epithelial cell line (P < 0.05). Positive TRDMT1 protein expression in the GC tissuewas higher than that in the adjacent tissue.The expression of TRDMT1 was positively associated with tumor size, histological grade, invasion depth, lymph node metastasis, and tumor node metastasis (TNM) stage (P < 0.05). High TRDMT1 expression predicted poor OSof GC patients.Tumor size, differentiation degree, invasion depth, lymph node metastasis, TNM stage, and TRDMT1 expression were independent predictors of the OS of GC patients. Knockdown of TRDMT1 inhibited the migration and invasion of MKN28 cells. TRDMT1 was highly expressed in GC celllines and tissues. TRDMT1 expression was independent predictor ofthe OS of GC patients. TRDMT1 knockdown reduced GC cell migration and invasion.AlltheseresultssuggestedthatTRDMT1 has the potential tobe used as a target for the diagnosis and treatment of GC.

Up-regulation of DGAT1 in cancer tissues and tumor-infiltrating macrophages influenced survival of patients with gastric cancer

BackgroundDiacylglycerol-acyltransferase 1 (DGAT1) plays an important role in the energy storage and is involved in cancer progression. A growing number of evidences showed that elevated expression of DGAT1 in cancer tissue indicated a poor outcome in cancer patients. However, the relationship between DGAT1 and gastric cancer is still unclear. Thus, Transcriptomic analysis and in vitro experiments were performed to investigate the role of DGAT1 in gastric cancer, as well as the potential therapy target in gastric cancer treatment.MethodsWe screened the public cancer datasets to identify the expression and function of DGAT1 in gastric cancer and tumor infiltrating lymphocytes. Then we testified the DGAT1 expression and function after sodium oleate treatment in AGS and MKN45 cell line. Finally, we analyzed ration of apoptosis, necrosis in gastric cancer cells by using flow cytometry after administration of DGAT1 inhibitor.ResultsOur results showed a highly expression of DGAT1 in gastric cancer tissues (n = 5, p = 0.0004), and tumor-infiltrating macrophages with elevated DGAT1 expression is associated with poor overall survival in gastric cancer patients. In addition, gastric cell lines AGS (n = 3, p < 0.05) and MKN45 (n = 3, p < 0.01) expressed higher level of DGAT1 than human gastric mucosal epithelial cell line GES-1. Administration of DGAT1 inhibitor effectively suppressed functional factors expression and induced cell death in MKN45.ConclusionThe findings of this research provide an in-depth insight into the potential role and influences involved in DGAT1 in the gastric cancer patients. And higher expression of DGAT1 leads to lower overall survival (OS) rate in patients with poorly differentiated gastric cancer. Our findings suggest a potential role for DGAT1 in the gastric cancer progression and inhibiting DGAT1 might be a promising strategy in gastric cancer treatment.

Effects of miR-362 in Regulating the Proliferation, Invasion and Apoptosis of Gastric Cancer by Inhibiting the Expression of Tumor-Promoting Factor PRDM2

Purpose - The high expression of positive regulatory domain zinc finger protein2 (PRDM2) is an important factor in inducing the formation and progression of gastric cancer. The current study was performed to explore the effect of micro-RNA-362 (miR-362) targeting PRDM2 on the proliferation and apoptosis of gastric cancer cells. Methods - The expression of miR-362 in gastric adenocarcinoma and normal gastric mucosa was detected by real-time fluorescence quantitative PCR (qPCR), and the expression of PRDM2 in gastric adenocarcinoma was detected by im-munohistochemical method. Gastric cancer cell line MGC-803 and human normal gastric mucosal epithelial cell line (GES-1) were selected for study. Blank control group, empty vector transfection group, miR-362 transfection group, and miR-362 and PRDM2 co-transfection group were established. CCK-8 assay was utilized to detect cell activity, flow cytometry was used to detect cell cycle and apoptosis, and invasion capability of cells was observed through transwell experiment. The expression of Cyclin D1 and Caspases-3 was detected by western blot method. Results - The expression of miR-362 in gastric adenocarcinoma was significantly lower than that in normal gastric mucosa. The expression of miR-362 in gastric adenocarcinoma was significantly different in the maximum diameter, depth of invasion, and different TNM stages. The expression of miR-362 was linked to prognosis. In addition, there was a negative correlation between miR-362 and PRDM2. The expression of miR-362 in gastric cancer cell line MGC-803 was significantly lower than that in GES-1. Compared with the blank control group and empty vector transfection group, the proliferation level of gastric cancer cells in miR-362 transfection group was remarkably decreased, the cells in S phase and G2/M phase were significantly decreased, the capability for invasion was evidently decreased, while the apoptosis was significantly increased. The expression of Caspases-3 increased significantly and the expression of Cyclin D1 decreased significantly. MiR-362 and PRDM2 co-transfection groups could reverse the abovementioned expression levels. Conclusion - MiR-362 can regulate the proliferation, invasion and apoptosis of gastric cancer by inhibiting the expression of tumor-promoting factor PRDM2. The expression of miR-362 in gastric adenocarcinoma is significantly decreased, which can regulate the formation and development of gastric adenocarcinoma by promoting the expression of PRDM2. Moreover, low expression of miR-362 in gastric adenocarcinoma is an important risk factor for tumor progression and poor prognosis.

Pyruvate Kinase M2 Knockdown Suppresses Migration, Invasion, and Epithelial-Mesenchymal Transition of Gastric Carcinoma via Hypoxia-Inducible Factor Alpha/B-Cell Lymphoma 6 Pathway.

Gastric carcinoma is a common malignant cancer. Pyruvate kinase M2 (PKM2) is highly expressed in cancers, including gastric carcinoma. However, its function and molecular mechanism in gastric carcinoma remains unclear. Here, we aimed to explore the function and the underlying mechanism of PKM2 on malignant phenotypes in gastric carcinoma. In this study, the mRNA levels and protein levels of PKM2 in gastric carcinoma cell lines and normal gastric mucosa epithelial cell lines were detected using quantitative real-time PCR and western blot, respectively. PKM2 was downregulated by siRNA transfection. HIF-1α or BCL-6 was upregulated by corresponding overexpression plasmid. Cell viability was detected using CCK-8 assay. Cell invasion and migration were determined using transwell assay. Higher expression of PKM2 was observed in human gastric carcinoma cell lines MKN-45 and SGC-7901 than in the normal gastric mucosa epithelial cell line GES-1. PKM2 knockdown suppressed cancer cell invasion and migration and inhibited the epithelial-mesenchymal transition (EMT) phenotype by inhibiting E-cadherin and promoting vimentin and N-cadherin expression. Also, we observed that PKM2 knockdown suppressed the hypoxia-inducible factor alpha (HIF-1α) and B-cell lymphoma 6 (BCL-6) signaling pathway. HIF-1α overexpression reversed the function of PKM2 silencing on cell invasion, migration, EMT, and BCL-6 expression. BCL-6 overexpression also reversed the function of PKM2 silencing on cell invasion, migration, and EMT but did not affect HIF-1α expression. Taken together, data from our study suggest that PKM2 knockdown impeded cell migration, invasion, and EMT of gastric carcinoma cells via the HIF-1α/BCL-6 pathway.

Crocin reverses 1-methyl-3-nitroso-1-nitroguanidine (MNNG)-induced malignant transformation in GES-1 cells through the Nrf2/Hippo signaling pathway.

Crocin, an active constituent of saffron, has anticancer activity. In this study, we investigated the relationship of Crocin with human gastric epithelial cells induced by 1-methyl-3-nitroso-1-nitroguanidine (MNNG), and explored the underlying mechanism. In vivo, the animal growth and atypical hyperplasia were observed in Sprague-Dawley rats. A cell model was established by treating the human gastric mucosa epithelial cell line GES-1 with MNNG. The effects of Crocin on proliferation, cell cycle, apoptosis, and epithelial-mesenchymal transition (EMT) in GES-1 cells were analyzed using Cell Counting Kit-8, colony formation, flow cytometry, and Transwell assay, respectively. Western blot was used to explore the potential mechanism.. The gastric mucosa of animal model deteriorated obviously, the weight growth rate slowed down, and the atypical hyperplasia of gastric mucosa increased. The GES-1 cells had characteristics of malignant cells such as proliferation, apoptosis, and metastasis ability. It was found that Crocin suppressed the cell proliferation, increased apoptosis, and blocked the cycle arrest in G0/G1 phase simultaneously. Furthermore, Crocin negatively regulated the invasion ability of MNNG-treated GES-1 cells and EMT process. Crocin also increased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), decreased TAZ in MNNG-treated GES-1 cells. Interestingly, Crocin regulated the expression of TAZ and yes-associated protein (YAP) by increasing Nrf2 level, as well as their upstream targets, mercaptopyruvate sulfurtransferase (MST) and large tumor suppressor (LATS). Crocin protected against MNNG-induced malignant transformation through the Nrf2/Hippo signaling pathway, which might be a drug candidate for clinical gastric cancer management.

MiR-212 as potential biomarker suppresses the proliferation of gastric cancer via targeting SOX4.

BackgroundCirculating microRNAs that post‐transcriptionally regulate gene expressions have been reported as promising biomarkers in cancer monitoring. This study was to identify the potential role of circulating miR‐212 in gastric cancer and whether it could serve as a novel biomarker for gastric cancer.MethodsWe detected the serum levels of miR‐212 in 100 health people and 110 gastric cancer patients and analyzed the relationships of the serum level of miR‐212 with gastric cancer. We detected the expression of miR‐212 in human gastric mucosal epithelial cell line (GES‐1) and human gastric cancer cell lines (NCI‐N87 and SNU‐16) using qRT‐PCR. Then, we detected the role of 5‐aza‐deoxycytidine on the epigenetic regulation of miR‐212 in human gastric cancer cell lines. Furthermore, luciferase reporter assay was used to detect binding activity of miR‐212 on SOX4 mRNA, and their functions on the cell proliferation and apoptosis.ResultsThe expression of miR‐212 was higher in health people than that in gastric cancer patients, higher in gastric mucosal epithelial cell line than that in gastric cancer cells. miR‐212 can be a circulating biomarker and an independent prognostic factor of gastric cancer. Moreover, miR‐212 can directly regulate the 3′UTR of SOX4 mRNA to suppress p53 and Bax, resulting gastric cancer cells proliferation inhibition and apoptosis induction.ConclusionOur study demonstrated that miR‐212 was epigenetically downregulated in gastric cancer, and resulting low level of miR‐212 can be a potential circulating biomarker and poor prognosis predicator of gastric cancer.

A low toxic CRM1 degrader: Synthesis and anti-proliferation on MGC803 and HGC27.

Chromosome region maintenance 1 (CRM1) is the sole nuclear exporter of several tumor suppressor, a growth regulatory protein as an attractive cancer drug target. In the present work, a novel CRM1 degrader was discovered from newly synthesized α, β-unsaturated-δ-lactone based on a natural product Goniothalamin. It induces apoptosis of both MGC803 and HGC27cell lines via degrading CRM1. Selective inhibition was observed for the proliferation of gastric cancer cell lines MGC803, HGC27 comparing to Human Gastric Mucosal Epithelial Cell Line (GES1). For the first time, CRM1 inhibitor or degrader inducing apoptosis in gastric carcinoma was investigated.

Hedgehog signaling activation required for glypican-6-mediated regulation of invasion, migration, and epithelial-mesenchymal transition of gastric cancer cells.

Gastric cancer (GC) is the fifth most common cancer worldwide and one of the most aggressive cancers in China. Glypican 6 is highly expressed in gastric adenocarcinoma and may act as a diagnostic and prognostic marker; however, the functional importance and molecular mechanism of glypican 6 in GC remains unclear. In the current study, we aimed to reveal the function and mechanism of glypican 6 in two GC cell lines: MKN-45 and SGC-7901. We found higher expression of glypican 6 in MKN-45 and SGC-7901 cells than in cells from the normal gastric mucosa epithelial cell line GES-1. Glypican 6 knockdown suppressed MKN-45 and SGC-7901 cell proliferation. A Transwell assay confirmed that glypican 6 silencing inhibited the migration and invasiveness of MKN-45 and SGC-7901 cells. Epithelial-to-mesenchymal transition (EMT) markers were determined by western blotting, and the results showed reduced Vimentin expression and elevated E-cadherin expression in glypican 6 short interfering RNA (siRNA) transfected MKN-45 and SGC-7901 cells. However, glypican 6 overexpression in GES-1 cells showed no significant promotion on GES-1 cells proliferation and migration. Further studies confirmed that glypican 6 siRNA regulated Hedgehog and Gli1 signaling and participated in the function of glypican 6 on MKN-45 and SGC-7901 cell migration and invasion. Our findings suggest that decreased glypican 6 expression inhibits the migration and invasion ability of GC cells.

Circular RNA-hsa-circ-0000670 promotes gastric cancer progression through the microRNA-384/SIX4 axis

Circular RNAs (circRNAs), a special type of non-coding RNA molecules, have been addressed to be implicated in gastric cancer progression. The GSE93541 and GSE83521 microarrays found hsa-circRNA-000670 (hsa-circ-0000670) as an up-regulated circRNAin gastric cancer. We mainly investigated the function and molecular mechanisms of hsa-circ-0000670 involved in gastric cancer. The expression of hsa-circ-0000670 was determined by RT-qPCR to be highly expressed in gastric cancer tissues relative to corresponding adjacent normal tissues, as well as in gastric cancer cell lines relative to normal gastric mucosal epithelial cell line. By conducting EdU, scratch test and Transwell assays, hsa-circ-000670 was found to be a tumor promoter by potentiating the proliferative, invasive and migrating capabilities of gastric cancer cells. Consistently, a tumor-promotive role of hsa-circ-000670 was validated in vivo. Dual-luciferase reporter gene and RIP assays identified the binding of hsa-circ-0000670 to microRNA-384 (miR-384) and the binding of miR-384 to sine oculis-related homeobox 4 (SIX4). The oncogenic potential of hsa-circ-0000670 in gastric cancer cells were inhibited by overexpressed miR-384. Mechanistically, SIX4 was targeted by miR-384 and was upregulated in gastric cancer. High SIX4 expression was suggested to correlate with the poor prognosis of gastric cancer patients. Additionally, silencing of SIX4 delayed tumor growth and progression, which were reversed by overexpression of hsa-circ-0000670. Taken together, hsa-circ-0000670 acts as a tumor promotor in gastric cancer progression and might be a potential target for gastric cancer treatment.

Overexpressed circ-RPL15 predicts poor survival and promotes the progression of gastric cancer via regulating miR-502-3p/OLFM4/STAT3 pathway

BackgroundIncreasing studies have revealed that circular RNAs (circRNAs) contribute to gastric cancer (GC) progression. The circular RNA ribosomal protein L15 (circ-RPL15) is involved in chronic lymphocytic leukemia. However, its expression and functions in GC remain elusive. MethodsThe expression of circ-RPL15 in human GC tissues and adjacent normal tissues, human gastric cancer cell lines (MGC-803, BGC-823, MGN-28, SGC-7901, AGS) and normal gastric mucosal epithelial cell line (GES-1) were detected by RT-PCR. The relationship between circ-RPL15 level and clinical-pathological indicators were also analyzed. Gain- of function experiments of circ-RPL15 and miR-502-3p were conducted to verify their roles in mediating GC cell proliferation, apoptosis and metastasis. Also, the downstream mechanisms of circ-RPL15 were predicted by bioinformatics analysis, and the interactions between circ-RPL15 and miR-502-3p, miR-502-3p and OLFM4 were verified by dual luciferase reporter gene assay and RNA FISH. Resultscirc-RPL15 was upregulated in GC tissues and cell lines, and the overexpressed circ-RPL15 was correlated with poorer survival of GC patients. Functionally, circ-RPL15 upregulation distinctly promoted the proliferation, migration and invasion of GC cells and inhibited apoptosis. Mechanistically, circ-RPL15 functioned as a competitive endogenous RNA via sponging miR-502-3p and activated OLFM4/STAT3 pathway. Conclusioncirc-RPL15 promotes GC progression and predicts poor prognosis of GC patients, and regulates the malignant phenotypes of GC cells by mediating the miR-502-3p/OLFM4/STAT3 axis.

Exosomal miR-155-5p promotes proliferation and migration of gastric cancer cells by inhibiting TP53INP1 expression

Exosomal microRNA (miRNA) secreted by tumor cells plays an important biological role in tumorigenesis and development. We aimed to explore the effects of exosomal miR-155-5p in gastric cancer (GC) and understand its mechanism of action in GC progression. We isolated exosomes from the human gastric mucosal epithelial cell line GES-1 and gastric cancer cell line AGS, and then identified them according to their surface markers by flow cytometry. Later, we detected the miR-155-5p expression levels in tissues and isolated exosomes using RT-qPCR. Bioinformatics analysis showed that miR-155-5p directly binds to the 3' untranslated region (3'-UTR) of tumor protein p53-induced nuclear protein 1 (TP53INP1) mRNA. We also investigated whether the miR-155-5p-rich exosomes caused changes in cell cycle, proliferation, and migration in AGS cells. In this study, we found that the levels of miR-155-5p were significantly increased in GC tissues and AGS cells, and that the TP53INP1 protein level was downregulated in GC tissues using IHC and IFC. TP53INP1 was found to be directly regulated by miR-155-5p following a dual luciferase-based reporter assay. After co-culturing with the isolated miR-155-5p-rich exosomes, the proliferation and migration capabilities of AGS cells were enhanced. Thus, our results reveal that exosomal miR-155-5p acts as an oncogene by targeting TP53INP1 mRNA in human gastric cancer.

MiR-21 Promotes the Invasion and Metastasis of Gastric Cancer Cells by Activating Epithelial-Mesenchymal Transition

Background: Gastric cancer (GC) is one of the most common malignant tumors. It is likely to occur in lymph nodes and is prone to distant metastasis in its early stages, which portends a poor prognosis. Previous studies have shown that miRNA-21 was abnormally highly expressed and associated with early metastasis in GC, but the mechanism by which it regulates the invasion and metastasis of GC has not been elucidated. Methods: Epithelial-mesenchymal transition (EMT) is an important pathologic basis of tumor invasion and metastasis, and in this study, the relationship between miRNA-21 and EMT in GC invasion and metastasis was investigated using RT-qPCR, Western blot, and wound scratch and transwell assays. Results: We found that miRNA-21 expression in GC cell lines was higher than in a gastric mucosal epithelial cell line. After transfection with an miRNA-21 mimic, the upregulation of EMT was found to promote migration and invasion of MGC-803 cells. However, the downregulation of EMT was found to accompany the inhibition of invasion and migration of GC cells after downregulation of miRNA-21 expression due to the transfection of an miRNA-21 inhibitor. Conclusions: These findings suggest that miRNA-21 might promote the invasion and metastasis of GC by upregulating EMT.

Oncogenic USP22 supports gastric cancer growth and metastasis by activating c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling.

In this study, we investigated the role of ubiquitin-specific protease 22 (USP22) in the growth and progression of gastric cancer (GC). USP22 mRNA and protein levels were significantly higher in GC tissue samples and GC cell lines than in adjacent noncancerous tissue samples and a normal gastric mucosal epithelial cell line (GES1), respectively. USP22 knockdown significantly decreased in vitro survival, proliferation, migration, and invasiveness of GC cells compared with the controls. Western blot analysis of control and USP22-silenced GC cells showed that USP22 modulates the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways. Subcutanenous injection of USP22-silenced GC cells into SCID mice generated significantly smaller xenograft tumors than did control cells. Moreover, USP22-silenced GC cells showed less lung metastasis than the controls following tail vein injection in SCID mice. In addition, high USP22 expression correlated positively with tumor size, advanced stage and metastasis, and correlated negatively with tumor differentiation and prognosis in GC patients. These results show that USP22 regulates growth and progression of GC via the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways.

Eukaryotic translation initiation factor 3B downregulation inhibits cell proliferation and promotes cell apoptosis through negatively regulating tumor necrosis factor receptor superfamily member 21 in gastric cancer

Background: This study aimed to detect eukaryotic translation initiation factor 3B (EIF3B) expression in gastric cancer (GC) cell lines, and further explore the effect of EIF3B downregulation on GC cell proliferation and apoptosis. Methods: EIF3B mRNA expression and protein expression in human GC cell lines (NCI-N87, AGS, HGC-27, BGC-823 and MGC80-3) and human gastric mucosal epithelial cell line (GES-1) were detected. Control siRNA (Si-NC group) and EIF3B siRNA (Si-EIF3B group) were transfected into NCI-N87 cells. Rescue experiment was performed by transfection of EIF3B siRNA (Si-EIF3B group) and EIF3B siRNA plus tumor necrosis factor receptor superfamily member 21 (TNFRSF21) siRNA (Si-EIF3B & Si-TNFRSF21 group) into NCI-N87 cells. Besides, cell proliferation, apoptosis, TNFRSF21 expression and TRAF1 expression were assessed. Results: EIF3B mRNA expression and protein expression were elevated in NCI-N87, AGS, HGC-27 and BGC-823 cell lines compared to GES-1 cell line. In NCI-N87 cells, proliferation was reduced in Si-EIF3B group compared to Si-NC group. For cell apoptosis, its rate and apoptotic marker C-Caspase 3 expression were increased but anti-apoptosis marker Bcl-2 expression was reduced in Si-EIF3B group compared to Si-NC group. Moreover, mRNA expression and protein expression of TNFRSF21 were increased in Si-EIF3B group compared to Si-NC group, while mRNA expression and protein expression of TRAF1 were reduced in Si-EIF3B group compared to Si-NC group. In rescue experiment, cell proliferation was increased but apoptosis was decreased in Si-EIF3B & Si-TNFRSF21 group compared to Si-EIF3B group. Conclusions: EIF3B is overexpressed in GC cell lines, and its downregulation inhibits cell proliferation while promotes apoptosis through negatively regulating TNFRSF21 in GC.