Gastric Cancer Cell Line SGC-7901 Research Articles

Silencing APRIL Gene by siRNA Leads to Inhibition of Proliferation and Cell Cycle Arrest in Gastric Cancer Cell Line MGC-803 and SGC-7901

The aim of this study was to explore the effects of silencing a proliferation-inducing ligand on the growth and cell cycle of human gastric cancer cells. MGC-803 and SGC-7901 cells were infected with lenti-a proliferation-inducing ligand si and mRNA expression was analyzed by real-time polymerase chain reaction. Cell viability, colony formation and cell cycle stages were detected by MTT assay, colony forming assay and Cellomics ArrayScan, respectively. Results from real-time polymerase chain reaction indicated that lenti-a proliferation-inducing ligand-si greatly reduced the proliferation-inducing ligand mRNA expression in both cell lines. Cell viability and colony formation ability were significantly hampered. Moreover, cell cycle was arrested in both cell lines, elucidating the mechanism underlying the inhibitory effects of siRNA on cell proliferation. The present study indicated that lentivirus-mediated gene delivery might be a promising strategy in the treatment of gastric cancer.

Effect of STIL on the Gene Expression Profile of Gastric Cancer Cells

Objective To explore the molecular mechanism underlying gastric carcinogenesis and progression by using gene expression profiling array together with bioinformatics. Methods Lentivirus short hairpin RNA targeting STIL(ShSTIL)and scrambled sequence RNA(ShCon)were transduced into the gastric cancer cell line SGC-7901.RNA extraction,complementary DNA synthesis,construction of biotin-labelled amplified RNA probes,and hybridization with gene expression profile were consecutively performed.We collected corresponding data and analyzed differentially expressing genes(DEGs),followed by the analysis of gene ontology(GO)and Kyoto encyclopedia of genes and genomes(KEGG)enrichment,transcription factor regulating network,and protein-protein interacting networks. Results Compared with ShCon,a total of 417 and 87 genes were respectively down-regulated and up-regulated,respectively,in the ShSTIL group(P<0.05,fold change>1 or <-1).GO and KEGG enrichment analysis indicated that genes regulated by STIL were localized in cytoplasm,extracellular exosome,Golgi apparatus and various biomembranes,and were implicated in the ubiquitin-mediated proteolysis,P53 signaling pathway,and pathways regulating pluripotency of stem cells.Evaluation on genes enriched in KEGG pathways,regulation of transcription factors,and protein-protein interacting network demonstrated that IGF1R,STUB1,SKP2,and FOXO1 were localized at the centre of the network and played a key role in the development and progression of gastric cancer. Conclusion Through the protein-protein interactions,STIL may activate E3 ubiquitin ligase STUB1 or SKP2,promote the proteolysis of FOXO1-a transcription factor,regulate the expression of IGF1R,and thus promote gastric carcinogenesis and progression.

Stat-3 signaling promotes cell proliferation and metastasis of gastric cancer through PDCD4 downregulation.

The present study explored a new downstream regulator of Stat-3 signaling, miR-499-5p and its target gene programmed cell death 4 (PDCD4) in cell survival and metastasis of gastric cancer. Our results showed that miR-499-5p is significantly upregulated in human gastric cancer cell line SGC-7901. We further demonstrated that miR-499-5p promotes gastric cancer cell proliferation and invasion in vitro. Mechanistically, we demonstrated that upregulation of miR-499-5p expression associated with inhibition of PDCD4; STAT3 transcriptional activation by IL-6 is crucial for the upregulation of miR-499-5p expression. These results indicate that the STAT3-miR-499-5p-PDCD4 signaling axis plays an important role in gastric cancer progression and a potentially therapeutic target for gastric cancer treatment.

Ganoderma lucidum Polysaccharide Enhanced the Antitumor Effects of 5-Fluorouracil against Gastric Cancer through Its Upregulation of NKG2D/MICA

5-Fluorouracil (5-Fu) is one of the frequently used first-line cytotoxic drugs for chemotherapy against gastric cancer. Chemotherapy and immunotherapy are currently the main methods for treating gastric cancer. Immunotherapy can enhance the antitumor effect of chemotherapy drugs at the same time reducing its toxicity. The combination of these two therapies to treat cancer has become a mainstay and has received increasing attention in clinical practice. Ganoderma lucidum polysaccharide (GLP) is isolated from the Ganoderma lucidum fruiting body. Studies have shown that GLP has antitumor effects, where GLP does not directly kill tumors, rather exerting its antitumor function by stimulating immune cells including natural killer (NK) cells and T cells. In this study, the antitumor effect of GLP combined with 5-Fu was studied in vivo. At the same time, the associated mechanism of GLP combined with 5-Fu in gastric cancer cell lines BGC823 and SGC7901 was investigated in vitro. The results showed that GLP could stimulate the killing effect of NK-92 cells on gastric cancer cell lines BGC823 and SGC7901 and synergistically enhance the toxic effects of NK-92 cells on gastric cancer cell lines BGC823 and SGC7901. Moreover, GLP could further promote the activity of NK-92 cells by activating the NK cell activating receptor NKG2D and its downstream DAP10/PI3K/ERK signaling pathway.

Impact and mechanism of Loganin on epithelial mesenchymal transformation of gastric cancer cells

Objective To explore impact and molecular mechanism of Loganin on epithelial mesenchymal transformation of gastric cancer cells. Methods Human gastric cancer cell lines AGS, BGC823 and SGC7901 were cultured routinely. The effect of Loganin on cells activity was tested by utilizing methyl thiazol tetrazolium (MTT) assay. Also Wound assay and Transwell assay were employed to detect the effect of Loganin on migration and invasion in BGC823 cells. Furthermore, real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) and Western blotting were used to examine the variations of associated genes and phosphatidylinositol 3 kinase (PI3K)-protein kinase B (Akt) signal pathway in BGC823 cells prior and post Loganin interventions. Results Results of MTT assay showed that the activity of BGC823 was lowest among AGS (0.748±0.051), BGC823 (0.581±0.042) and SGC7901 (0.412±0.037) (F=44.101, P<0.01); the expression level of PCNA mRNA and protein declined gradually with the increase dose of Loganin (F=36.298, 47.942, P<0.01). Compared with the control group, the ability of migration and invasion in BGC 823 cells decreased, and this changes were particularly distinct in high dose Loganin group (200 mg/L), which were more significant than in low dose group (50 mg/L) (migration: F=87.750, P<0.01; invasion: F=85.749, P<0.01). Results of qPCR and Western blotting showed that expressions of migration, invasion associated genes in BGC823 cells changes significantly compared with the control group, especially in high dose Loganin group (P<0.01). Results of qPCR and Western blotting illustrated that EMT related gene in BGC823 cells changes significantly compared with the control group, especially in high dose Loganin group (P<0.01). The activity of PI3K-Akt signal pathway declined significantly post Loganin intervention, and expression of p-PI3K, p-Akt decreased significantly, especially in high dose Loganin group (F=38.590, 63.563; P<0.01). Conclusion Loganin may inhibit EMT in gastric cancer cells via regulating PI3K-Akt signal pathway. Key words: Gastric cancer; Loganin; Invasion; Epithelial mesenchymal transformation; Phosphatidylinositol 3 kinase-protein kinase B signal pathways

The Therapeutic Effect of Melatonin on GC by Inducing Cell Apoptosis and Autophagy Induced by Endoplasmic Reticulum Stress.

BackgroundGastric cancer (GC) is the main malignancy affecting a large population worldwide. Lack of effective enough treatment is one of the leading factors contributing to the high mortality rate. Melatonin, a naturally occurring compound, has been proven to exert cytotoxic and antiproliferative effects on human gastric cancers. Nevertheless, the mechanisms of anti-gastric cancer of melatonin remain elucidated. It is believed that endoplasmic reticulum (ER) stress and its resultant unfolded protein response (UPR) are connected to the survival, progression, and chemoresistance of various tumor cells via multiple cellular procedures, such as autophagy. In this study, the effects of melatonin on human gastric cancer cell lines AGS and SGC-7901 was assessed to reveal the interaction between melatonin, endoplasmic reticulum stress, and autophagy in gastric cancer.MethodsCCK-8, the wound healing analysis, colony formation assay, immunofluorescence analysis, Western blotting, flow cytometry, and animal models were used in the current study.ResultsThe data demonstrated that melatonin could inhibit GC growth, proliferation, and invasion both in vivo and in vitro. Apoptosis and autophagy induced in a concentration-dependent manner is response to melatonin-induced ER stress. Melatonin induced the expression of apoptotic and autophagy-related proteins, which was markedly attenuated by the ER stress inhibitor 4-PBA and autophagy inhibitor 3-MA. In addition, we used the specific IRE1 inhibitor STF 083010, finding that inhibiting IRE1 could considerably relieve ER stress-induced autophagy activity, as revealed by the reduction of LC3-II and Beclin-1.ConclusionThis study confirmed that melatonin-induced inhibition of GC cell proliferation is mediated by the activation of the IRE/JNK/Beclin1 signaling.

Calcium-sensing receptor bridges calcium and telomerase reverse transcriptase in gastric cancers via Akt.

Human telomerase reverse transcriptase (hTERT) and calcium-sensing receptor (CaSR) act as an oncogene in gastric cancers, however, their relationship in the progression of gastric cancers is yet to be elucidated. Herein, we aimed to access the potential interaction between hTERT and CaSR in the development of gastric cancers. The clinical data of 41 patients with gastric cancers were analyzed regarding the expressions of hTERT and CaSR by immunohistochemistry. Among them, five patients' specimens were also analyzed by Western blotting. The regulation of calcium on the expression level of hTERT and the possible underlying mechanism via CaSR were explored in gastric cancer cell lines MKN45 and SGC-7901. Both hTERT and CaSR were increased and positively correlated in human gastric cancers, which also occurs in gastric cancer cells MKN45 and SGC-7901. Calcium induced hTERT expression at the transcriptional level in a CaSR-dependent manner followed by an increase in telomerase activity, as either a CaSR shRNA or the CaSR antagonist NPS2143 abolished the calcium-mediated regulation of hTERT and telomerase activity. Further studies showed that CaSR-mediated cytosolic calcium rise followed by Akt activation was involved in the regulation of hTERT by extracellular calcium. Finally, neither CaSR overexpression nor shRNA-mediated CaSR downregulation had an effect on the expression level of hTERT. Our findings established a functional linkage between CaSR and hTERT in the development of gastric cancers and CaSR-hTERT coupling might serve as a novel target for therapeutic strategy against human gastric cancers.

Schisantherin A induces cell apoptosis through ROS/JNK signaling pathway in human gastric cancer cells

Gastric cancer is one of the most lethal cancers with unmet clinical treatment and low 5-year survival rate. Schisantherin A is a major compound derived from Fructusschisandrae while its anti-tumor role remains nearly unknown. Here, we reported that schisantherin A had an anti-proliferation effect on gastric cancer cell lines MKN45 and SGC-7901. Schisantherin A induced cell cycle arrest at G2/M phase and cell apoptosis, and inhibited cell migration in gastric cancer MKN45 and SGC7901 cells. Meanwhile, upregulation of cleaved caspase-9, cleaved caspase-3 and cleaved PARP were accompanied with the loss of mitochondrial membrane potential (MMP). Moreover, schisantherin A induced ROS-dependent JNK phosphorylation with higher ROS production. The JNK inhibitor and ROS scavenger NAC rescued the cell apoptosis and cycle inhibition elicited by schisantherin A. Furthermore, the expression level of antioxidant factor Nrf2 was suppressed by schisantherin A. These findings suggest that schisantherin A possesses an anti-tumor activity via activation of ROS/JNK with Nrf2 inhibition, indicating that schisantherin A is a promising chemotherapeutic candidate for gastric cancer.

The mechanism of action of HOX antisense intergenic RNA in gastric cancer

Objective Investigate the mechanism of HOX antisense intergenic RNA (HOTAIR) in the pathogenesis of gastric cancer. Methods 40 patients with gastric cancer were selected, there were 29 males and 21 females with an average age of (51.7±10.8) years; Ⅰ period 20 cases, Ⅱ period 10 cases, Ⅲ period 6 cases, Ⅳ period 4 cases; 9 cases of high differentiation, 12 cases of middle differentiation and 19 cases of low differentiation. The expression levels of long non-coding RNA (lncRNA) HOTAIR in cancer tissues and adjacent tissues of gastric cancer patients were detected by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR), andanalyzed the correlation between the expression of HOTAIR and the clinical characteristics of gastric cancer patients. lncRNA HOTAIR small interfering RNA (siRNA) were designed and synthesized, and the silencing model was established in the primary SGC-7901 gastric cancer cell line. The expression of lncRNA HOTAIR in primary SGC-7901 gastric cancer cells was detected, add the effects of lncRNA HOTAIR on the proliferation and apoptosis of cancer cellsanalyzed. The molecular regulatory mechanism was studied by Western blotting and RT-qPCR. Results The expression of lncRNA HOTAIR in cancer tissues was (4.367±0.352), higher than that in adjacent tissues (0.984±0.782) (P 0.05). After 48 h of lncRNA HOTAIR siRNA transfection, the ratio of early apoptotic cells [(22.69±3.21)% vs. (10.97±1.52)%], late apoptotic cells [(30.41±3.97)% vs. (7.40±1.71)%] and necrotic cells [(5.53±0.74)% vs. (3.44±0.42)%] was significantly higher than that of untransfected cells (t=5.715, 9.220, 4.254, P<0.05). The relative expression of Wnt3a protein in the cells after transfection was significantly lower than that in the untransfected group (0.39±0.07 vs. 0.92±0.13, t=6.217, P<0.05). Conclusion lncRNA HOTAIR is up-regulated in gastric cancer, while inhibiting HOTAIR expression can inhibit the activation of Wnt/β-catenin signaling pathway by down-regulating Wnt3a protein expression, thereby promoting the apoptosis of gastric cancer cells. Key words: Long non-coding RNA HOX antisense intergenic RNA; Gastric cancer; Apoptosis

Curcumin Promoted miR-34a Expression and Suppressed Proliferation of Gastric Cancer Cells.

Background: To investigate the effects of curcumin on miR-34a and proliferation of gastric cancer cells. Materials and Methods: Human gastric cancer cell line SGC-7901 was divided into control, curcumin, miR-34a agomir (miR-34a), miR-34a agomir negative control, and curcumin combined miR-34a antagomir (combine) groups. 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay, scratch damage test, and transwell assay were used to detect cell proliferation, migration, and invasion. The cell apoptosis and cell cycle were detected by flow cytometry. Western blot was used to detect the expression of B-cell lymphoma-2 (Bcl-2), cyclin-dependent kinase 4 (CDK4), and cyclin D1. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was used to detect apoptosis of tumors and Western blot was used to detect the expression of Bcl-2, CDK4, and cyclin D1 in tumors. Results: The results showed that curcumin markedly increased the content of miR-34a microRNA (mRNA) in SGC-7901 cells, inhibited proliferation, migration, and invasion of SGC-7901 cells, when compared to control group (p < 0.05). Compared with control group, curcumin significantly inhibited cell cycle progression in G0/G1-S phase, increased the cell number of G0/G1 phase, and downregulated the Bcl-2, CDK4, and cyclin D1 protein expression in cells and tissues (p < 0.05). After transfection of miR-34a agomir or antagomir into cells it was found that miR-34a agomir and curcumin had similar effects on resisting malignant biological behavior. Curcumin combined with miR-34a antagomir could weaken or reverse the above results. Conclusions: Curcumin could inhibit the proliferation and induce apoptosis of SGC-7901 cells. Its mechanism might be related to the miR-34a expression in cells, thus affecting the expression of Bcl-2, CDK4, and cyclin D1.

Effects of microRNA-877 on proliferation and invasion of gastric cancer cells

Objective To investigate the effects of microRNA (miRNA, miR)-877 on proliferation and invasion of SGC7901 gastric cancer cells. Methods The relative expression level of miR-877 in gastric cancer cell lines (SGC7901, MGC803, MKN-45, BSG823, HGC-27, AGS) and normal gastric cell line (GES-1) were measured by real-time quantitative polymerase chain reaction (Real-time PCR). MiR-877 agonist (miR-877 mimics) was synthesized. MiR-877 mimics and miR-877 negative control were transfected into SGC7901 cells by liposome Lipofectamine™ 2000. Cell proliferation ability was detected by cell counting kit-8 (CCK-8) assay. Cell invasion ability was evaluated by Transwell method. The expression of phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB, also called Akt), phosphorylated Akt (p-Akt) were detected by Western blotting. Results The relative expression level of miR-877 was significantly lower in gastric cancer cell lines SGC7901 (0.21±0.05), MGC803 (0.63±0.11), MKN-45 (0.35±0.07), BSG823 (0.49±0.08), HGC-27 (0.75±0.10), AGS (0.43±0.07) than that in GSE-1 cells (1.09±0.13, all P<0.05). The relative expression level of miR-877 in miR-877 mimics group (0.27±0.05) was significantly lower than that in negative control group (1.06±0.11, t=11.690, P<0.01). The results of CCK-8 assay showed that the absorbance value of miR-877 mimics group (1.59±0.09) was significantly lower than that of negative control group (2.28±0.11, t=4.746, P<0.01) after culturing 72 h. The results of Transwell assay revealed that cell invasion number in miR-877 mimics group (43.60±17.30) was significantly lower than that in negative control group (129.35±16.70, t=8.148, P<0.01). The results of Western blotting manifested that the expression level of PI3K, Akt, p-Akt in miR-877 mimics group were significantly lower than that in negative control group (all P<0.01). Conclusion MiR-877 could inhibit the proliferation and invasion of gastric cancer cells, which is involved in suppressing PI3K/AKt signaling pathway. Key words: Gastric cancer; MicroRNA-877; Proliferation; Invasion; Phosphatidylinositol-3-kinase/protein kinase B signaling pathway

The Effect of Dihydroartemisinin on the Malignancy and Epithelial-Mesenchymal Transition of Gastric Cancer Cells.

This study aimed to observe the effects of dihydroartemisinin (DHA) on the proliferation, apoptosis, invasion, migration, and epithelial-mesenchymal transition (EMT) of the human gastric cancer cell line SGC7901 cultured in vitro. We applied varying concentrations of DHA to SGC7901 cells. Cell proliferation was measured using the cell counting kit-8 (CCK-8). Flow cytometry, Transwell invasion assay, and cell scratch assay were used to investigate the cells' apoptosis, invasion, and migration. Western blot was used to assess the expression levels of EMT markers E-cadhein and Vimentin, protein kinases Akt and phosphorylated AKT (p-AKT), and the cell transcription factor Snail. DHA can effectively inhibit the malignant proliferation of gastric cancer cells in a time- and dose-dependent manner. In this study, with longer incubation times and increased drug concentrations, the antiproliferation effect of DHA on SGC7901 cells increased gradually (P<0.05). In addition, with the increase of drug concentration, the expression levels of E-cadhein, an epithelial-mesenchymal transition marker, remarkably increased, whereas the protein expression levels of the mesenchymal markers Vimentin, Akt, p-Akt, and Snail significantly decreased (P<0.05). DHA can effectively inhibit the proliferation, invasion, and metastasis of the gastric cancer cell line SGC7901 and induce cancer cell apoptosis. DHA can also downregulate PI3K/AKT and Snail activities and inhibit the epithelial-mesenchymal transition of gastric cancer cells. The potential anticancer effects of DHA deserve further investigation.

Exosome-mediated transfer of CLIC1 contributes to the vincristine-resistance in gastric cancer.

Our previous study shows that high Chloride intracellular channel 1 (CLIC1) expression can efficiently enhance invasion and migration of gastric cancer (GC) cells in vitro. Growing evidences have found that exosomes are involved in chemotherapy resistance in several cancers including GC. We aimed to evaluate the effect of the exosome-mediated transfer of CLIC1 in the vincristine-resistance of GC. The effect of exosome-mediated transfer of CLIC1 on the development of resistance to vincristine in GC cell line SGC-7901 and the potential underlying mechanisms were investigated by Cell Counting Kit-8 (CCK8), RT-PCR, and Western blotting. Exosomes were isolated from cell supernatants by differential ultracentrifugation. Comparing with SGC-7901, the expression level of CLIC1 is higher in vincristine‑resistant cell line SGC-7901/VCR (P < 0.05). After silencing the expression of CLIC1 by RNA interference, the half inhibition concentration (IC50) to vincristine decreased significantly in SGC-7901/VCR, and the expression of CLIC1 decreased significantly in exosomes from SGC-7901/VCR. After 48h co-culturing with exosomes from SGC-7901/VCR, the IC50 to vincristine in SGC-7901 increased significantly, and the expression of CLIC1, P-gp, and Bcl-2 were significantly up-regulated. CLIC1 was closely associated with the resistance to vincristine in GC, and exosome-mediated transfer of CLIC1 could induce the development of resistance to vincristine in vitro. The possible mechanism was related to up-regulated P-gp and Bcl-2. However, in vivo study was needed to confirm the results in future.

Effect of peroxiredoxin 1 on apoptosis and autophagy of human gastric cancer cells and possible mechanism

Objective To investigate the effect and molecular mechanism of peroxiredoxin 1 (PRDX1) in human gastric cancer cell lines. Methods The expression of PRDX1 was detected in gastric cancer cell lines SGC7901, AGS and the normal gastric mucosa cell line GES-1 with real-time quantitative polymerase chain reaction (Real-time PCR). Small interfering RNA to PRDX1 was synthetized for the transfection with lentivirus vector of LV-PRDX1-small interfering RNA (siRNA), which was transfected into AGS. Methyl thiazol tetrazolium (MTT) assay was used to test activity of cells. Flow cytometry (FCM) was used to detect the apoptosis rate and mitochondrial trans-membrane potential. Real-time PCR and Western blotting were used to detect the expression of mRNAs and proteins associated with apoptosis and autophagy. Results The expression of PRDX1 mRNA (1.049±0.124, 1.597±0.103) and proteins (0.873±0.135, 1.083±0.204) in SGC7901, AGS cells was significantly higher than that in GES-1 cells (mRNA: 0.451±0.060, and protein: 0.305±0.022), and the difference was significant (F=200.162, 48.432, P 0.05), and the expression of Beclin-1 and LC-3Ⅱ/LC-3Ⅰ increased significantly (F=30.332, 24.260, P<0.01). Conclusion PRDX1 was up-regulated in gastric cancer cells, and inhibition of PRDX1 can regulate apoptosis and autophagy via regulating apoptosis and autophagy associated genes. Key words: Gastric cancer; Peroxiredoxin1; Autophagy; Target gene

Malic enzyme 1 (ME1) is a potential oncogene in gastric cancer cells and is associated with poor survival of gastric cancer patients.

Background and objectiveGastric cancer is one of the most common cancers worldwide. However, the mechanisms associated with this disease are still not clear. Malic enzyme 1 (ME1) is a metabolic enzyme that is overexpressed in various cancers. Here, we examined whether it is involved in gastric cancer.MethodsME1 expression was knocked down in the gastric cancer cell line SGC7901. Cell growth and migration were measured using a real-time microelectronic cell sensor system. Cell invasion was measured using a Transwell assay. Cell cycle analysis was also performed to examine cell cycle arrest. A gastric cancer tissue microarray of gastric cancer was stained using immunohistochemistry. ME1 expression levels were also statistically analysed.ResultsME1 knockdown in gastric cancer SGC7901 cells significantly inhibited cell proliferation, migration, and invasion. Cell cycle arrest was induced in the G2 phase. Further, ME1 expression was significantly correlated with gastric cancer patient prognosis based on both univariable and multivariable survival analysis. No significant difference was found between ME1 expression in gastric cancer tissues and that in adjacent tissues.ConclusionOur results provide evidence that ME1 is a key factor for gastric cancer. ME1 might be pro-oncogenic during both the development and migration of gastric cancer; it also might be related to gastric cancer patient survival.

MicroRNA-362-5p enhances the cisplatin sensitivity of gastric cancer cells by targeting suppressor of zeste 12 protein.

Chemotherapy resistance is a major obstacle to the effective treatment of patients with gastric cancer (GC). Mounting evidence has indicated that the dysregulation of microRNAs (miRNAs) is associated with the sensitivity of cancer cells to chemotherapy. However, the mechanisms underlying miRNA-mediated chemoresistance in GC cells remain to be elucidated. The present study aimed to identify functional miRNAs that may regulate the sensitivity of human GC cells to cisplatin (DDP) treatment. miRNA microarray analysis was used to identify differentially expressed miRNAs between the human cisplatin-sensitive GC cell line SGC7901 and the corresponding cisplatin-resistant cell line SGC7901/DDP. miRNA (miR)-362-5p, which is associated with numerous types of tumors, was identified to be downregulated in the SGC7901/DDP cell line. However, the biological role of miR-362-5p in SGC7901/DDP cells remains to be explored. The expression level of miR-362-5p was demonstrated to be reduced in SGC7901/DDP cells compared with SGC7901 cells by reverse transcription-quantitative PCR. Upregulation of miR-362-5p significantly increased cisplatin sensitivity and cisplatin-induced apoptosis, whereas downregulation of miR-362-5p attenuated these effects. Databases predicted that suppressor of zeste 12 protein (SUZ12) may function as a target of miR-362-5p. In addition, the mRNA and protein expression levels of SUZ12 in SGC7901/DDP cells were significantly higher compared with SGC7901 cells and negatively associated with miR-362-5p expression. MTT and western blot analysis assays confirmed that knockdown of SUZ12 enhanced cisplatin sensitivity and decreased NF-κB/p65 protein levels in SGC7901/DDP cells. In addition, upregulation of miR-362-5p in SGC7901/DDP cells decreased the protein expression level of SUZ12, whereas downregulation of miR-362-5p increased the SUZ12 expression level. The results of the present study suggested that dysregulated miR-362-5p may target SUZ12 to promote the development of cisplatin resistance and attenuate cisplatin-induced apoptosis. Therefore, miR-362-5p upregulation combined with cisplatin treatment may serve as a promising therapeutic strategy for patients with cisplatin-resistant GC.

Apoptosis-promoting and migration-suppressing effect of alantolactone on gastric cancer cell lines BGC-823 and SGC-7901 via regulating p38MAPK and NF-κB pathways

Gastric cancer is a malignant tumor with high incidence rate and mortality rate. In this study, we investigated the anti-cancer effect of alantolactone, a sesquiterpene lactone, on gastric cancer cell lines BGC-823 and SGC-7901. BGC-823 and SGC-7901 cells were treated with different concentrations of alantolactone, Hoechst 33258 staining, flow cytometry, wound healing assay, invasion assay, colony forming assay, quantative polymerase chain reaction, and western blot analysis were used to evaluate the anticancer activity of alantolactone to gastric cancer. Alantolactone induced apoptosis of gastric cancer cells by regulating the expression of Bax, Bcl-2, and p53, which related to intrinsic apoptotic pathway, and suppressed colony formation, migration, and invasion by mediating the expression of matrix metalloproteinase (MMP)-2, MMP-7, and MMP-9. Cell signaling pathway analysis showed that alantolactone enhanced the phosphorylation of p38 and decreased the translocation of nucleus p65, suggesting that the apoptosis-promoting and migration-suppressing effect of alantolactone might at least partially rely on regulating p38 mitogen-activated protein kinase (p38MAPK) pathway and nuclear factor-κB (NF-κB) pathway. Alantolactone can be used as a potential therapeutic agent for treating gastric cancer.

&lt;p&gt;Effect of overexpression of Oct4 and Sox2 genes on the biological and oncological characteristics of gastric cancer cells&lt;/p&gt;

Objective: Using the gastric cancer cell line SGC7901, we constructed a cell line that overexpressed octamer-binding protein 4 (Oct4) and SRY-box 2 (Sox2) to explore the stem cell oncological and biological characteristics of these cells and to elucidate the mechanisms of Oct4 and Sox2 in cancer.Methods: A lentiviral vector containing the Sox2 gene was constructed and transfected into a gastric cancer cell line overexpressing Oct4 (SGC7901-Oct4) to obtain a stably transfected cell line (SGC7901-Oct4-Sox2). Oct4 and Sox2 expression was detected by RT-PCR and Western blotting. The proliferation, drug resistance, migration, and invasion abilities of the cells were assessed using in vitro (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium), drug resistance, scratch-wound migration, transwell migration, transwell invasion, and spherical clone formation assays, and their tumorigenic ability was assessed using a tumor formation experiment in mice.Results: Compared with the control group, the expression of Oct4, Sox2, CD44, and E-cadherin was significantly higher in the group that overexpressed Oct4 and Sox2, while the expression of c-Myc and Klf4 did not significantly change. The proliferation, drug resistance, migration, and invasion abilities were significantly enhanced in the overexpression group, and the tumorigenic ability in mice was also significantly enhanced, with significantly increased tumor size and weight.Conclusion: The proliferation, drug resistance, migration, invasion, and tumorigenic abilities of SGC7901 cells overexpressing Oct4 and Sox2 were significantly improved. Oct4 and Sox2 play important roles in the proliferation, migration, invasion, and tumorigenicity of gastric cancer cells, and the two genes may be synergistic to a certain degree.

Expression of PSMA 7 and its effect on proliferation, invasion, migration and tumorigenesis of gastric cancer

To study the expression of PSMA7 and its effect on proliferation, invasion and migration of gastric cancer and subcutaneous tumorigenesis in nude mice. &gt;and subcutaneous tumorigenesis in nude mice. Specimens of tumor tissues and paired adjacent tissues were collected from 60 patients with gastric cancer for detecting the expression levels of PSMA7 using immunohistochemical method. Gastric cancer cell line SGC7901 was transfected with a lentiviral vector to inhibit PSMA7 expression, and the changes in cell proliferation and invasion were observed using cell counting kit-8 (CCK-8), clone formation assay and Transwell assay. A BALB/c mouse model bearing subcutaneous gastric cancer xenograft was established using SGC7901 cells with stable PSMA7 knockdown to assess the effect of low expression of PSMA7 on xenograft growth. Gastric cancer tissues expressed significantly higher levels of PSMA7 than the paired adjacent tissues (P &lt; 0.05). In SGC7901 cells, interference of PSMA7 expression significantly inhibited the cell proliferation and invasion (P &lt; 0.05). In the tumor-bearing BALB/c mice, the xenografts derived from SGC7901 cells with PSMA7 expression interference showed significant growth suppression as compared with the control xenografts (P &lt; 0.05). PPSMA 7 is overexpressed in gastric cancer tissues, and PSMA7 knockdown inhibits the proliferation, invasion, migration and subcutaneous tumorigenesis of gastric cancer cells in nude mice.

Divergolides T⁻W with Apoptosis-Inducing Activity from the Mangrove-Derived Actinomycete Streptomyces sp. KFD18.

Four new ansamycins, named divergolides T–W (1–4), along with two known analogs were isolated from the fermentation broth of the mangrove-derived actinomycete Streptomyces sp. KFD18. The structures of the compounds, including the absolute configurations of their stereogenic carbons, were determined by spectroscopic data and single-crystal X-ray diffraction analysis. Compounds 1–4 showed cytotoxic activity against the human gastric cancer cell line SGC-7901, the human leukemic cell line K562, the HeLa cell line, and the human lung carcinoma cell line A549, with 1 being the most active while compounds 5 and 6 were inactive against all the tested cell lines. Compounds 1 and 3 showed very potent and specific cytotoxic activities (IC50 2.8 and 4.7 µM, respectively) against the SGC-7901 cells. Further, the apoptosis-inducing effect of 1 and 3 against SGC-7901 cells was demonstrated by two kinds of staining methods for the first time.