• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5463-5468
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• 2014

MicroRNAs might act as oncogenes or tumor suppressors in cancer. Recent studies have shown that miR-421 is up-regulated in human gastric cancer. Here, we found that miR-421 was over-expressed in gastric cancer tissues and cell lines. Bioinformatics analysis predicted that the caspase-3 gene was a target of miR-421. Caspase-3 was negatively regulated by miR-421 at the post-transcriptional level. Bax and Bcl-2 were also regulated by miR-421. Moreover, tumor necrosis factor receptor-I and -II, death receptors in the apoptosis pathway, were up-regulated by miR-421. The over-expression of miR-421 promoted gastric cancer cell growth and inhibited apoptosis of the BGC-823 gastric cancer cell line. These observations indicate that miR-421 acts as a tumor promoter by targeting the caspase-3 gene and preventing apoptosis of gastric cancer cells through inhibition of caspase-3 expression. These findings contribute to our understanding of the functions of miR-421 in gastric cancer.

• Molecules and Cells
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• v.39 no.10
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• pp.742-749
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• 2016

The cancer chemo-preventive effects of equol have been demonstrated for a wide variety of experimental tumours. In a previous study, we found that equol inhibited proliferation and induced apoptotic death of human gastric cancer MGC-803 cells. However, the mechanisms underlying equol-mediated apoptosis have not been well understood. In the present study, the dual AO (acridine orange)/EB (ethidium bromide) fluorescent assay, the comet assay, MTS, western blotting and flow cytometric assays were performed to further investigate the pro-apoptotic effect of equol and its associated mechanisms in MGC-803 cells. The results demonstrated that equol induced an apoptotic nuclear morphology revealed by AO/EB staining, the presence of a comet tail, the cleavage of caspase-3 and PARP and the depletion of cIAP1, indicating its pro-apoptotic effect. In addition, equol-induced apoptosis involves the mitochondria-dependent cell-death pathway, evidenced by the depolarization of the mitochondrial membrane potential, the cleavage of caspase-9 and the depletion of Bcl-xL and full-length Bid. Moreover, treating MGC-803 cells with equol induced the sustained activation of extracellular signal-regulated kinase (ERK), and inhibiting ERK by U0126, a MEK/ERK pathway inhibitor, significantly attenuated the equol-induced cell apoptosis. These results suggest that equol induces mitochondria-dependent apoptosis in human gastric cancer MGC-803 cells via the sustained activation of the ERK1/2 pathway. Therefore, equol may be a novel candidate for the chemoprevention and therapy of gastric cancer.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6791-6798
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• 2014

Background: To investigate the effect of silibinin on proliferation and apoptosis in human gastric cancer cell line MGC803 and its possible mechanisms. Materials and Methods: Human gastric cancer cell line MGC803 cells were treated with various concentration of silibinin. Cellular viability was assessed by CCK-8 assay andapoptosis and cell cycle distribution by flow cytometry. Protein expression and mRNA of STAT3, and cell cycle and apoptosis regulated genes were detected by Western blotting and real-time polymerase chain reaction, respectively. Results: Silibinin inhibits growth of MGC803 cells in a dose- and time-dependent manner. Silibinin effectively induces apoptosis of MGC803 cells and arrests MGC803 cells in the G2/M phase of the cell cycle, while decreasing the protein expression of p-STAT3, and of STAT3 downstream target genes including Mcl-1, Bcl-xL, survivin at both protein and mRNA levels. In addition, silibinin caused an increase in caspase 3 and caspase 9 protein as well as mRNA levels. Silibinin caused G2/M phage arrest accompanied by a decrease in CDK1 and Cyclin B1 at protein and mRNA levels.. Conclusions: These results suggest that silibinin inhibits the proliferation of MGC803 cells, and it induces apoptosis and causes cell cycle arrest by down-regulating CDK1, cyclinB1, survivin, Bcl-xl, Mcl-1 and activating caspase 3 and caspase 9, potentially via the STAT3 pathway.

• Molecules and Cells
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• v.41 no.6
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• pp.532-544
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• 2018

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. In order to investigate a new treatment fot GIST, we hypothesized the effect of miR-374b targeting PTEN gene-mediated PI3K/Akt signal transduction pathway on proliferation and apoptosis of human gastrointestinal stromal tumor (GIST) cells. We obtained GIST tissues and adjacent normal tissues from 143 patients with GIST to measure the levels of miR-374b, PTEN, PI3K, Akt, caspase9, Bax, MMP2, MMP9, ki67, PCNA, P53 and cyclinD1. Finally, cell viability, cell cycle and apoptosis were detected. According to the KFGG analysis of DEGs, PTEN was involved in a variety of signaling pathways and miRs were associated with cancer development. The results showed that MiR-374b was highly expressed, while PTEN was downregulated in the GIST tissues. The levels of miR-374b, PI3K, AKT and PTEN were related to tumor diameter and pathological stage. Additionally, miR-374b increased the mRNA and protein levels of PI3K, Akt, MMP2, MMP9, P53 and cyclinD1, suggesting that miR-374b activates PI3K/Akt signaling pathway in GIST-T1 cells. Moreover, MiR374b promoted cell viability, migration, invasion, and cell cycle entry, and inhibited apoptosis in GIST cells. Taken together, the results indicated that miR-374b promotes viability and inhibits apoptosis of human GIST cells by targeting PTEN gene through the PI3K/Akt signaling pathway. Thus, this study provides a new potential target for GIST treatment.

• Molecular Medicine Reports
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• v.19 no.3
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• pp.1911-1918
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• 2019

Traditional herbal medicines are being increasingly used worldwide to treat cancer. Radix Sophorae Flavescentis (RSF) is a Chinese herb, which has numerous pharmacological properties, including anti-tumour effects. In this study, we investigated the mechanisms underlying RSF-induced apoptosis in human gastric cancer cells (AGS cells). We found that RSF treatment (20-200 ㎍/ml) inhibited the proliferation of AGS cells and increased the sub-G1 phase ratio. RSF-induced cell death was associated with the downregulation of BCl-2 and upregulation of Bax. In addition to increasing the expression levels of apoptosis-mediating surface antigen FAS and Fas ligand, RSF also activated caspase-3; however, mitogen-activated protein kinase appeared to inhibit RSF-induced cell death. RSF also led to an increased production of reactive oxygen species. Based on these results, we propose that RSF could be a potential therapeutic agent for gastric cancer.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.10
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• pp.4203-4209
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• 2015

Exosomes, membranous nanovesicles, naturally carry bio-macromolecules or miRNA and play impoetant roles in tumor pathogenesis. Here, we showed that macrophages cell-derived exosomes can function as vehicles to deliver exogenous miR-21 inhibitor into BGC-823 gastric cancer cells. Exosomes loaded with miR-21inhibitor significantly increased miR-21 levels in BGC-823, but miR-21inhibitor loaded in exosomes exerted an opposite effect. miRNA transfected with exosomes had less cellular toxicity to host cells compared to conventional transfection methods. The miR-21inhibitor loaded exosomes promoted the migration ability and reduced apoptosis of BGC-823 gastric cancer cells. These observations indicate that miR-21 acts as a tumor promoter by targeting the PDCD4 gene and preventing apoptosis of gastric cancer cells through inhibition of PDCD4 expression. Furthermore, exosome -mediated miR-21 inhibitor delivery resulted in functionally more efficient inhibition and less cellular toxicity compared to conventional transfection methods. Similar approaches could be useful in modification of target biomolecules in vitro and in vivo. These findings contribute to our understanding of the functions of miR-21 and exosomes as a carrier for therapy of gastric cancer.

• Herbal Formula Science
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• v.30 no.2
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• pp.59-66
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• 2022

Objectives : This study is to investigate whether Carthami flos exhibits a synergistic effect on the apoptotic effect of doxorubicin on human gastric cancer cells. Methods : We used AGS, a human gastric cancer cell line. To investigate the apoptotic efficacy of doxorubicin and Carthami flos, MTT and CCK-8 methods were used. To confirm apoptosis, cell cycle and mitochondrial membrane potential changes were confirmed. To investigate the mechanism of apoptosis, the reactive oxygen species (ROS) experiment was performed. Results : 1. Doxorubicin or Carthami flos induced cell death in the human gastric cancer cell line AGS. 2. Carthami flos showed a synergistic effect of cell death by doxorubicin. 3. The cell cycle and mitochondrial membrane potential changes revealed that cell death was apoptosis. 4. Apoptosis was related to reactive oxygen species (ROS) generation. Conclusions : This result shows the anticancer synergistic effect of Carthami flos in gastric cancer cells, and is considered to be an important basis for the development of anticancer drugs for Carthami flos.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2425-2430
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• 2015

Clinical resistance to chemotherapeutic agents is one of the major hindrances in the treatment of human cancers. EHZ2 is involved in drug resistance and is overexpressed in drug-resistant cancer cell lines. In this study, we investigated the effects of EHZ2 on cisplatin -resistance in A549/DDP and AGS/DDP cells. EHZ2 mRNA and protein were found to be significantly overexpressed in A549/DDP and AGS/DDP cells, compared to parental cells. EHZ2 siRNA successfully silenced EHZ2 mRNA and protein expression. Proliferation was inhibited and drug resistance to cisplatin was improved. Flow cytometry showed that silencing of EHZ2 arrested A549/DDP and AGS/DDP cells in the G0/G1 phase, increasing apoptosis, rh-123 fluorescence intensity and caspase-3/8 activities. Silencing of EHZ2 also significantly reduced the mRNA and protein expression levels of cyclin D1 and MDR1,while up-regulating p15, p21, p27 and miR-218 in A549/DPP cells. Furthermore, silencing of EHZ2 also significantly increased the expression level of tumor suppressor factor miR-218. We also found down-regulating EHZ2 expression increased methylation in A549/DDP and AGS/DDP cells. This study demonstrates that drug resistance can be effectively reversed in human cisplatin-resistant lung and gastric cancer cells through delivery of siRNAs targeting EHZ2.

• Biomolecules & Therapeutics
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• v.20 no.5
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• pp.470-476
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• 2012

Resveratrol, a chemopreventive agent, is rapidly metabolized in the intestine and liver via glucuronidation. Thus, the pharmacokinetics of resveratrol limits its efficacy. To improve efficacy, the activity of resveratrol was investigated in the context of sphingolipid metabolism in human gastric cancer cells. Diverse sphingolipid metabolites, including dihydroceramides (DHCer), were tested for their ability to induce resveratrol cytotoxicity. Exposure to resveratrol ($100{\mu}M$) for 24 hr induced cell death and cell cycle arrest in gastric cancer cells. Exposure to the combination of resveratrol and dimethylsphingosine (DMS) increased cytotoxicity, demonstrating that sphingolipid metabolites intensify resveratrol activity. Specifically, DHCer accumulated in a resveratrol concentration-dependent manner in SNU-1 and HT-29 cells, but not in SNU-668 cells. LC-MS/MS analysis showed that specific DHCer species containing C24:0, C16:0, C24:1, and C22:0 fatty acids chain were increased by up to 30-fold by resveratrol, indicating that resveratrol may partially inhibit DHCer desaturase. Indeed, resveratrol mildly inhibited DHCer desaturase activity compared to the specific inhibitor GT-11 or to retinamide (4-HPR); however, in SNU-1 cells resveratrol alone exhibited a typical cell cycle arrest pattern, which GT-11 did not alter, indicating that inhibition of DHCer desaturase is not essential to the cytotoxicity induced by the combination of resveratrol and sphingolipid metabolites. Resveratrol-induced p53 expression strongly correlated with the enhancement of cytotoxicity observed upon combination of resveratrol with DMS or 4-HPR. Taken together, these results show that DHCer accumulation is a novel lipid biomarker of resveratrol-induced cytotoxicity in human gastric cancer cells.

• YAKHAK HOEJI
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• v.56 no.6
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• pp.358-363
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• 2012

Nemo-like kinase (NLK), an evolutionarily conserved serine/threonine protein kinase, plays an important role in wide variety of developmental events. NLK phosphorylates T-cell factor/lymphoid enhancer factor (TCF/LEF) transcriptional complex and suppresses wnt signaling pathway through inhibition of ${\beta}$-catenin/TCF complex interaction. However, the function of NLK in gastric carcinogenesis has not been investigated. In the present study, we have examined whether the NLK gene is involved in the development and/or progression of gastric cancers. NLK expression was analyzed by immunohistochemical staining in 153 advanced gastric cancer specimens. Immunhistochemical analysis showed increased expression of NLK in 91 (59.5%) out of 153 gastric cancer specimens. Statistically, there was no significant relationship between altered expression of NLK protein and clinicopathological parameters, including tumor differentiation, location, lymph node metastasis. We identified that mRNA and protein expression of NLK was significantly up-regulated in human gastric cancer tissues compare to corresponding normal gastric tissues. In addition, we found that human gastric cancer cell lines exhibited relatively high expression of NLK, as compared with normal gastric cells. The results of this study suggest that aberrant regulation of NLK may contribute to the development or progression of gastric cancers and serve as a potential biomarker for advanced gastric cancer patients.