Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The major obstacle to successful treatment of gastric cancer is chemotherapy resistance. Our study was designed to investigate the role of phosphoinositide 3-kinase (PI3K)/Akt pathway in the development of chemoresistance in gastric cancer. In the present study, elevated Akt expression and Akt phosphorylation (Ser 473), as well as decreased PTEN expression were observed in 28 cases of gastric cancer tissues. Etoposide and doxorubicin stimulated Akt and PI3K activities in 2 gastric cancer cell lines (BGC-823 and SGC-7901), and the activities were concentration and time-dependent. Up-regulation of PTEN expression in BGC-823 cells by PEAK8-PTEN transient transfection obviously decreased the basal and anticancer drugs induced Akt activities, then sensitized BGC-823 cells to etoposide and doxorubicin. Pretreatment of BGC-823 and SGC-7901 cells with wortmannin, a PI3K inhibitor, attenuated cells's resistance to etoposide and doxorubicin. In addition, pretreatment of wortmannin blocked etoposide and doxorubicin induced IkappaB-alpha degradation, NFkappaB activation, phosphorylation of Akt, MDM-2 and forkhead transcription factors. Wortmannin pretreatment also promoted the accumulation of p27/Kip, but inhibited the Mcl-1 expression. Furthermore, wortmannin promoted etoposide and doxorubicin induced caspase-3, caspase-9 activation and poly ADP-ribose polymerase cleavage. Taken together, the observations indicate the PI3K/Akt pathway plays an important role in the chemoresistance of gastric cancer cells. A new strategy for combined chemotherapy of gastric cancer should be designed to more specifically block PI3K/Akt pathway and then decrease the amount of resistant cells.
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PMID:Phosphoinositide 3-kinase/Akt pathway plays an important role in chemoresistance of gastric cancer cells against etoposide and doxorubicin induced cell death. 1793 37

Altered signaling pathways or deregulated transcription factors represent an important category of molecular events leading to aberrant gene regulation in gastric cancer, among which the role of WNT/beta-catenin pathway remains unclear. LRH-1 is a critical transcription factor in controlling cell proliferation via crosstalk with the beta-catenin signaling pathway. In order to gain a knowledge of the expression of hLRH-1v1 and hLRH-1 in gastric cancer, a Q-PCR analysis was carried out. Our results showed that in about 50 and 47.6% of 42 tested patients with gastric cancer, the mRNA expression of hLRH-1v1 and hLRH-1 was significantly upregulated, as compared with self-paired normal control, respectively. Besides, overexpression of hLRH-1 was shown to promote the proliferation of gastric adenocarcinoma cell SGC-7901 via induction of cyclin E1. Taken together, our present study demonstrated for the first time the increased expression of hLRH-1v1 and hLRH-1 in human gastric cancer, an alteration which may implicate in tumorigenesis.
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PMID:Increased expression of hLRH-1 in human gastric cancer and its implication in tumorigenesis. 1795 62

Although cisplatin has been shown to induce both apoptosis and necrosis in cancer cells, the potential interconnections between these modes of cell death induced by the drug remain unknown. We studied this phenomenon in gastric cancer cell lines and identified one cell line (SGC-7901) that underwent apoptosis, and another cell line (BGC-823) that primarily underwent nonapoptotic cell death, in response to cisplatin. Apoptosis in cisplatin-treated SGC-7901 cells seemed to be caspase dependent and was mediated, at least in part, by the BH3-only protein, Noxa. This was evidenced by the rapid upregulation of Noxa and inhibition of apoptosis by small interfering RNA knockdown of Noxa. Nonapoptotic cell death induced by cisplatin in BGC-823 cells was characterized by lack of DNA fragmentation, delayed externalization of phosphatidylserine, caspase independence, plasma membrane disruption, and intracellular vacuole formation, indicative of necrosis. Surprisingly, blockage of apoptosis induction by a general caspase inhibitor or by Noxa small interfering RNA in SGC-7901 failed to protect against cisplatin-induced cell death. Under such conditions, SGC-7901 cells displayed cellular features associated with necrosis. Cisplatin-induced apoptosis, thus, seems to precede necrosis when the apoptotic machinery is operative. When the apoptosis program is defective, necrotic cell death takes place as an alternative pathway leading to cell demise. Induction of different modes of cell death that are interrelated in the same cells by cisplatin has the potential to be exploited in formulating new adjuvant cancer therapies.
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PMID:Inhibition of apoptosis facilitates necrosis induced by cisplatin in gastric cancer cells. 1817 12

RhoA is a critical signaling molecule regulating a variety of cellular processes, such as cytoskeletal organization, adhesion, and apoptosis. It is recently considered responsive to reactive oxygen species (ROS). Nevertheless, how RhoA regulates anoikis, a detachment-initiated apoptosis, and how this regulation is affected by ROS are not clear. The present study investigated the role of RhoA in apoptosis/anoikis in gastric cancer cells and the changes of RhoA and anoikis under oxidative stress. Immunohistochemistry showed that RhoA expression was upregulated in the primary gastric carcinoma compared with normal gastric mucosa. Overactivation of RhoA by transfection with the V14RhoA mutant prevented gastric cancer line SGC-7901 cells from arsenic-induced apoptosis and conferred anoikis resistance through, at least in part, promoting formations of F-actin fibers and focal adhesion. Oxidative stress caused by emodin, an ROS producer, in combination with arsenic trioxide (ATO) led to RhoA inactivation that triggered structural disruption of focal adhesion complex and eventually resulted in anoikis, and these effects could be partially reversed by antioxidant N-acetylcysteine (NAC). In conclusion, activation of RhoA is required for the maintenance of anoikis resistance phenotype of gastric cancer cells, and oxidative stress might be a therapeutic strategy for the inhibition of RhoA in cancer cells.
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PMID:Emodin-induced generation of reactive oxygen species inhibits RhoA activation to sensitize gastric carcinoma cells to anoikis. 1823 37

Telomerase activity is detected in more than 90% of examined tumors but not in most normal somatic cells. Among three subunits of human telomerase, human telomerase reverse transcriptase (hTERT) is the rate-limiting component for telomerase activity. Therefore, targeting hTERT represents a promising approach for diminishing telomerase function that will probably not cause substantial side effects on telomerase negative somatic cells. To explore the effects of antisense hTERT (ahTERT) on the malignant phenotypes of human SGC-7901 gastric cancer cell line in vitro, an antisense eukaryotic expression vector of hTERT was constructed by gene recombinant technology. Telomerase activity by telomeric repeat amplification protocol-ELISA, mRNA of telomerase subunits, c-myc and bcl-2 by reverse transcript-PCR, terminal restriction fragment (TRF) by Southern blot, cell cycle distribution by flow cytometry and protein expression of hTERT, c-myc and bcl-2 by Western blot were analyzed in SGC-7901 cells before and after transfection. Cloning efficiency assay in soft agar and tumorigenesis in nude mice were also examined and evaluated in the above cells. The results demonstrated that after ahTERT transfection, the proliferation of SGC-7901 cells was significantly inhibited. Further study showed that telomerase activity, telomere length, the mRNA and protein expression of hTERT, bcl-2 and c-myc were decreased in ahTERT-transfected cells. There were, however, no obvious effects on transcription of human telomerase RNA (hTR) and human telomerase associated protein1 (TP1) in both transfected and untransfected cells. Flow cytometric analysis displayed an accumulation of G0/G1 phase and a decreasing proliferation index (PI) in ahTERT-transfected cells. Moreover, no tumorigenicity was found after subcutaneous injection of ahTERT-transfected cells in nude mice, whereas palpable tumors were observed in mice injected with control cells. Our study indicates that exogenous ahTERT can inhibit proliferation and partially reverse malignant phenotypes of SGC-7901 cells via the suppression of telomerase activity, hTERT, c-myc and bcl-2 expression. Antisense technology targeted hTERT strategy might be a potential approach for gastric cancer therapy.
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PMID:Antisense human telomerase reverse transcriptase could partially reverse malignant phenotypes of gastric carcinoma cell line in vitro. 1841 91

Aloe-emodin is a hydroxyanthraquinone found in Aloe vera, as well as in leaves and roots of other plants. The mechanisms of its anticancer effect are largely unknown. The present study investigated its molecular mechanisms. Crystal violet assay showed that aloe-emodin had a long-term anti-proliferation effect on human gastric cancer MGC-803 and SGC-7901 cells. Scratch wound-healing motility assays indicated its anti-migration effect. Aloe-emodin arrested SGC-7901 cells at G2/M phase. More importantly, aloe-emodin inhibited the expressions of protein kinase C and c-myc. In conclusion, the anticancer effect of aloe-emodin on gastric cancer cells involves suppression of c-myc expression.
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PMID:Suppression of C-myc expression associates with anti-proliferation of aloe-emodin on gastric cancer cells. 1844 57

Tocotrienols are naturally occurring isoprenoid compounds highly enriched in palm oil, rice bran, oat, wheat germ, barley and rye. Tocotrienols have antioxidant properties as well as potent anticancer properties. In this study, the mechanisms underlying the apoptosis of gamma-tocotrienol on human gastric adenocarcinoma SGC-7901 cells were further studied, especially in correlation with the involvement of the apoptotic pathway. gamma-Tocotrienol inhibited SGC-7901 cell growth in a concentration- and time-dependent manner. The inhibitory effects of SGC-7901 cells were correlated with the DNA damage and arresting cell cycle at G(0)/G(1) phase in a time-dependent manner at 60 mumol/L concentration of gamma-tocotrienol. gamma-Tocotrienol induced activation of caspase-3 and increased the cleavage of the downstream substrate poly(ADP-ribose) polymerase. Furthermore, gamma-tocotrienol-induced apoptosis on SGC-7901 cells was mediated by activation of caspase-9. The data in this study suggested that gamma-tocotrienol could induce the apoptosis on human gastric cancer SGC-7901 cells via mitochondria-dependent apoptosis pathway. Thus, our findings revealed gamma-tocotrienol as a potential, new chemopreventive agent for human gastric cancer.
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PMID:gamma-Tocotrienol induces mitochondria-mediated apoptosis in human gastric adenocarcinoma SGC-7901 cells. 1860 11

Although thiazolidinediones (TZDs) were found to be ligands for peroxisome proliferators-activated receptorgamma (PPARgamma), the mechanism by which TZDs exert their anticancer effect remains unclear. Furthermore, the effect of TZDs on metastatic and angiogenesis potential of cancer cells is unknown. Our results in this paper show that rosiglitazone inhibited SGC-7901 gastric cancer cells growth, caused G1 cell cycle arrest and induced apoptosis in a dose-dependent manner. The effects of rosiglitazone on SGC-7901 cancer cells were completely reversed by treatment with PPARgamma antagonist GW9662. Rosiglitazone inhibited SGC-7901 cell migration, invasiveness, and the expression of MMP-2 in dose-dependent manner via PPARgamma-independent manner. Rosiglitazone reduced the VEGF induced angiogenesis of HUVEC in dose-dependent manner through PPARgamma-dependent pathway. Moreover, rosiglitazone did not affect the expression of VEGF by SGC-7901 cells. Our results demonstrated that by PPARgamma ligand, rosiglitazone inhibited growth and invasiveness of SGC-7901 gastric cancer cells and angiogenesis in vitro via PPARgamma-dependent or -independent pathway.
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PMID:Rosiglitazone Suppresses the Growth and Invasiveness of SGC-7901 Gastric Cancer Cells and Angiogenesis In Vitro via PPARgamma Dependent and Independent Mechanisms. 3295 39

A new pregnanone, named calotropone (1), was isolated from the EtOH extract of the roots of Calotropis gigantea L. together with a known cardiac glycoside. The structures were elucidated by a study of their physical and spectral data. Compounds 1 and 2 displayed inhibitory effects towards chronic myelogenous leukemia K562 and human gastric cancer SGC-7901 cell lines.
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PMID:A new cytotoxic pregnanone from Calotropis gigantea. 1905 26

This study was aimed to investigate the effect of arsenic trioxide (As2O3) on expression of vascular endothelial growth factor-C (VEGF-C) and its receptor VEGFR-3 in gastric cancer in order to clarify the role of As2O3 in lymphangiogenesis and metastasis of tumor. The gastric cancer model was established in nude mice by using gastric cancer cell line SGC-7901. As2O3 was injected to the two treatment groups (2.5 mg/kg and 5 mg/kg) and the same volume of saline solution was injected to the control group. Expression of VEGF-C and VEGFR-3 were detected by immunohistochemistry and were analyzed with QWin550cW image Acquiring & Analysis System. The results showed that the expression of VEGF-C and VEGFR-3 in cancer cells significantly reduced in the arsenic -treated groups. The expression of VEGF-C and VEGFR-3 in 5 mg/kg group was significantly less than that in 2.5 mg/kg group. The gray ratio analysis confirmed that there were significant difference between control group and two treated group, as well as between 2.5 mg/kg-treated group and 5 mg/kg-treated group. It is concluded that As2O3 can inhibit expression of VEGF-C and VEGFR-3 of human gastric cancer xenografts in nude mice, which suggests that As2O3 may inhibit the lymphangiogenesis by suppressing the expression of VEGF-C and VEGFR-3.
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PMID:[Effect of arsenic trioxide on vascular endothelial growth factor-C and its receptor (VEGFR-3) in nude mice with gastric cancer]. 1909 32


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