COX-2 Inhibitor, NS398, Enhances Fas-Mediated Apoptosis via Modulation of the PTEN–Akt Pathway in Human Gastric Carcinoma Cell Lines

Division of Organ Pathology, Department of Microbiology and Pathology, Faculty of Medicine, Tottori University, Yonago, Tottori, Japan.
DNA and Cell Biology (Impact Factor: 2.06). 04/2005; 24(3):141-7. DOI: 10.1089/dna.2005.24.141
Source: PubMed


A variety of human cancer cells are resistant to Fas ligand and anti-Fas antibody induced apoptosis. Previously, we reported that human gastric carcinoma cell lines were resistant to the anti-Fas antibody, CH-11, without interferon-gamma pretreatment in vitro. Cyclooxygenase (COX)-2 is known to be expressed in many human malignancies, and is correlated with tumor progression and resistance to apoptosis. This study examined whether NS398, a COX-2 inhibitor, inhibited cell proliferation and increased Fas-mediated apoptosis in human gastric carcinoma cell lines. Treatment of NS398 inhibited cell proliferation in MKN-45, which expressed the highest level of COX-2 among seven human gastric carcinoma cell lines, in a dose- and time-dependent manner, in contrast to less prominent effects in KATO-III, which expresses no COX-2. Although the treatment of CH-11 induced apoptosis in both cells, the simultaneous treatment of NS398 and CH-11 remarkably induced apoptosis, as confirmed by Hoechst 33258 staining and the terminal deoxynucleotidyl transferase- mediated dUTP-digoxigenin nick-end labeling (TUNEL) method in MKN-45. Flow cytometric analysis also revealed the increased pre-G1 fraction by the simultaneous treatment. The treatment of NS398 induced upregulation of Bad and PTEN, and downregulation of phosphorylated Akt (Thr308). These findings suggest that COX-2 might inhibit Fas-mediated apoptosis in human gastric carcinoma cell lines, especially MKN-45, by modulating PTEN and Akt.

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    • "As PTEN can antagonize PI3K activity by dephosphorylating PIP3 and thereby negatively regulates the activity of Akt pathway [24,25]. Several studies suggest that the loss of the PTEN function might be the underlying factor in Akt pathway activation [43-45]; thus, our findings are consistent with an emerging body of literature. "
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    ABSTRACT: MicroRNAs (miRNAs) can function as either oncogenes or tumor suppressor genes via regulation of cell proliferation and/or apoptosis. MiR-221 and miR-222 were discovered to induce cell growth and cell cycle progression via direct targeting of p27 and p57 in various human malignancies. However, the roles of miR-221 and miR-222 have not been reported in human gastric cancer. In this study, we examined the impact of miR-221 and miR-222 on human gastric cancer cells, and identified target genes for miR-221 and miR-222 that might mediate their biology. The human gastric cancer cell line SGC7901 was transfected with AS-miR-221/222 or transduced with pMSCV-miR-221/222 to knockdown or restore expression of miR-221 and miR-222, respectively. The effects of miR-221 and miR-222 were then assessed by cell viability, cell cycle analysis, apoptosis, transwell, and clonogenic assay. Potential target genes were identified by Western blot and luciferase reporter assay. Upregulation of miR-221 and miR-222 induced the malignant phenotype of SGC7901 cells, whereas knockdown of miR-221 and miR-222 reversed this phenotype via induction of PTEN expression. In addition, knockdonwn of miR-221 and miR-222 inhibited cell growth and invasion and increased the radiosensitivity of SGC7901 cells. Notably, the seed sequence of miR-221 and miR-222 matched the 3'UTR of PTEN, and introducing a PTEN cDNA without the 3'UTR into SGC7901 cells abrogated the miR-221 and miR-222-induced malignant phenotype. PTEN-3'UTR luciferase reporter assay confirmed PTEN as a direct target of miR-221 and miR-222. These results demonstrate that miR-221 and miR-222 regulate radiosensitivity, and cell growth and invasion of SGC7901 cells, possibly via direct modulation of PTEN expression. Our study suggests that inhibition of miR-221 and miR-222 might form a novel therapeutic strategy for human gastric cancer.
    BMC Cancer 07/2010; 10(1):367. DOI:10.1186/1471-2407-10-367 · 3.36 Impact Factor
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    • "Thus PTEN is considered as a tumor suppressor gene. It has been shown that NS-398 was able to increase the level of PTEN in human gastric carcinoma cell line MKN45 [114]. "
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    ABSTRACT: It is well admitted that the link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways, which act during the different steps of tumorigenesis. The cyclooxygenases (COXs) are a family of enzymes, which catalyze the rate-limiting step of prostaglandin biosynthesis. This family contains three members: ubiquitously expressed COX-1, which is involved in homeostasis; the inducible COX-2 isoform, which is upregulated during both inflammation and cancer; and COX-3, expressed in brain and spinal cord, whose functions remain to be elucidated. COX-2 was described to modulate cell proliferation and apoptosis mainly in solid tumors, that is, colorectal, breast, and prostate cancers, and, more recently, in hematological malignancies. These findings prompt us to analyze here the effects of a combination of COX-2 inhibitors together with different clinically used therapeutic strategies in order to further improve the efficiency of future anticancer treatments. COX-2 modulation is a promising field investigated by many research groups.
    International Journal of Cell Biology 03/2010; 2010(1687-8876):215158. DOI:10.1155/2010/215158
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    • "Higher levels of COX-2 are identified in hepatocellular carcinoma cells, which increases PGE2 production and growth rate17. Whereas COX-2 inhibitor enhances cell apoptosis in human carcinoma cell lines34, non-steroidal anti-inflammatory drugs (NSAIDs), the inhibitors of COX-1 and COX-2, are also shown to reduce the risk of sporadic colorectal, breast, prostate, and lung cancers35, 36. In our study, rosiglitazone reduced COX-2 expression via the PPARγ signaling pathway. "
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    ABSTRACT: Resistance to 5-fluorouracil (5-FU) is a major cause of chemotherapy failure in advanced hepatocellular carcinoma (HCC). Rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, has a crucial role in growth inhibition and induction of apoptosis in several carcinoma cell lines. In this study, we examine rosiglitazone-induced sensitization of HCC cell lines (BEL-7402 and Huh-7 cells) to 5-FU. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate cell viability. Western blotting analysis was performed to detect the protein expression (PPARgamma, PTEN, and COX-2) in BEL-7402 cells. Immunohistochemistry staining was used to examine the expression of PTEN in 100 advanced HCC tissues and paracancerous tissues. In addition, small interfering RNA was used to suppress PPARgamma, PTEN, and COX-2 expression. Rosiglitazone facilitates the anti-tumor effect of 5-FU in HCC cell lines, which is mediated by the PPARgamma signaling pathway. Activation of PPARgamma by rosiglitazone increases PTEN expression and decreases COX-2 expression. Since distribution of PTEN in HCC tissues is significantly decreased compared with the paracancerous tissue, over-expression of PTEN by rosiglitazone enhances 5-FU-inhibited cell growth of HCC. Moreover, down-regulation of COX-2 is implicated in the synergistic effect of 5-FU. Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-FU antitumor activity through the activation of PPARgamma. The results suggest potential novel therapies for the treatment of advanced liver cancer.
    Acta Pharmacologica Sinica 09/2009; 30(9):1316-22. DOI:10.1038/aps.2009.119 · 2.91 Impact Factor
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