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Na HK, Yang H, Surh YJ. 15-Deoxy-Δ 12,14-prostaglandin J 2 Induces Apoptosis in Ha- ras-transformed Human Breast Epithelial Cells by Targeting IκB kinase-NF-κB Signaling. J Cancer Prev 2020; 25:100-110. [PMID: 32647651 PMCID: PMC7337001 DOI: 10.15430/jcp.2020.25.2.100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 06/24/2020] [Accepted: 06/24/2020] [Indexed: 11/17/2022] Open
Abstract
15-Deoxy-Δ12,14-prostaglandin J2
(15d-PGJ2), an endogenous ligand for PPARγ, has differential
effects on cancer cell proliferation and survival depending on the dose and the
type of cells. In the present study, we have investigated the effects of
15d-PGJ2 on apoptosis of the Ha-ras transformed
human breast epithelial (MCF10A-ras) cells. When
MCF10A-ras cells were treated with 15d-PGJ2 (10
μM) for 24 hours, they underwent apoptosis as evidenced by characteristic
morphological features, an increased proportion of
sub-G0/G1 cell population, a typical pattern of
annexin V/propidium iodide staining, perturbation of mitochondrial transmembrane
potential (Δψm), and cleavage of caspase-3 and its
substrate PARP. A pan-caspase inhibitor, Z-Val-Ala-Asp
(OCH3)-fluoromethyl ketone attenuated cytotoxicity and proteolytic
cleavage of caspase-3 induced by 15d-PGJ2. The
15d-PGJ2-induced apoptosis was accompanied by enhanced intracellular
accumulation of reactive oxygen species (ROS), which was abolished by the
antioxidant N-acetyl-L-cysteine (NAC). 15d-PGJ2
inhibited the DNA binding activity of NF-κB which was associated with
inhibition of expression and catalytic activity of IκB kinase β
(IKKβ). 15d-PGJ2-mediated inhibition of IKKβ and nuclear
translocation of phospho-p65 was blocked by NAC treatment.
9,10-Dihydro-PGJ2, a non-electrophilic analogue of
15d-PGJ2, failed to produce ROS, to inhibit NF-κB DNA
binding, and to induce apoptosis, suggesting that the electrophilic
α,β-unsaturated carbonyl group of 15d-PGJ2 is essential for
its pro-apoptotic activity. 15d-PGJ2-induced inactivation of
IKKβ was also attributable to its covalent thiol modification at the
cysteine 179 residue of IKKβ. Based on these findings, we propose that
15d-PGJ2 inactivates IKKβ–ΝF-κB signaling
through oxidative or covalent modification of IKKβ, thereby inducing
apoptosis in Ha-ras transformed human breast epithelial
cells.
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Affiliation(s)
- Hye-Kyung Na
- Department of Food Science and Biotechnology, College of Knowledge-Based Services Engineering, Sungshin Women's University, Seoul, Korea.,Department of Future Applied Sciences, College of Natural Sciences, Sungshin Women's University, Seoul, Korea
| | - Hongkyung Yang
- Department of Future Applied Sciences, College of Natural Sciences, Sungshin Women's University, Seoul, Korea
| | - Young-Joon Surh
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, Seoul, Korea
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2
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Walther U, Emmrich K, Ramer R, Mittag N, Hinz B. Lovastatin lactone elicits human lung cancer cell apoptosis via a COX-2/PPARγ-dependent pathway. Oncotarget 2016; 7:10345-62. [PMID: 26863638 PMCID: PMC4891124 DOI: 10.18632/oncotarget.7213] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 01/01/2016] [Indexed: 12/13/2022] Open
Abstract
Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors) are well-established agents to treat hyperlipidemic states. Experimental and epidemiological evidence further implies an anticancer effect of these substances. This study investigates the mechanism underlying human lung cancer cell death by lovastatin and the role of the prostaglandin (PG)-synthesizing enzyme cyclooxygenase-2 (COX-2) in this process. In A549 and H358 lung carcinoma cells the lipophilic prodrug lovastatin lactone led to a concentration-dependent decrease of viability and induction of DNA fragmentation, whereas its HMG-CoA-inhibitory, ring-open acid form was inactive in this respect. Apoptotic cell death by lovastatin was accompanied by high intracellular levels of the lactone form, by upregulation of COX-2 mRNA and protein, as well as by increased formation of peroxisome proliferator-activated receptor γ (PPARγ)-activating PGD2 and 15-deoxy-Δ12,14-PGJ2. Cells were significantly less sensitive to lovastatin-induced apoptotic cell death, when the expression or activity of COX-2 was suppressed by siRNA or by the COX-2 inhibitor NS-398. Apoptosis by lovastatin was likewise reversed by the PPARγ antagonist GW9662. Fluorescence microscopy analyses revealed a lovastatin-induced cytosol-to-nucleus translocation of PPARγ that was inhibited by NS-398. Collectively, this study demonstrates COX-2 induction and subsequent COX-2-dependent activation of PPARγ as a hitherto unknown mechanism by which lovastatin lactone induces human lung cancer cell death.
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Affiliation(s)
- Udo Walther
- Institute of Toxicology and Pharmacology, Rostock University Medical Center, Rostock, Germany
| | - Kristin Emmrich
- Institute of Toxicology and Pharmacology, Rostock University Medical Center, Rostock, Germany
| | - Robert Ramer
- Institute of Toxicology and Pharmacology, Rostock University Medical Center, Rostock, Germany
| | - Nadine Mittag
- Institute of Toxicology and Pharmacology, Rostock University Medical Center, Rostock, Germany
| | - Burkhard Hinz
- Institute of Toxicology and Pharmacology, Rostock University Medical Center, Rostock, Germany
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3
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Gowda R, Kardos G, Sharma A, Singh S, Robertson GP. Nanoparticle-Based Celecoxib and Plumbagin for the Synergistic Treatment of Melanoma. Mol Cancer Ther 2016; 16:440-452. [PMID: 28003325 DOI: 10.1158/1535-7163.mct-16-0285] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 11/08/2016] [Accepted: 11/23/2016] [Indexed: 12/19/2022]
Abstract
Using multiple drugs to kill cancer cells can decrease drug resistance development. However, this approach is frequently limited by the bioavailability and toxicity of the combined agents and delivery at ratios to specific locations that synergistically kill cancer cells. Loading the individual agents into a nanoparticle that releases the drugs at synergizing ratios at a single location is one approach to resolve this concern. Celecoxib and plumbagin are two drugs that were identified from a screen to synergistically kill melanoma cells compared with normal cells. Combined use of these agents by traditional approaches was not possible due to poor bioavailability and toxicologic concerns. This study details the development of a nanoliposomal-based agent containing celecoxib and plumbagin, called CelePlum-777, which is stable and releases these drugs at an optimal ratio for maximal synergistic killing efficacy. CelePlum-777 was more effective at killing melanoma than normal cells and inhibited xenograft melanoma tumor growth by up to 72% without apparent toxicity. Mechanistically, the drug combination in CelePlum-777 led to enhanced inhibition of melanoma cell proliferation mediated by decreasing levels of key cyclins important for cancer cell proliferation and survival, which was not observed with the individual agents. Thus, a novel nanoparticle-based drug has been developed containing celecoxib and plumbagin that lacks toxicity and delivers the agents at a synergistically killing drug ratio to kill cancer cells. Mol Cancer Ther; 16(3); 440-52. ©2016 AACR.
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Affiliation(s)
- Raghavendra Gowda
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,The Penn State Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Penn State Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Foreman Foundation for Melanoma Research, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Gregory Kardos
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Arati Sharma
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Sanjay Singh
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Gavin P Robertson
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania. .,The Penn State Melanoma and Skin Cancer Center, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Penn State Melanoma Therapeutics Program, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Foreman Foundation for Melanoma Research, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Department of Pathology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Department of Dermatology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.,Department of Surgery, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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4
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Pleiotropic effects of antitumour alkylphospholipids on cholesterol transport and metabolism. Exp Cell Res 2015; 340:81-90. [PMID: 26712518 DOI: 10.1016/j.yexcr.2015.12.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND Alkylphospholipid (APL) analogs are a new class of membrane-directed synthetic compounds with a variety of biological actions and clinical applications. In particular, these agents are promising candidates in cancer treatment. We have demonstrated that after prolonged treatment APLs alter intracellular cholesterol traffic and metabolism in human tumor-cell lines, leading to an accumulation of cholesterol inside the cell. After further investigation concerning the mode of action of APLs, we have explored the influence of several APLs on novel aspects of cholesterol and lipoprotein homeostasis using hepatoma HepG2 cells and THP1-derived macrophages. METHODS Quantitative real-time PCR analysis with a pathway-focused PCR array system was performed to measure relative changes in the mRNA expression of a number of genes related to cholesterol transport and metabolism. We compared the gene-expression profiles of HepG2 cells treated with miltefosine, edelfosine or perifosine for 6h and 24h with the profile of control cells. We also analysed particular genes of interest in both HepG2 and macrophage-like THP1 cells using specific PCR assays. Immunoblots were used to confirm protein-expression changes. Measurement of ABCA1-mediated cholesterol efflux was determined using apoA1 as cholesterol acceptor. RESULTS We found global changes in gene-expression patterns to maintain cholesterol homeostasis after exposure of cells to APLs. The pathways for cholesterol biosynthesis and LDL-cholesterol uptake were both transcriptionally upregulated by the three APLs assayed. Conversely, major pathways involved in the catabolism of cholesterol to bile acids and lipoprotein-associated cholesterol export were impaired after APL incubation, which may well contribute to the higher cell-cholesterol levels induced by these compounds. CONCLUSION Incubation of cells with different APLs stimulated cholesterol biosynthesis and uptake at the same time as it depressed common pathways for excess cholesterol removal in tumor cells, ultimately leading to altered cholesterol homeostasis.
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5
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Ramer R, Walther U, Borchert P, Laufer S, Linnebacher M, Hinz B. Induction but not inhibition of COX-2 confers human lung cancer cell apoptosis by celecoxib. J Lipid Res 2013; 54:3116-29. [PMID: 23943857 DOI: 10.1194/jlr.m042283] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antitumorigenic mechanism of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib is still a matter of debate. Among different structurally related COX-2 inhibitors, only celecoxib was found to cause apoptosis and cell death of human lung cancer cells (IC₅₀ values of 19.96 µM [A549], 12.48 µM [H460], and 41.39 µM [H358]) that was paralleled by a time- and concentration-dependent upregulation of COX-2 and peroxisome proliferator-activated receptor γ (PPARγ) at mRNA and protein levels. Apoptotic death of celecoxib-treated cancer cells was suppressed by the PPARγ antagonist GW9662 and by siRNA targeting PPARγ and, surprisingly, also by the selective COX-2 inhibitor NS-398 and siRNA targeting COX-2. NS-398 (1 µM) was shown to suppress celecoxib-induced COX-2 activity. Among the COX-2-dependent prostaglandins (PG) induced upon celecoxib treatment, PGD₂ and 15-deoxy-Δ¹²,¹⁴-PGJ₂ were found to induce a cytosol-to-nucleus translocation of PPARγ as well as a PPARγ-dependent apoptosis. Celecoxib-elicited PPARγ translocation was inhibited by NS-398. Finally, a COX-2- and PPARγ-dependent cytotoxic action of celecoxib was proven for primary human lung tumor cells. Together, our data demonstrate a proapoptotic mechanism of celecoxib involving initial upregulation of COX-2 and PPARγ and a subsequent nuclear translocation of PPARγ by COX-2-dependent PGs.
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Affiliation(s)
- Robert Ramer
- Institute of Toxicology and Pharmacology, University of Rostock, Schillingallee 70, D-18057 Rostock, Germany
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Ramer R, Heinemann K, Merkord J, Rohde H, Salamon A, Linnebacher M, Hinz B. COX-2 and PPAR-γ confer cannabidiol-induced apoptosis of human lung cancer cells. Mol Cancer Ther 2012; 12:69-82. [PMID: 23220503 DOI: 10.1158/1535-7163.mct-12-0335] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The antitumorigenic mechanism of cannabidiol is still controversial. This study investigates the role of COX-2 and PPAR-γ in cannabidiol's proapoptotic and tumor-regressive action. In lung cancer cell lines (A549, H460) and primary cells from a patient with lung cancer, cannabidiol elicited decreased viability associated with apoptosis. Apoptotic cell death by cannabidiol was suppressed by NS-398 (COX-2 inhibitor), GW9662 (PPAR-γ antagonist), and siRNA targeting COX-2 and PPAR-γ. Cannabidiol-induced apoptosis was paralleled by upregulation of COX-2 and PPAR-γ mRNA and protein expression with a maximum induction of COX-2 mRNA after 8 hours and continuous increases of PPAR-γ mRNA when compared with vehicle. In response to cannabidiol, tumor cell lines exhibited increased levels of COX-2-dependent prostaglandins (PG) among which PGD(2) and 15-deoxy-Δ(12,14)-PGJ(2) (15d-PGJ(2)) caused a translocation of PPAR-γ to the nucleus and induced a PPAR-γ-dependent apoptotic cell death. Moreover, in A549-xenografted nude mice, cannabidiol caused upregulation of COX-2 and PPAR-γ in tumor tissue and tumor regression that was reversible by GW9662. Together, our data show a novel proapoptotic mechanism of cannabidiol involving initial upregulation of COX-2 and PPAR-γ and a subsequent nuclear translocation of PPAR-γ by COX-2-dependent PGs.
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Affiliation(s)
- Robert Ramer
- Institute of Toxicology and Pharmacology, University of Rostock, Rostock, Germany
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7
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GUO TAO, QIAN JIAMING, ZHAO YUQING, LI XIAOBO, ZHANG JIANZHONG. Effects of IL-1β on the proliferation and apoptosis of gastric epithelial cells and acid secretion from isolated rabbit parietal cells. Mol Med Rep 2012; 7:299-305. [DOI: 10.3892/mmr.2012.1165] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 10/09/2012] [Indexed: 11/05/2022] Open
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8
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Diallyl trisulfide induces apoptosis in human breast cancer cells through ROS-mediated activation of JNK and AP-1. Biochem Pharmacol 2012; 84:1241-50. [DOI: 10.1016/j.bcp.2012.08.024] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 08/27/2012] [Accepted: 08/29/2012] [Indexed: 11/20/2022]
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9
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PPARgamma and Apoptosis in Cancer. PPAR Res 2011; 2008:704165. [PMID: 18615184 PMCID: PMC2442903 DOI: 10.1155/2008/704165] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 04/21/2008] [Accepted: 06/11/2008] [Indexed: 12/22/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand binding transcription factors which function in many physiological roles including lipid metabolism, cell growth, differentiation, and apoptosis. PPARs and their ligands have been shown to play a role in cancer. In particular, PPARγ ligands including endogenous prostaglandins and the synthetic thiazolidinediones (TZDs) can induce apoptosis of cancer cells with antitumor activity. Thus, PPARγ ligands have a potential in both chemoprevention and therapy of several types of cancer either as single agents or in combination with other antitumor agents. Accordingly, the involvement of PPARγ and its ligands in regulation of apoptosis of cancer cells have been extensively studied. Depending on cell types or ligands, induction of apoptosis in cancer cells by PPARγ ligands can be either PPARγ-dependent or -independent. Through increasing our understanding of the mechanisms of PPARγ ligand-induced apoptosis, we can develop better strategies which may include combining other antitumor agents for PPARγ-targeted cancer chemoprevention and therapy. This review will highlight recent research advances on PPARγ and apoptosis in cancer.
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Elrod HA, Yue P, Khuri FR, Sun SY. Celecoxib antagonizes perifosine's anticancer activity involving a cyclooxygenase-2-dependent mechanism. Mol Cancer Ther 2009; 8:2575-85. [PMID: 19755515 DOI: 10.1158/1535-7163.mct-09-0390] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Perifosine is an orally bioavailable alkylphospholipid currently being tested in phase II clinical trials as a potential anticancer drug. In this study, we reveal a novel mechanism underlying the anticancer activity of perifosine that involves the induction of cyclooxygenase 2 (COX-2) in human cancer cells. Perifosine induced apoptosis and/or cell cycle arrest in several lung and head and neck cancer cell lines. However, the combination of perifosine with low concentrations of celecoxib rendered cells less sensitive to perifosine both in cell culture systems and in lung cancer xenograft models. Subsequently, we examined the effects of perifosine on COX-2 expression and activity in a set of lung and head and neck cancer cell lines, and found that perifosine rapidly and potently increased COX-2 levels and activity, the degrees of which correlated to the abilities of perifosine to inhibit the growth of cancer cells. We also detected increased COX-2 levels in lung cancer xenografts treated with perifosine. Moreover, blockage of COX-2 induction by both antisense and small interfering RNA approaches decreased cell sensitivity to perifosine. Collectively, these data indicate that the activation of COX-2 contributes to the anticancer activity of perifosine, including apoptosis induction and growth arrest. These data are clinically relevant as they suggest that the combination of perifosine and COX-2 inhibitors such as celecoxib, may produce a potential drug contradiction.
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Affiliation(s)
- Heath A Elrod
- Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
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Eichele K, Ramer R, Hinz B. R(+)-methanandamide-induced apoptosis of human cervical carcinoma cells involves a cyclooxygenase-2-dependent pathway. Pharm Res 2008; 26:346-55. [PMID: 19015962 DOI: 10.1007/s11095-008-9748-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 10/06/2008] [Indexed: 01/21/2023]
Abstract
PURPOSE Cannabinoids have received renewed interest due to their antitumorigenic effects. Using human cervical carcinoma cells (HeLa), this study investigates the role of cyclooxygenase-2 (COX-2) in apoptosis elicited by the endocannabinoid analog R(+)-methanandamide (MA). METHODS COX-2 expression was assessed by RT-PCR and Western blotting. PGE2/PGD2 levels in cell culture supernatants and DNA fragmentation were measured by ELISA. RESULTS MA led to an induction of COX-2 expression, PGD2 and PGE2 synthesis. Cells were significantly less sensitive to MA-induced apoptosis when COX-2 was suppressed by siRNA or the selective COX-2 inhibitor NS-398. COX-2 expression and apoptosis by MA was also prevented by the ceramide synthase inhibitor fumonisin B1, but not by antagonists to cannabinoid receptors and TRPV1. In line with the established role of peroxisome proliferator-activated receptor gamma (PPARgamma) in the proapoptotic action of PGs of the D and J series, inhibition of MA-induced apoptosis was also achieved by siRNA targeting lipocalin-type PGD synthase (L-PGDS) or PPARgamma. A role of COX-2 and PPARgamma in MA-induced apoptosis was confirmed in another human cervical cancer cell line (C33A) and in human lung carcinoma cells (A549). CONCLUSION This study demonstrates COX-2 induction and synthesis of L-PGDS-derived, PPARgamma-activating PGs as a possible mechanism of apoptosis by MA.
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Affiliation(s)
- Karin Eichele
- Institute for Toxicology and Pharmacology, University of Rostock, Schillingallee 70, D-18057, Rostock, Germany
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Decisive role of cyclooxygenase-2 and lipocalin-type prostaglandin D synthase in chemotherapeutics-induced apoptosis of human cervical carcinoma cells. Oncogene 2007; 27:3032-44. [PMID: 18071320 DOI: 10.1038/sj.onc.1210962] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The role of cyclooxygenase-2 (COX-2) in cancer remains controversial. Using cervical carcinoma cells (HeLa), the present study investigates the involvement of COX-2 in apoptosis elicited by the chemotherapeutics paclitaxel, cisplatin and 5-fluorouracil. Each compound led to a profound induction of COX-2 expression and prostaglandin (PG) synthesis, accompanied by a substantial decrease of viability and enhanced apoptosis. Cells were significantly less sensitive to apoptotic death when either COX-2 expression or its activity was suppressed by small-interfering RNA (siRNA) and by the selective COX-2 inhibitor NS-398, respectively. Experiments performed to clarify how COX-2 leads to apoptosis revealed a profound proapoptotic action of PGD2 and its dehydration product, 15-deoxy-Delta(12,14) PGJ2 (15d-PGJ2). In line with these findings, chemotherapeutics-induced apoptosis was prevented by siRNA targeting lipocalin-type PGD synthase (L-PGDS), which catalyses the isomerization of PGH(2) to PGD2. Moreover, apoptosis by chemotherapeutics, PGD2 and 15d-PGJ2 was suppressed by the peroxisome proliferator-activated receptor gamma (PPARgamma) antagonist, GW-9662 or PPARgamma siRNA. Finally, a COX-2-dependent apoptotic mechanism of all investigated chemotherapeutics was confirmed in human lung cancer cells (A549) as well as in another cervical carcinoma cell line (C33A). Collectively, this study suggests COX-2 induction and synthesis of L-PGDS-derived, PPARgamma-activating PGs as a decisive target by which several chemotherapeutics induce apoptosis. COX-2 is therefore suspected to sensitize cancer cells to apoptotic death under certain circumstances, suggesting that COX-2 inhibition during cancer therapy could diminish its efficacy.
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