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Yamamoto Y, Yamamoto T, Koma H, Nishii A, Yagami T. Synergistic effects of 15-deoxy Δ 12,14-prostaglandin J 2 on the anti-tumor activity of doxorubicin in renal cell carcinoma. Biochem Biophys Rep 2017; 9:61-66. [PMID: 28955990 PMCID: PMC5614541 DOI: 10.1016/j.bbrep.2016.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 11/04/2016] [Accepted: 11/08/2016] [Indexed: 12/24/2022] Open
Abstract
An endogenous anticancer agent, 15-deoxy -Δ12,14-prostaglandin J2 (15d-PGJ2) induces apoptosis in the chemoresistant renal cell carcinoma (RCC). Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear receptor for 15d-PGJ2, and mediates the cytotoxicity of 15d-PGJ2 in many cancerous cells. However, 15d-PGJ2 induces apoptosis independently of PPARγ in human RCC cell line such as Caki-2. In the present study, we found that 15d-PGJ2 ameliorated the chemoresistance to one of anthracycline antibiotics, doxorubicin, in Caki-2 cells. Doxorubicin alone exhibited weak cytotoxicity at the concentrations effective for other cancer cells such as Hela cells. In addition, it did not activate caspase 3. However, the cytotoxicity of doxorubicin was increased remarkably and accompanied with the caspase- 3 activation in the presence of 15d-PGJ2. Doxorubicin alone damaged plasma membrane, and the combined application of 15d-PGJ2 with doxorubicin increased the membrane permeability slightly. PPARγ was involved in neither the anti-tumor activity nor the synergistic effect of 15d-PGJ2. 15d-PGJ2 induces apoptosis in Caki-2 cells via suppressing the phosphoinositide 3-kinase (PI3K)-Akt pathway. The effect of PI3K inhibitor on the cytotoxicity of doxorubicin was additive, but not synergistic. Although the PI3K inhibitor mimicked the cytotoxicity of 15d-PGJ2, it might not be involved in the synergism between 15d-PGJ2 and doxorubicin. In conclusion, 15d-PGJ2 enhanced the chemosensitivity of doxorubicin via the pathway independent of PPARγ and PI3K.
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Affiliation(s)
- Yasuhiro Yamamoto
- Division of Physiology, Department of Pharmaceutical Health Care, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, 2-1, kami-ohno 7-Chome, Himeji, Hyogo 670-8524, Japan
| | - Takehiro Yamamoto
- Hyogo Prefectural Kobe High School, 1-5-1 Shironoshita-dori, Nada-ku, Kobe, Hyogo 657-0804, Japan
| | - Hiromi Koma
- Division of Physiology, Department of Pharmaceutical Health Care, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, 2-1, kami-ohno 7-Chome, Himeji, Hyogo 670-8524, Japan
| | - Ayaka Nishii
- Division of Physiology, Department of Pharmaceutical Health Care, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, 2-1, kami-ohno 7-Chome, Himeji, Hyogo 670-8524, Japan
| | - Tatsurou Yagami
- Division of Physiology, Department of Pharmaceutical Health Care, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, 2-1, kami-ohno 7-Chome, Himeji, Hyogo 670-8524, Japan
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Koyani CN, Kitz K, Rossmann C, Bernhart E, Huber E, Trummer C, Windischhofer W, Sattler W, Malle E. Activation of the MAPK/Akt/Nrf2-Egr1/HO-1-GCLc axis protects MG-63 osteosarcoma cells against 15d-PGJ2-mediated cell death. Biochem Pharmacol 2016; 104:29-41. [PMID: 26801686 PMCID: PMC4782222 DOI: 10.1016/j.bcp.2016.01.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/14/2016] [Indexed: 12/21/2022]
Abstract
Despite considerable efforts to improve treatment modalities for osteosarcoma (OS), patient survival remains poor mainly due to pro-survival pathways in OS cells. Among others, prostaglandins (PGs) are the potent regulators of bone homoeostasis and OS pathophysiology. Therefore, the present study aimed to elucidate the impact of 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2, a stable PGD2 degradation product) on cell death/cell survival pathways in p53-deficient MG-63 OS cells. Our findings show that 15d-PGJ2 induces generation of reactive oxygen species that promote p38 MAPK activation and subsequent Akt phosphorylation. This pathway induced nuclear expression of Nrf2 and Egr1, and increased transcription of haem oxygenase-1 (HO-1) and the catalytic subunit of glutamate cysteine ligase (GCLc), catalysing the first step in GSH synthesis. Silencing of Nrf2, Egr1 and HO-1 significantly elevated 15d-PGJ2-mediated reduction of cellular metabolic activity. Activation of cell survival genes including HO-1 and GCLc inhibited 15d-PGJ2-induced cleavage of pro-caspase-3 and PARP. Annexin V/propidium iodide staining showed an increase in early/late apoptotic cells in response to 15d-PGJ2. The observed 15d-PGJ2-mediated signalling events are independent of PGD2 receptors (DP1 and DP2) and PPARγ. In addition, the electrophilic carbon atom C9 is a prerequisite for the observed activity of 15d-PGJ2. The present data show that the intracellular redox imbalance acted as a node and triggered both death and survival pathways in response to 15d-PGJ2. Pharmacological or genetic interference of the pro-survival pathway, the p38 MAPK/Akt/Nrf2-Egr1/HO-1-GCLc axis, sensitizes MG-63 cells towards 15d-PGJ2-mediated apoptosis.
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Affiliation(s)
- Chintan N Koyani
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Kerstin Kitz
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria; Department of Pediatrics and Adolescence Medicine, Research Unit of Osteological Research and Analytical Mass Spectrometry, Medical University of Graz, Graz, Austria
| | - Christine Rossmann
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Eva Bernhart
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Evelyn Huber
- Department of Pediatrics and Adolescence Medicine, Research Unit of Osteological Research and Analytical Mass Spectrometry, Medical University of Graz, Graz, Austria
| | - Christopher Trummer
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Werner Windischhofer
- Department of Pediatrics and Adolescence Medicine, Research Unit of Osteological Research and Analytical Mass Spectrometry, Medical University of Graz, Graz, Austria
| | - Wolfgang Sattler
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Ernst Malle
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
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Hsu HT, Chi CW. Emerging role of the peroxisome proliferator-activated receptor-gamma in hepatocellular carcinoma. J Hepatocell Carcinoma 2014; 1:127-35. [PMID: 27508182 PMCID: PMC4918273 DOI: 10.2147/jhc.s48512] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the major leading cause of cancer death worldwide. Hepatitis B virus, hepatitis C virus, alcohol consumption, non-alcoholic fatty liver disease, and diabetes are the major risks for developing HCC. Until now, recurrence and metastasis are the major cause of death in HCC patients. Therefore, identification of new effective molecular targets is an urgent need for treatment of HCC. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor which could be activated by PPARγ agonists such as thiazolidinediones, and natural PPARγ ligand (such as 15-deoxy-Δ12,14-prostaglandin J2, 15d-PGJ2). Increasing in vitro and in vivo evidence has demonstrated that PPARγ agonists exhibit an inhibitory role on tumor cell growth, migration, and invasion, suggesting that PPARγ activation may play an important role in the regulation of growth of HCC. It has been reported that PPARγ activation by thiazolidinediones or overexpression of PPARγ by virus-mediated gene transfer has shown growth inhibitory effects in hepatoma cells, but the expression level of PPARγ in HCC tissues still remains conflicting. Notably, a novel PPARγ agonist, honokiol, has recently been found to activate the PPARγ/RXR heterodimer, and has also exhibited significant anti-cancer effects in hepatoma cells. In the present review, we summarized studies on the role and the molecular regulation of PPARγ in HCC development in vitro and in vivo. PPARγ has the potential to be a therapeutic target for future treatment of HCC.
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Affiliation(s)
- Hui-Tzu Hsu
- Department and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chin-Wen Chi
- Department and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan
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Resolution of inflammation as a novel chemopreventive strategy. Semin Immunopathol 2013; 35:151-61. [PMID: 23370700 DOI: 10.1007/s00281-013-0363-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 01/14/2013] [Indexed: 12/15/2022]
Abstract
Acute inflammation, a physiologic response to protect cells from microbial infection and other noxious stimuli, is automatically terminated by endogenous anti-inflammatory and pro-resolving mediators to restore homeostatic conditions. However, if timely resolution of inflammation is failed, inflammation persists and can progress to a chronic inflammation which has long been thought as a predisposing factor to carcinogenesis. Excessive and pathologic inflammation causes DNA damage, genomic instability, epigenetic dysregulation, and alteration of intracellular signaling, all of which are involved in neoplastic transformation. To prevent chronic inflammation and resulting inflammation-promoted cancer development, understanding the process that resolves inflammation is essential. Resolution of inflammation is an active coordinated process regulated by distinct anti-inflammatory and pro-resolving endogenous lipid mediators, such as resolvins and lipoxins. The role of pro-inflammatory signaling in carcinogenesis has become more and more evident and well characterized, but the potential role of pro-resolving mediators in cancer prevention remains still elusive. In searching for an efficacious way to prevent chronic inflammation-associated cancer, the pro-resolving signal transduction pathways and their regulators should be unraveled.
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Fujita M, Tohji C, Honda Y, Yamamoto Y, Nakamura T, Yagami T, Yamamori M, Okamura N. Cytotoxicity of 15-deoxy-Δ(12,14)-prostaglandin J(2) through PPARγ-independent pathway and the involvement of the JNK and Akt pathway in renal cell carcinoma. Int J Med Sci 2012; 9:555-66. [PMID: 22991494 PMCID: PMC3444976 DOI: 10.7150/ijms.4455] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 08/31/2012] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Agonists of peroxisome proliferator-activated receptor gamma (PPARγ) have been examined as chemopreventive and chemotherapeutic agents. The aim was to investigate the cytotoxicity and action mechanisms of 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)), one of endogenous ligands for PPARγ, in terms of PPARγ-dependency and the mitogen-activated protein kinase (MAPK) and Akt pathway in three human renal cell carcinoma (RCC)-derived cell lines. METHODS 786-O, Caki-2 and ACHN cells were used as human RCC-derived cell lines. Cell viability and caspase-3 activity was detected by fluorescent reagents, and chromatin-condensation was observed with a brightfield fluorescent microscope after staining cells with Hoechst33342. The expression levels of proteins were detected by Western blot analysis. RESULTS 15d-PGJ(2) showed cytotoxicity in dose-dependent manner. 15d-PGJ(2) induced chromatin-condensation and elevated caspase-3 activity, and the cell viability was restored by co-treatment with a pan-caspase inhibitor, Z-VAD-FMK, indicating the involvement of caspase-dependent apoptosis. The cytotoxicity was not impaired by a PPARγ inhibitor, GW9662, suggesting that 15d-PGJ(2) exerted the cytotoxicity in a PPARγ-independent manner. Some antioxidants rescued cells from cell death induced by 15d-PGJ(2), but some did not, suggesting that reactive oxygen species (ROS) did not contribute to the apoptosis. 15d-PGJ(2) also increased the expression levels of phospho-c-Jun N terminal kinase (JNK) in Caki-2 cells, and decreased those of phospho-Akt in 786-O cells, indicating that the JNK MAPK and the Akt pathways participated in the anticancer effects of 15d-PGJ(2) in some cell lines. CONCLUSION 15d-PGJ(2) exerted cytotoxic effects accompanying caspase-dependent apoptosis, and this effect was elicited in a PPARγ-independent manner in three cell lines. In addition, the JNK MAPK and Akt pathway was involved in the cytotoxicity of 15d-PGJ(2) to some extent in some cell line. Therefore, our study showed the 15d-PGJ(2) to potentially be an interesting approach for RCC treatment.
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Affiliation(s)
- Megumi Fujita
- Department of Clinical Pharmacy, School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, 11-68 Koshien-kyuban-cho, Nishinomiya, Hyogo 663-8179, Japan
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The Critical Role of PPARgamma in Human Malignant Melanoma. PPAR Res 2011; 2008:503797. [PMID: 18483619 PMCID: PMC2377344 DOI: 10.1155/2008/503797] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Accepted: 04/21/2008] [Indexed: 11/18/2022] Open
Abstract
The past 30 years have only seen slight improvement in melanoma therapy. Despite a wide variety of therapeutic options, current survival for patients with metastatic disease is only 6-8 months. Part of the reason for this treatment failure is the broad chemoresistance of melanoma, which is due to an altered survival capacity and an inactivation of apoptotic pathways. Several targetable pathways, responsible for this survival/apoptosis resistance in melanoma, have been described and current research has focused on mechanism inactivating these pathways. As PPARgamma was shown to be constitutively active in several tumour entities and PPARgamma agonists extent strong anticancer effects, the role of PPARgamma as a possible target for specific anticancer strategy was investigated in numerous studies. However, only a few studies have focused on the effects of PPARgamma agonists in melanoma, showing conflicting results. The use of PPARgamma agonists in melanoma therapy has to be carefully weighted against considerable, undesirable side effects, as their mode of action is not fully understood and even pro-proliferative effects have been described. In the current review, we discuss the role of PPARs, in particular PPARgamma in melanoma and their potential role as a molecular target for melanoma therapy.
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Rosiglitazone Suppresses the Growth and Invasiveness of SGC-7901 Gastric Cancer Cells and Angiogenesis In Vitro via PPARgamma Dependent and Independent Mechanisms. PPAR Res 2011; 2008:649808. [PMID: 18810275 PMCID: PMC2542845 DOI: 10.1155/2008/649808] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2008] [Accepted: 07/01/2008] [Indexed: 12/18/2022] Open
Abstract
Although thiazolidinediones (TZDs) were found to be ligands for peroxisome proliferators-activated receptorγ (PPARγ), 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 PPARγ antagonist GW9662. Rosiglitazone inhibited SGC-7901 cell migration, invasiveness, and the expression of MMP-2 in dose-dependent manner via PPARγ-independent manner. Rosiglitazone reduced the VEGF induced angiogenesis of HUVEC in dose-dependent manner through PPARγ-dependent pathway. Moreover, rosiglitazone did not affect the expression of VEGF by SGC-7901 cells. Our results demonstrated that by PPARγ ligand, rosiglitazone inhibited growth and invasiveness of SGC-7901 gastric cancer cells and angiogenesis in vitro via PPARγ-dependent or -independent pathway.
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The Role of PPARgamma in Hepatocellular Carcinoma. PPAR Res 2011; 2008:209520. [PMID: 18509497 PMCID: PMC2396389 DOI: 10.1155/2008/209520] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 05/14/2008] [Indexed: 12/12/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. This cancer develops mainly in cirrhotic patients. The cirrhotic liver is considered to be a preneoplastic organ, suggesting the rationale for cancer prevention. PPARγ is a nuclear transcription factor whose activation leads to interaction in the metabolism of lipids, insulin sensitization of peripheral cells, anti-inflammatory action. It can also induce differentiation and inhibits proliferation of cancer cells. Until now, data using PPARγ ligands in HCC have demonstrated mainly in in vitro models that its activation could be due to an antiproliferative effect. PPARγ ligand administration has also been associated with a diminution of liver fibrosis in animal models, and potentially also on tumoral cell death. Soma data show that the favorable effect of natural and synthetized PPARγ agonists could also be independent of PPARγ activation. Furthermore, in some situations, PPARγ antagonists have also an anticancer effect. Therefore, we can conclude that the link between activation of the PPARγ pathway and an anticancer activity is suggested but until now not firmly established in HCC.
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Bräutigam K, Biernath-Wüpping J, Bauerschlag DO, von Kaisenberg CS, Jonat W, Maass N, Arnold N, Meinhold-Heerlein I. Combined treatment with TRAIL and PPARγ ligands overcomes chemoresistance of ovarian cancer cell lines. J Cancer Res Clin Oncol 2010; 137:875-86. [PMID: 20878528 DOI: 10.1007/s00432-010-0952-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 09/16/2010] [Indexed: 01/24/2023]
Abstract
PURPOSE Ovarian cancer accounts for the highest mortality among all gynecological cancers, mainly due to the fast developing chemoresistance. The death ligand TRAIL induces apoptosis and is able to sensitize tumor cells to cytostatic drugs without affecting physiological tissue. Combined treatment of TRAIL and the antidiabetic acting PPARγ ligands was shown to induce apoptosis synergistically in different ovarian cancer cell lines. METHODS To investigate feasible TRAIL-dependent inhibition of proliferation and induction of apoptosis in chemoresistant ovarian cancer cell lines, the drug- and TRAIL-sensitive HEY cell line was utilized to develop subclones with selective resistance against cisplatin, etoposide, docetaxel, paclitaxel, gemcitabine and pemetrexed, as well as against TRAIL as control cell line. Expression of the key factors of the TRAIL signaling pathway, TRAIL receptors 1-4, caspase-8, FLIP and XIAP, was analyzed before and after TRAIL treatment by immunoblotting. RESULTS Cell proliferation experiments showed TRAIL-dependent inhibition that was further increased by combination treatment with the PPARγ ligands. Simultaneous exposure of TRAIL and the PPARγ ligands also resulted in enhanced induction of apoptosis even in partial TRAIL-resistant HEY cell lines. In the parental HEY cell line, additional treatment with the PPARγ ligands led to an increased protein expression of DR5 and a further decline of XIAP expression. CONCLUSION Therefore, the combinational treatment with TRAIL and PPARγ ligands might be a promising experimental therapy because the PPARγ ligands, especially d15-PGJ(2), sensitize drug-resistant ovarian cancer cells to TRAIL-induced apoptosis.
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Affiliation(s)
- Karen Bräutigam
- Department of Gynecology and Obstetrics, University Hospital Aachen, Pauwelsstr. 30, 52074, Aachen, Germany.
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Biliary innate immunity: function and modulation. Mediators Inflamm 2010; 2010. [PMID: 20798866 PMCID: PMC2926654 DOI: 10.1155/2010/373878] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 06/22/2010] [Indexed: 12/18/2022] Open
Abstract
Biliary innate immunity is involved in the pathogenesis of cholangiopathies in patients with primary biliary cirrhosis (PBC) and biliary atresia. Biliary epithelial cells possess an innate immune system consisting of the Toll-like receptor (TLR) family and recognize pathogen-associated molecular patterns (PAMPs). Tolerance to bacterial PAMPs such as lipopolysaccharides is also important to maintain homeostasis in the biliary tree, but tolerance to double-stranded RNA (dsRNA) is not found. In PBC, CD4-positive Th17 cells characterized by the secretion of IL-17 are implicated in the chronic inflammation of bile ducts and the presence of Th17 cells around bile ducts is causally associated with the biliary innate immune responses to PAMPs. Moreover, a negative regulator of intracellular TLR signaling, peroxisome proliferator-activated receptor-γ (PPARγ), is involved in the pathogenesis of cholangitis. Immunosuppression using PPARγ ligands may help to attenuate the bile duct damage in PBC patients. In biliary atresia characterized by a progressive, inflammatory, and sclerosing cholangiopathy, dsRNA viruses are speculated to be an etiological agent and to directly induce enhanced biliary apoptosis via the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Moreover, the epithelial-mesenchymal transition (EMT) of biliary epithelial cells is also evoked by the biliary innate immune response to dsRNA.
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Ma XM, Yu H, Huai N. Peroxisome proliferator-activated receptor-γ is essential in the pathogenesis of gastric carcinoma. World J Gastroenterol 2009; 15:3874-83. [PMID: 19701967 PMCID: PMC2731249 DOI: 10.3748/wjg.15.3874] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate whether peroxisome proliferator-activated receptor γ (PPAR-γ) is expressed in human gastric carcinoma and whether PPAR-γ is a potential target for gastric carcinoma therapy.
METHODS: PPAR-γ protein in gastric carcinoma was examined by immunohistochemistry. In the gastric carcinoma cell line MGC803, PPAR-γ, survivin, Skp2 and p27 protein and mRNA were examined by Western blotting and real-time reverse transcription-polymerase chain reaction, respectively; proliferation was examined by MTT; apoptosis was examined by chromatin staining with Hoechst 33342 and fluorescence activated cell sorting (FACS). and cell cycle was examined by FACS; the knockdown of PPAR-γ was done by RNA interference.
RESULTS: A high level of expression of PPAR-γ was observed in human gastric carcinoma and in a human gastric carcinoma cell line MGC803. The PPAR-γ agonist 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) inhibited growth, and induced apoptosis and G1/G0 cell cycle arrest in MGC803 cells in a concentration-dependent and time-dependent manner. The effect of 15d-PGJ2 on MGC803 cells was not reversed by the selective and irreversible antagonist GW9662 for PPAR-γ. Furthermore, survivin and Skp2 expression were decreased, whereas p27 expression was enhanced following 15d-PGJ2 treatment in a dose-dependent manner in MGC803 cells. Interestingly, we also found that small interfering RNA for PPAR-γ inhibited growth and induced apoptosis in MGC803 cells. The inhibition of PPAR-γ function may be a potentially important and novel modality for treatment and prevention of gastric carcinoma.
CONCLUSION: A PPAR-γ agonist inhibited growth of human gastric carcinoma MGC803 cells by inducing apoptosis and G1/G0 cell cycle arrest with the involvement of survivin, Skp2 and p27 and not via PPAR-γ.
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Lee DR, Kwon CH, Park JY, Kim YK, Woo JS. 15-Deoxy-Delta(12,14)-prostaglandin J(2) induces mitochondrial-dependent apoptosis through inhibition of PKA/NF-kappaB in renal proximal epithelial cells. Toxicology 2009; 258:17-24. [PMID: 19167456 DOI: 10.1016/j.tox.2009.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 01/05/2009] [Indexed: 11/30/2022]
Abstract
We have previously reported the cyclopentenone prostaglandin 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) induces renal proximal epithelial cell death through NF-kappaB inhibition. However, the upstream and down-stream signaling pathways that NF-kappaB inhibition mediates 15d-PGJ(2)-induced apoptosis remain to be defined. In the present study, we determined whether NF-kappaB inhibition induces cell death through the mitochondrial apoptotic pathway and whether protein kinase A (PKA) functions upstream of NF-kappaB inhibition by 15d-PGJ(2). The role of NF-kappaB inhibition in this apoptotic pathway was evaluated using NF-kappaB p65 transfected cells. 15d-PGJ(2) induced cell death by a PPARgamma-independent mechanism and the cell death was prevented by NF-kappaB p65 transfection. 15d-PGJ(2) treatment caused disruption of mitochondrial membrane potential, cytochrome c release, and caspase-3 activation, suggesting that 15d-PGJ(2) induces cell death through a mitochondria-dependent apoptotic mechanism. These changes by 15d-PGJ(2) were attenuated by NF-kappaB p65 transfection. 15d-PGJ(2) treatment resulted in an increase in Bax expression, which were blocked by NF-kappaB p65 transfection. 15d-PGJ(2) treatment caused PKA inhibition and 15d-PGJ(2)-induced cell death was enhanced by the PKA specific inhibitor H89. Inhibition of NF-kappaB by 15d-PGJ(2) was prevented by addition of forskolin, a PKA activator. Taken together, these results suggest that PKA-dependent NF-kappaB inhibition stimulates 15d-PGJ(2)-mediated mitochondrial apoptotic pathway through alterations in expression of the NF-kappaB target genes Bax.
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Affiliation(s)
- Dong Ryeol Lee
- Department of Physiology, College of Medicine, Pusan National University, Pusan 602-739, Republic of Korea
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Ryan SD, Harris CS, Carswell CL, Baenziger JE, Bennett SA. Heterogeneity in the sn-1 carbon chain of platelet-activating factor glycerophospholipids determines pro- or anti-apoptotic signaling in primary neurons. J Lipid Res 2008; 49:2250-8. [DOI: 10.1194/jlr.m800263-jlr200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Qiao L, Dai Y, Gu Q, Chan KW, Ma J, Lan HY, Zou B, Rocken C, Ebert MPA, Wong BCY. Loss of XIAP sensitizes colon cancer cells to PPARgamma independent antitumor effects of troglitazone and 15-PGJ2. Cancer Lett 2008; 268:260-71. [PMID: 18477501 DOI: 10.1016/j.canlet.2008.04.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/28/2008] [Accepted: 04/02/2008] [Indexed: 11/17/2022]
Abstract
We investigated whether the anticancer effect of a combination of XIAP down-regulation and PPAR gamma activation on colon cancer is PPARgamma receptor dependent. HCT116-XIAP(+/+) cells and HCT116-XIAP(-/-) cells were treated with troglitazone or 15-deoxy-Delta(12,14)-prostaglandin J2 (15-PGJ2) with or without prior exposure to PPARgamma inhibitor GW9662. Cell proliferation and apoptosis was evaluated. Athymic mice carrying HCT116-XIAP(-/-) cells-derived tumors were treated with troglitazone in the presence or absence of GW9662. Inhibition of cell proliferation and induction of apoptosis by troglitazone and 15-PGJ2 were more prominent in HCT116-XIAP(-/-) cells. PPARgamma ligand-induced growth inhibition, apoptosis, caspase and PARP cleavage could not be blocked by GW9662. Troglitazone significantly retarded growth of xenograft tumors and this effect was not blocked by GW9662. Marked apoptosis and an up-regulation of E-cadherin were observed in xenograft tumor tissues, and GW9662 did not affect these effects. Thus, a combination of XIAP down-regulation and PPARgamma ligands exert a significant anticancer effect in colon cancer via a PPARgamma independent pathway.
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Affiliation(s)
- Liang Qiao
- Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong
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Lee SJ, Kim MS, Park JY, Woo JS, Kim YK. 15-Deoxy-delta 12,14-prostaglandin J2 induces apoptosis via JNK-mediated mitochondrial pathway in osteoblastic cells. Toxicology 2008; 248:121-9. [PMID: 18450357 DOI: 10.1016/j.tox.2008.03.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 03/17/2008] [Accepted: 03/18/2008] [Indexed: 11/15/2022]
Abstract
The cyclopentenone prostaglandin 15-deoxy-delta 12,14-prostaglandin J2 (15d-PGJ2) induces apoptosis in various cell types. However, the underlying mechanism of 15d-PGJ2-induced apoptosis is not fully understood. The present study was undertaken to determine the molecular mechanism by which 15d-PGJ2 induces apoptosis in MC3T3-E1 mouse osteoblastic cells. 15d-PGJ2 caused a concentration- and time-dependent apoptotic cell death. 15d-PGJ2 induced a transient activation of ERK1/2 and sustained activation of JNK. 15d-PGJ2-induced cell death was prevented by the JNK inhibitor SP6001, but not by inhibitors of ERK1/2 and p38. JNK activation by 15d-PGJ2 was blocked by antioxidants N-acetylcysteine (NAC) and GSH. 15d-PGJ2 caused ROS generation and 15d-PGJ2-induced cell death was prevented by antioxidants, suggesting involvement of ROS generation in 15d-PGJ2-induced cell death. 15d-PGJ2 triggered the mitochondrial apoptotic pathway indicated by enhanced Bax expression, loss of mitochondrial membrane potential, cytochrome c release, and caspase-3 activation. The JNK inhibitor blocked these events induced by 15d-PGJ2. Taken together, these results suggest that the 15d-PGJ2 induces cell death through the mitochondrial apoptotic pathway dependent of ROS and JNK activation in osteoblastic cells.
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Affiliation(s)
- Sung Ju Lee
- Department of Physiology, College of Medicine, Pusan National University, Pusan 602-739, Republic of Korea
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16
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Eastham LL, Mills CN, Niles RM. PPARα/γ Expression and Activity in Mouse and Human Melanocytes and Melanoma Cells. Pharm Res 2008; 25:1327-33. [DOI: 10.1007/s11095-007-9524-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 12/07/2007] [Indexed: 02/08/2023]
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17
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Mitterberger M, Neuwirt H, Cavarretta IT, Hobisch A, Culig Z. Increased resistance to trail-induced apoptosis in prostate cancer cells selected in the presence of bicalutamide. Prostate 2007; 67:1194-201. [PMID: 17520660 DOI: 10.1002/pros.20584] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Following prolonged treatment with the non-steroidal anti-androgen bicalutamide (Casodex), LNCaP cells have become resistant to this drug. Previously, we found that the bicalutamide-refractory subline LNCaP-Bic acquires a growth advantage and does not respond to androgenic stimulation. In the present study, we have asked whether changes in response to the tumor-selective apoptosis inducer TNF-related apoptosis-inducing ligand (TRAIL) occur in LNCaP-Bic cells. METHODS LNCaP and LNCaP-Bic cells were incubated with increasing concentrations of TRAIL and apoptosis rate was analyzed using FACS. Expression of death receptors (DR), adaptor protein Fas-associated death domain (FADD), members of the Bcl-2 family, and caspases were investigated by Western blot. RESULTS The percentage of cells undergoing apoptosis was lower in LNCaP-Bic in comparison to LNCaP cells. There were no major differences in death receptor expression between control LNCaP and bicalutamide-selected cells. Surprisingly, treatment with TRAIL increased the levels of Bcl-2 by 50% in LNCaP-Bic cells. The ratio cleaved caspase/procaspase-8 was substantially lower in LNCaP-Bic cells. CONCLUSIONS Reduced sensitivity to TRAIL-induced apoptosis is a novel mechanism relevant to resistance to bicalutamide in prostate cancer. Inability of TRAIL to cause programmed cell death might be caused by multiple perturbations in the TRAIL-signaling pathway.
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18
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Sertznig P, Seifert M, Tilgen W, Reichrath J. Present concepts and future outlook: function of peroxisome proliferator-activated receptors (PPARs) for pathogenesis, progression, and therapy of cancer. J Cell Physiol 2007; 212:1-12. [PMID: 17443682 DOI: 10.1002/jcp.20998] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily of transcriptional regulators that regulate lipid, glucose, and amino acid metabolism. In recent studies it also has been shown that these receptors are implicated in tumor progression, cellular differentiation, and apoptosis and modulation of their function is therefore considered as a potential target for cancer prevention and treatment. PPAR ligands and other agents influencing PPAR signalling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in a variety of human cancers and could represent a potential novel strategy to inhibit tumor carcinogenesis and progression. This review summarizes the currently available data on the roles of PPARs in relation to the processes of cell differentiation and carcinogenesis as well as their role as promising future therapeutic targets.
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Affiliation(s)
- P Sertznig
- Department of Dermatology, The Saarland University Hospital, Homburg/Saar, Germany
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19
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Cao LQ, Chen XL, Wang Q, Huang XH, Zhen MC, Zhang LJ, Li W, Bi J. Upregulation of PTEN involved in rosiglitazone-induced apoptosis in human hepatocellular carcinoma cells. Acta Pharmacol Sin 2007; 28:879-87. [PMID: 17506947 DOI: 10.1111/j.1745-7254.2007.00571.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
AIM To investigate the effects of rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, on the expression of the phosphatase and tensin homologue deleted on chromosome 10 gene (PTEN) and cell growth in hepatocellular carcinoma cells, as well as the underlying mechanisms of these effects. METHODS RT-PCR and Western blotting analyses were performed to detect transcription and the expression of PTEN in Hep3B cells treated with rosiglitazone. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was used to evaluate cell growth. Flow cytometry, DNA fragmentation analysis, caspase enzymatic assay, and Hoechst 33258 staining were used to determine cell apoptosis. Furthermore, small interfering RNA was used to suppress PTEN expression. RESULTS Rosiglitazone increased the expression of PTEN in a dose- and time-dependent manner through the PPARgamma-dependent signal transduction pathway. PTEN upregulation was concomitant with a decreased level of Akt phosphorylation, subsequently resulting in cell growth inhibition and apoptosis in Hep3B cells. PTEN knockdown dramatically blocked these effects of rosiglitazone. Moreover, the exposure of cells to rosiglitazone activated caspases-9 and -3 during apoptotic proceeding. CONCLUSION Thus, upregulation of PTEN is involved in the inhibition of cell growth and the induction of cell apoptosis by rosiglitazone, suggesting that rosiglitazone may be useful in liver cancer therapy via apoptosis.
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Affiliation(s)
- Liang-Qi Cao
- Department of Hepatobiliary Surgery, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, China
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20
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Yang YC, Tsao YP, Ho TC, Choung IP. Peroxisome proliferator-activated receptor-gamma agonists cause growth arrest and apoptosis in human ovarian carcinoma cell lines. Int J Gynecol Cancer 2007; 17:418-25. [PMID: 17316361 DOI: 10.1111/j.1525-1438.2006.00866.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. PPARgamma agonists inhibit the growth of many types of cancers. To our knowledge, the effect of PPARgamma agonist on ovarian tumors is not reported. In this study, we used two human ovarian carcinoma cell lines (ES-2 and PA-1) to examine the effects of the PPARgamma agonists troglitazone (TGZ) and ciglitazone (CGZ) on cell survival. CGZ and TGZ inhibited viability in a dose-dependent manner in both types of ovarian cancer cells. The agonists also decreased cellular proliferation in association with an increase in the number of cells arrested in the G0/G1 phase of the cell cycle. Moreover, they increased apoptosis while increasing caspase-3 activity. Incubation of both the cell lines with the PPARgamma agonists led to upregulated PPARgamma expression. This effect appeared to be PPARgamma independent because the PPARgamma antagonist GW9662 did not reverse it. Along with the induction of apoptosis in ovarian cancer cells, protein expression levels of p53 and Bax markedly increased in response to the PPARgamma agonists. Our results demonstrated that PPARgamma agonists inhibited the viability of human ovarian cancer cells, at least partly by inducing apoptosis. As a result, these agonists may serve as future drugs for the prevention and treatment of ovarian cancer.
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Affiliation(s)
- Y-C Yang
- Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
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21
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Toyoshiba H, Sone H, Yamanaka T, Parham FM, Irwin RD, Boorman GA, Portier CJ. Gene interaction network analysis suggests differences between high and low doses of acetaminophen. Toxicol Appl Pharmacol 2006; 215:306-16. [PMID: 16701773 DOI: 10.1016/j.taap.2006.03.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 03/14/2006] [Accepted: 03/21/2006] [Indexed: 11/16/2022]
Abstract
Bayesian networks for quantifying linkages between genes were applied to detect differences in gene expression interaction networks between multiple doses of acetaminophen at multiple time points. Seventeen (17) genes were selected from the gene expression profiles from livers of rats orally exposed to 50, 150 and 1500 mg/kg acetaminophen (APAP) at 6, 24 and 48 h after exposure using a variety of statistical and bioinformatics approaches. The selected genes are related to three biological categories: apoptosis, oxidative stress and other. Gene interaction networks between all 17 genes were identified for the nine dose-time observation points by the TAO-Gen algorithm. Using k-means clustering analysis, the estimated nine networks could be clustered into two consensus networks, the first consisting of the low and middle dose groups, and the second consisting of the high dose. The analysis suggests that the networks could be segregated by doses and were consistent in structure over time of observation within grouped doses. The consensus networks were quantified to calculate the probability distribution for the strength of the linkage between genes connected in the networks. The quantifying analysis showed that, at lower doses, the genes related to the oxidative stress signaling pathway did not interact with the apoptosis-related genes. In contrast, the high-dose network demonstrated significant interactions between the oxidative stress genes and the apoptosis genes and also demonstrated a different network between genes in the oxidative stress pathway. The approaches shown here could provide predictive information to understand high- versus low-dose mechanisms of toxicity.
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Affiliation(s)
- Hiroyoshi Toyoshiba
- Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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22
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Chen Y, Wang SM, Wu JC, Huang SH. Effects of PPARgamma agonists on cell survival and focal adhesions in a Chinese thyroid carcinoma cell line. J Cell Biochem 2006; 98:1021-35. [PMID: 16795079 DOI: 10.1002/jcb.20839] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists cause cell death in several types of cancer cells. The aim of this study was to examine the effects of two PPARgamma agonists, ciglitazone and 15-deoxy-delta(12,14)-prostaglandin J2 (15dPGJ2), on the survival of thyroid carcinoma CGTH W-2 cells. Both ciglitazone and 15dPGJ2 decreased cell viability in a time- and dose-dependent manner. Cell death was mainly due to apoptosis, with a minor contribution from necrosis. Increased levels of active caspase 3, cleaved poly (ADP-ribose) polymerase (PARP), and cytosolic cytochrome-c were noted. In addition, ciglitazone and 15dPGJ2 induced detachment of CGTH W-2 cells from the culture substratum. Both the protein levels and immunostaining signals of focal adhesion (FA) proteins, including vinculin, integrin beta1, focal adhesion kinase (FAK), and paxillin were decreased after PPARgamma agonist treatment. Meanwhile, reduced phosphorylation of FAK and paxillin was noted. Furthermore, PPARgamma agonists induced expression of protein tyrosine phosphatase-PEST (PTP-PEST), and of phosphatase and tensin homologue deleted on chromosome ten (PTEN). The upregulation of these phosphatases might contribute to the dephosphorylation of FAK and paxillin, since pre-treatment with orthovanadate prevented PPARgamma agonist-induced dephosphorylation of FAK and paxillin. Perturbation of CGTH W-2 cells with anti-integrin beta1 antibodies induced FA disruption and apoptosis in the same cells, thus the downregulation of integrin beta1 by PPARgamma agonists resulted in FA disassembly and might induce apoptosis via anoikis. Our results suggested the presence of crosstalk between apoptosis and integrin-FA signaling. Moreover, upregulation and activation of PTEN was correlated with reduced phosphorylation of Akt, and this consequence disfavored cell survival. In conclusion, PPARgamma agonists induced apoptosis of thyroid carcinoma cells via the cytochrome-c caspase 3 and PTEN-Akt pathways, and induced necrosis via the PARP pathway.
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Affiliation(s)
- Ying Chen
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
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23
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Abstract
Peroxisome proliferator-activated receptors gamma (PPAR?) is a transcriptional factor belonging to the ligand-activated nuclear receptor superfamily. PPAR? is highly expressed in adipose tissue and has a dominant regulatory role in adipocyte differentiation. In humans, PPAR? is expressed in multiple tissues such as the breast, colon, lung, ovary, and placenta. In addition to adipogenic and anti-inflammatory effects, PPAR? activation has been shown to be anti-proliferative by virtue of its differentiation-promoting effect, suggesting that activation of PPAR? may be useful in slowing or arresting the proliferation of de-differentiated tumor cells. A number of PPAR? ligands, such as natural prostaglandins and synthetic anti-diabetic thiazolidinediones (TZDs), have been identified. The discovery of PPAR? agonists has enabled the elucidation of the mechanisms involved in the multiple effects of PPAR? on the inhibition of tumor cell growth. The importance of this transcription factor in physiology and pathophysiology has stimulated much research in this field. This review describes structural features of PPAR?, mechanisms of PPAR? gene transcription, and recent developments in the discovery of its biological functions on growth inhibition of lung tumors. Prospects for future research leading to new therapies for lung cancer are also discussed.
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Affiliation(s)
- Ming-Yue Li
- Department of Surgery, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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24
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Chaffer CL, Thomas DM, Thompson EW, Williams ED. PPARgamma-independent induction of growth arrest and apoptosis in prostate and bladder carcinoma. BMC Cancer 2006; 6:53. [PMID: 16519808 PMCID: PMC1450298 DOI: 10.1186/1471-2407-6-53] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 03/06/2006] [Indexed: 11/10/2022] Open
Abstract
Background Although PPARγ antagonists have shown considerable pre-clinical efficacy, recent studies suggest PPARγ ligands induce PPARγ-independent effects. There is a need to better define such effects to permit rational utilization of these agents. Methods We have studied the effects of a range of endogenous and synthetic PPARγ ligands on proliferation, growth arrest (FACS analysis) and apoptosis (caspase-3/7 activation and DNA fragmentation) in multiple prostate carcinoma cell lines (DU145, PC-3 and LNCaP) and in a series of cell lines modelling metastatic transitional cell carcinoma of the bladder (TSU-Pr1, TSU-Pr1-B1 and TSU-Pr1-B2). Results 15-deoxy-prostaglandin J2 (15dPGJ2), troglitazone (TGZ) and to a lesser extent ciglitazone exhibited inhibitory effects on cell number; the selective PPARγ antagonist GW9662 did not reverse these effects. Rosiglitazone and pioglitazone had no effect on proliferation. In addition, TGZ induced G0/G1 growth arrest whilst 15dPGJ2 induced apoptosis. Conclusion Troglitazone and 15dPGJ2 inhibit growth of prostate and bladder carcinoma cell lines through different mechanisms and the effects of both agents are PPARγ-independent.
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Affiliation(s)
- Christine L Chaffer
- Bernard O'Brien Institute of Microsurgery, Victoria, Australia
- The University of Melbourne Department of Surgery, St. Vincent's Hospital, Victoria, Australia
| | - David M Thomas
- Ian Potter Foundation Centre for Cancer Genomics and Predictive Medicine, Peter MacCallum Cancer Centre, Victoria, Australia
| | - Erik W Thompson
- Bernard O'Brien Institute of Microsurgery, Victoria, Australia
- The University of Melbourne Department of Surgery, St. Vincent's Hospital, Victoria, Australia
- St Vincent's Institute of Medical Research, Victoria, Australia
| | - Elizabeth D Williams
- Bernard O'Brien Institute of Microsurgery, Victoria, Australia
- The University of Melbourne Department of Surgery, St. Vincent's Hospital, Victoria, Australia
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Lee CJ, Han JS, Seo CY, Park TH, Kwon HC, Jeong JS, Kim IH, Yun J, Bae YS, Kwak JY, Park JI. Pioglitazone, a synthetic ligand for PPARγ, induces apoptosis in RB-deficient human colorectal cancer cells. Apoptosis 2006; 11:401-11. [PMID: 16520894 DOI: 10.1007/s10495-006-4003-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
No published data are available about the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) and the role of PPARgamma in retinoblastoma protein (RB)-deficient human colorectal cancer (CRC) cells (SNU-C4 and SNU-C2A). Our aim was to investigate whether PPARgamma is expressed in SNU-C4 and SNU-C2A cells and to elucidate possible molecular mechanisms underlying the effect of pioglitazone, a synthetic ligand for PPARgamma, on cell growth in these cell lines. RT-PCR and Western blot analysis showed that both human CRC cell lines expressed PPARgamma mRNA and protein. Pioglitazone inhibited the cell growth of both cell lines through G2/M phase block and apoptosis. In addition, pioglitazone caused a down-regulation of the X chromosome-linked inhibitor of apoptosis (XIAP), Bcl-2, and cyclooxygenase-2 (COX-2) under conditions leading to PPARgamma down-regulation. These results suggest that pioglitazone may have therapeutic relevance or significance in the treatment of human CRC, and the down-regulation of XIAP, Bcl-2, and COX-2 may contribute to pioglitazone-induced apoptosis in these and other RB-deficient cell lines and tumors.
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Affiliation(s)
- C J Lee
- Department of Biochemistry, Department of Biochemistry, Dong-A University College of Medicine, Busan, South Korea
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26
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Liu H, Zang C, Fenner MH, Liu D, Possinger K, Koeffler HP, Elstner E. Growth inhibition and apoptosis in human Philadelphia chromosome-positive lymphoblastic leukemia cell lines by treatment with the dual PPARalpha/gamma ligand TZD18. Blood 2006; 107:3683-92. [PMID: 16403907 DOI: 10.1182/blood-2005-05-2103] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Treatment of adult Philadelphia chromosome-positive lymphocytic leukemia is rarely successful. We report here the effects of TZD18, a novel dual ligand specific for peroxisome proliferator-activated receptor alpha and gamma (PPARalpha/gamma) on Ph(+) lymphocytic leukemia cell lines BV173, SD1, and SupB-15. Exposure of these cells to TZD18 resulted in growth inhibition in a dose- and time-dependent manner that was associated with G(1) cell cycle arrest. This effect was much stronger than that mediated by the PPARgamma ligand pioglitazone (PGZ), which also belongs to the thiazolidinediones (TZD) class of ligands. However, it may not be mediated through PPARgamma or PPARalpha activation because antagonists of PPARgamma and PPARalpha cannot reverse it. Study of the key regulators of cell cycle progression by Western blot analysis showed that the expression of the cyclin-dependent kinase inhibitor (CDKI) p27(kip1), but not that of p21(cip1), was enhanced, whereas that of c-Myc, cyclin E, cyclin D2, and cyclin-dependent kinases 2 and 4 (CDK-2 and CDK-4) was decreased when these cells were treated with TZD18 (10 or 20 microM). Therefore, the up-regulation of p27(kip1) and the down-regulation of CDK-2 and CDK-4 may, at least in part, account for the G(1) cell cycle arrest. Furthermore, a remarkable induction of apoptosis was observed in the cells treated with this dual ligand. No obvious alteration of bcl-2 protein level occurred, but bax was up-regulated in these TZD18-treated cells. Activation of caspase 8 and caspase 9 by TZD18 was also observed. Importantly, NF-kappaB DNA-binding activity was markedly decreased by the TZD18 treatment. In addition, TZD18 enhanced the growth inhibitory effect of imatinib, a specific tyrosine kinase inhibitor therapeutically used in the treatment of Ph(+) leukemia. Overall, our findings strongly suggest that TZD18 may offer a new therapeutic approach to aid in the treatment of Ph(+) lymphocytic leukemia.
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MESH Headings
- Apoptosis/drug effects
- Benzamides
- Cell Cycle/drug effects
- Cell Division/drug effects
- Cell Line, Tumor
- Cyclin-Dependent Kinase Inhibitor p27
- Humans
- Imatinib Mesylate
- Intracellular Signaling Peptides and Proteins/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Ligands
- NF-kappa B/metabolism
- PPAR alpha/agonists
- PPAR alpha/genetics
- PPAR gamma/agonists
- PPAR gamma/genetics
- Phenyl Ethers/administration & dosage
- Phenyl Ethers/pharmacology
- Piperazines/administration & dosage
- Pyrimidines/administration & dosage
- Thiazolidinediones/administration & dosage
- Thiazolidinediones/pharmacology
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Affiliation(s)
- Hongyu Liu
- Division of Hematology/Oncology, School of Medicine Charité, Humboldt University, Schumannstrasse 20/21, 10117 Berlin, Germany
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27
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Murakami A, Nishizawa T, Egawa K, Kawada T, Nishikawa Y, Uenakai K, Ohigashi H. New class of linoleic acid metabolites biosynthesized by corn and rice lipoxygenases: suppression of proinflammatory mediator expression via attenuation of MAPK- and Akt-, but not PPARgamma-, dependent pathways in stimulated macrophages. Biochem Pharmacol 2005; 70:1330-42. [PMID: 16143312 DOI: 10.1016/j.bcp.2005.07.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 07/26/2005] [Accepted: 07/26/2005] [Indexed: 01/01/2023]
Abstract
In response to endogenous and exogenous stimuli, macrophages are activated to produce a cocktail of proinflammatory and anti-apoptotic mediators, thereby participating in the processes of inflammation-associated oncogenesis. Cereals, including corn and rice, have biological potentials to synthesize self-protective chemicals in order to repel the invasion of microorganisms and insects. We examined the suppressive effects of several fatty acids, including a new class of lipoxygenase metabolites of linoleic acid (LA) found in cereals, namely (+/-)-9-hydroxy-trans,cis-10,12-octadecadienoic acid (9-HOA from rice), (+/-)-13-hydroxy-10-oxo-trans-11-octadecenoic acid (13-HOA from corn), and (+/-)-10-oxo-trans-11-octadecen-13-olide (10-ODO from corn), on lipopolysaccharide (LPS)-induced mRNA expression of proinflammatory mediators in RAW264.7 murine macrophages. Each metabolite exhibited a suppressive activity toward nitrite production than LA, octadeca-9Z,11E-dienoic acid (a conjugated LA), and 13S-hydroxyoctadeca-9Z,11E-dienoic acid. LPS-up-regulated mRNA expression of inducible nitric oxide synthase, cyclooxygenase (COX)-2, interleukin-6, and toll-like receptor-2, -4, and -9 was also markedly attenuated without affecting the expression levels of several constitutive genes, including COX-1, as detected by reverse transcription-polymerase chain reactions. In addition, Western blot and luciferase reporter assay results showed that 13-HOA suppressed the phosphorylation of mitogen-activated protein kinases (extracellular signal-regulated kinasel/2, c-Jun N-terminal kinasel/2, p38 mitogen-activated protein kinase), and Akt (Ser473), and also attenuated degradation of inhibitor kappaB, nuclear translocation of nuclear factor kappaB (NFkappaB), and the transcriptional activities of NFkappaB and activator protein-1, both of which have essential roles in the transcription of numerous proinflammatory and oncogenic genes. In contrast, 13-HOA did not serve as a ligand for peroxisome proliferator-activated receptor-gamma. Based on our findings, we propose that 13-HOA, a functionally novel LA-derivative, is a promising agent for anti-inflammatory and chemopreventive strategies with reasonable molecular mechanisms.
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Affiliation(s)
- Akira Murakami
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
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Lu J, Imamura K, Nomura S, Mafune KI, Nakajima A, Kadowaki T, Kubota N, Terauchi Y, Ishii G, Ochiai A, Esumi H, Kaminishi M. Chemopreventive Effect of Peroxisome Proliferator–Activated Receptor γ on Gastric Carcinogenesis in Mice. Cancer Res 2005; 65:4769-74. [PMID: 15930296 DOI: 10.1158/0008-5472.can-04-2293] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is known to be expressed in several cancers, and the treatment of these cancer cells with PPARgamma ligands often induces cell differentiation and apoptosis. Recently, the chemopreventive potential of PPARgamma ligands on colon carcinogenesis was reported, although the effect of PPARgamma on colon carcinogenesis and the mechanism of the effect remain controversial. In this study, we attempted to elucidate the role of PPARgamma in gastric carcinogenesis and explored the possible use of PPARgamma ligand as a chemopreventive agent for gastric cancer. N-methyl-N-nitrosourea (MNU, 240 ppm) was given in drinking water for 10 weeks to induce gastric cancer in PPARgamma wild-type (+/+) and heterozygous-deficient (+/-) mice, followed by treatment with PPARgamma ligand [troglitazone, 0.15% (w/w) in powder food] or the vehicle alone for 42 weeks. At the end of the experiment, PPARgamma (+/-) mice were more susceptible to MNU-induced gastric cancer than wild-type (+/+) mice (89.5%/55.5%), and troglitazone significantly reduced the incidence of gastric cancer in PPARgamma (+/+) mice (treatment 55.5%/vehicle 9%) but not in PPARgamma (+/-) mice. The present study showed that (a) PPARgamma suppresses gastric carcinogenesis, (b) the PPARgamma ligand troglitazone is a potential chemopreventive agent for gastric carcinogenesis, and (c) troglitazone's chemopreventive effect is dependent on PPARgamma.
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Affiliation(s)
- Jie Lu
- Department of Gastrointestinal Surgery, Faculty of Medicine, University of Tokyo, Japan.
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Harada K, Isse K, Kamihira T, Shimoda S, Nakanuma Y. Th1 cytokine-induced downregulation of PPARgamma in human biliary cells relates to cholangitis in primary biliary cirrhosis. Hepatology 2005; 41:1329-38. [PMID: 15880426 DOI: 10.1002/hep.20705] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Peroxisome proliferator-activated receptor-gamma (PPARgamma) is known to inhibit the production of proinflammatory cytokines. In Th1-predominant diseases, PPARgamma ligands can ameliorate clinical severity by downregulating the expression of proinflammatory cytokines. Primary biliary cirrhosis (PBC) is characterized by chronic destructive cholangitis with a Th1-predominant cytokine milieu. Unusual immune responses to infectious agents are suspected to underlie its etiopathogenesis. We examined the significance of PPARgamma in biliary inflammation in connection to PBC. To this end, we performed immunohistochemistry, quantitative polymerase chain reaction, and nuclear factor-kappaB (NF-kappaB) DNA-binding assays to clarify the intrahepatic distribution of PPARgamma and the regulation of PPARgamma by inflammatory cytokines and PPARgamma ligand in five cultured biliary cell lines including one derived from PBC liver. In liver specimens from patients with PBC, PPARgamma protein was ubiquitously expressed in intrahepatic biliary epithelium, whereas the expression of PPARgamma protein and mRNA was reduced in damaged bile ducts. PPARgamma expression in cultured cells was upregulated by interleukin-4 (IL-4; Th2-type), but downregulated by IFN-gamma (Th1-type). PPARgamma ligand negatively modulated lipopolysaccharide-induced NF-kappaB activation. Moreover, this inhibitory effect of PPARgamma ligand was attenuated by pretreatment with IFN-gamma. In conclusion, PPARgamma may be important to maintain homeostasis in the intrahepatic biliary epithelium, and its reduction in the bile ducts of PBC liver may be associated with the Th1-predominant milieu and with the development of chronic cholangitis in PBC. Immunosuppression using PPARgamma ligands may be of therapeutic benefit to attenuate biliary inflammation in PBC.
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Affiliation(s)
- Kenichi Harada
- Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan
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Park JW, Zarnegar R, Kanauchi H, Wong MG, Hyun WC, Ginzinger DG, Lobo M, Cotter P, Duh QY, Clark OH. Troglitazone, the peroxisome proliferator-activated receptor-gamma agonist, induces antiproliferation and redifferentiation in human thyroid cancer cell lines. Thyroid 2005; 15:222-31. [PMID: 15785241 DOI: 10.1089/thy.2005.15.222] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Troglitazone is a potent agonist for the peroxisome proliferator-activated receptor-gamma (PPARgamma) that is a ligand-activated transcription factor regulating cell differentiation and growth. PPARgamma may play a role in thyroid carcinogenesis since PAX8-PPARgamma1 chromosomal translocations are commonly found in follicular thyroid cancers. We investigated the antiproliferative and redifferentiation effects of troglitazone in 6 human thyroid cancer cell lines: TPC-1 (papillary), FTC-133, FTC-236, FTC-238 (follicular), XTC-1 (Hürthle cell), and ARO82-1 (anaplastic) cell lines. PPARgamma was expressed variably in these cell lines. FTC-236 and FTC-238 had a rearranged chromosome at 3p25, possibly implicating the involvement of the PPARgamma encoding gene whereas the other cell lines did not. Troglitazone significantly inhibited cell growth by cell cycle arrest and apoptotic cell death. PPARgamma overexpression did not appear to be a prerequisite for a response to treatment with troglitazone. Troglitazone also downregulated surface expression of CD97, a novel dedifferentiation marker, in FTC-133 cells and upregulated sodium iodide symporter (NIS) mRNA in TPC-1 and FTC-133 cells. Our investigations document that human thyroid cancer cell lines commonly express PPARgamma, but chromosomal translocations involving PPARgamma are uncommon. Troglitazone, a PPARgamma agonist, induced antiproliferation and redifferentiation in thyroid cancer cell lines. PPARgamma agonists may therefore be effective therapeutic agents for the treatment of patients with thyroid cancer that fails to respond to traditional treatments.
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Affiliation(s)
- Jin-Woo Park
- Department of Surgery University of California, San Francisco, UCSF/Mount Zion Medical Center, San Francisco, CA 94143, USA
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Guzman ML, Rossi RM, Karnischky L, Li X, Peterson DR, Howard DS, Jordan CT. The sesquiterpene lactone parthenolide induces apoptosis of human acute myelogenous leukemia stem and progenitor cells. Blood 2005; 105:4163-9. [PMID: 15687234 PMCID: PMC1895029 DOI: 10.1182/blood-2004-10-4135] [Citation(s) in RCA: 488] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Recent studies have described malignant stem cells as central to the initiation, growth, and potential relapse of acute and chronic myelogenous leukemia (AML and CML). Because of their important role in pathogenesis, rare and biologically distinct leukemia stem cells (LSCs) represent a critical target for therapeutic intervention. However, to date, very few agents have been shown to directly target the LSC population. The present studies demonstrate that parthenolide (PTL), a naturally occurring small molecule, induces robust apoptosis in primary human AML cells and blast crisis CML (bcCML) cells while sparing normal hematopoietic cells. Furthermore, analysis of progenitor cells using in vitro colony assays, as well as stem cells using the nonobese diabetic/severe combined immunodeficient (NOD/SCID) xenograft model, show that PTL also preferentially targets AML progenitor and stem cell populations. Notably, in comparison to the standard chemotherapy drug cytosine arabinoside (Ara-C), PTL is much more specific to leukemia cells. The molecular mechanism of PTL-mediated apoptosis is strongly associated with inhibition of nuclear factor kappa B (NF-kappaB), proapoptotic activation of p53, and increased reactive oxygen species (ROS). On the basis of these findings, we propose that the activity of PTL triggers LSC-specific apoptosis and as such represents a potentially important new class of drugs for LSC-targeted therapy.
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Affiliation(s)
- Monica L Guzman
- University of Rochester School of Medicine, 601 Elmwood Ave, Box 703, Rochester, NY 14642, USA.
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Han S, Rivera HN, Roman J. Peroxisome proliferator-activated receptor-gamma ligands inhibit alpha5 integrin gene transcription in non-small cell lung carcinoma cells. Am J Respir Cell Mol Biol 2005; 32:350-9. [PMID: 15677767 DOI: 10.1165/rcmb.2004-0345oc] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We previously showed that fibronectin stimulates the growth of non-small cell lung carcinoma (NSCLC) cells through integrin alpha5beta1-dependent signals. We also demonstrated that peroxisome proliferator-activated receptor (PPAR)gamma ligands inhibit lung carcinoma cell growth. Because alpha5beta1 activation elicits cellular signals linked to cell survival and regulation of cell cycle progression, we studied the effects of PPARgamma ligands on its expression. We found that PPARgamma ligands decreased mRNA and protein expression of the alpha5 subunit of the alpha5beta1 heterodimer in NSCLC; this was associated with reduced NSCLC adhesion to fibronectin. The suppressive effect of the PPARgamma ligands BRL 49653 and GW1929, but not PGJ(2), on alpha5 gene expression were reversed by GW9662, an antagonist of PPARgamma. GW1929 activated the extracellular regulated kinase (Erk), and an inhibitor of the Erk pathway (PD98095) prevented its effect on alpha5. PPARgamma ligands also reduced alpha5 gene promoter activity, and this was blocked by Erk antisense oligonucleotides. PPARgamma ligands GW1929 and BRL49653 inhibited AP-1 DNA binding, whereas 15d-PGJ(2) inhibited Sp1 DNA binding; both effects were blocked by Erk antisense oligonucleotides. GW1929 partially blocked fibronectin-induced NSCLC cell growth, but did not affect cell growth induced by epidermal growth factor. These results suggest that PPARgamma ligands inhibit alpha5 expression in NSCLC through Erk-related signals.
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Affiliation(s)
- ShouWei Han
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University School of Medicine, Whitehead Bioresearch Building, 615 Michael Street, Suite 205-M, Atlanta, GA 30322, USA.
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Chen YC, Shen SC, Tsai SH. Prostaglandin D(2) and J(2) induce apoptosis in human leukemia cells via activation of the caspase 3 cascade and production of reactive oxygen species. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1743:291-304. [PMID: 15843042 DOI: 10.1016/j.bbamcr.2004.10.016] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Revised: 10/05/2004] [Accepted: 10/06/2004] [Indexed: 10/26/2022]
Abstract
The presence of prostaglandins (PGs) has been demonstrated in the processes of carcinogenesis and inflammation. In the present study, we found that 12-o-tetradecanoylphorbol 13-acetate (TPA) induced cyclooxygenase 2 (COX-2), but not COX-1, protein expression in HL-60 cells, and the addition of arachidonic acid (AA) in the presence or absence of TPA significantly reduced the viability of HL-60 cells, an effect that was blocked by adding the COX inhibitors, NS398 and aspirin. The AA metabolites, PGD(2) and PGJ(2), but not PGE(2) or PGF(2alpha), reduced the viability of the human HL60 and Jurkat leukemia cells according to the MTT assay and LDH release assay. Apoptotic characteristics including DNA fragmentation, apoptotic bodies, and hypodiploid cells were observed in PGD(2)- and PGJ(2)-treated leukemia cells. A dose- and time-dependent induction of caspase 3 protein procession, and PARP and D4-GDI protein cleavage with activation of caspase 3, but not caspase 1, enzyme activity was detected in HL-60 cells treated with PGD(2) or PGJ(2). Additionally, DNA ladders induced by PGD(2) and PGJ(2) were significantly inhibited by the caspase 3 peptidyl inhibitor, Ac-DEVD-FMK, but not by the caspase 1 peptidyl inhibitor, Ac-YVAD-FMK, in accordance with the blocking of caspase 3, PARP, and D4-GDI protein procession. An increase in intracellular peroxide levels by PGD(2) and PGJ(2) was identified by the DCHF-DA assay, and anti-oxidant N-acetyl cysteine (NAC), mannitol (MAN), and tiron significantly inhibited cell death induced by PGD(2) and PGJ(2) by reducing reactive oxygen species (ROS) production. The PGJ(2) metabolites, 15-deoxy-Delta(12,14)-PGJ(2) and Delta(12)-PGJ(2), exhibited effective apoptosis-inducing activity in HL-60 cells through ROS production via activation of the caspase 3 cascade. The proliferator-activated receptor-gamma (PPAR-gamma) agonists, rosiglitazone (RO), troglitazone (TR), and ciglitazone (CI), induced apoptosis in cells which was blocked by the addition of the PPAR-gamma antagonists, GW9662 and BADGE, via blocking of caspase 3 and PARP cleavage. However, neither GW9662 nor BADGE showed any protective effect on PGD(2)- and PGJ(2)-induced apoptosis. A differential apoptotic effect of PGs through ROS production, followed by activation of the caspase 3 cascade, was demonstrated.
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Affiliation(s)
- Yen-Chou Chen
- Graduate Institute of Pharmacognosy, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan.
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Han S, Roman J. Suppression of prostaglandin E2 receptor subtype EP2 by PPARgamma ligands inhibits human lung carcinoma cell growth. Biochem Biophys Res Commun 2004; 314:1093-9. [PMID: 14751245 DOI: 10.1016/j.bbrc.2004.01.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Prostaglandin E(2) (PGE(2)), a major cyclooxygenase (COX-2) metabolite, plays important roles in tumor biology and its functions are mediated through one or more of its receptors EP1, EP2, EP3, and EP4. We have shown that the matrix glycoprotein fibronectin stimulates lung carcinoma cell proliferation via induction of COX-2 expression with subsequent PGE(2) protein biosynthesis. Ligands of peroxisome proliferator-activated receptor gamma (PPARgamma) inhibited this effect and induced cellular apoptosis. Here, we explore the role of the PGE(2) receptor EP2 in this process and whether the inhibition observed with PPARgamma ligands is related to effects on this receptor. We found that human non-small cell lung carcinoma cell lines (H1838 and H2106) express EP2 receptors, and that the inhibition of cell growth by PPARgamma ligands (GW1929, PGJ2, ciglitazone, troglitazone, and rosiglitazone [also known as BRL49653]) was associated with a significant decrease in EP2 mRNA and protein levels. The inhibitory effects of BRL49653 and ciglitazone, but not PGJ2, were reversed by a specific PPARgamma antagonist GW9662, suggesting the involvement of PPARgamma-dependent and -independent mechanisms. PPARgamma ligand treatment was associated with phosphorylation of extracellular regulated kinase (Erk), and inhibition of EP2 receptor expression by PPARgamma ligands was prevented by PD98095, an inhibitor of the MEK-1/Erk pathway. Butaprost, an EP2 agonist, like exogenous PGE(2) (dmPGE(2)), increased lung carcinoma cell growth, however, GW1929 and troglitazone blocked their effects. Our studies reveal a novel role for EP2 in mediating the proliferative effects of PGE(2) on lung carcinoma cells. PPARgamma ligands inhibit human lung carcinoma cell growth by decreasing the expression of EP2 receptors through Erk signaling and PPARgamma-dependent and -independent pathways.
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Affiliation(s)
- ShouWei Han
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
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