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Goodla L, Xue X. The Role of Inflammatory Mediators in Colorectal Cancer Hepatic Metastasis. Cells 2022; 11:2313. [PMID: 35954156 PMCID: PMC9367504 DOI: 10.3390/cells11152313] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/24/2022] [Accepted: 07/26/2022] [Indexed: 01/27/2023] Open
Abstract
Colorectal cancer (CRC) is the second leading cause of death in cancer patients in the USA, whereas the major cause of CRC deaths is hepatic metastases. The liver is the most common site of metastasis in patients with CRC due to hepatic portal veins receiving blood from the digestive tract. Understanding the cellular and molecular mechanisms of hepatic metastases is of dire need for the development of potent targeted therapeutics. Immuno-signaling molecules including cytokines and chemokines play a pivotal role in hepatic metastases from CRC. This brief review discusses the involvement of three representative cytokines (TNF-α, IL-6 and IL-1β), a lipid molecule PGE2 and two chemokines (CXCL1 and CXCL2) in the process of CRC liver metastases.
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Affiliation(s)
| | - Xiang Xue
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA;
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2
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Bonura A, Giacomarra M, Montana G. The Keap1 signaling in the regulation of HSP90 pathway. Cell Stress Chaperones 2022; 27:197-204. [PMID: 35362892 PMCID: PMC9106781 DOI: 10.1007/s12192-022-01253-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/23/2021] [Accepted: 01/07/2022] [Indexed: 11/03/2022] Open
Abstract
The Keap1 protein is the master modulator of Nrf2 pathway; moreover, it is the hub of such important processes as cancer, cell stress, inflammation, and chemio- and radio-resistance. That is why Keap1 has become an intriguing pharmacological target. Many recent data show that Keap1 interacts with HSP90 protein. In this study, we use ferulic acid (FA) as antioxidant and anti-inflammatory agent, able to relieve inflammatory response. It is known that treatment with 100 μg of FA can significantly decrease the oxidative stress, so it turns to be useful to study the antioxidant regulation. The RAW 264.7 cells transfected with si-Keap1 and LPS treated are the in vitro model used to study the effects of Keap1 silencing on HSP90 activities and the FA antioxidant modulation. Immunoblot data and qPCR analysis show that Keap1 is involved in HSP90 modulation and on anti-oxidative response. Keap1 silencing affects negatively COX2 activation; in fact western blot and qPCR analysis conducted on RAW 264.7 cells Keap1silenced highlight that LPS treatment does not induce COX2 activation. In addition, the FA anti-oxidative and modulatory effect is abolished in COX2 pathway. The same results are point out using human A549 cell line with an allelic mutation on Keap1 gene, and the protein results are partially inactive. This preliminary study points out that Keap1protein is involved in HSP90 and anti-oxidative pathway regulation.
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Affiliation(s)
- Angela Bonura
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Ricerca e Innovazione Biomedica, Via Ugo La Malfa 153, 90146, Palermo, Italy
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Farmacologia Traslazionale, 00133, Roma, Italy
| | - Miriam Giacomarra
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Ricerca e Innovazione Biomedica, Via Ugo La Malfa 153, 90146, Palermo, Italy
| | - Giovanna Montana
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Ricerca e Innovazione Biomedica, Via Ugo La Malfa 153, 90146, Palermo, Italy.
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Farmacologia Traslazionale, 00133, Roma, Italy.
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3
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Masato M, Miyata Y, Kurata H, Ito H, Mitsunari K, Asai A, Nakamura Y, Araki K, Mukae Y, Matsuda T, Harada J, Matsuo T, Ohba K, Sakai H. Oral administration of E-type prostanoid (EP) 1 receptor antagonist suppresses carcinogenesis and development of prostate cancer via upregulation of apoptosis in an animal model. Sci Rep 2021; 11:20279. [PMID: 34645904 PMCID: PMC8514456 DOI: 10.1038/s41598-021-99694-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/24/2021] [Indexed: 12/23/2022] Open
Abstract
Prostaglandin E2 plays an important role in carcinogenesis and malignant potential of prostate cancer (PC) cells by binding to its specific receptors, E-type prostanoid (EP) receptors. However, anti-carcinogenic effects of the EP receptor antagonist are unclear. In this study, we used a mouse model of PC. The mice were provided standard feed (control) or feed containing the EP1 receptor antagonist and were sacrificed at 10, 15, 30, and 52 weeks of age. Apoptosis was evaluated by immunohistochemical analysis using a cleaved caspase-3 assay. The incidence of cancer in the experimental group was significantly lower than that in the control group at 15, 30, and 52 weeks of age. The percentage of poorly differentiated PC cells was significantly lower in the experimental group than in the control group at 30 and 52 weeks of age. The percentage of apoptotic cells in the experimental group was significantly higher than that in the control group at 15, 30, and 52 weeks of age. These findings indicate that feeding with the addition of EP1 receptor antagonist delayed PC progression via the upregulation of apoptosis. We suggest that the EP1 receptor antagonist may be a novel chemopreventive agent for PC.
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Affiliation(s)
- Masahito Masato
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Yasuyoshi Miyata
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan.
| | - Hiroki Kurata
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Hidenori Ito
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Kensuke Mitsunari
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Akihiro Asai
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Yuichiro Nakamura
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Kyohei Araki
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Yuta Mukae
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Tsuyoshi Matsuda
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Junki Harada
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Tomohiro Matsuo
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Kojiro Ohba
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
| | - Hideki Sakai
- Department of Urology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan
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4
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Yilmaz Ç, Köksoy S, Çeker T, Aslan M. Diclofenac down-regulates COX-2 induced expression of CD44 and ICAM-1 in human HT29 colorectal cancer cells. Naunyn Schmiedebergs Arch Pharmacol 2021; 394:2259-2272. [PMID: 34436652 DOI: 10.1007/s00210-021-02139-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/06/2021] [Indexed: 02/06/2023]
Abstract
Cyclooxygenase-2 (COX-2) is expressed in a variety of human colorectal cancer cells and can contribute to carcinogenesis. This study aimed to investigate the effect of diclofenac (DCF), a selective COX-2 inhibitor, on cell adhesion molecules and apoptosis in human colon adenocarcinoma cells. Levels of homing cell adhesion molecule (H-CAM, CD44), intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule-1 (VCAM-1, CD106), and epithelial cell adhesion molecule (EpCAM, CD326) were evaluated in cancer cells overexpressing (HT29) or not expressing (HCT116) COX-2. Cell viability was determined by MTT assay, COX-2 protein levels and activity were assessed by immunofluorescence and fluorometric analysis, respectively. Endogenous levels of polyunsaturated fatty acids (PUFAs) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) while expression of cell adhesion molecules was analyzed by flow cytometry. Annexin V-FITC/propidium iodide-labelling and fluorometric caspase-3 activity measurements were carried out to determine apoptosis. Flow cytometry analysis revealed that the percentage of CD44 and ICAM-1 staining in HCT116 cells was significantly lower compared to HT29 cells. In HT29 cells, phorbol 12-myristate 13-acetate (PMA) induced COX-2 expression and increased CD44 and ICAM-1 levels were down-regulated by diclofenac. Stimulation of COX-2 activity in HT29 cells via PMA significantly decreased diclofenac associated increase in PUFA levels. Treatment with both diclofenac and PMA significantly increased the number of apoptotic cells and caspase-3 activity in colon adenocarcinoma cells compared to control groups. In conclusion, diclofenac's effect to retard colorectal tumor growth and metastasis occurs in COX-2 overexpressing colon cancer cells by increased apoptosis and decreased expression of CD44 and ICAM-1.
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Affiliation(s)
- Çağatay Yilmaz
- Department of Medical Biochemistry, Faculty of Medicine, Akdeniz University, 07070, Antalya, Turkey
| | - Sadi Köksoy
- Department of Medical Microbiology, Faculty of Medicine, Akdeniz University, 07070, Antalya, Turkey.,Department of Gene and Cell Therapy, Faculty of Medicine, Akdeniz University, 07070, Antalya, Turkey
| | - Tuğçe Çeker
- Department of Medical Biochemistry, Faculty of Medicine, Akdeniz University, 07070, Antalya, Turkey
| | - Mutay Aslan
- Department of Medical Biochemistry, Faculty of Medicine, Akdeniz University, 07070, Antalya, Turkey. .,Department of Gene and Cell Therapy, Faculty of Medicine, Akdeniz University, 07070, Antalya, Turkey.
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Sareen N, Srivastava A, Dhingra S. Role of prostaglandin E2 in allogeneic mesenchymal stem cell therapy for cardiac repair. Can J Physiol Pharmacol 2021; 99:140-150. [PMID: 33559528 DOI: 10.1139/cjpp-2020-0413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ischemic heart disease is among the primary causes of cardiovascular-related deaths worldwide. Conventional treatments including surgical interventions and medical therapies aid in preventing further damage to heart muscle but are unable to provide a permanent solution. In recent years, stem cell therapy has emerged as an attractive alternative to restore damaged myocardium after myocardial injury. Allogeneic (donor-derived) mesenchymal stem cells (MSCs) have shown great promise in preclinical and clinical studies, making them the most widely accepted candidates for cardiac cell therapy. MSCs promote cardiac repair by modulating host immune system and secreting various soluble factors, of which prostaglandin E2 (PGE2) is an important one. PGE2 plays a significant role in regulating cardiac remodeling following myocardial injury. In this review, we provide an overview of allogeneic MSCs as candidates for myocardial regeneration with a focus on the role of the PGE2/cyclooxygenase-2 (COX2) pathway in mediating these effects.
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Affiliation(s)
- Niketa Sareen
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Abhay Srivastava
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Sanjiv Dhingra
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Department of Physiology and Pathophysiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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Daniele S, Pietrobono D, Costa B, Giustiniano M, La Pietra V, Giacomelli C, La Regina G, Silvestri R, Taliani S, Trincavelli ML, Da Settimo F, Novellino E, Martini C, Marinelli L. Bax Activation Blocks Self-Renewal and Induces Apoptosis of Human Glioblastoma Stem Cells. ACS Chem Neurosci 2018; 9:85-99. [PMID: 28368610 DOI: 10.1021/acschemneuro.7b00023] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Glioblastoma (GBM) is characterized by a poor response to conventional chemotherapeutic agents, attributed to the insurgence of drug resistance mechanisms and to the presence of a subpopulation of glioma stem cells (GSCs). GBM cells and GSCs present, among others, an overexpression of antiapoptotic proteins and an inhibition of pro-apoptotic ones, which help to escape apoptosis. Among pro-apoptotic inducers, the Bcl-2 family protein Bax has recently emerged as a promising new target in cancer therapy along with first BAX activators (BAM7, Compound 106, and SMBA1). Herein, a derivative of BAM-7, named BTC-8, was employed to explore the effects of Bax activation in different human GBM cells and in their stem cell subpopulation. BTC-8 inhibited GBM cell proliferation, arrested the cell cycle, and induced apoptosis through the induction of mitochondrial membrane permeabilization. Most importantly, BTC-8 blocked proliferation and self-renewal of GSCs and induced their apoptosis. Notably, BTC-8 was demonstrated to sensitize both GBM cells and GSCs to the alkylating agent Temozolomide. Overall, our findings shed light on the effects and the relative molecular mechanisms related to Bax activation in GBM, and they suggest Bax-targeting compounds as promising therapeutic tools against the GSC reservoir.
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Affiliation(s)
- Simona Daniele
- Department
of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | | | - Barbara Costa
- Department
of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | | | - Valeria La Pietra
- Department
of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy
| | | | - Giuseppe La Regina
- Istituto
Pasteur Italia—Fondazione Cenci Bolognetti, Dipartimento di
Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, 00185 Roma, Italy
| | - Romano Silvestri
- Istituto
Pasteur Italia—Fondazione Cenci Bolognetti, Dipartimento di
Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, 00185 Roma, Italy
| | - Sabrina Taliani
- Department
of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | | | | | - Ettore Novellino
- Department
of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy
| | - Claudia Martini
- Department
of Pharmacy, University of Pisa, 56126 Pisa, Italy
| | - Luciana Marinelli
- Department
of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy
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7
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Role of HSPA1L as a cellular prion protein stabilizer in tumor progression via HIF-1α/GP78 axis. Oncogene 2017; 36:6555-6567. [PMID: 28759037 DOI: 10.1038/onc.2017.263] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/05/2017] [Accepted: 06/08/2017] [Indexed: 02/06/2023]
Abstract
The cellular prion protein (PrPC) is associated with metastasis, tumor progression and recurrence; however, the precise mechanisms underlying its action is not well understood. Our study found that PrPC degradation decreased tumor progression in colorectal cancer (CRC). In a CRC cell line and human CRC tissue exposed to hypoxia, induced heat-shock 70-kDa protein-1-like (HSPA1L) expression stabilized hypoxia-inducible factor-1α (HIF-1α) protein and promoted PrPC accumulation and tumorigenicity in vivo. PrPC was degraded via the proteasome pathway mediated by the ubiquitin-protein E3 ligase glycoprotein 78 (GP78), which interacts directly with PrPC. However, hypoxia-induced HSPA1L interacted with GP78 and inhibited its functions. HSPA1L knockdown facilitated the interaction of GP78 and PrPC, thereby increasing PrPC ubiquitination. Thus, GP78 was identified as the ubiquitinase for PrPC, thereby revealing an essential mechanism that controls PrPC levels in CRC. Our results suggest that the HSPA1L/HIF-1α/GP78 axis has a crucial role in PrPC accumulation during tumor progression.
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Shay AE, Diwakar BT, Guan BJ, Narayan V, Urban JF, Prabhu KS. IL-4 up-regulates cyclooxygenase-1 expression in macrophages. J Biol Chem 2017; 292:14544-14555. [PMID: 28684424 PMCID: PMC5582846 DOI: 10.1074/jbc.m117.785014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/30/2017] [Indexed: 12/11/2022] Open
Abstract
Macrophages use various cell-surface receptors to sense their environment and undergo polarized responses. The cytokines, interleukin (IL)-4 and IL-13, released from T-helper type 2 (Th2) cells, drive macrophage polarization toward an alternatively activated phenotype (M2). This phenotype is associated with the expression of potent pro-resolving mediators, such as the prostaglandin (PG) D2-derived cyclopentenone metabolite, 15d-PGJ2, produced by the cyclooxygenase (Ptgs; Cox) pathway. Interestingly, IL-4 treatment of bone marrow-derived macrophages (BMDMs) significantly down-regulates Cox-2 protein expression, whereas Cox-1 levels are significantly increased. This phenomenon not only challenges the dogma that Cox-1 is only developmentally regulated, but also demonstrates a novel mechanism in which IL-4-dependent regulation of Cox-1 involves the activation of the mechanistic target of rapamycin complex (mTORC). Using specific chemical inhibitors, we demonstrate here that IL-4-dependent Cox-1 up-regulation occurs at the post-transcriptional level via the Fes-Akt-mTORC axis. Activation of AMP-activated protein kinase (AMPK) by metformin, inhibition of mTORC by torin 1, or CRISPR/Cas9-mediated genetic knock-out of tuberous sclerosis complex-2 (Tsc2) blocked the IL-4-dependent expression of Cox-1 and the ability of macrophages to polarize to M2. However, use of 15d-PGJ2 partially rescued the effects of AMPK activation, suggesting the importance of Cox-1 in macrophage polarization as also observed in a model of gastrointestinal helminth clearance. In summary, these findings suggest a new paradigm where IL-4-dependent up-regulation of Cox-1 expression may play a key role in tissue homeostasis and wound healing during Th2-mediated immune responses, such as parasitic infections.
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Affiliation(s)
- Ashley E Shay
- From the Department of Veterinary and Biomedical Sciences, Center for Molecular Immunology and Infectious Disease and Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Bastihalli T Diwakar
- From the Department of Veterinary and Biomedical Sciences, Center for Molecular Immunology and Infectious Disease and Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Bo-Jhih Guan
- the Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio 44106
| | - Vivek Narayan
- the Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, and
| | - Joseph F Urban
- the United States Department of Agriculture (USDA), Agriculture Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics, and Immunology Laboratory, Beltsville, Maryland 20705
| | - K Sandeep Prabhu
- From the Department of Veterinary and Biomedical Sciences, Center for Molecular Immunology and Infectious Disease and Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, Pennsylvania 16802,
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Anti-Inflammatory Effects of Chloranthalactone B in LPS-Stimulated RAW264.7 Cells. Int J Mol Sci 2016; 17:ijms17111938. [PMID: 27879664 PMCID: PMC5133933 DOI: 10.3390/ijms17111938] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/08/2016] [Accepted: 11/11/2016] [Indexed: 12/20/2022] Open
Abstract
Chloranthalactone B (CTB), a lindenane-type sesquiterpenoid, was obtained from the Chinese medicinal herb Sarcandra glabra, which is frequently used as a remedy for inflammatory diseases. However, the anti-inflammatory mechanisms of CTB have not been fully elucidated. In this study, we investigated the molecular mechanisms underlying these effects in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. CTB strongly inhibited the production of nitric oxide and pro-inflammatory mediators such as prostaglandin E2, tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and IL-6 in RAW264.7 cells stimulated with LPS. A reverse-transcription polymerase chain reaction assay and Western blot further confirmed that CTB inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, and IL-1β at the transcriptional level, and decreased the luciferase activities of activator protein (AP)-1 reporter promoters. These data suggest that inhibition occurred at the transcriptional level. In addition, CTB blocked the activation of p38 mitogen-activated protein kinase (MAPK) but not c-Jun N-terminal kinase or extracellular signal-regulated kinase 1/2. Furthermore, CTB suppressed the phosphorylation of MKK3/6 by targeting the binding sites via formation of hydrogen bonds. Our findings clearly show that CTB inhibits the production of inflammatory mediators by inhibiting the AP-1 and p38 MAPK pathways. Therefore, CTB could potentially be used as an anti-inflammatory agent.
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