1
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Cannarella R, Crafa A, Curto R, Mongioì LM, Garofalo V, Cannarella V, Condorelli RA, La Vignera S, Calogero AE. Human sperm RNA in male infertility. Nat Rev Urol 2024:10.1038/s41585-024-00920-9. [PMID: 39256514 DOI: 10.1038/s41585-024-00920-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2024] [Indexed: 09/12/2024]
Abstract
The function and value of specific sperm RNAs in apparently idiopathic male infertility are currently poorly understood. Whether differences exist in the sperm RNA profile between patients with infertility and fertile men needs clarification. Similarly, the utility of sperm RNAs in predicting successful sperm retrieval and assisted reproductive technique (ART) outcome is unknown. Patients with infertility and fertile individuals seem to have differences in the expression of non-coding RNAs that regulate genes controlling spermatogenesis. Several RNAs seem to influence embryo quality and development. Also, RNA types seem to predict successful sperm retrieval in patients with azoospermia. These findings suggest that sperm RNAs could influence decision-making during the management of patients with infertility. This evidence might help to identify possible therapeutic approaches aimed at modulating the expression of dysregulated genes in patients with infertility. Performing prospective studies with large sample sizes is necessary to investigate cost-effective panels consisting of proven molecular targets to ensure that this evidence can be translated to clinical practice.
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Affiliation(s)
- Rossella Cannarella
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy.
- Glickman Urological & Kidney Institute, Cleveland Clinic Foundation, Cleveland, OH, USA.
| | - Andrea Crafa
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Roberto Curto
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Laura M Mongioì
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Vincenzo Garofalo
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Vittorio Cannarella
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Rosita A Condorelli
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Sandro La Vignera
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Aldo E Calogero
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
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2
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Koh R, Szeverenyi I, Lunny DP, Eng GH, Lane EB. Loss of keratin 14 expression from immortalized keratinocytes by promoter methylation. Exp Dermatol 2024; 33:e15143. [PMID: 39073059 DOI: 10.1111/exd.15143] [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] [Received: 09/18/2023] [Revised: 05/29/2024] [Accepted: 06/02/2024] [Indexed: 07/30/2024]
Abstract
Immortalized keratinocytes can offer a low-cost experimental platform for human skin research, with increased cell yield compared to primary cultures. However, the usefulness of these surrogate cell models is highly dependent on their ability to retain the phenotypic attributes of the parent cells. Keratins K14 and K5 are the hallmarks of undifferentiated, mitotically active basal keratinocytes. We observed occasional progressive loss of K14 expression in growing keratinocyte cell lines, with persistent retention of K5 and an epithelial phenotype, and investigated possible reasons for this. We show that K14 repression occurs by DNA promoter methylation of KRT14 gene and is compounded by histone deacetylation and by the presence of EGF. In vivo, keratinocytes shut down K14 synthesis as they commit to terminal differentiation and move from the basal to spinous layer, but by laser-capture microdissection of human epidermis we could detect no evidence of increased selective KRT14 methylation in this normal process. Loss of K14 expression suggests that epidermal identity of cultured keratinocytes can be compromised in certain tissue culture situations, possibly due to the immortalization method and persistent EGF supplementation.
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Affiliation(s)
- Rosita Koh
- Skin Research Institute of Singapore, Singapore, Singapore
| | - Ildiko Szeverenyi
- Institute of Medical Biology, Singapore, Singapore
- Hungarian University of Agriculture and Life Sciences, Georgikon Campus, Keszthely, Hungary
| | - Declan P Lunny
- Skin Research Institute of Singapore, Singapore, Singapore
| | - Goi Hui Eng
- Institute of Medical Biology, Singapore, Singapore
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3
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Todesca LM, Gerke M, Bulk EE, Bachmann M, Rudersdorf A, Antonuzzo L, Pillozzi S, Düfer M, Szabo I, Schwab A. Targeting K Ca3.1 channels to overcome erlotinib resistance in non-small cell lung cancer cells. Cell Death Discov 2024; 10:2. [PMID: 38177097 PMCID: PMC10767088 DOI: 10.1038/s41420-023-01776-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/08/2023] [Accepted: 12/12/2023] [Indexed: 01/06/2024] Open
Abstract
Almost all non-small cell lung cancer (NSCLC) patients initially responding to EGFR tyrosine kinase inhibitors (TKIs) develop acquired resistance. Since KCa3.1 channels, expressed in mitochondria and plasma membrane, regulate similar behavioral traits of NSCLC cells as EGFR, we hypothesized that their blockade contributes to overcoming EGFR-TKI resistance. Meta-analysis of microarray data revealed that KCa3.1 channel expression in erlotinib-resistant NSCLC cells correlates with that of genes of integrin and apoptosis pathways. Using erlotinib-sensitive and -resistant NSCLC cells we monitored the role of mitochondrial KCa3.1 channels in integrin signaling by studying cell-matrix adhesion with single-cell force spectroscopy. Apoptosis was quantified with fluorescence-based assays. The function of mitochondrial KCa3.1 channels in these processes was assessed by measuring the mitochondrial membrane potential and by quantifying ROS production. Functional assays were supplemented by biochemical analyses. We show that KCa3.1 channel inhibition with senicapoc in erlotinib-resistant NSCLC cells increases cell adhesion by increasing β1-integrin expression, that in turn depends on mitochondrial ROS release. Increased adhesion impairs migration of NSCLC cells in a 3D matrix. At the same time, the senicapoc-dependent ROS production induces cytochrome C release and triggers apoptosis of erlotinib-resistant NSCLC cells. Thus, KCa3.1 channel blockade overcomes EGFR-TKI resistance by inhibiting NSCLC motility and inducing apoptosis.
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Affiliation(s)
| | - Matthias Gerke
- Institute of Physiology II, University of Münster, Münster, Germany
| | - Emma Etmar Bulk
- Institute of Physiology II, University of Münster, Münster, Germany
| | | | - Alisa Rudersdorf
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Lorenzo Antonuzzo
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Serena Pillozzi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Martina Düfer
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padua, Italy
| | - Albrecht Schwab
- Institute of Physiology II, University of Münster, Münster, Germany
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4
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Chen T, Cai C, Wang L, Li S, Chen L. Farnesyl Transferase Inhibitor Lonafarnib Enhances α7nAChR Expression Through Inhibiting DNA Methylation of CHRNA7 and Increases α7nAChR Membrane Trafficking. Front Pharmacol 2021; 11:589780. [PMID: 33447242 PMCID: PMC7801264 DOI: 10.3389/fphar.2020.589780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/15/2020] [Indexed: 11/25/2022] Open
Abstract
Inhibition of Ras farnesylation in acute has been found to upregulate the α7 nicotinic acetylcholine receptor (α7nAChR) activity. This study was carried out to investigate the effect of chronic administration for 7 days of farnesyl transferase inhibitor lonafarnib (50 mg/kg, intraperitoneally injected) to male mice on the expression and activity of α7nAChR in hippocampal CA1 pyramidal cells. Herein, we show that lonafarnib dose dependently enhances the amplitude of ACh-evoked inward currents (IACh), owning to the increased α7nAChR expression and membrane trafficking. Lonafarnib inhibited phosphorylation of c-Jun and JNK, which was related to DNA methylation. In addition, reduced DNA methyltransferase 1 (DNMT1) expression was observed in lonafarnib-treated mice, which was reversed by JNK activator. Lonafarnib-upregulated expression of α7nAChR was mimicked by DNMT inhibitor, and repressed by JNK activator. However, only inhibited DNA methylation did not affect IACh, and the JNK activator partially decreased the lonafarnib-upregulated IACh. On the other hand, lonafarnib also increased the membrane expression of α7nAChR, which was partially inhibited by JNK activator or CaMKII inhibitor, without changes in the α7nAChR phosphorylation. CaMKII inhibitor had no effect on the expression of α7nAChR. Lonafarnib-enhanced spatial memory of mice was also partially blocked by JNK activator or CaMKII inhibitor. These results suggest that Ras inhibition increases α7nAChR expression through depressed DNA methylation of CHRNA7 via Ras-c-Jun-JNK pathway, increases the membrane expression of α7nAChR resulting in part from the enhanced CaMKII pathway and total expression of this receptor, and consequently enhances the spatial memory.
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Affiliation(s)
- Tingting Chen
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, China.,Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, China
| | - Chengyun Cai
- School of Life Science, Nantong University, Nantong, China
| | - Lifeng Wang
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, China.,Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, China
| | - Shixin Li
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, China.,Jiangsu Province Key Laboratory of Inflammation and Molecular Drug Target, Nantong, China
| | - Ling Chen
- Department of Physiology, Nanjing Medical University, Nanjing, China
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5
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Moradi Sarabi M, Mohammadrezaei Khorramabadi R, Zare Z, Eftekhar E. Polyunsaturated fatty acids and DNA methylation in colorectal cancer. World J Clin Cases 2019; 7:4172-4185. [PMID: 31911898 PMCID: PMC6940323 DOI: 10.12998/wjcc.v7.i24.4172] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/27/2019] [Accepted: 12/13/2019] [Indexed: 02/05/2023] Open
Abstract
Colorectal cancer (CRC) has been designated a major global problem, especially due to its high prevalence in developed countries. CRC mostly occurs sporadically (75%-80%), and only 20%-25% of patients have a family history. Several processes are involved in the development of CRC such as a combination of genetic and epigenetic alterations. Epigenetic changes, including DNA methylation play a vital role in the progression of CRC. Complex interactions between susceptibility genes and environmental factors, such as a diet and sedentary lifestyle, lead to the development of CRC. Clinical and experimental studies have confirmed the beneficial effects of dietary polyunsaturated fatty acids (PUFAs) in preventing CRC. From a mechanistic viewpoint, it has been suggested that PUFAs are pleiotropic agents that alter chromatin remodeling, membrane structure and downstream cell signaling. Moreover, PUFAs can alter the epigenome via modulation of DNA methylation. In this review, we summarize recent investigations linking PUFAs and DNA methylation-associated CRC risk.
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Affiliation(s)
- Mostafa Moradi Sarabi
- Department of Biochemistry and Genetics, School of Medicine, Lorestan University of Medical Sciences, Khorramabad 381251698, Iran
| | - Reza Mohammadrezaei Khorramabadi
- Department of Biochemistry and Genetics, School of Medicine, Lorestan University of Medical Sciences, Khorramabad 381251698, Iran
| | - Zohre Zare
- Department of Pharmaceutics, School of Pharmacy, Lorestan University of Medical Sciences, Khorramabad 381251698, Iran
| | - Ebrahim Eftekhar
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas 7919915519, Iran
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6
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Moradi Sarabi M, Zahedi SA, Pajouhi N, Khosravi P, Bagheri S, Ahmadvand H, Shahryarhesami S. The effects of dietary polyunsaturated fatty acids on miR-126 promoter DNA methylation status and VEGF protein expression in the colorectal cancer cells. GENES AND NUTRITION 2018; 13:32. [PMID: 30598703 PMCID: PMC6299631 DOI: 10.1186/s12263-018-0623-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 11/29/2018] [Indexed: 02/06/2023]
Abstract
Background There is increasing evidence indicating an aberrant expression of miRNAs in colorectal cancer (CRC) development. Growing evidence has suggested that polyunsaturated fatty acids (PUFAs) could modulate the remodeling of the epigenome. No study has yet been published to examine the direct effect of PUFA on the promoter methylation of miRNAs. This study aimed to examine the potential clinical application of PUFA on the promoter DNA methylation of miR-126 and its angiogenic target molecule (VEGF) in the CRC cells. Methods We investigated the direct effect of 100 μM EPA, DHA, and LA for 24 h on promoter methylation status of miR-126 in a panel of five CRC cell lines (HCT116, HT29/219, Caco2, SW742, and LS180) by methylation-specific PCR (MSP). We also quantified the miR-126 and VEGF transcript expression levels in five CRC cell lines affected by PUFA by real-time PCR. Moreover, we analyzed the protein expression level of VEGF, as a target of miR-126, by western blotting assay. Results MSP analysis showed extensive DNA methylation of the miR-126 promoter in all five CRC cell lines, and among all three PUFAs, only DHA completely demethylated the promoter of miR-126 in HCT116 and Caco2 cell lines. We found that only DHA significantly induces the expression level of miR-126 in HCT116 and Caco2 cell lines, respectively, by 20.1-fold and 1.68-fold (p < 0.05). Our finding indicates that the downregulation of VEGF protein level is also effectively observed only in DHA-treated HCT116 and Caco2 cells compared to control cells (p < 0.05). Conclusions Our results provide evidence that n-3 PUFAs are able to modulate cellular miR-126 DNA methylation and inhibit VEGF expression level in a cell-type specific manner in colorectal cancer cells. DHA always showed higher efficacy than EPA and LA in our experiment. Overall, our results suggest a potential clinical application of n-3 PUFAs as anti-angiogenic agents in CRC therapy.
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Affiliation(s)
- Mostafa Moradi Sarabi
- 1Department of Biochemistry and Genetics, Lorestan University of Medical Sciences, School of Medicine, Khorramabad, 381251698 Iran.,3Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Seyed Abdollah Zahedi
- 1Department of Biochemistry and Genetics, Lorestan University of Medical Sciences, School of Medicine, Khorramabad, 381251698 Iran
| | - Naser Pajouhi
- 2Department of Physiology, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran.,3Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Peyman Khosravi
- 1Department of Biochemistry and Genetics, Lorestan University of Medical Sciences, School of Medicine, Khorramabad, 381251698 Iran.,4Student Research Committee, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Shahrokh Bagheri
- 1Department of Biochemistry and Genetics, Lorestan University of Medical Sciences, School of Medicine, Khorramabad, 381251698 Iran
| | - Hassan Ahmadvand
- 1Department of Biochemistry and Genetics, Lorestan University of Medical Sciences, School of Medicine, Khorramabad, 381251698 Iran
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7
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Misregulation of DNA Methylation Regulators in Cancer. DNA AND HISTONE METHYLATION AS CANCER TARGETS 2017. [DOI: 10.1007/978-3-319-59786-7_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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8
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Balada E, Felip L, Ordi-Ros J, Vilardell-Tarrés M. DUSP23 is over-expressed and linked to the expression of DNMTs in CD4 + T cells from systemic lupus erythematosus patients. Clin Exp Immunol 2016; 187:242-250. [PMID: 27737517 DOI: 10.1111/cei.12883] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2016] [Indexed: 12/17/2022] Open
Abstract
We evaluated the transcriptional expression of dual-specificity protein phosphatase 23 (DUSP23) in CD4+ T cells from 30 systemic lupus erythematosus (SLE) patients and 30 healthy controls. DUSP23 mRNA levels were considerably higher in the patient group: 1490 ± 1713 versus 294·1 ± 204·2. No association was found between DUSP23 mRNA expression and the presence of typical serological and clinical parameters associated with SLE. Meaningful statistical values were obtained in the patient group between the levels of DUSP23 and integrin subunit alpha L (ITGAL), perforin 1 (PRF1) and CD40L. Similarly, transcript levels of different DNA methylation-related enzymes [DNA methylation-related enzymes (DNMT1, DNMT3A, DNMT3B, MBD2, and MBD4)] were also correlated positively with the expression of DUSP23. In an attempt to counteract the hypomethylation status of the promoters of certain genes known to be over-expressed in SLE, it is possible that DUSP23 acts as a negative regulatory mechanism which ultimately silences the transcription of these epigenetically regulated genes by triggering an increase in the expression of different DNMTs.
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Affiliation(s)
- E Balada
- Research Unit in Systemic Autoimmune Diseases, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - L Felip
- Research Unit in Systemic Autoimmune Diseases, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - J Ordi-Ros
- Research Unit in Systemic Autoimmune Diseases, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - M Vilardell-Tarrés
- Research Unit in Systemic Autoimmune Diseases, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
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9
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Liu F, Wang L, Perna F, Nimer SD. Beyond transcription factors: how oncogenic signalling reshapes the epigenetic landscape. Nat Rev Cancer 2016; 16:359-72. [PMID: 27220480 PMCID: PMC5548460 DOI: 10.1038/nrc.2016.41] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cancer, once thought to be caused largely by genetic alterations, is now considered to be a mixed genetic and epigenetic disease. The epigenetic landscape, which is dictated by covalent DNA and histone modifications, is profoundly altered in transformed cells. These abnormalities may arise from mutations in, or altered expression of, chromatin modifiers. Recent reports on the interplay between cellular signalling pathways and chromatin modifications add another layer of complexity to the already complex regulation of the epigenome. In this Review, we discuss these new studies and how the insights they provide can contribute to a better understanding of the molecular pathogenesis of neoplasia.
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Affiliation(s)
- Fan Liu
- Department of Biochemistry and Molecular Biology, University of Miami, Miller School of Medicine, Miami, FL 33136
- Sylvester Comprehensive Cancer Center, University of Miami, Miller School of Medicine, Miami, FL 33136
| | - Lan Wang
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Fabiana Perna
- Molecular Pharmacology and Chemistry Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Stephen D. Nimer
- Department of Biochemistry and Molecular Biology, University of Miami, Miller School of Medicine, Miami, FL 33136
- Sylvester Comprehensive Cancer Center, University of Miami, Miller School of Medicine, Miami, FL 33136
- Department of Internal Medicine, University of Miami, Miller School of Miami, FL33136
- Corresponding Author:
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10
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Cheishvili D, Boureau L, Szyf M. DNA demethylation and invasive cancer: implications for therapeutics. Br J Pharmacol 2015; 172:2705-15. [PMID: 25134627 DOI: 10.1111/bph.12885] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/01/2014] [Accepted: 08/13/2014] [Indexed: 02/06/2023] Open
Abstract
One of the hallmarks of cancer is aberrant DNA methylation, which is associated with abnormal gene expression. Both hypermethylation and silencing of tumour suppressor genes as well as hypomethylation and activation of prometastatic genes are characteristic of cancer cells. As DNA methylation is reversible, DNA methylation inhibitors were tested as anticancer drugs with the idea that such agents would demethylate and reactivate tumour suppressor genes. Two cytosine analogues, 5-azacytidine (Vidaza) and 5-aza-2'-deoxycytidine, were approved by the Food and Drug Administration as antitumour agents in 2004 and 2006 respectively. However, these agents might cause activation of a panel of prometastatic genes in addition to activating tumour suppressor genes, which might lead to increased metastasis. This poses the challenge of how to target tumour suppressor genes and block cancer growth with DNA-demethylating drugs while avoiding the activation of prometastatic genes and precluding the morbidity of cancer metastasis. This paper reviews current progress in using DNA methylation inhibitors in cancer therapy and the potential promise and challenges ahead.
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Affiliation(s)
- David Cheishvili
- Department of Pharmacology and Therapeutics, McGill University Medical School, Montreal, QC, Canada
| | - Lisa Boureau
- Department of Pharmacology and Therapeutics, McGill University Medical School, Montreal, QC, Canada.,Department of Physiology Medical Sciences, University of Toronto 1 King's College Circle Toronto, ON, Canada
| | - Moshe Szyf
- Department of Pharmacology and Therapeutics, McGill University Medical School, Montreal, QC, Canada.,Sackler Program for Epigenetics and Developmental Psychobiology, McGill University Medical School, Montreal, QC, Canada.,Canadian Institute for Advanced Research, Faculty of Medicine, University of Toronto 1 King's College Circle Toronto, ON, Canada
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11
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Xiao Y, Word B, Lyn-Cook L, Lyn-Cook B, Hammons G. Cigarette smoke condensate and individual constituents modulate DNA methyltransferase expression in human liver cells. SAGE Open Med 2015; 3:2050312115578317. [PMID: 26770776 PMCID: PMC4679232 DOI: 10.1177/2050312115578317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/03/2015] [Indexed: 01/02/2023] Open
Abstract
Objectives: Previous studies found higher expression levels of DNA methyltransferase 1 in liver samples from smokers compared to those from non-smokers. In contrast, expression levels of DNA methyltransferase 3a and DNA methyltransferase 3b were similar in smokers and non-smokers. This study extends these studies to establish a causal linkage to cigarette smoke exposure by examining whether DNA methyltransferase expression is modulated by cigarette smoke condensate. Methods: These experiments were conducted in an in vitro system using HepG2 human liver cells. The dose range of cigarette smoke condensate was 0.1–120 µg/mL. The duration of exposure was up to 72 h. Results: In a 24-h exposure, DNA methyltransferase 1 expression was found to increase significantly in a dose-dependent manner (greater than threefold at 100 µg/mL cigarette smoke condensate). Expression levels of DNA methyltransferase 3a and DNA methyltransferase 3b were, however, not affected under these conditions. The effect of two cigarette constituents, nicotine and cotinine, on DNA methyltransferase 1 expression was also examined. Nicotine exposure significantly increased DNA methyltransferase 1 expression in a dose-dependent manner (greater than twofold at 50 µM). However, under these conditions, cotinine did not increase DNA methyltransferase 1 expression. Conclusion: These results clearly provide additional support of the modulating effect of cigarette smoke on DNA methyltransferase 1 expression. Given the potential of alterations in DNA methyltransferase expression to affect cellular function, this pathway may play a critical role in cigarette smoke-induced toxicity.
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Affiliation(s)
- Yongmei Xiao
- National Center for Toxicological Research, Jefferson, AR, USA
| | - Beverly Word
- National Center for Toxicological Research, Jefferson, AR, USA
| | | | | | - George Hammons
- National Center for Toxicological Research, Jefferson, AR, USA
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12
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Janardhan SV, Marks R, Gajewski TF. Primary murine CD4+ T cells fail to acquire the ability to produce effector cytokines when active Ras is present during Th1/Th2 differentiation. PLoS One 2014; 9:e112831. [PMID: 25397617 PMCID: PMC4232516 DOI: 10.1371/journal.pone.0112831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 10/16/2014] [Indexed: 01/10/2023] Open
Abstract
Constitutive Ras signaling has been shown to augment IL-2 production, reverse anergy, and functionally replace many aspects of CD28 co-stimulation in CD4+ T cells. These data raise the possibility that introduction of active Ras into primary T cells might result in improved functionality in pathologic situations of T cell dysfunction, such as cancer or chronic viral infection. To test the biologic effects of active Ras in primary T cells, CD4+ T cells from Coxsackie-Adenovirus Receptor Transgenic mice were transduced with an adenovirus encoding active Ras. As expected, active Ras augmented IL-2 production in naive CD4+ T cells. However, when cells were cultured for 4 days under conditions to promote effector cell differentiation, active Ras inhibited the ability of CD4+ T cells to acquire a Th1 or Th2 effector cytokine profile. This differentiation defect was not due to deficient STAT4 or STAT6 activation by IL-12 or IL-4, respectively, nor was it associated with deficient induction of T-bet and GATA-3 expression. Impaired effector cytokine production in active Ras-transduced cells was associated with deficient demethylation of the IL-4 gene locus. Our results indicate that, despite augmenting acute activation of naïve T cells, constitutive Ras signaling inhibits the ability of CD4+ T cells to properly differentiate into Th1/Th2 effector cytokine-producing cells, in part by interfering with epigenetic modification of effector gene loci. Alternative strategies to potentiate Ras pathway signaling in T cells in a more regulated fashion should be considered as a therapeutic approach to improve immune responses in vivo.
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Affiliation(s)
- Sujit V. Janardhan
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Reinhard Marks
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
| | - Thomas F. Gajewski
- Department of Pathology, The University of Chicago, Chicago, Illinois, United States of America
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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13
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Dysregulated transcriptional and post-translational control of DNA methyltransferases in cancer. Cell Biosci 2014; 4:46. [PMID: 25949795 PMCID: PMC4422219 DOI: 10.1186/2045-3701-4-46] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/01/2014] [Indexed: 01/29/2023] Open
Abstract
Cancer is a leading cause of death worldwide. Aberrant promoter hypermethylation of CpG islands associated with tumor suppressor genes can lead to transcriptional silencing and result in tumorigenesis. DNA methyltransferases (DNMTs) are the enzymes responsible for DNA methylation and have been reported to be over-expressed in various cancers. This review highlights the current status of transcriptional and post-translational regulation of the DNMT expression and activity with a focus on dysregulation involved in tumorigenesis. The transcriptional up-regulation of DNMT gene expression can be induced by Ras-c-Jun signaling pathway, Sp1 and Sp3 zinc finger proteins and virus oncoproteins. Transcriptional repression on DNMT genes has also been reported for p53, RB and FOXO3a transcriptional regulators and corepressors. In addition, the low expressions of microRNAs 29 family, 143, 148a and 152 are associated with DNMTs overexpression in various cancers. Several important post-translational modifications including acetylation and phosphorylation have been reported to mediate protein stability and activity of the DNMTs especially DNMT1. In this review, we also discuss drugs targeting DNMT protein expression and activation for therapeutic strategy against cancer.
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14
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Subramaniam D, Thombre R, Dhar A, Anant S. DNA methyltransferases: a novel target for prevention and therapy. Front Oncol 2014; 4:80. [PMID: 24822169 PMCID: PMC4013461 DOI: 10.3389/fonc.2014.00080] [Citation(s) in RCA: 320] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 03/31/2014] [Indexed: 12/14/2022] Open
Abstract
Cancer is the second leading cause of death in US. Despite the emergence of new, targeted agents, and the use of various therapeutic combinations, none of the available treatment options are curative in patients with advanced cancer. Epigenetic alterations are increasingly recognized as valuable targets for the development of cancer therapies. DNA methylation at the 5-position of cytosine, catalyzed by DNA methyltransferases (DNMTs), is the predominant epigenetic modification in mammals. DNMT1, the major enzyme responsible for maintenance of the DNA methylation pattern is located at the replication fork and methylates newly biosynthesized DNA. DNMT2 or TRDMT1, the smallest mammalian DNMT is believed to participate in the recognition of DNA damage, DNA recombination, and mutation repair. It is composed solely of the C-terminal domain, and does not possess the regulatory N-terminal region. The levels of DNMTs, especially those of DNMT3B, DNMT3A, and DNMT3L, are often increased in various cancer tissues and cell lines, which may partially account for the hypermethylation of promoter CpG-rich regions of tumor suppressor genes in a variety of malignancies. Moreover, it has been shown to function in self-renewal and maintenance of colon cancer stem cells and need to be studied in several cancers. Inhibition of DNMTs has demonstrated reduction in tumor formation in part through the increased expression of tumor suppressor genes. Hence, DNMTs can potentially be used as anti-cancer targets. Dietary phytochemicals also inhibit DNMTs and cancer stem cells; this represents a promising approach for the prevention and treatment of many cancers.
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Affiliation(s)
- Dharmalingam Subramaniam
- Department of Molecular and Integrative Physiology, The University of Kansas Medical Center , Kansas City, KS , USA ; The University of Kansas Cancer Center , Kansas City, KS , USA
| | - Ravi Thombre
- Department of Molecular and Integrative Physiology, The University of Kansas Medical Center , Kansas City, KS , USA
| | - Animesh Dhar
- The University of Kansas Cancer Center , Kansas City, KS , USA ; Department of Cancer Biology, The University of Kansas Medical Center , Kansas City, KS , USA
| | - Shrikant Anant
- Department of Molecular and Integrative Physiology, The University of Kansas Medical Center , Kansas City, KS , USA ; The University of Kansas Cancer Center , Kansas City, KS , USA ; Department of Cancer Biology, The University of Kansas Medical Center , Kansas City, KS , USA
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Santos ES, Raez LE, DeCesare T, Singal R. DNA methylation: its role in lung carcinogenesis and therapeutic implications. Expert Rev Anticancer Ther 2014; 5:667-79. [PMID: 16111467 DOI: 10.1586/14737140.5.4.667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new era in the treatment of malignant diseases has been observed through the use of biologic agents targeting growth factor receptors, signaling pathways, gene mutations and others. The results have been impressive in some diseases and modest in others. The discovery of new targets has expanded our knowledge of different mechanisms in tumorigenesis. One of these mechanisms has been DNA methylation, which is an important gene transcription regulator. Although the role of methylation in lung carcinogenesis is not well understood, there is an enormous quantity of evolving data suggesting its critical role in lung cancer. In this review, the authors will discuss methylation in lung carcinogenesis and its possible clinical implications.
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Affiliation(s)
- Edgardo S Santos
- Division of Hematology-Oncology, Tulane University Health Sciences Center, 1430 Tulane Avenue, SL-78, New Orleans, LA 70112, USA.
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Abstract
SLC5A8 is a putative tumor suppressor that is inactivated in more than 10 different types of cancer, but neither the oncogenic signaling responsible for SLC5A8 inactivation nor the functional relevance of SLC5A8 loss to tumor growth has been elucidated. Here, we identify oncogenic HRAS (HRAS(G12V)) as a potent mediator of SLC5A8 silencing in human nontransformed normal mammary epithelial cell lines and in mouse mammary tumors through DNMT1. Further, we demonstrate that loss of Slc5a8 increases cancer-initiating stem cell formation and promotes mammary tumorigenesis and lung metastasis in an HRAS-driven murine model of mammary tumors. Mammary-gland-specific overexpression of Slc5a8 (mouse mammary tumor virus-Slc5a8 transgenic mice), as well as induction of endogenous Slc5a8 in mice with inhibitors of DNA methylation, protects against HRAS-driven mammary tumors. Collectively, our results provide the tumor-suppressive role of SLC5A8 and identify the oncogenic HRAS as a mediator of tumor-associated silencing of this tumor suppressor in mammary glands. These findings suggest that pharmacological approaches to reactivate SLC5A8 expression in tumor cells have potential as a novel therapeutic strategy for breast cancer treatment.
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Afshar Y, Hastings J, Roqueiro D, Jeong JW, Giudice LC, Fazleabas AT. Changes in eutopic endometrial gene expression during the progression of experimental endometriosis in the baboon, Papio anubis. Biol Reprod 2013; 88:44. [PMID: 23284138 DOI: 10.1095/biolreprod.112.104497] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Endometriosis is associated with aberrant gene expression in the eutopic endometrium of women with disease. To determine if the development of endometriotic lesions directly impacts eutopic endometrial gene expression, we sequentially analyzed the eutopic endometrium across the time course of disease progression in a baboon model of induced disease. Endometriosis was induced in baboons (n = 4) by intraperitoneal inoculation of autologous menstrual endometrium. Eutopic endometria were collected during the midsecretory phase (Days 9-11 postovulation) at 1, 3, 6-7, 10-12, and 15-16 mo after disease induction and compared with tissue from disease-free baboons. RNA was hybridized to Human Genome U133 Plus 2.0 Arrays, and data were extracted using Gene-Chip Operating Software. Subsequently, both Gene Set Enrichment Analysis and Ingenuity Pathways Analysis were used to find biological states that have a statistically significant enrichment concomitant with pairwise comparison of human endometriosis arrays. Within 1 mo of induction of the disease, 4331 genes were differentially expressed (P < 0.05). Hierarchical clustering revealed self-segregation into two groups-a) 1, 3, and 10-12 mo and b) 6-7 and 15-16 mo-together with controls. Clustering analysis at each stage of disease validated dysregulation of several signaling pathways, including Nodal-like receptor, EGF, ERK/MAPK, and PI3/AKT. Sequential analysis of the same animals during disease progression demonstrated an early disease insult and a transitory dominance of an estrogenic phenotype; however, as the disease progressed, a progesterone-resistant phenotype became evident. Furthermore, we demonstrate a 38.6% differential gene expression overlap with endometrial samples in the midsecretory phase from women with endometriosis, concomitant with similar dysregulation in human disease candidate genes Fos, Nodal, Suclg2, and Kras, among others. Molecular changes in the eutopic endometrium, associated with endometriosis, are directly impacted by endometriotic lesions, providing strong evidence that it is the disease rather than inherent defective endometrium that results in aberrant gene expression in the eutopic endometrium. Furthermore, this baboon model provides a powerful means whereby the early events associated with the pathology of disease and the resulting infertility may be elucidated.
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Affiliation(s)
- Yalda Afshar
- Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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Gorelik GJ, Yarlagadda S, Patel DR, Richardson BC. Protein kinase Cδ oxidation contributes to ERK inactivation in lupus T cells. ACTA ACUST UNITED AC 2012; 64:2964-74. [PMID: 22549474 DOI: 10.1002/art.34503] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE CD4+ T cells from patients with active lupus have impaired ERK pathway signaling that decreases DNA methyltransferase expression, resulting in DNA demethylation, overexpression of immune genes, and autoimmunity. The ERK pathway defect is due to impaired phosphorylation of T(505) in the protein kinase Cδ (PKCδ) activation loop. However, the mechanisms that prevent PKCδ T(505) phosphorylation in lupus T cells are unknown. Others have reported that oxidative modifications, and nitration in particular, of T cells as well as serum proteins correlate with lupus disease activity. We undertook this study to test our hypothesis that nitration inactivates PKCδ, contributing to impaired ERK pathway signaling in lupus T cells. METHODS CD4+ T cells were purified from lupus patients and controls and then stimulated with phorbol myristate acetate (PMA). Signaling protein levels, nitration, and phosphorylation were quantitated by immunoprecipitation and immunoblotting of T cell lysates. Transfections were performed by electroporation. RESULTS Treating CD4+ T cells with peroxynitrite nitrated PKCδ, preventing PKCδ T(505) phosphorylation and inhibiting ERK pathway signaling similar to that observed in lupus T cells. Patients with active lupus had higher nitrated T cell PKCδ levels than did controls, which correlated directly with disease activity, and antinitrotyrosine immunoprecipitations demonstrated that nitrated PKCδ, but not unmodified PKCδ, was refractory to PMA-stimulated T(505) phosphorylation, similar to PKCδ in peroxynitrite-treated cells. CONCLUSION Oxidative stress causes PKCδ nitration, which prevents its phosphorylation and contributes to the decreased ERK signaling in lupus T cells. These results identify PKCδ as a link between oxidative stress and the T cell epigenetic modifications in lupus.
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Christophi GP, Rong R, Holtzapple PG, Massa PT, Landas SK. Immune markers and differential signaling networks in ulcerative colitis and Crohn's disease. Inflamm Bowel Dis 2012; 18:2342-56. [PMID: 22467146 PMCID: PMC3407828 DOI: 10.1002/ibd.22957] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Accepted: 02/27/2012] [Indexed: 12/14/2022]
Abstract
BACKGROUND Cytokine signaling pathways play a central role in the pathogenesis of inflammatory bowel disease (IBD). Ulcerative colitis (UC) and Crohn's disease (CD) have unique as well as overlapping phenotypes, susceptibility genes, and gene expression profiles. This study aimed to delineate patterns within cytokine signaling pathways in colonic mucosa of UC and CD patients, explore molecular diagnostic markers, and identify novel immune mediators in IBD pathogenesis. METHODS We quantified 70 selected immune genes that are important in IBD signaling from formalin-fixed, paraffin-embedded (FFPE) colon biopsy samples from normal control subjects and UC and CD patients having either severe colitis or quiescent disease (n = 98 subjects). We utilized and validated a new modified real-time reverse-transcription polymerase chain reaction (RT-PCR) technique for gene quantification. RESULTS Expression levels of signaling molecules including IL-6/10/12/13/17/23/33, STAT1/3/6, T-bet, GATA3, Foxp3, SOCS1/3, and downstream inflammatory mediators such as chemokines CCL-2/11/17/20, oxidative stress inducers, proteases, and mucosal genes were differentially regulated between UC and CD and between active and quiescent disease. We also document the possible role of novel genes in IBD, including SHP-1, IRF-1,TARC, Eotaxin, NOX2, arginase I, and ADAM 8. CONCLUSIONS This comprehensive approach to quantifying gene expression provides insights into the pathogenesis of IBD by elucidating distinct immune signaling networks in CD and UC. Furthermore, this is the first study demonstrating that gene expression profiling in FFPE colon biopsies might be a practical and effective tool in the diagnosis and prognosis of IBD and may help identify molecular markers that can predict and monitor response to individualized therapeutic treatments.
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Affiliation(s)
- George P. Christophi
- Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse NY
,Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
,Corresponding Author: Mailing Address: Washington University School of Medicine Department of Internal Medicine, 660 S. Euclid Ave., Box 8121, St. Louis, MO 63110, , Tel: 314-956-9640
| | - Rong Rong
- Department of Pathology, SUNY Upstate Medical University, Syracuse NY
| | | | - Paul T. Massa
- Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse NY
| | - Steve K. Landas
- Department of Pathology, SUNY Upstate Medical University, Syracuse NY
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Abstract
Asthma is a complex genetic disease, which arises from the interaction of multiple genes and environmental stimuli. These influences are important to asthma pathogenesis. These can be mechanically explained by the Epigenetic phenomenon, which consists of the chromatin and its modifications, as well as a covalent modification of cytosines residing at the dinucleotide sequence CG in DNA by methylation. This reaction is catalyzed by a family of DNA methyltransferase enzyme (DNMTs). DNMT1 is one of them which maintained the methylation status during replication and also critical for the development, differentiation and regulation of Th1 and Th2 cells. Therefore we studied the DNMT1 mRNA expression profiling as well as CpG methylation status in promoter region. For these studies we developed asthma mouse model, and used Flow cytometer, qRT(2)-PCR, Methylation specific PCR, bisulfate conversion and BiQ analyzer. We found that DNMT1 expression level was low in all the tissues (lung, trachea and BALF cells) of asthmatic in comparison to normal mice. This was due to the methylation of regulatory sites of DNMT1 promoter region at cytosine residue. As the incidence of asthma is increasing globally and in world, this study assumes greater significance in designing and developing therapeutic means.
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Luo L, Chen S, Gong Q, Luo N, Lei Y, Guo J, He S. Hepatitis B virus X protein modulates remodelling of minichromosomes related to hepatitis B virus replication in HepG2 cells. Int J Mol Med 2012; 31:197-204. [PMID: 23128981 DOI: 10.3892/ijmm.2012.1165] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 08/14/2012] [Indexed: 11/05/2022] Open
Abstract
Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is organised into minichromosomes by histone and non-histone proteins. Remodelling of minichromosomes is crucial for the regulation of HBV replication, which is dependent on the presence of the hepatitis B virus X protein (HBx). However, the mechanisms of HBx-dependent HBV replication remain obscure. The objective of this study was to investigate the mechanism of HBx-dependent HBV replication through the pathway of chromatin remodelling. The role of HBx was investigated by transfecting human HepG2 cells with the linear full-length HBV genome (wild-type) or HBx-deficient mutant HBV DNA (HBx mutant). Our results showed that although the formation of cccDNA was not affected by HBx, HBV replication, transcription and antigen secretion were all significantly reduced, resulting from the absence of HBx. The acetylation, mono-methylation and phosphorylation of cccDNA-bound histone H3 were associated with HBV replication. In addition, the levels of cccDNA-bound methylated, phosphorylated and acetylated histone H3 decreased sharply in HBx mutant HBV DNA. HBx modulated not only the status of acetylation but also the methylation and phosphorylation of histone H3 bound to the cccDNA during HBV replication in HepG2 cells. These findings suggest that HBx plays an important role in modulating the remodelling of minichromosomes related to HBV replication and it may regulate viral replication through the pathway of chromatin remodelling.
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Affiliation(s)
- Li Luo
- Department of Gastroenterology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, PR China
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22
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Kar S, Deb M, Sengupta D, Shilpi A, Parbin S, Torrisani J, Pradhan S, Patra S. An insight into the various regulatory mechanisms modulating human DNA methyltransferase 1 stability and function. Epigenetics 2012; 7:994-1007. [PMID: 22894906 DOI: 10.4161/epi.21568] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
DNA methylation is one of the principal epigenetic signals that participate in cell specific gene expression in vertebrates. DNA methylation plays a quintessential role in the control of gene expression, cellular differentiation and development. It also plays a central role in the preservation of chromatin structure and chromosomal integrity, parental imprinting, X-chromosome inactivation, aging and carcinogenesis. The foremost contributor in the mammalian methylation scheme is DNMT1, a maintenance methyltransferase that faithfully copies the pre-existing methyl marks onto hemimethylated daughter strands during DNA replication to maintain the established methylation patterns across successive cell divisions. The ever-changing cellular physiology and the significant part that DNA methylation plays in genome regulation necessitate rigid management of this enzyme. In mammalian cells, a host of intrinsic and extrinsic mechanisms regulate the expression, activity and stability of DNMT1. Transcriptional regulation, post-transcriptional auto-inhibitory controls and post-translational modifications of the enzyme are responsible for the efficient inheritance of DNA methylation patterns. Also, a large number of intra- and intercellular signaling cascades and numerous interactions with other modulator molecules that affect the catalytic activity of the enzyme at multiple levels function as major checkpoints of the DNMT1 control system. An in-depth understanding of the DNMT1 enzyme, its targeting and function is crucial for comprehending how DNA methylation is coordinated with other critical developmental and physiological processes. This review aims to provide a comprehensive account of the various regulatory mechanisms and interactions of DNMT1 so as to elucidate its function at the molecular level and understand the dynamics of DNA methylation at the cellular level.
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Affiliation(s)
- Swayamsiddha Kar
- Epigenetics and Cancer Research Laboratory, Biochemistry and Molecular Biology Group, Department of Life Science, National Institute of Technology, Rourkela, India
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Particulate matter Air Pollution induces hypermethylation of the p16 promoter Via a mitochondrial ROS-JNK-DNMT1 pathway. Sci Rep 2012; 2:275. [PMID: 22355787 PMCID: PMC3281276 DOI: 10.1038/srep00275] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 01/20/2012] [Indexed: 01/03/2023] Open
Abstract
Exposure of human populations to chronically elevated levels of ambient particulate matter air pollution < 2.5 μm in diameter (PM2.5) has been associated with an increase in lung cancer incidence. Over 70% of lung cancer cell lines exhibit promoter methylation of the tumor suppressor p16, an epigenetic modification that reduces its expression. We exposed mice to concentrated ambient PM2.5 via inhalation, 8 hours daily for 3 weeks and exposed primary murine alveolar epithelial cells to daily doses of fine urban PM (5 µg/cm2). In both mice and alveolar epithelial cells, PM exposure increased ROS production, expression of the DNA methyltransferase 1 (DNMT1), and methylation of the p16 promoter. In alveolar epithelial cells, increased transcription of DNMT1 and methylation of the p16 promoter were inhibited by a mitochondrially targeted antioxidant and a JNK inhibitor. These findings provide a potential mechanism by which PM exposure increases the risk of lung cancer.
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Strickland FM, Hewagama A, Lu Q, Wu A, Hinderer R, Webb R, Johnson K, Sawalha AH, Delaney C, Yung R, Richardson BC. Environmental exposure, estrogen and two X chromosomes are required for disease development in an epigenetic model of lupus. J Autoimmun 2011; 38:J135-43. [PMID: 22142890 DOI: 10.1016/j.jaut.2011.11.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 11/03/2011] [Accepted: 11/08/2011] [Indexed: 10/14/2022]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease primarily afflicting women. The reason for the gender bias is unclear, but genetic susceptibility, estrogen and environmental agents appear to play significant roles in SLE pathogenesis. Environmental agents can contribute to lupus susceptibility through epigenetic mechanisms. We used (C57BL/6xSJL)F1 mice transgenic for a dominant-negative MEK (dnMEK) that was previously shown to be inducibly and selectively expressed in T cells. In this model, induction of the dnMEK by doxycycline treatment suppresses T cell ERK signaling, decreasing DNA-methyltransferase expression and resulting in DNA demethylation, overexpression of immune genes Itgal (CD11a) and Tnfsf7 (CD70), and anti-dsDNA antibody. To examine the role of gender and estrogen in this model, male and female transgenic mice were neutered and implanted with time-release pellets delivering placebo or estrogen. Doxycycline induced IgG anti-dsDNA antibodies in intact and neutered, placebo-treated control female but not male transgenic mice. Glomerular IgG deposits were also found in the kidneys of female but not male transgenic mice, and not in the absence of doxycycline. Estrogen enhanced anti-dsDNA IgG antibodies only in transgenic, ERK-impaired female mice. Decreased ERK activation also resulted in overexpression and demethylation of the X-linked methylation-sensitive gene CD40lg in female but not male mice, consistent with demethylation of the second X chromosome in the females. The results show that both estrogen and female gender contribute to the female predisposition in lupus susceptibility through hormonal and epigenetic X-chromosome effects and through suppression of ERK signaling by environmental agents.
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Affiliation(s)
- Faith M Strickland
- Department of Internal Medicine, Rheumatology Division, The University of Michigan, Ann Arbor, MI 48109-2200, USA.
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Hughes T, Sawalha AH. The role of epigenetic variation in the pathogenesis of systemic lupus erythematosus. Arthritis Res Ther 2011; 13:245. [PMID: 22044622 PMCID: PMC3308098 DOI: 10.1186/ar3484] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The focus of the present review is on the extent to which epigenetic alterations influence the development of systemic lupus erythematosus. Lupus is a systemic autoimmune disease characterized by the production of autoantibodies directed at nuclear self-antigens. A DNA methylation defect in CD4+ T cells has long been observed in idiopathic and drug-induced lupus. Recent studies utilizing high-throughput technologies have further characterized the nature of the DNA methylation defect in lupus CD4+ T cells. Emerging evidence in the literature is revealing an increasingly interconnected network of epigenetic dysregulation in lupus. Recent reports describe variable expression of a number of regulatory microRNAs in lupus CD4+ T cells, some of which govern the expression of DNA methyltransferase 1. While studies to date have revealed a significant role for epigenetic defects in the pathogenesis of lupus, the causal nature of epigenetic variation in lupus remains elusive. Future longitudinal epigenetic studies in lupus are therefore needed.
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Affiliation(s)
- Travis Hughes
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Amr H Sawalha
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- US Department of Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
- 825 NE 13th Street, MS#24, Oklahoma City, OK 73104, USA
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Diaz-Moralli S, Tarrado-Castellarnau M, Alenda C, Castells A, Cascante M. Transketolase-like 1 expression is modulated during colorectal cancer progression and metastasis formation. PLoS One 2011; 6:e25323. [PMID: 21980427 PMCID: PMC3181277 DOI: 10.1371/journal.pone.0025323] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 09/01/2011] [Indexed: 12/19/2022] Open
Abstract
Background Transketolase-like 1 (TKTL1) induces glucose degradation through anaerobic pathways, even in presence of oxygen, favoring the malignant aerobic glycolytic phenotype characteristic of tumor cells. As TKTL1 appears to be a valid biomarker for cancer prognosis, the aim of the current study was to correlate its expression with tumor stage, probability of tumor recurrence and survival, in a series of colorectal cancer patients. Methodolody/Principal Findings Tumor tissues from 63 patients diagnosed with colorectal cancer at different stages of progression were analyzed for TKTL1 by immunohistochemistry. Staining was quantified by computational image analysis, and correlations between enzyme expression, local growth, lymph-node involvement and metastasis were assessed. The highest values for TKTL1 expression were detected in the group of stage III tumors, which showed significant differences from the other groups (Kruskal-Wallis test, P = 0.000008). Deeper analyses of T, N and M classifications revealed a weak correlation between local tumor growth and enzyme expression (Mann-Whitney test, P = 0.029), a significant association of the enzyme expression with lymph-node involvement (Mann-Whitney test, P = 0.0014) and a significant decrease in TKTL1 expression associated with metastasis (Mann-Whitney test, P = 0.0004). Conclusions/Significance To our knowledge, few studies have explored the association between variations in TKTL1 expression in the primary tumor and metastasis formation. Here we report downregulation of enzyme expression when metastasis appears, and a correlation between enzyme expression and regional lymph-node involvement in colon cancer. This finding may improve our understanding of metastasis and lead to new and more efficient therapies against cancer.
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Affiliation(s)
- Santiago Diaz-Moralli
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Institut de Biomedicina at Universitat de Barcelona IBUB and IDIBAPS-Hospital Clinic, University of Barcelona, Barcelona, Spain
| | - Miriam Tarrado-Castellarnau
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Institut de Biomedicina at Universitat de Barcelona IBUB and IDIBAPS-Hospital Clinic, University of Barcelona, Barcelona, Spain
| | - Cristina Alenda
- Pathology Department, Hospital General Universitario de Alicante, Alicante, Spain
| | - Antoni Castells
- Gastroenterology Department, Hospital Clínic, IDIBAPS, CIBEREHD, University of Barcelona, Barcelona, Spain
| | - Marta Cascante
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Institut de Biomedicina at Universitat de Barcelona IBUB and IDIBAPS-Hospital Clinic, University of Barcelona, Barcelona, Spain
- * E-mail:
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Yue X, Yang F, Yang Y, Mu Y, Sun W, Li W, Xu D, Wu J, Zhu Y. Induction of cyclooxygenase-2 expression by hepatitis B virus depends on demethylation-associated recruitment of transcription factors to the promoter. Virol J 2011; 8:118. [PMID: 21401943 PMCID: PMC3066118 DOI: 10.1186/1743-422x-8-118] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 03/14/2011] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The hepatitis B virus (HBV) is a major etiological factor of inflammation and damage to the liver resulting in hepatocellular carcinoma. Transcription factors play important roles in the disordered gene expression and liver injury caused by HBV. However, the molecular mechanisms behind this observation have not been defined. RESULTS In this study, we observed that circulating prostaglandin (PGE) 2 synthesis was increased in patients with chronic hepatitis B infection, and detected elevated cyclooxygenase (COX)-2 expression in HBV- and HBx-expressing liver cells. Likewise, the association of HBx with C/EBPβ contributed to the induction of COX-2. The COX-2 promoter was hypomethylated in HBV-positive cells, and specific demethylation of CpG dinucleotides within each of the two NF-AT sites in the COX-2 promoter resulted in the increased binding affinity of NF-AT to the cognate sites in the promoter, followed by increased COX-2 expression and PGE2 accumulation. The DNA methylatransferase DNMT3B played a key role in the methylation of the COX-2 promoter, and its decreased binding to the promoter was responsible for the regional demethylation of CpG sites, and for the increased binding of transcription factors in HBV-positive cells. CONCLUSION Our results indicate that upregulation of COX-2 by HBV and HBx is mediated by both demethylation events and recruitment of multiple transcription factors binding to the promoter.
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Affiliation(s)
- Xin Yue
- State Key Laboratory of Virology and College of Life Sciences, Chinese-French Liver Disease Research Institute of Wuhan University (Zhongnan Hospital), Wuhan University, Wuhan 430072, PR China
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Kinney SRM, Pradhan S. Regulation of expression and activity of DNA (cytosine-5) methyltransferases in mammalian cells. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 101:311-33. [PMID: 21507356 DOI: 10.1016/b978-0-12-387685-0.00009-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Three active DNA (cytosine-5) methyltransferases (DNMTs) have been identified in mammalian cells, Dnmt1, Dnmt3a, and Dnmt3b. DNMT1 is primarily a maintenance methyltransferase, as it prefers to methylate hemimethylated DNA during DNA replication and in vitro. DNMT3A and DNMT3B are de novo methyltransferases and show similar activity on unmethylated and hemimethylated DNA. DNMT3L, which lacks the catalytic domain, binds to DNMT3A and DNMT3B variants and facilitates their chromatin targeting, presumably for de novo methylation. There are several mechanisms by which mammalian cells regulate DNMT levels, including varied transcriptional activation of the respective genes and posttranslational modifications of the enzymes that can affect catalytic activity, targeting, and enzyme degradation. In addition, binding of miRNAs or RNA-binding proteins can also alter the expression of DNMTs. These regulatory processes can be disrupted in disease or by environmental factors, resulting in altered DNMT expression and aberrant DNA methylation patterns.
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Li W, Sun W, Liu L, Yang F, Li Y, Chen Y, Fang J, Zhang W, Wu J, Zhu Y. IL-32: a host proinflammatory factor against influenza viral replication is upregulated by aberrant epigenetic modifications during influenza A virus infection. THE JOURNAL OF IMMUNOLOGY 2010; 185:5056-65. [PMID: 20889550 DOI: 10.4049/jimmunol.0902667] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Our previous studies with clinical data analysis have shown that the proinflammatory factor IL-32 is activated in response to influenza virus infection. However, little is known about how influenza virus induces IL-32 production, and the role of IL-32 in the host immune responses during viral infection remains unclear. In this study, we show that IL-32 production is stimulated by influenza A virus or dsRNA in human PBMCs from healthy volunteers. We demonstrate that the NF-κB and CREB pathways play key roles in the activation of IL-32 production in response to influenza virus infection in A549 human lung epithelial cells. We then show that aberrant epigenetic modifications in the IL32 promoter are important in the transcriptional regulation of IL-32 expression. Interestingly, one CpG demethylation within the CREB binding site increases the binding of CREB to the promoter, which is followed by IL32 transcriptional activation in influenza A virus-infected cells. Overexpression assays combined with RNA interference show that DNA methyltransferases DNMT1 and DNMT3b are critical for IL32 promoter methylation and gene silencing before viral infection. We have demonstrated the anti-influenza virus function of IL-32. Assays for each of the six IL-32 isoforms (α, β, γ, δ, ε, and ζ) during influenza virus infection indicated that all the isoforms have antiviral activity, with different inhibitory rates, and that the effect of IL-32γ is strongest. Our results indicate that the elevated IL-32 levels triggered by influenza virus infection in turn hamper viral replication.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
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30
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Thaler R, Karlic H, Spitzer S, Klaushofer K, Varga F. Extra-cellular matrix suppresses expression of the apoptosis mediator Fas by epigenetic DNA methylation. Apoptosis 2010; 15:728-37. [PMID: 20428952 DOI: 10.1007/s10495-010-0462-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The extracellular matrix (ECM) of bone consists mainly of collagen type I, which induces osteoblastic differentiation and prevents apoptosis. Fas induces apoptosis in cells improperly adhering to ECM. Recently, it was described that Fas expression is modulated by epigenetic DNA methylation. Mouse MC3T3-E1 pre-osteoblastic cells were cultured either on collagen coated or on uncoated culture dishes for control. mRNA was isolated and gene expression was analyzed by quantitative RT-PCR. Furthermore, we measured global and specific DNA methylation. Compared to controls, cells cultured on collagen-coated dishes increased the expression of Runx2 and OCN indicating differentiation of pre-osteoblastic cells. Additionally, collagen up-regulated cyclin-A2 and down-regulated Fas expression suggesting increased cell multiplication. Furthermore, the expression of Dnmt1 and Hells, key mediators of the DNA-methylation process, was increased. As a consequence, we demonstrate that global DNA methylation and specific methylation of the Fas promoter was higher in MC3T3-E1 cells cultured on collagen when compared to controls. Investigation of signal transduction pathways by mean of inhibitors suggests that focal adhesion kinase, MAP- and Jun-kinases and AP-1 are involved in this process. In summary, we demonstrate that ECM prevents activation of Fas by epigenetic DNA-methylation.
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Affiliation(s)
- Roman Thaler
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Center Meidling, Medical Department, Vienna, Austria
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31
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Abstract
Epigenetic mechanisms, such as DNA methylation and histone modifications, drive stable, clonally propagated changes in gene expression and can therefore serve as molecular mediators of pathway dysfunction in neoplasia. Myelodysplastic syndrome (MDS) is characterized by frequent epigenetic abnormalities, including the hypermethylation of genes that control proliferation, adhesion, and other characteristic features of this leukemia. Aberrant DNA hypermethylation is associated with a poor prognosis in MDS that can be accounted for by more rapid progression to acute myeloid leukemia. In turn, treatment with drugs that modify epigenetic pathways (DNA methylation and histone deacetylation inhibitors) induces durable remissions and prolongs life in MDS, offering some hope and direction in the future management of this deadly disease.
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Affiliation(s)
- Jean-Pierre Issa
- Department of Leukemia, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe, Houston, TX 77030, USA.
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32
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Pan W, Zhu S, Yuan M, Cui H, Wang L, Luo X, Li J, Zhou H, Tang Y, Shen N. MicroRNA-21 and microRNA-148a contribute to DNA hypomethylation in lupus CD4+ T cells by directly and indirectly targeting DNA methyltransferase 1. THE JOURNAL OF IMMUNOLOGY 2010; 184:6773-81. [PMID: 20483747 DOI: 10.4049/jimmunol.0904060] [Citation(s) in RCA: 409] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Systemic lupus erythematosus is a complex autoimmune disease caused by genetic and epigenetic alterations. DNA methylation abnormalities play an important role in systemic lupus erythematosus disease processes. MicroRNAs (miRNAs) have been implicated as fine-tuning regulators controlling diverse biological processes at the level of posttranscriptional repression. Dysregulation of miRNAs has been described in various disease states, including human lupus. Whereas previous studies have shown miRNAs can regulate DNA methylation by targeting the DNA methylation machinery, the role of miRNAs in aberrant CD4+ T cell DNA hypomethylation of lupus is unclear. In this study, by using high-throughput microRNA profiling, we identified that two miRNAs (miR-21 and miR-148a) overexpressed in CD4+ T cells from both patients with lupus and lupus-prone MRL/lpr mice, which promote cell hypomethylation by repressing DNA methyltransferase 1 (DNMT1) expression. This in turn leads to the overexpression of autoimmune-associated methylation-sensitive genes, such as CD70 and LFA-1, via promoter demethylation. Further experiments revealed that miR-21 indirectly downregulated DNMT1 expression by targeting an important autoimmune gene, RASGRP1, which mediated the Ras-MAPK pathway upstream of DNMT1; miR-148a directly downregulated DNMT1 expression by targeting the protein coding region of its transcript. Additionally, inhibition of miR-21 and miR-148a expression in CD4+ T cells from patients with lupus could increase DNMT1 expression and attenuate DNA hypomethylation. Together, our data demonstrated a critical functional link between miRNAs and the aberrant DNA hypomethylation in lupus CD4+ T cells and could help to develop new therapeutic approaches.
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Affiliation(s)
- Wen Pan
- Joint Molecular Rheumatology Laboratory, Institute of Health Sciences and Shanghai Renji Hospital, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiaotong University School of Medicine, Shanghai, China
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33
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Wild L, Funes JM, Boshoff C, Flanagan JM. In vitro transformation of mesenchymal stem cells induces gradual genomic hypomethylation. Carcinogenesis 2010; 31:1854-62. [PMID: 20466760 DOI: 10.1093/carcin/bgq080] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Genome-wide DNA hypomethylation was one of the first epigenetic alterations described in cancer cells. However, the cause of this hypomethylation is still poorly understood. We have previously developed a line of primary mesenchymal stem cells (MSC, the putative origin of various types of sarcoma) in which five oncogenic steps toward a fully transformed state are sequentially introduced including: human telomerase, inactivation of p53 and pRb tumor suppressor genes and activation of the oncogenes c-Myc and H-Ras. We hypothesized that DNA hypomethyation would occur during stepwise transformation of MSC and could be a model to investigate the mechanism of global hypomethylation in cancer. Here we show, firstly, that satellite-2 and long interspersed nuclear element 1 repetitive elements became hypomethylated (54 and 30% reduction, respectively) on the introduction of oncogenic H-Ras after the final step of transformation. Secondly, we observed hypomethylation only after 4 weeks in culture following the introduction of H-Ras, suggesting a gradual loss of methylation. Finally, using an inducible estrogen receptor-Ras fusion construct, we were able to transform MSC's in the absence of detectable hypomethylation, suggesting that it was not a requirement for transformation. These studies show that DNA hypomethylation can occur late during stepwise transformation, although in vitro transformation could also take place in the absence of hypomethylation. These data support the hypothesis that DNA hypomethylation occurs via a gradual mechanism and is not a requirement for transformation.
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Affiliation(s)
- Laurence Wild
- CRUK Viral Oncology Group, UCL Cancer Institute, University College London, 72 Huntley Street, WC1E 6BT, UK
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34
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Fan H, Wang L, Guo F, Wei S, Zhao R. Neonatal intramuscular injection of plasmid encoding glucagon-like peptide-1 affects anxiety behaviour and expression of the hippocampal glucocorticoid receptor in adolescent rats. J Biosci 2010; 35:63-71. [DOI: 10.1007/s12038-010-0008-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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35
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Abstract
Profound changes in the epigenetic landscape of cancer cells underlie the development of human malignancies. These changes include large-scale DNA methylation changes throughout the genome as well as alterations in the compendium of post-translational chromatin modifications. Epigenetic aberrations impact multiple steps during tumorigenesis, ultimately promoting the selection of neoplastic cells with increasing pathogenicity. Identification of these alterations for use as predictive and prognostic biomarkers has been a highly sought after goal. Recent advances in the field have not only greatly expanded our knowledge of the epigenetic changes driving neoplasia but also demonstrated their significant clinical utility as cancer biomarkers. These biomarkers have proved to be useful for identifying patients whose malignancies are sensitive to specific cytotoxic chemotherapies and may hold promise for predicting which patients will benefit from newer targeted agents directed at oncogenes. The recent application of global analysis strategies has further accelerated our understanding of the epigenome and promises to enhance the identification of epigenomic programs underlying cancer progression and treatment response.
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Affiliation(s)
- Timothy A Chan
- Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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36
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Chen Y, Gorelik GJ, Strickland FM, Richardson BC. Decreased ERK and JNK signaling contribute to gene overexpression in "senescent" CD4+CD28- T cells through epigenetic mechanisms. J Leukoc Biol 2009; 87:137-45. [PMID: 19843577 DOI: 10.1189/jlb.0809562] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
An inflammatory and cytotoxic CD4+CD28- T cell subset infiltrates atherosclerotic plaques and is implicated in plaque rupture and myocardial infarctions. This pathologic subset develops with replicative stress and is found in patients with chronic inflammatory diseases such as RA as well as with aging. CD4+CD28- cells overexpress genes normally suppressed by DNA methylation in CD4+CD28+ T cells, such as KIR, perforin, and CD70. How this subset over expresses methylation-sensitive genes is unknown. DNA methylation patterns are maintained in proliferating cells by Dnmts, which are up-regulated during mitosis by the ERK and JNK signaling pathways. We hypothesized that defects in these signaling pathways contribute to altered gene expression in human CD4+CD28- cells through effects on DNA methylation. We report that signaling through the ERK and JNK pathways is decreased in CD4+CD28- relative to CD4+CD28+ cells from the same individuals and that ERK and JNK pathway inhibition decreases Dnmt1 and -3a levels, which in turn, causes demethylation and overexpression of the TNFSF7 (CD70) gene. We also report that CD4+CD28- T cells overexpress PP5, a stress-induced inhibitor of the ERK and JNK signaling pathways that may contribute to the signaling defects. We conclude that decreased ERK and JNK signaling in the CD4+CD28- subset, arising with replicative stress, can lead to the overexpression of normally suppressed genes through effects on Dnmts and consequently, chromatin structure.
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Affiliation(s)
- Yingxuan Chen
- Department of Medicine, University of Michigan, Ann Arbor, MI 48109-2200, USA
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37
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Sers C, Kuner R, Falk CS, Lund P, Sueltmann H, Braun M, Buness A, Ruschhaupt M, Conrad J, Mang-Fatehi S, Stelniec I, Krapfenbauer U, Poustka A, Schäfer R. Down-regulation of HLA Class I and NKG2D ligands through a concerted action of MAPK and DNA methyltransferases in colorectal cancer cells. Int J Cancer 2009; 125:1626-39. [PMID: 19569244 DOI: 10.1002/ijc.24557] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Most malignant features of cancer cells are triggered by activated oncogenes and the loss of tumor suppressors due to mutation or epigenetic inactivation. It is still unclear, to what extend the escape of emerging cancer cells from recognition and elimination by the immune system is determined by similar mechanisms. We compared the transcriptomes of HCT116 colorectal cancer cells deficient in DNA methyltransferases (DNMTs) and of cells, in which the RAS pathway as the major growth-promoting signaling system is blocked by inhibition of MAPK. We identified the MHC Class I genes HLA-A1/A2 and the ULBP2 gene encoding 1 of the 8 known ligands of the activating NK receptor NKG2D among a cluster of immune genes up-regulated under the conditions of both DNMT-deficiency and MEK-inhibition. Bisulphite sequencing analyses of HCT116 with DNMT deficiency or after MEK-inhibition showed that de-methylation of the ULPB2 promoter correlated with its enhanced surface expression. The HLA-A promoters were not methylated indicating that components of the HLA assembly machinery were also suppressed in DNMT-deficient and MEK-inhibited cells. Increased HLA-A2 surface expression was correlated with enhanced recognition and lysis by A2-specific CTL. On the contrary, elevated ULBP2 expression was not reflected by enhanced recognition and lysis by NK cells. Cosuppression of HLA Class I and NKG2D ligands and genes encoding peptide transporters or proteasomal genes mediates a strong functional link between RAS activation, DNMT activity and disruption of the antigen presenting system controlling immune recognition in colorectal cancer cells.
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Affiliation(s)
- Christine Sers
- Institute of Pathology, Charité, Universitätsmedizin Berlin, Berlin, Germany.
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38
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Macrophages of multiple sclerosis patients display deficient SHP-1 expression and enhanced inflammatory phenotype. J Transl Med 2009; 89:742-59. [PMID: 19398961 PMCID: PMC2725397 DOI: 10.1038/labinvest.2009.32] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of proinflammatory cytokine signaling, TLR signaling, and inflammatory gene expression. Furthermore, mice genetically lacking SHP-1 (me/me) display a profound susceptibility to inflammatory CNS demyelination relative to wild-type mice. In particular, SHP-1 deficiency may act predominantly in inflammatory macrophages to increase CNS demyelination as SHP-1-deficient macrophages display coexpression of inflammatory effector molecules and increased demyelinating activity in me/me mice. Recently, we reported that PBMCs of multiple sclerosis (MS) patients have a deficiency in SHP-1 expression relative to normal control subjects indicating that SHP-1 deficiency may play a similar role in MS as to that seen in mice. Therefore, it became essential to examine the specific expression and function of SHP-1 in macrophages from MS patients. Herein, we document that macrophages of MS patients have deficient SHP-1 protein and mRNA expression relative to those of normal control subjects. To examine functional consequences of the lower SHP-1, the activation of STAT6, STAT1, and NF-kappaB was quantified and macrophages of MS patients showed increased activation of these transcription factors. In accordance with this observation, several STAT6-, STAT1-, and NF-kappaB-responsive genes that mediate inflammatory demyelination were increased in macrophages of MS patients following cytokine and TLR agonist stimulation. Supporting a direct role of SHP-1 deficiency in altered macrophage function, experimental depletion of SHP-1 in normal subject macrophages resulted in an increased STAT/NF-kappaB activation and increased inflammatory gene expression to levels seen in macrophages of MS patients. In conclusion, macrophages of MS patients display a deficiency of SHP-1 expression, heightened activation of STAT6, STAT1, and NF-kappaB and a corresponding inflammatory profile that may be important in controlling macrophage-mediated demyelination in MS.
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39
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Butler JS, Palam LR, Tate CM, Sanford JR, Wek RC, Skalnik DG. DNA Methyltransferase protein synthesis is reduced in CXXC finger protein 1-deficient embryonic stem cells. DNA Cell Biol 2009; 28:223-31. [PMID: 19388845 DOI: 10.1089/dna.2009.0854] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
CXXC finger protein 1 (CFP1) binds to unmethylated CpG dinucleotides and is required for embryogenesis. CFP1 is also a component of the Setd1A and Setd1B histone H3K4 methyltransferase complexes. Murine embryonic stem (ES) cells lacking CFP1 fail to differentiate, and exhibit a 70% reduction in global genomic cytosine methylation and a 50% reduction in DNA methyltransferase (DNMT1) protein and activity. This study investigated the underlying mechanism for reduced DNMT1 expression in CFP1-deficient ES cells. DNMT1 transcript levels were significantly elevated in ES cells lacking CFP1, despite the observed reduction in DNMT1 protein levels. To address the posttranscriptional mechanisms by which CFP1 regulates DNMT1 protein activity, pulse/chase analyses were carried out, demonstrating a modest reduction in DNMT1 protein half-life in CFP1-deficient ES cells. Additionally, global protein synthesis was decreased in ES cells lacking CFP1, contributing to a reduction in the synthesis of DNMT1 protein. ES cells lacking CFP1 were found to contain elevated levels of phosphorylated eIF2alpha, and an accompanying reduction in translation initiation as revealed by a lower level of polyribosomes. These results reveal a novel role for CFP1 in the regulation of translation initiation, and indicate that loss of CFP1 function leads to decreased DNMT1 protein synthesis and half-life.
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Affiliation(s)
- Jill S Butler
- Section of Pediatric Hematology/Oncology, Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indianapolis, Indiana, USA
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40
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Liu Y, Chen Y, Richardson B. Decreased DNA methyltransferase levels contribute to abnormal gene expression in "senescent" CD4(+)CD28(-) T cells. Clin Immunol 2009; 132:257-65. [PMID: 19394279 DOI: 10.1016/j.clim.2009.03.529] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 03/20/2009] [Accepted: 03/25/2009] [Indexed: 12/29/2022]
Abstract
A senescent CD4(+)CD28(-) T cell subset develops with aging and in chronic inflammatory diseases like rheumatoid arthritis, and is implicated in plaque rupture and myocardial infarctions. This subset is pro-inflammatory, cytotoxic for endothelial cells, and aberrantly expresses genes like CD70, perforin and killer cell immunoglobulin-like receptor (KIR) genes. Why CD4(+)CD28(-) cells overexpress these genes is unclear. We found that the CD70, perforin and KIR2DL4 promoters are demethylated in CD4(+)CD28(-) T cells, and that DNA methyltransferase 1 (Dnmt1) and Dnmt3a levels are decreased in this subset. siRNA "knockdown" of Dnmt1, but not Dnmt3a, in CD4(+)CD28(+) T cells caused similar demethylation and overexpression of KIR2DL4, perforin and CD70, while simultaneous knockdown of Dnmt1 and Dnmt3a caused greater demethylation and overexpression of these genes than Dnmt1 alone. We conclude that decreased Dnmt1 and Dnmt3a cause demethylation and overexpression of these and perhaps other genes in CD4(+)CD28(-) cells, potentially contributing to pathologic functions by this subset.
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Affiliation(s)
- Ying Liu
- Department of Medicine, University of Michigan, USA
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41
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Wang X, Sun DF, Lu R, Chen ZF, Chen YX, Fang JY. RAF may induce cell proliferation through hypermethylation of tumor suppressor gene promoter in gastric epithelial cells. Cancer Sci 2009; 100:117-25. [PMID: 19037990 PMCID: PMC11158421 DOI: 10.1111/j.1349-7006.2008.01017.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) is critical in human malignancies. It remained to be established whether DNA methyltransferases (Dnmt) and proliferating cell nuclear antigen (PCNA) involved in DNA methylation during RAF-transformed cell proliferation. The plasmid of constitutively active RAF was used to transfect gastric cell GES-1 and cancer cell AGS. RAF promoted cell proliferation, growth in soft agar and induced cell cycle progress faster than empty plasmid by accelerating G1/S transition in both cell lines, a massive induction of cyclin D1 and PCNA expression was observed, along with reduced expression of p16INK4A, p21WAF1 and p27KIP1. Methylation-specific polymerase chain reaction and bisulfite sequencing showed that the promoter of p16INK4A was methylated in RAF-transformed cells, treatment with 5-aza-dC or PD98059 restored the expression of p16INK4A, increased p21WAF1 and p27KIP1 partially, associated with upregulation of the activity of Dnmt in RAF-transformed cell GES-1, and also decreased the hypermethylation status of p16INK4A, but not all CpG islands of p21WAF1 and p27KIP1. These data suggest that RAF may induce cell proliferation through hypermethylation of tumor suppressor gene p16INK4A, while the epigenetic inactivation of p21WAF1 and p27KIP1 may be not a key factor in RAF-transformed cells.
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Affiliation(s)
- Xia Wang
- Shanghai Jiao-Tong University School of Medicine Renji Hospital, Shanghai Institute of Digestive Disease, Shanghai, China
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42
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Patra SK, Szyf M. DNA methylation-mediated nucleosome dynamics and oncogenic Ras signaling: insights from FAS, FAS ligand and RASSF1A. FEBS J 2008; 275:5217-35. [PMID: 18803665 DOI: 10.1111/j.1742-4658.2008.06658.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cytosine methylation at the 5-carbon position is the only known stable base modification found in the mammalian genome. The organization and modification of chromatin is a key factor in programming gene expression patterns. Recent findings suggest that DNA methylation at the junction of transcription initiation and elongation plays a critical role in suppression of transcription. This effect is mechanistically mediated by the state of chromatin modification. DNA methylation attracts binding of methyl-CpG-binding domain proteins that trigger repression of transcription, whereas DNA demethylation facilitates transcription activation. Understanding the rules that guide differential gene expression, as well as transcription dynamics and transcript abundance, has proven to be a taxing problem for molecular biologists and oncologists alike. The use of novel molecular modeling methods is providing exciting insights into the challenging problem of how methylation mediates chromatin dynamics. New data implicate lipid rafts as the coordinators of signals emanating from the cell membrane and are converging on the mechanisms linking DNA methylation and chromatin dynamics. This review focuses on some of these recent advances and uses lipid-raft-facilitated Ras signaling as a paradigm for understanding DNA methylation, chromatin dynamics and apoptosis.
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43
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Xiao Y, Word B, Starlard-Davenport A, Haefele A, Lyn-Cook BD, Hammons G. Age and gender affect DNMT3a and DNMT3b expression in human liver. Cell Biol Toxicol 2008; 24:265-72. [PMID: 17929180 DOI: 10.1007/s10565-007-9035-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 09/03/2007] [Indexed: 12/31/2022]
Abstract
DNA methylation is catalyzed by a family of DNA methyltransferases (DNMTs) including the maintenance enzyme DNMT 1 and de novo methyltransferases DNMT 3a and DNMT 3b. Elevated levels of DNMTs have been found in cancer cells and in several types of human tumors. A polymorphism found in DNMT3b has been associated with increased risk for several cancers. The factors influencing DNMT expression in human tissues have not been clearly determined. he present study examined TDNMT3a and DNMT3b levels in human liver tissue samples and compared the effect of ageing, cigarette smoking, and gender. DNMT3a and DNMT3b expression levels in the samples from older individuals (56-78 years, n = 28) were both significantly higher than those of the younger group (16-48 years, n = 27) (73.2 +/- 3.4 vs 8.3 +/- 2.8 and 56.1 +/- 1.9 vs 17.5 +/- 5.7, respectively; p < 0.05). Levels of DNMT3b in females were significantly higher than those in males (75.4 +/- 2.2 vs 16.3 +/- 4.7; p < 0.05); however, DNMT3a levels were similar for females and males (52.7 +/- 2.7 vs 48.4 +/- 2.0). Expression levels of DNMT3a and DNMT3b were similar in smokers and nonsmokers (58.1 +/- 3.5 vs 60.8 +/- 3.1 and 54.5 +/- 2.3 vs 48.3 +/- 1.8, respectively). Genotyping for DNMT3b (C-->T) variant in this sample pool showed a frequency distribution of CC (41%), CT (50%), and TT (9%). The findings from this study suggest that ageing and gender may be important factors influencing DNA methylation status.
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Affiliation(s)
- Yongmei Xiao
- Division of Personalized Nutrition and Medicine, National Center for Toxicological Research, Jefferson, AR 72079, USA
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44
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Kirk Field A, Goodchild J. Section Review: Biologicals & Immunologicals: Antisense oligonucleotides: Rational drug design for genetic pharmacology. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.4.9.799] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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45
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Christophi GP, Hudson CA, Gruber RC, Christophi CP, Mihai C, Mejico LJ, Jubelt B, Massa PT. SHP-1 deficiency and increased inflammatory gene expression in PBMCs of multiple sclerosis patients. J Transl Med 2008; 88:243-55. [PMID: 18209728 PMCID: PMC2883308 DOI: 10.1038/labinvest.3700720] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of cytokine signaling, inflammatory gene expression, and demyelination in central nervous system. The present study investigates a possible similar role for SHP-1 in the human disease multiple sclerosis (MS). The levels of SHP-1 protein and mRNA in PBMCs of MS patients were significantly lower compared to normal subjects. Moreover, promoter II transcripts, expressed from one of two known promoters, were selectively deficient in MS patients. To examine functional consequences of the lower SHP-1 in PBMCs of MS patients, we measured the intracellular levels of phosphorylated STAT6 (pSTAT6). As expected, MS patients had significantly higher levels of pSTAT6. Accordingly, siRNA to SHP-1 effectively increased the levels of pSTAT6 in PBMCs of controls to levels equal to MS patients. Additionally, transduction of PBMCs with a lentiviral vector expressing SHP-1 lowered pSTAT6 levels. Finally, multiple STAT6-responsive inflammatory genes were increased in PBMCs of MS patients relative to PBMCs of normal subjects. Thus, PBMCs of MS patients display a stable deficiency of SHP-1 expression, heightened STAT6 phosphorylation, and an enhanced state of activation relevant to the mechanisms of inflammatory demyelination.
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Affiliation(s)
- George P Christophi
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
,Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Chad A Hudson
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
,Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Ross C Gruber
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
| | | | - Cornelia Mihai
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Luis J Mejico
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Burk Jubelt
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
,Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Paul T Massa
- Department of Neurology, SUNY Upstate Medical University, Syracuse, NY, USA
,Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, USA
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46
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Patra SK. Ras regulation of DNA-methylation and cancer. Exp Cell Res 2008; 314:1193-201. [PMID: 18282569 DOI: 10.1016/j.yexcr.2008.01.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 01/13/2008] [Accepted: 01/16/2008] [Indexed: 01/14/2023]
Abstract
Genome wide hypomethylation and regional hypermethylation of cancer cells and tissues remain a paradox, though it has received a convincing confirmation that epigenetic switching systems, including DNA-methylation represent a fundamental regulatory mechanism that has an impact on genome maintenance and gene transcription. Methylated cytosine residues of vertebrate DNA are transmitted by clonal inheritance through the strong preference of DNA methyltransferase, DNMT1, for hemimethylated-DNA. Maintenance of methylation patterns is necessary for normal development of mice, and aberrant methylation patterns are associated with many human tumours. DNMT1 interacts with many proteins during cell cycle progression, including PCNA, p53, EZH2 and HP1. Ras family of GTPases promotes cell proliferation by its oncogenic nature, which transmits signals by multiple pathways in both lipid raft dependent and independent fashion. DNA-methylation-mediated repression of DNA-repair protein O6-methylguanine DNA methyltransferase (MGMT) gene and increased rate of K-Ras mutation at codon for amino acids 12 and 13 have been correlated with a secondary role for Ras-effector homologues (RASSFs) in tumourigenesis. Lines of evidence suggest that DNA-methylation associated repression of tumour suppressors and apoptotic genes and ceaseless proliferation of tumour cells are regulated in part by Ras-signaling. Control of Ras GTPase signaling might reduce the aberrant methylation and accordingly may reduce the risk of cancer development.
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Affiliation(s)
- Samir Kumar Patra
- Cancer Epigenetics Research, Kalyani (B-7/183), Nadia, West Bengal, India.
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Gorelik G, Fang JY, Wu A, Sawalha AH, Richardson B. Impaired T cell protein kinase C delta activation decreases ERK pathway signaling in idiopathic and hydralazine-induced lupus. THE JOURNAL OF IMMUNOLOGY 2007; 179:5553-63. [PMID: 17911642 DOI: 10.4049/jimmunol.179.8.5553] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
T cells from patients with lupus or treated with the lupus-inducing drug hydralazine have defective ERK phosphorylation. The reason for the impaired signal transduction is unknown but important to elucidate, because decreased T cell ERK pathway signaling causes a lupus-like disease in animal models by decreasing DNA methyltransferase expression, leading to DNA hypomethylation and overexpression of methylation-sensitive genes with subsequent autoreactivity and autoimmunity. We therefore analyzed the PMA stimulated ERK pathway phosphorylation cascade in CD4(+) T cells from patients with lupus and in hydralazine-treated cells. The defect in these cells localized to protein kinase C (PKC)delta. Pharmacologic inhibition of PKCdelta or transfection with a dominant negative PKCdelta mutant caused demethylation of the TNFSF7 (CD70) promoter and CD70 overexpression similar to lupus and hydralazine-treated T cells. These results suggest that defective T cell PKCdelta activation may contribute to the development of idiopathic and hydralazine-induced lupus through effects on T cell DNA methylation.
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Affiliation(s)
- Gabriela Gorelik
- Department of Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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Promoter methylation of RASSF1A and DAPK and mutations of K-ras, p53, and EGFR in lung tumors from smokers and never-smokers. BMC Cancer 2007; 7:74. [PMID: 17477876 PMCID: PMC1877812 DOI: 10.1186/1471-2407-7-74] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2007] [Accepted: 05/03/2007] [Indexed: 01/02/2023] Open
Abstract
Background Epidemiological studies indicate that some characteristics of lung cancer among never-smokers significantly differ from those of smokers. Aberrant promoter methylation and mutations in some oncogenes and tumor suppressor genes are frequent in lung tumors from smokers but rare in those from never-smokers. In this study, we analyzed promoter methylation in the ras-association domain isoform A (RASSF1A) and the death-associated protein kinase (DAPK) genes in lung tumors from patients with primarily non-small cell lung cancer (NSCLC) from the Western Pennsylvania region. We compare the results with the smoking status of the patients and the mutation status of the K-ras, p53, and EGFR genes determined previously on these same lung tumors. Methods Promoter methylation of the RASSF1A and DAPK genes was analyzed by using a modified two-stage methylation-specific PCR. Data on mutations of K-ras, p53, and EGFR were obtained from our previous studies. Results The RASSF1A gene promoter methylation was found in tumors from 46.7% (57/122) of the patients and was not significantly different between smokers and never-smokers, but was associated significantly in multiple variable analysis with tumor histology (p = 0.031) and marginally with tumor stage (p = 0.063). The DAPK gene promoter methylation frequency in these tumors was 32.8% (40/122) and did not differ according to the patients' smoking status, tumor histology, or tumor stage. Multivariate analysis adjusted for age, gender, smoking status, tumor histology and stage showed that the frequency of promoter methylation of the RASSF1A or DAPK genes did not correlate with the frequency of mutations of the K-ras, p53, and EGFR gene. Conclusion Our results showed that RASSF1A and DAPK genes' promoter methylation occurred frequently in lung tumors, although the prevalence of this alteration in these genes was not associated with the smoking status of the patients or the occurrence of mutations in the K-ras, p53 and EGFR genes, suggesting each of these events may represent independent event in non-small lung tumorigenesis.
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Park IY, Sohn BH, Yu E, Suh DJ, Chung YH, Lee JH, Surzycki SJ, Lee YI. Aberrant epigenetic modifications in hepatocarcinogenesis induced by hepatitis B virus X protein. Gastroenterology 2007; 132:1476-94. [PMID: 17408664 DOI: 10.1053/j.gastro.2007.01.034] [Citation(s) in RCA: 227] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 12/14/2006] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS The involvement of the hepatitis B virus X (HBx) protein in epigenetic modifications during hepatocarcinogenesis has not been previously characterized. The aim of the present study was to identify the involvement of HBx in regional hypermethylation and global hypomethylation during the formation of hepatocellular carcinoma (HCC). METHODS Liver cell lines were transiently or stably transfected with an HBx-expressing vector. DNA methyltransferase (DNMT) promoter activity changes were examined by luciferase assay and chromatin immunoprecipitation. The methylation status of insulin-like growth factor binding protein-3 was examined by methyl-specific polymerase chain reaction and bisulfite sequencing. Global DNA methylation levels were examined using 5-methylcytosine dot blot and methylation-sensitive Southern blot analysis. HBx-mediated DNA methylation abnormalities were confirmed in patient HCC samples using methyl-specific polymerase chain reaction and 5-methylcytosine dot blot analysis. RESULTS HBx expression increased total DNMT activities by up-regulation of DNMT1, DNMT3A1, and DNMT3A2 and selectively promoted regional hypermethylation of specific tumor suppressor genes. HBx specifically repressed insulin-like growth factor-3 expression through de novo methylation via DNMT3A1 and DNMT3A2 and by inhibiting SP1 binding via recruiting methyl CpG binding protein 2 to the newly methylated SP1 binding element. HBx also induced global hypomethylation of satellite 2 repeat sequences by down-regulating DNMT3B. The prevalence of these specific methylation abnormalities by HBx was significantly correlated with HBx expression in HBV-infected HCC patients. CONCLUSIONS Targeted deregulation of DNMTs by HBx promotes both specific regional hypermethylation and global hypomethylation. These epigenetic modulations by HBx may suggest a mechanism for epigenetic tumorigenesis during HBV-mediated hepatocarcinogenesis.
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Affiliation(s)
- In Young Park
- Liver Cell Signal Transduction Laboratory, Molecular Cancer Research Center, KRIBB, Daejeon, Korea
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Atkinson SP, Keith WN. Epigenetic control of cellular senescence in disease: opportunities for therapeutic intervention. Expert Rev Mol Med 2007; 9:1-26. [PMID: 17352843 DOI: 10.1017/s1462399407000269] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Understanding how senescence is established and maintained is an important area of study both for normal cell physiology and in tumourigenesis. Modifications to N-terminal tails of histone proteins, which can lead to chromatin remodelling, appear to be key to the regulation of the senescence phenotype. Epigenetic mechanisms such as modification of histone proteins have been shown to be sufficient to regulate gene expression levels and specific gene promoters can become epigenetically altered at senescence. This suggests that epigenetic mechanisms are important in senescence and further suggests epigenetic deregulation could play an important role in the bypass of senescence and the acquisition of a tumourigenic phenotype. Tumour suppressor proteins and cellular senescence are intimately linked and such proteins are now known to regulate gene expression through chromatin remodelling, again suggesting a link between chromatin modification and cellular senescence. Telomere dynamics and the expression of the telomerase genes are also both implicitly linked to senescence and tumourigenesis, and epigenetic deregulation of the telomerase gene promoters has been identified as a possible mechanism for the activation of telomere maintenance mechanisms in cancer. Recent studies have also suggested that epigenetic deregulation in stem cells could play an important role in carcinogenesis, and new models have been suggested for the attainment of tumourigenesis and bypass of senescence. Overall, proper regulation of the chromatin environment is suggested to have an important role in the senescence pathway, such that its deregulation could lead to tumourigenesis.
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Affiliation(s)
- Stuart P Atkinson
- Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Bearsden, Glasgow, G61 1BD, UK
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