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Papakonstantinou E, Pappa I, Androutsopoulos G, Adonakis G, Maroulis I, Tzelepi V. Comprehensive Analysis of DNA Methyltransferases Expression in Primary and Relapsed Ovarian Carcinoma. Cancers (Basel) 2023; 15:4950. [PMID: 37894317 PMCID: PMC10605797 DOI: 10.3390/cancers15204950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/21/2023] [Accepted: 10/02/2023] [Indexed: 10/29/2023] Open
Abstract
BACKGROUND Despite recent advances in epithelial ovarian carcinoma (EOC) treatment, its recurrence and mortality rates have not improved significantly. DNA hypermethylation has generally been associated with an ominous prognosis and chemotherapy resistance, but the role of DNA methyltransferases (DNMTs) in EOC remains to be investigated. METHODS In the current study, we systematically retrieved gene expression data from patients with EOC and studied the immunohistochemical expression of DNMTs in 108 primary and 26 relapsed tumors. RESULTS Our results showed that the DNMT1, DNMT3A, DNMT3B and DNMT3L RNA levels were higher and the DNMT2 level was lower in tumors compared to non-neoplastic tissue, and DNMT3A and DNMT2 expression decreased from Stage-II to Stage-IV carcinomas. The proteomic data also suggested that the DNMT1 and DNMT3A levels were increased in the tumors. Similarly, the DNMT1, DNMT3A and DNMT3L protein levels were overexpressed and DNMT2 expression was reduced in high-grade carcinomas compared to non-neoplastic tissue and low-grade tumors. Moreover, DNMT1 and DNMT3L were increased in relapsed tumors compared to their primaries. The DNMT3A, DNMT1 and DNMT3B mRNA levels were correlated with overall survival. CONCLUSIONS Our study demonstrates that DNMT1 and DNMT3L are upregulated in primary high-grade EOC and further increase in relapses, whereas DNMT3A is upregulated only in the earlier stages of cancer progression. DNMT2 downregulation highlights the presumed tumor-suppressor activity of this gene in ovarian carcinoma.
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Affiliation(s)
- Efthymia Papakonstantinou
- Department of Obstetrics and Gynecology, School of Medicine, University of Patras, 26504 Patras, Greece; (E.P.); (G.A.)
| | - Ioanna Pappa
- Multidimensional Data Analysis and Knowledge Management Laboratory, Computer Engineering and Informatics Department, School of Engineering, University of Patras, 26504 Patras, Greece;
| | - Georgios Androutsopoulos
- Gynecological Oncology Unit, Department of Obstetrics and Gynecology, Medical School, University of Patras, 26504 Patras, Greece;
| | - Georgios Adonakis
- Department of Obstetrics and Gynecology, School of Medicine, University of Patras, 26504 Patras, Greece; (E.P.); (G.A.)
| | - Ioannis Maroulis
- Department of General Surgery, School of Medicine, University of Patras, 26504 Patras, Greece;
| | - Vasiliki Tzelepi
- Department of Pathology, School of Medicine, University of Patras, 26504 Patras, Greece
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2
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Seo E, Jee B, Chung JH, Song W, Sung HH, Jeon HG, Jeong BC, Seo SI, Jeon SS, Lee HM, Kang M. Repression of SLC22A3 by the AR-V7/YAP1/TAZ axis in enzalutamide-resistant castration-resistant prostate cancer. FEBS J 2023; 290:1645-1662. [PMID: 36254631 DOI: 10.1111/febs.16657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 08/11/2022] [Accepted: 10/17/2022] [Indexed: 03/18/2023]
Abstract
Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive and fatal disease, with most patients succumbing within 1-2 years despite undergoing multiple treatments. Androgen-receptor (AR) inhibitors, including enzalutamide (ENZ), are used for the treatment of mCRPC; however, most patients develop resistance to ENZ. Herein, we propose that the repression of SLC22A3 by AR-V7/YAP1/TAZ conferred ENZ resistance in mCRPC. SLC22A3 expression is specifically downregulated in the ENZ-resistant C4-2B MDVR cells, and when YAP1/TAZ is hyperactivated by AR full-length or AR-V7, these proteins interact with DNMT1 to repress SLC22A3 expression. We observed low SLC22A3 expression and high levels of TAZ or YAP1 in mCRPC patient tissues harbouring AR-V7 and the opposite expression patterns in normal patient tissues. Our findings suggest a mechanism underlying ENZ resistance by providing evidence that the AR-V7/YAP1/TAZ axis represses SLC22A3, which could be a potential treatment target in prostate cancer.
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Affiliation(s)
- Eunjeong Seo
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Byula Jee
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Jae Hoon Chung
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Wan Song
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Hyun Hwan Sung
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Hwang Gyun Jeon
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Byong Chang Jeong
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Seong Il Seo
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Seong Soo Jeon
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Hyun Moo Lee
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Minyong Kang
- Department of Urology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, Korea
- Samsung Genome Institute, Samsung Medical Center, Seoul, Korea
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3
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Downregulation of CAMK2N1 due to DNA Hypermethylation Mediated by DNMT1 that Promotes the Progression of Prostate Cancer. JOURNAL OF ONCOLOGY 2023; 2023:4539045. [PMID: 36755811 PMCID: PMC9902116 DOI: 10.1155/2023/4539045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/03/2022] [Accepted: 11/24/2022] [Indexed: 02/01/2023]
Abstract
Calcium/calmodulin-dependentprotein kinase II inhibitor I (CAMK2N1) as one of the tumor suppressor genes is significantly downregulated in prostate cancer (PCa). Reduced expression of CAMK2N1 is positively correlated with PCa progression. However, the mechanisms of CAMK2N1 downregulation in PCa are still unclear. The promoter region of CAMK2N1 contains a large number of CG loci, providing the possibility for DNA methylation. Consequently, we hypothesized that DNA methylation can result in the reduced expression of CAMK2N1 in PCa. In the presented study, the DNA methylation level of CAMK2N1 in prostate cells and clinical specimens was determined by bisulfite sequencing (BS), pyrosequencing, and in silico analysis. Results showed that CAMK2N1 was highly methylated in PCa cells and tissues compared to normal prostate epithelial cells and nonmalignant prostate tissues, which was associated with the clinicopathological characteristics in PCa patients. Afterwards, we explored the expression of CAMK2N1 and its DNA methylation level by qRT-PCR, western blot, BS, and methylation-specific PCR in PCa cells after 5-Aza-CdR treatment or DNMT1 genetic modification, which demonstrated that the reduced expression of CAMK2N1 can be restored by 5-Aza-CdR treatment via demethylation. Moreover, DNMT1 formed a positive feedback loop with CAMK2N1 in PCa cells. The expression of CAMK2N1 was downregulated by DNMT1-mediated DNA methylation, which reversely induced DNMT1 expression through activating AKT or ERK signaling pathway. Finally, functional assays including wound healing, invasion, and migration assay, as well as the xenograft model in nude mice indicated that CAMK2N1 inhibited the invasion, migration, and proliferation of PCa cells and these effects were reversed by DNMT1 overexpression. In conclusion, DNMT1-mediated hypermethylation of CAMK2N1 not only downregulates the gene expression but also promotes the progression of PCa.
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4
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Bertocci LA, Rovatti JR, Wu A, Morey A, Bose DD, Kinney SRM. Calcium handling genes are regulated by promoter DNA methylation in colorectal cancer cells. Eur J Pharmacol 2022; 915:174698. [PMID: 34896109 DOI: 10.1016/j.ejphar.2021.174698] [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: 07/07/2021] [Revised: 11/18/2021] [Accepted: 12/07/2021] [Indexed: 11/24/2022]
Abstract
Calcium signaling regulates various cellular processes, including proliferation and cell death. DNA methylation of gene promoters is an epigenetic modification that facilitates transcriptional suppression. Disruption of calcium homeostasis and DNA methylation in cancer are each linked to tumor development and progression. However, the possible connection between these two processes has not been thoroughly studied. Therefore, we measured the expression of six gene families involved in calcium regulation (ATP2A, ITPR, ORAI, RyR, STIM, and TRPC) in a colorectal cancer cell model, HCT116, with either genetic (Double Knock-out/DKO) or pharmacological (5-aza-2'-deoxycytidine/DAC) inhibition of DNA methyltransferases. Fourteen of the 20 examined calcium handling genes were expressed at higher levels in DKO cells as compared to HCT116. Expression of five genes was increased in HCT116 cells treated with DAC, three matching DKO. Due to a unique expression pattern of the three ATP2A genes in our model, encoding the Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase (SERCA) pumps, we chose to evaluate the methylation status of these genes, protein expression, and potential associated physiological effects, using the SERCA inhibitor thapsigarin (TG). We observed an expected pattern of promoter methylation coinciding with reduced expression and vice versa. This differential mRNA expression was associated with altered SERCA3 protein expression and cytosolic calcium levels with TG exposure. As a result, DKO cells displayed less TG-induced cytotoxicity, as compared to HCT116 cells. Overall, it is likely that at least several calcium regulatory genes are transcriptionally regulated by DNA methylation, and this may play a role in tumorigenesis through altering apoptosis in cancer.
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Affiliation(s)
- Lauren A Bertocci
- Department of Pharmaceutical and Health Sciences, Western New England University, College of Pharmacy and Health Sciences, Springfield, MA, USA.
| | - Jeffrey R Rovatti
- Department of Pharmaceutical and Health Sciences, Western New England University, College of Pharmacy and Health Sciences, Springfield, MA, USA.
| | - Alex Wu
- Department of Pharmaceutical and Health Sciences, Western New England University, College of Pharmacy and Health Sciences, Springfield, MA, USA.
| | - Amber Morey
- Department of Pharmaceutical and Health Sciences, Western New England University, College of Pharmacy and Health Sciences, Springfield, MA, USA.
| | - Diptiman D Bose
- Department of Pharmaceutical and Health Sciences, Western New England University, College of Pharmacy and Health Sciences, Springfield, MA, USA.
| | - Shannon R M Kinney
- Department of Pharmaceutical and Health Sciences, Western New England University, College of Pharmacy and Health Sciences, Springfield, MA, USA.
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5
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Moderate DNA hypomethylation suppresses intestinal tumorigenesis by promoting caspase-3 expression and apoptosis. Oncogenesis 2021; 10:38. [PMID: 33947834 PMCID: PMC8096944 DOI: 10.1038/s41389-021-00328-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/18/2021] [Accepted: 04/09/2021] [Indexed: 12/14/2022] Open
Abstract
Global DNA hypomethylation is a most common epigenetic alteration in human neoplasia. However, accumulative evidence shows that global DNA hypomethylation impacts tumorigenesis in a tissue-specific manner, promoting tumorigenesis in some but suppressing tumorigenesis in others including colorectal cancer. The underlying mechanisms, especially how DNA hypomethylation suppresses tumorigenesis, remain largely unknown. Here, we investigate how DNA hypomethylation affects intestinal tumorigenesis by using an Uhrf1 tandem tudor domain knockin mutant mouse model (Uhrf1ki/ki) that exhibits a moderate ~10% reduction of global DNA methylation. We found that both chemical-induced colorectal carcinogenesis and Apc loss of heterozygosity (LOH)-induced intestinal tumorigenesis are substantially suppressed in the Uhrf1 mutant mice. Furthermore, unlike Dnmt1 hypomorphic mice in which DNA hypomethylation suppresses the incidence of macroscopic intestinal tumors but promotes the formation of microadenoma in ApcMin/+ background, Uhrf1ki/ki/ApcMin/+ mice have markedly reduced incidence of both microadenoma and macroadenoma. DNA hypomethylation does not appear to affect Apc LOH, activation of the Wnt or Hippo pathway, or tumor cell proliferation, but acts cooperatively with activated Wnt pathway to enhance the caspase-3 gene expression, activation, and apoptosis. Furthermore, increased caspase-3 expression correlates with DNA hypomethylation within the caspase-3 enhancer regions. Taken together, we present a new mouse model for investigating the role of and the molecular mechanisms by which DNA hypomethylation suppresses intestinal tumorigenesis. Our finding that a moderate DNA hypomethylation is sufficient to suppress intestinal tumorigenesis by promoting caspase-3 expression and apoptosis sheds new light on DNA-methylation inhibitor-based colorectal cancer therapeutics.
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6
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Lee JE, Kim MY. Cancer epigenetics: Past, present and future. Semin Cancer Biol 2021; 83:4-14. [PMID: 33798724 DOI: 10.1016/j.semcancer.2021.03.025] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 03/22/2021] [Accepted: 03/25/2021] [Indexed: 12/14/2022]
Abstract
Cancer was thought to be caused solely by genetic mutations in oncogenes and tumor suppressor genes. In the last 35 years, however, epigenetic changes have been increasingly recognized as another primary driver of carcinogenesis and cancer progression. Epigenetic deregulation in cancer often includes mutations and/or aberrant expression of chromatin-modifying enzymes, their associated proteins, and even non-coding RNAs, which can alter chromatin structure and dynamics. This leads to changes in gene expression that ultimately contribute to the emergence and evolution of cancer cells. Studies of the deregulation of chromatin modifiers in cancer cells have reshaped the way we approach cancer and guided the development of novel anticancer therapeutics that target epigenetic factors. There remain, however, a number of unanswered questions in this field that are the focus of present research. Areas of particular interest include the actions of emerging classes of epigenetic regulators of carcinogenesis and the tumor microenvironment, as well as epigenetic tumor heterogeneity. In this review, we discuss past findings on epigenetic mechanisms of cancer, current trends in the field of cancer epigenetics, and the directions of future research that may lead to the identification of new prognostic markers for cancer and the development of more effective anticancer therapeutics.
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Affiliation(s)
- Jae Eun Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Mi-Young Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea; KAIST Institute for the BioCentury, Cancer Metastasis Control Center, Daejeon, Republic of Korea.
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7
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Redl E, Sheibani-Tezerji R, Cardona CDJ, Hamminger P, Timelthaler G, Hassler MR, Zrimšek M, Lagger S, Dillinger T, Hofbauer L, Draganić K, Tiefenbacher A, Kothmayer M, Dietz CH, Ramsahoye BH, Kenner L, Bock C, Seiser C, Ellmeier W, Schweikert G, Egger G. Requirement of DNMT1 to orchestrate epigenomic reprogramming for NPM-ALK-driven lymphomagenesis. Life Sci Alliance 2021; 4:e202000794. [PMID: 33310759 PMCID: PMC7768196 DOI: 10.26508/lsa.202000794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 11/28/2020] [Accepted: 12/01/2020] [Indexed: 12/31/2022] Open
Abstract
Malignant transformation depends on genetic and epigenetic events that result in a burst of deregulated gene expression and chromatin changes. To dissect the sequence of events in this process, we used a T-cell-specific lymphoma model based on the human oncogenic nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) translocation. We find that transformation of T cells shifts thymic cell populations to an undifferentiated immunophenotype, which occurs only after a period of latency, accompanied by induction of the MYC-NOTCH1 axis and deregulation of key epigenetic enzymes. We discover aberrant DNA methylation patterns, overlapping with regulatory regions, plus a high degree of epigenetic heterogeneity between individual tumors. In addition, ALK-positive tumors show a loss of associated methylation patterns of neighboring CpG sites. Notably, deletion of the maintenance DNA methyltransferase DNMT1 completely abrogates lymphomagenesis in this model, despite oncogenic signaling through NPM-ALK, suggesting that faithful maintenance of tumor-specific methylation through DNMT1 is essential for sustained proliferation and tumorigenesis.
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Affiliation(s)
- Elisa Redl
- Department of Pathology, Medical University of Vienna, Vienna, Austria
| | | | | | - Patricia Hamminger
- Division of Immunobiology, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Gerald Timelthaler
- Institute of Cancer Research, Medical University of Vienna, Vienna, Austria
| | - Melanie Rosalia Hassler
- Department of Pathology, Medical University of Vienna, Vienna, Austria
- Department of Urology, Medical University of Vienna, Vienna, Austria
| | - Maša Zrimšek
- Department of Pathology, Medical University of Vienna, Vienna, Austria
| | - Sabine Lagger
- Unit of Laboratory Animal Pathology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Thomas Dillinger
- Department of Pathology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute Applied Diagnostics (LBI AD), Vienna, Austria
| | - Lorena Hofbauer
- Department of Pathology, Medical University of Vienna, Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Kristina Draganić
- Department of Pathology, Medical University of Vienna, Vienna, Austria
| | - Andreas Tiefenbacher
- Department of Pathology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute Applied Diagnostics (LBI AD), Vienna, Austria
| | - Michael Kothmayer
- Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Charles H Dietz
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Bernard H Ramsahoye
- Centre for Genetic and Experimental Medicine, Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Lukas Kenner
- Department of Pathology, Medical University of Vienna, Vienna, Austria
- Unit of Laboratory Animal Pathology, University of Veterinary Medicine Vienna, Vienna, Austria
- Christian Doppler Laboratory for Applied Metabolomics (CDL-AM), Medical University of Vienna, Vienna, Austria
- Center for Biomarker Research in Medicine (CBmed), CoreLab 2, Medical University of Vienna, Vienna, Austria
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Christian Seiser
- Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Wilfried Ellmeier
- Division of Immunobiology, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Gabriele Schweikert
- Max Planck Institute for Intelligent Systems, Tübingen, Germany
- Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Gerda Egger
- Department of Pathology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute Applied Diagnostics (LBI AD), Vienna, Austria
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Shanak S, Helms V. DNA methylation and the core pluripotency network. Dev Biol 2020; 464:145-160. [PMID: 32562758 DOI: 10.1016/j.ydbio.2020.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 05/01/2020] [Accepted: 06/04/2020] [Indexed: 01/06/2023]
Abstract
From the onset of fertilization, the genome undergoes cell division and differentiation. All of these developmental transitions and differentiation processes include cell-specific signatures and gradual changes of the epigenome. Understanding what keeps stem cells in the pluripotent state and what leads to differentiation are fascinating and biomedically highly important issues. Numerous studies have identified genes, proteins, microRNAs and small molecules that exert essential effects. Notably, there exists a core pluripotency network that consists of several transcription factors and accessory proteins. Three eminent transcription factors, OCT4, SOX2 and NANOG, serve as hubs in this core pluripotency network. They bind to the enhancer regions of their target genes and modulate, among others, the expression levels of genes that are associated with Gene Ontology terms related to differentiation and self-renewal. Also, much has been learned about the epigenetic rewiring processes during these changes of cell fate. For example, DNA methylation dynamics is pivotal during embryonic development. The main goal of this review is to highlight an intricate interplay of (a) DNA methyltransferases controlling the expression levels of core pluripotency factors by modulation of the DNA methylation levels in their enhancer regions, and of (b) the core pluripotency factors controlling the transcriptional regulation of DNA methyltransferases. We discuss these processes both at the global level and in atomistic detail based on information from structural studies and from computer simulations.
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Affiliation(s)
- Siba Shanak
- Faculty of Science, Arab-American University, Jenin, Palestine; Center for Bioinformatics, Saarland University, Saarbruecken, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbruecken, Germany.
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Zhang W, Klinkebiel D, Barger CJ, Pandey S, Guda C, Miller A, Akers SN, Odunsi K, Karpf AR. Global DNA Hypomethylation in Epithelial Ovarian Cancer: Passive Demethylation and Association with Genomic Instability. Cancers (Basel) 2020; 12:cancers12030764. [PMID: 32213861 PMCID: PMC7140107 DOI: 10.3390/cancers12030764] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 03/19/2020] [Indexed: 02/08/2023] Open
Abstract
A hallmark of human cancer is global DNA hypomethylation (GDHO), but the mechanisms accounting for this defect and its pathological consequences have not been investigated in human epithelial ovarian cancer (EOC). In EOC, GDHO was associated with advanced disease and reduced overall and disease-free survival. GDHO (+) EOC tumors displayed a proliferative gene expression signature, including FOXM1 and CCNE1 overexpression. Furthermore, DNA hypomethylation in these tumors was enriched within genomic blocks (hypomethylated blocks) that overlapped late-replicating regions, lamina-associated domains, PRC2 binding sites, and the H3K27me3 histone mark. Increased proliferation coupled with hypomethylated blocks at late-replicating regions suggests a passive hypomethylation mechanism. This hypothesis was further supported by our observation that cytosine DNA methyltransferases (DNMTs) and UHRF1 showed significantly reduced expression in GDHO (+) EOC after normalization to canonical proliferation markers, including MKI67. Finally, GDHO (+) EOC tumors had elevated chromosomal instability (CIN), and copy number alterations (CNA) were enriched at the DNA hypomethylated blocks. Together, these findings implicate a passive DNA demethylation mechanism in ovarian cancer that is associated with genomic instability and poor prognosis.
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Affiliation(s)
- Wa Zhang
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, NE 68198, USA; (W.Z.); (C.J.B.)
| | - David Klinkebiel
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA; (D.K.); (C.G.)
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Carter J. Barger
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, NE 68198, USA; (W.Z.); (C.J.B.)
| | - Sanjit Pandey
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Chittibabu Guda
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA; (D.K.); (C.G.)
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Austin Miller
- Department of Biostatistics, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA;
| | - Stacey N. Akers
- Department of Gynecologic Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA; (S.N.A.); (K.O.)
| | - Kunle Odunsi
- Department of Gynecologic Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA; (S.N.A.); (K.O.)
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA
- Center for Immunotherapy, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA
| | - Adam R. Karpf
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, NE 68198, USA; (W.Z.); (C.J.B.)
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA; (D.K.); (C.G.)
- Correspondence: ; Tel.: +1-402-559-6115; Fax: +1-402-599-4651
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10
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Epigenetic modulations and lineage plasticity in advanced prostate cancer. Ann Oncol 2020; 31:470-479. [PMID: 32139297 DOI: 10.1016/j.annonc.2020.02.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 12/25/2022] Open
Abstract
Prostate cancer is the most common cancer and second leading cause of cancer-related death in American men. Antiandrogen therapies are part of the standard of therapeutic regimen for advanced or metastatic prostate cancers; however, patients who receive these treatments are more likely to develop castration-resistant prostate cancer (CRPC) or neuroendocrine prostate cancer (NEPC). In the development of CRPC or NEPC, numerous genetic signaling pathways have been under preclinical investigations and in clinical trials. Accumulated evidence shows that DNA methylation, chromatin integrity, and accessibility for transcriptional regulation still play key roles in prostate cancer initiation and progression. Better understanding of how epigenetic change regulates the progression of prostate cancer and the interaction between epigenetic and genetic modulators driving NEPC may help develop a better risk stratification and more effective treatment regimens for prostate cancer patients.
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11
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Tzelepi V, Logotheti S, Efstathiou E, Troncoso P, Aparicio A, Sakellakis M, Hoang A, Perimenis P, Melachrinou M, Logothetis C, Zolota V. Epigenetics and prostate cancer: defining the timing of DNA methyltransferase deregulation during prostate cancer progression. Pathology 2019; 52:218-227. [PMID: 31864524 DOI: 10.1016/j.pathol.2019.10.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/25/2019] [Accepted: 10/08/2019] [Indexed: 01/31/2023]
Abstract
DNA methyltransferases (DNMTs) regulate gene expression by methylating cytosine residues within CpG dinucleotides. Aberrant methylation patterns have been shown in a variety of human tumours including prostate cancer. However, the expression of DNMTs in clinical samples across the spectrum of prostate cancer progression has not been studied before. Tissue microarrays were constructed from the prostatectomy specimens of 309 patients across the spectrum of prostate cancer progression: hormone-naïve low-grade prostate cancer (n=49), hormone-naïve high-grade prostate cancer (n=151), hormonally treated high-grade prostate cancer (n=65), and castrate-resistant prostate cancer (CRPC) including neuroendocrine carcinoma (n=44). Adjacent non-neoplastic parenchyma was also available in 100 patients. In 71 patients with high-grade carcinoma and lymph node metastasis, tissue from the metastasis was also available for analysis. Immunohistochemical staining was performed with antibodies against DNMT1, DNMT2, DNMT3A, DNMT3B, and DNMT3L. Our results showed that DNMT1 and DNMT3L were upregulated early in prostate cancer progression, whereas DNMT2 was upregulated as a response to androgen ablation. DNMT1, DNMT3A, and DNMT3B were higher in the late stages of prostate cancer progression, i.e., the emergence of castrate resistance and androgen-independent growth. Lastly, DNMT1, DNMT2, and DNMT3L were upregulated in lymph node metastases compared to primary carcinomas. Our results highlight a cascade of epigenetic events in prostate cancer progression.
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Affiliation(s)
- Vasiliki Tzelepi
- Department of Pathology, Medical School, University of Patras, Greece.
| | - Souzana Logotheti
- Department of Pathology, Medical School, University of Patras, Greece
| | - Eleni Efstathiou
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, USA
| | - Patricia Troncoso
- Department of Pathology, The University of Texas MD Anderson Cancer Center, USA
| | - Ana Aparicio
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, USA
| | - Minas Sakellakis
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, USA
| | - Anh Hoang
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, USA
| | - Petros Perimenis
- Department of Urology, Medical School, University of Patras, Greece
| | - Maria Melachrinou
- Department of Pathology, Medical School, University of Patras, Greece
| | - Christopher Logothetis
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, USA
| | - Vasiliki Zolota
- Department of Pathology, Medical School, University of Patras, Greece
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12
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Lin C, Salzillo TC, Bader DA, Wilkenfeld SR, Awad D, Pulliam TL, Dutta P, Pudakalakatti S, Titus M, McGuire SE, Bhattacharya PK, Frigo DE. Prostate Cancer Energetics and Biosynthesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1210:185-237. [PMID: 31900911 PMCID: PMC8096614 DOI: 10.1007/978-3-030-32656-2_10] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cancers must alter their metabolism to satisfy the increased demand for energy and to produce building blocks that are required to create a rapidly growing tumor. Further, for cancer cells to thrive, they must also adapt to an often changing tumor microenvironment, which can present new metabolic challenges (ex. hypoxia) that are unfavorable for most other cells. As such, altered metabolism is now considered an emerging hallmark of cancer. Like many other malignancies, the metabolism of prostate cancer is considerably different compared to matched benign tissue. However, prostate cancers exhibit distinct metabolic characteristics that set them apart from many other tumor types. In this chapter, we will describe the known alterations in prostate cancer metabolism that occur during initial tumorigenesis and throughout disease progression. In addition, we will highlight upstream regulators that control these metabolic changes. Finally, we will discuss how this new knowledge is being leveraged to improve patient care through the development of novel biomarkers and metabolically targeted therapies.
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Affiliation(s)
- Chenchu Lin
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Travis C Salzillo
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - David A Bader
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Sandi R Wilkenfeld
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Dominik Awad
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Thomas L Pulliam
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, USA
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Prasanta Dutta
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Shivanand Pudakalakatti
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mark Titus
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Sean E McGuire
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Pratip K Bhattacharya
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Daniel E Frigo
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, USA.
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA.
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- Molecular Medicine Program, The Houston Methodist Research Institute, Houston, TX, USA.
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13
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Abstract
Despite the high long-term survival in localized prostate cancer, metastatic prostate cancer remains largely incurable even after intensive multimodal therapy. The lethality of advanced disease is driven by the lack of therapeutic regimens capable of generating durable responses in the setting of extreme tumor heterogeneity on the genetic and cell biological levels. Here, we review available prostate cancer model systems, the prostate cancer genome atlas, cellular and functional heterogeneity in the tumor microenvironment, tumor-intrinsic and tumor-extrinsic mechanisms underlying therapeutic resistance, and technological advances focused on disease detection and management. These advances, along with an improved understanding of the adaptive responses to conventional cancer therapies, anti-androgen therapy, and immunotherapy, are catalyzing development of more effective therapeutic strategies for advanced disease. In particular, knowledge of the heterotypic interactions between and coevolution of cancer and host cells in the tumor microenvironment has illuminated novel therapeutic combinations with a strong potential for more durable therapeutic responses and eventual cures for advanced disease. Improved disease management will also benefit from artificial intelligence-based expert decision support systems for proper standard of care, prognostic determinant biomarkers to minimize overtreatment of localized disease, and new standards of care accelerated by next-generation adaptive clinical trials.
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Affiliation(s)
- Guocan Wang
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Di Zhao
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Denise J Spring
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Ronald A DePinho
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
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14
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Bai J, Zhang X, Hu K, Liu B, Wang H, Li A, Lin F, Zhang L, Sun X, Du Z, Song J. Silencing DNA methyltransferase 1 (DNMT1) inhibits proliferation, metastasis and invasion in ESCC by suppressing methylation of RASSF1A and DAPK. Oncotarget 2018; 7:44129-44141. [PMID: 27286455 PMCID: PMC5190084 DOI: 10.18632/oncotarget.9866] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 03/31/2016] [Indexed: 11/25/2022] Open
Abstract
Our previous study showed DNMT1 is up-regulated in esophageal squamous cell carcinoma (ESCC), which is associated with methylation of tumor suppressors. In the current study, we investigate the role of DNMT1 in ESCC. We found silencing DNMT1 inhibited proliferation, metastasis and invasion of three different ESCC cells, K150, K410 and K450. We also found silencing DNMT1 induced G1 arrest and cell apoptosis in K150, K410 and K450 cells. In vivo study showed silencing DNMT1 suppressed tumor growth in nude mice. In addition, silencing DNMT1 increased expression of tumor suppressor genes, RASSF1A and DAPK, in ESCC cells and ESCC xenograft in nude mice. Moreover, silencing DNMT1 decreased methylation in promoter of RASSF1A and DAPK. In conclusion, our data demonstrated that silencing DNMT1 inhibits proliferation, metastasis and invasion in ESCC by suppressing methylation of RASSF1A and DAPK.
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Affiliation(s)
- Jian Bai
- Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Xue Zhang
- Department of ICU, The Second Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Kai Hu
- Department of Thoracic & Cardiovascular Surgery, The Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Bangqing Liu
- Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Haiyong Wang
- Department of Thoracic & Cardiovascular Surgery, The Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Angui Li
- Department of Thoracic & Cardiovascular Surgery, The Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Feng Lin
- Department of Thoracic & Cardiovascular Surgery, The Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Lifei Zhang
- Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Xiaolin Sun
- Department of Thoracic & Cardiovascular Surgery, The Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Zhenzong Du
- Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Guilin, China.,Current address: Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Lingui District, Guilin, China
| | - Jianfei Song
- Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Guilin, China.,Current address: Department of Thoracic & Cardiovascular Surgery, The Second Affiliated Hospital of Guilin Medical University, Lingui District, Guilin, China
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15
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Lee E, Wang J, Yumoto K, Jung Y, Cackowski FC, Decker AM, Li Y, Franceschi RT, Pienta KJ, Taichman RS. DNMT1 Regulates Epithelial-Mesenchymal Transition and Cancer Stem Cells, Which Promotes Prostate Cancer Metastasis. Neoplasia 2017; 18:553-66. [PMID: 27659015 PMCID: PMC5031902 DOI: 10.1016/j.neo.2016.07.007] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 12/30/2022] Open
Abstract
Cancer metastasis is a multistep process associated with the induction of an epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). Although significant progress has been made in understanding the molecular mechanisms regulating EMT and the CSC phenotype, little is known of how these processes are regulated by epigenetics. Here we demonstrate that reduced expression of DNA methyltransferase 1 (DNMT1) plays an important role in the induction of EMT and the CSC phenotype by prostate cancer (PCa) cells, with enhanced tumorigenesis and metastasis. First, we observed that reduction of DNMT1 by 5-azacitidine (5-Aza) promotes EMT induction as well as CSCs and sphere formation in vitro. Reduced expression of DNMT1 significantly increased PCa migratory potential. We showed that the increase of EMT and CSC activities by reduction of DNMT1 is associated with the increase of protein kinase C. Furthermore, we confirmed that silencing DNMT1 is correlated with enhancement of the induction of EMT and the CSC phenotype in PCa cells. Additionally, chromatin immunoprecipitation assay reveals that reduction of DNMT1 promotes the suppression of H3K9me3 and H3K27me3 on the Zeb2 and KLF4 promoter region in PCa cells. Critically, we found in an animal model that significant tumor growth and more disseminated tumor cells in most osseous tissues were observed following injection of 5-Aza pretreated-PCa cells compared with vehicle-pretreated PCa cells. Our results suggest that epigenetic alteration of histone demethylation regulated by reduction of DNMT1 may control induction of EMT and the CSC phenotype, which facilitates tumorigenesis in PCa cells and has important therapeutic implications in targeting epigenetic regulation.
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Affiliation(s)
- Eunsohl Lee
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Jingcheng Wang
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Kenji Yumoto
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Younghun Jung
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Frank C Cackowski
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA; Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Ann M Decker
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Yan Li
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA
| | - Renny T Franceschi
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Kenneth J Pienta
- Department of Urology, The James Buchanan Brady Urological Institute, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA
| | - Russell S Taichman
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI 48109, USA.
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16
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Corbin JM, Ruiz-Echevarría MJ. One-Carbon Metabolism in Prostate Cancer: The Role of Androgen Signaling. Int J Mol Sci 2016; 17:E1208. [PMID: 27472325 PMCID: PMC5000606 DOI: 10.3390/ijms17081208] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/16/2016] [Accepted: 07/18/2016] [Indexed: 01/06/2023] Open
Abstract
Cancer cell metabolism differs significantly from the metabolism of non-transformed cells. This altered metabolic reprogramming mediates changes in the uptake and use of nutrients that permit high rates of proliferation, growth, and survival. The androgen receptor (AR) plays an essential role in the establishment and progression of prostate cancer (PCa), and in the metabolic adaptation that takes place during this progression. In its role as a transcription factor, the AR directly affects the expression of several effectors and regulators of essential catabolic and biosynthetic pathways. Indirectly, as a modulator of the one-carbon metabolism, the AR can affect epigenetic processes, DNA metabolism, and redox balance, all of which are important factors in tumorigenesis. In this review, we focus on the role of AR-signaling on one-carbon metabolism in tumorigenesis. Clinical implications of one-carbon metabolism and AR-targeted therapies for PCa are discussed in this context.
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Affiliation(s)
- Joshua M Corbin
- Department of Pathology, Oklahoma University Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Maria J Ruiz-Echevarría
- Department of Pathology, Oklahoma University Health Sciences Center and Stephenson Cancer Center, Oklahoma City, OK 73104, USA.
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17
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Wu BK, Mei SC, Brenner C. RFTS-deleted DNMT1 enhances tumorigenicity with focal hypermethylation and global hypomethylation. Cell Cycle 2015; 13:3222-31. [PMID: 25485502 DOI: 10.4161/15384101.2014.950886] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Site-specific hypermethylation of tumor suppressor genes accompanied by genome-wide hypomethylation are epigenetic hallmarks of malignancy. However, the molecular mechanisms that drive these linked changes in DNA methylation remain obscure. DNA methyltransferase 1 (DNMT1), the principle enzyme responsible for maintaining methylation patterns is commonly dysregulated in tumors. Replication foci targeting sequence (RFTS) is an N-terminal domain of DNMT1 that inhibits DNA-binding and catalytic activity, suggesting that RFTS deletion would result in a gain of DNMT1 function. However, a substantial body of data suggested that RFTS is required for DNMT1 activity. Here, we demonstrate that deletion of RFTS alters DNMT1-dependent DNA methylation during malignant transformation. Compared to full-length DNMT1, ectopic expression of hyperactive DNMT1-ΔRFTS caused greater malignant transformation and enhanced promoter methylation with condensed chromatin structure that silenced DAPK and DUOX1 expression. Simultaneously, deletion of RFTS impaired DNMT1 chromatin association with pericentromeric Satellite 2 (SAT2) repeat sequences and produced DNA demethylation at SAT2 repeats and globally. To our knowledge, RFTS-deleted DNMT1 is the first single factor that can reprogram focal hypermethylation and global hypomethylation in parallel during malignant transformation. Our evidence suggests that the RFTS domain of DNMT1 is a target responsible for epigenetic changes in cancer.
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Affiliation(s)
- Bo-Kuan Wu
- a Department of Biochemistry; Carver College of Medicine ; University of Iowa ; Iowa City , IA USA
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18
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Liu Q, Su PF, Zhao S, Shyr Y. Transcriptome-wide signatures of tumor stage in kidney renal clear cell carcinoma: connecting copy number variation, methylation and transcription factor activity. Genome Med 2014; 6:117. [PMID: 25648588 PMCID: PMC4293006 DOI: 10.1186/s13073-014-0117-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 11/26/2014] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Comparative analysis of expression profiles between early and late stage cancers can help to understand cancer progression and metastasis mechanisms and to predict the clinical aggressiveness of cancer. The observed stage-dependent expression changes can be explained by genetic and epigenetic alterations as well as transcription dysregulation. Unlike genetic and epigenetic alterations, however, activity changes of transcription factors, generally occurring at the post-transcriptional or post-translational level, are hard to detect and quantify. METHODS Here we developed a statistical framework to infer the activity changes of transcription factors by simultaneously taking into account the contributions of genetic and epigenetic alterations to mRNA expression variations. RESULTS Applied to kidney renal clear cell carcinoma (KIRC), the model underscored the role of methylation as a significant contributor to stage-dependent expression alterations and identified key transcription factors as potential drivers of cancer progression. CONCLUSIONS Integrating copy number, methylation, and transcription factor activity signatures to explain stage-dependent expression alterations presented a precise and comprehensive view on the underlying mechanisms during KIRC progression.
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Affiliation(s)
- Qi Liu
- Center for Quantitative Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232 USA ; Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Pei-Fang Su
- Department of Statistics, National Cheng Kung University, Tainan, 70101 Taiwan
| | - Shilin Zhao
- Center for Quantitative Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Yu Shyr
- Center for Quantitative Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232 USA ; Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232 USA ; Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37232 USA ; School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China
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19
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Valdez CD, Kunju L, Daignault S, Wojno KJ, Day ML. The E2F1/DNMT1 axis is associated with the development of AR negative castration resistant prostate cancer. Prostate 2013; 73:1776-85. [PMID: 24038143 DOI: 10.1002/pros.22715] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/06/2013] [Indexed: 11/09/2022]
Abstract
BACKGROUND Research on castration resistant prostate cancer (CRPC) has focused primarily on functional alterations of the androgen receptor (AR). However, little is known about the loss of AR gene expression itself and the possible contribution of AR negative cells to CRPC. METHODS Human and murine prostate cancer tissue microarrays (TMAs) were evaluated with antibodies specific for E2F1, DNA methyltransferase 1 or AR. The human prostate cancer TMA consisted of clinical samples ranging from normal tissue to samples of metastatic disease. The murine TMA was comprised of benign, localized or metastatic prostate cancer acquired from TRAMP mice treated with castration and/or 5'-Aza-2'-deoxycytidine (5Aza). RESULTS Immunohistochemical analysis revealed increased nuclear DNMT1 staining in localized PCa (P < 0.0001) and metastatic PCa (P < 0.0001) compared to normal tissue. Examination of specific diagnoses revealed that Gleason seven tumors exhibited greater nuclear DNMT1 staining than Gleason six tumors (P < 0.05) and that metastatic tissue exhibited greater levels of nuclear DNMT1 than Gleason seven tumors (P < 0.01). Evaluation of the murine tissue cores revealed that 8.2% and 8.1% of benign tissue cores stained positive for E2F1 and DNMT1 respectively, while 97.0% were AR positive. Conversely, 81% and 100% of tumors were positive for E2F1 and DNMT1 respectively. This was in stark contrast to only 18% of tumors positive for AR. Treatment of mice with 5Aza reduced DNMT1 staining by 30%, while AR increased by 27%. CONCLUSIONS These findings demonstrate that the E2F1/DNMT1 inhibitory axis of AR transcription is activated during the emergence of CRPC.
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Affiliation(s)
- Conrad David Valdez
- Department of Urology, University of Michigan, Ann Arbor, Michigan; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan
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20
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Armstrong VL, Rakoczy S, Rojanathammanee L, Brown-Borg HM. Expression of DNA methyltransferases is influenced by growth hormone in the long-living Ames dwarf mouse in vivo and in vitro. J Gerontol A Biol Sci Med Sci 2013; 69:923-33. [PMID: 24201695 DOI: 10.1093/gerona/glt133] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Methyltransferase expression and DNA methylation are linked to aging and age-related disease. We utilized 3-, 12-, and 24-month-old Ames dwarf and their wild-type siblings to examine the genotype and age-related differences in the expression of methyltransferase enzymes related to DNA methylation in the liver, glycine-N-methyltransferase and DNA methyltransferase (DNMT). We found that DNMT proteins and transcripts are differentially expressed in dwarf mice compared with wild-type siblings that can be attributed to age and/or genotype. However, DNMT1 protein expression is drastically reduced compared with wild-type controls at every age. DNMT3a protein levels coincide with differences observed in DNMT activity. Growth hormone appears to modulate expression of DNMT1 and 3a in dwarf liver tissue and primary hepatocytes. Therefore, growth hormone may contribute to age-related processes, DNA methylation, and, ultimately, longevity.
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Affiliation(s)
- Vanessa L Armstrong
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks
| | - Sharlene Rakoczy
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks
| | - Lalida Rojanathammanee
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks
| | - Holly M Brown-Borg
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks.
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21
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Essential role for Dnmt1 in the prevention and maintenance of MYC-induced T-cell lymphomas. Mol Cell Biol 2013; 33:4321-33. [PMID: 24001767 DOI: 10.1128/mcb.00776-13] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
DNA cytosine methylation is an epigenetic modification involved in the transcriptional repression of genes controlling a variety of physiological processes, including hematopoiesis. DNA methyltransferase 1 (Dnmt1) is a key enzyme involved in the somatic inheritance of DNA methylation and thus plays a critical role in epigenomic stability. Aberrant methylation contributes to the pathogenesis of human cancer and of hematologic malignancies in particular. To gain deeper insight into the function of Dnmt1 in lymphoid malignancies, we genetically inactivated Dnmt1 in a mouse model of MYC-induced T-cell lymphomagenesis. We show that loss of Dnmt1 delays lymphomagenesis by suppressing normal hematopoiesis and impairing tumor cell proliferation. Acute inactivation of Dnmt1 in primary lymphoma cells rapidly induced apoptosis, indicating that Dnmt1 is required to sustain T-cell lymphomas. Using high-resolution genome-wide profiling, we identified differentially methylated regions between control and Dnmt1-deficient lymphomas, demonstrating a locus-specific function for Dnmt1 in both maintenance and de novo promoter methylation. Dnmt1 activity is independent of the presence of Dnmt3a or Dnmt3b in de novo promoter methylation of the H2-Ab1 gene. Collectively, these data show for the first time that Dnmt1 is critical for the prevention and maintenance of T-cell lymphomas and contributes to aberrant methylation by both de novo and maintenance methylation.
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22
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Stepanenko AA, Vassetzky YS, Kavsan VM. Antagonistic functional duality of cancer genes. Gene 2013; 529:199-207. [PMID: 23933273 DOI: 10.1016/j.gene.2013.07.047] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/08/2013] [Accepted: 07/09/2013] [Indexed: 12/21/2022]
Abstract
Cancer evolution is a stochastic process both at the genome and gene levels. Most of tumors contain multiple genetic subclones, evolving in either succession or in parallel, either in a linear or branching manner, with heterogeneous genome and gene alterations, extensively rewired signaling networks, and addicted to multiple oncogenes easily switching with each other during cancer progression and medical intervention. Hundreds of discovered cancer genes are classified according to whether they function in a dominant (oncogenes) or recessive (tumor suppressor genes) manner in a cancer cell. However, there are many cancer "gene-chameleons", which behave distinctly in opposite way in the different experimental settings showing antagonistic duality. In contrast to the widely accepted view that mutant NADP(+)-dependent isocitrate dehydrogenases 1/2 (IDH1/2) and associated metabolite 2-hydroxyglutarate (R)-enantiomer are intrinsically "the drivers" of tumourigenesis, mutant IDH1/2 inhibited, promoted or had no effect on cell proliferation, growth and tumorigenicity in diverse experiments. Similar behavior was evidenced for dozens of cancer genes. Gene function is dependent on genetic network, which is defined by the genome context. The overall changes in karyotype can result in alterations of the role and function of the same genes and pathways. The diverse cell lines and tumor samples have been used in experiments for proving gene tumor promoting/suppressive activity. They all display heterogeneous individual karyotypes and disturbed signaling networks. Consequently, the effect and function of gene under investigation can be opposite and versatile in cells with different genomes that may explain antagonistic duality of cancer genes and the cell type- or the cellular genetic/context-dependent response to the same protein. Antagonistic duality of cancer genes might contribute to failure of chemotherapy. Instructive examples of unexpected activity of cancer genes and "paradoxical" effects of different anticancer drugs depending on the cellular genetic context/signaling network are discussed.
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Affiliation(s)
- A A Stepanenko
- State Key Laboratory of Molecular and Cellular Biology, Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03680, Ukraine.
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23
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Pogribny IP, Rusyn I. Environmental toxicants, epigenetics, and cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 754:215-32. [PMID: 22956504 PMCID: PMC4281087 DOI: 10.1007/978-1-4419-9967-2_11] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tumorigenesis, a complex and multifactorial progressive process of transformation of normal cells into malignant cells, is characterized by the accumulation of multiple cancer-specific heritable phenotypes triggered by the mutational and/or non-mutational (i.e., epigenetic) events. Accumulating evidence suggests that environmental and occupational exposures to natural substances, as well as man-made chemical and physical agents, play a causative role in human cancer. In a broad sense, carcinogenesis may be induced through either genotoxic or non-genotoxic mechanisms; however, both genotoxic and non-genotoxic carcinogens also cause prominent epigenetic changes. This review presents current evidence of the epigenetic alterations induced by various chemical carcinogens, including arsenic, 1,3-butadine, and pharmaceutical and biological agents, and highlights the potential for epigenetic changes to serve as markers for carcinogen exposure and cancer risk assessment.
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Affiliation(s)
- Igor P. Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Ivan Rusyn
- Department of Environmental Sciences & Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
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24
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Kutay H, Klepper C, Wang B, Hsu SH, Datta J, Yu L, Zhang X, Majumder S, Motiwala T, Khan N, Belury M, McClain C, Jacob S, Ghoshal K. Reduced susceptibility of DNA methyltransferase 1 hypomorphic (Dnmt1N/+) mice to hepatic steatosis upon feeding liquid alcohol diet. PLoS One 2012; 7:e41949. [PMID: 22905112 PMCID: PMC3414497 DOI: 10.1371/journal.pone.0041949] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 06/29/2012] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Methylation at C-5 (5-mdC) of CpG base pairs, the most abundant epigenetic modification of DNA, is catalyzed by 3 essential DNA methyltransferases (Dnmt1, Dnmt3a and Dnmt3b). Aberrations in DNA methylation and Dnmts are linked to different diseases including cancer. However, their role in alcoholic liver disease (ALD) has not been elucidated. METHODOLOGY/PRINCIPAL FINDINGS Dnmt1 wild type (Dnmt1(+/+)) and hypomorphic (Dnmt1(N/+)) male mice that express reduced level of Dnmt1 were fed Lieber-DeCarli liquid diet containing ethanol for 6 weeks. Control mice were pair-fed calorie-matched alcohol-free liquid diet, and Dnmtase activity, 5-mdC content, gene expression profile and liver histopathology were evaluated. Ethanol feeding caused pronounced decrease in hepatic Dnmtase activity in Dnmt1(+/+) mice due to decrease in Dnmt1 and Dnmt3b protein levels and upregulation of miR-148 and miR-152 that target both Dnmt1 and Dnmt3b. Microarray and qPCR analysis showed that the genes involved in lipid, xenobiotic and glutathione metabolism, mitochondrial function and cell proliferation were dysregulated in the wild type mice fed alcohol. Surprisingly, Dnmt1(N/+) mice were less susceptible to alcoholic steatosis compared to Dnmt1(+/+) mice. Expression of several key genes involved in alcohol (Aldh3b1), lipid (Ppara, Lepr, Vldlr, Agpat9) and xenobiotic (Cyp39a1) metabolism, and oxidative stress (Mt-1, Fmo3) were significantly (P<0.05) altered in Dnmt1(N/+) mice relative to the wild type mice fed alcohol diet. However, CpG islands encompassing the promoter regions of Agpat9, Lepr, Mt1 and Ppara were methylation-free in both genotypes irrespective of the diet, suggesting that promoter methylation does not regulate their expression. Similarly, 5-mdC content of the liver genome, as measured by LC-MS/MS analysis, was not affected by alcohol diet in the wild type or hypomorphic mice. CONCLUSIONS/SIGNIFICANCE Although feeding alcohol diet reduced Dnmtase activity, the loss of one copy of Dnmt1 protected mice from alcoholic hepatosteatosis by dysregulating genes involved in lipid metabolism and oxidative stress.
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Affiliation(s)
- Huban Kutay
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Corie Klepper
- Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Bo Wang
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Molecular, Cellular and Developmental Biology Program, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Shu-hao Hsu
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Molecular, Cellular and Developmental Biology Program, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Jharna Datta
- Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Lianbo Yu
- Center for Biostatistics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Xiaoli Zhang
- Center for Biostatistics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Sarmila Majumder
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Tasneem Motiwala
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Nuzhat Khan
- Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Martha Belury
- Department of Nutrition, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Craig McClain
- Department of Medicine, University of Louisville and the Robley Rex Louisville VAMC, Louisville, Kentucky, United States of America
| | - Samson Jacob
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Comprehensive Cancer Center, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Experimental Therapeutics Program, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Kalpana Ghoshal
- Department of Molecular and Cellular Biochemistry, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Experimental Therapeutics Program, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- Department of Pathology, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
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Yang B, Sun H, Lin W, Hou W, Li H, Zhang L, Li F, Gu Y, Song Y, Li Q, Zhang F. Evaluation of global DNA hypomethylation in human prostate cancer and prostatic intraepithelial neoplasm tissues by immunohistochemistry. Urol Oncol 2011; 31:628-34. [PMID: 21704537 DOI: 10.1016/j.urolonc.2011.05.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 04/03/2011] [Accepted: 05/10/2011] [Indexed: 01/17/2023]
Abstract
OBJECTIVE To identify the differences of 5-methylcytosine (5-MC) level between primary prostate cancer tissues (PCTs), prostate cancer-adjacent benign tissues (PCABTs), low-grade prostatic intraepithelial neoplasia (LGPIN), and high-grade prostatic intraepithelial neoplasia (HGPIN), and further analysis the 5-MC alterations in prostate cancer with pathologic grade and clinical prognosis. MATERIALS AND METHODS Immunohistochemistry method with a 5-MC monoclonal antibody was used to identify the 5-methylcytosine (5-MC) levels in PCTs, PCABTs, LGPIN, and HGPIN specimens in the present study. Statistical analysis with SPSS software (SPSS Inc., Chicago, IL) was used to compare differences of 5-MC levels in the four groups and evaluate the 5-MC alterations in prostate cancer with pathologic grade and clinical prognosis. RESULTS We found that 38 of 48 (79.1%) patients studied showed a decrease in 5-MC staining of PCTs compared with PCABTs. The difference in the methylation levels for the PCTs and the PCABTs was highly statistically significant (P < 0.001). Spearman correlation showed there was no statistically significant association between the average score of 5-MC staining and Gleason score sum. Kaplan-Meier survival analysis showed that patient group with no or weak 5-MC staining compared with group with moderate and strong 5-MC staining was associated with better survival of patients, although there was no statistically significant difference between the 2 groups in predicating prognosis (P = 0.385). The average scores of 5-MC staining for LGPIN, HGPIN, PCABTs, and PCTs groups were 6.91, 1.58, 6.63, and 3.10, respectively. The methylation level of HGPIN group, as well as that of PCTs group, was significantly lower than those of LGPIN (P < 0.001; P < 0.001) and PCABTs groups (P < 0.001; P < 0.001), respectively, with the 5-MC levels of PCABTS group similar to that of LGPIN group (P = 0.476). 5-MC levels of HGPIN group was lower than that PCTs group (P = 0.004). CONCLUSIONS We found that global DNA methylation was low in most prostate cancer compared with benign regions from the same patient's sections. None of the DNA hypomethylation changes in primary cancers were associated with pathologic grade and clinical prognosis. In addition, immunohistochemistry showed that the global methylation was lower in HGPIN compared with LGPIN and methylcytosine staining in HGPIN was lower than that of PCTs. The results suggest that global DNA hypomethylation might play an important role in the process of prostate cancer initiation rather than progression.
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Affiliation(s)
- Bo Yang
- Department of Urology, Xijing Hospital, Fourth Military Medical University, State Key Laboratory of Cancer Biology, Shaanxi, 710032, 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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