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Maka E, Csákány B, Tóth J. Bilateral Retinoblastoma Presenting with Unilateral Phthisis. J Pediatr Ophthalmol Strabismus 2009. [PMID: 19928701 DOI: 10.3928/01913913-20091118-06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 06/12/2009] [Indexed: 11/20/2022]
Abstract
Phthisis of the eye is an uncommon presenting sign of retinoblastoma. The authors report a case of bilateral retinoblastoma in a 14-month-old girl who presented with phthisis of the left eye. Enucleation of the painful left eye was performed. Spontaneously regressed, mostly calcified retinoblastoma was diagnosed. The patient underwent chemoreduction. Plaque radiotherapy and transpupillary thermotherapy were applied on the right side. Subsequent ophthalmoscopic examination revealed lesions showing "cottage-cheese" regression. Retinoblastoma should be suspected in any child presenting with phthisis bulbi of unknown origin and a detailed examination of the other eye should be performed.
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202
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Kristensen LS, Nielsen HM, Hansen LL. Epigenetics and cancer treatment. Eur J Pharmacol 2009; 625:131-42. [PMID: 19836388 DOI: 10.1016/j.ejphar.2009.10.011] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 09/01/2009] [Accepted: 10/08/2009] [Indexed: 12/17/2022]
Abstract
In addition to the genetic alterations, observed in cancer cells, are mitotically heritable changes in gene expression not encoded by the DNA sequences, which are referred to as epigenetic changes. DNA methylation is among the most studied epigenetic mechanisms together with various histone modifications involved in chromatin remodeling. As opposed to genetic lesions, the epigenetic changes are potentially reversible by a number of small molecules, known as epi-drugs. This review will focus on the biological mechanisms underlying the epigenetic silencing of tumor suppressor genes observed in cancer cells, and the targeted molecular strategies that have been investigated to reverse these aberrations. In particular, we will focus on DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) as epigenetic targets for cancer treatment. A synergistic effect of a combined use of DNMT and HDAC inhibitors has been observed. Moreover, epi-drugs sensitize multiple different cancer cells to a large variety of other treatment strategies. In particular, we have focused on the ability of DNMT and HDAC inhibitors to restore the estrogen receptor alpha (ERalpha) activity in breast cancer. Finally, we will discuss the potential of DNA methylation changes as biomarkers to be used in diverse areas of cancer treatment, especially for predicting response to treatment with DNMT and HDAC inhibitors.
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Affiliation(s)
- Lasse Sommer Kristensen
- Institute of Human Genetics, The Bartholin Building, University of Aarhus, 8000 Aarhus C, Denmark
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203
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Epigenetics: origins and implications for cancer epidemiology. Med Hypotheses 2009; 74:377-82. [PMID: 19818564 DOI: 10.1016/j.mehy.2009.09.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Accepted: 09/06/2009] [Indexed: 11/23/2022]
Abstract
This paper provides information on the evolution of the 'epigenetics' concept since Aristotle and draws attention to the importance of epigenetic implications for cancer epidemiology in the years to come. Clearly, to understand origins of the concept of epigenetics, it is worthwhile to consider historical arguments associated with evolution. Equally clearly, in the last half of the 20th century, great advances in the understanding of epigenetics and, more specifically, great advances in the understanding of epigenetics in cancer have been made. However, reaping the full benefits of epigenetics lies beyond the predominant experimental studies of today. In general, epigenetics opens many doors in the field of cancer, but it also adds another level of complex, inter-related, and multi-dimensional information to research, and to its interpretation. Overall, future cancer studies should consider, or at least be sensitive to, epigenetic effects and mechanisms. Moving the focus beyond 'pristine' inheritance via DNA alone, cancer epidemiology investigating epigenetic exposures such as environmental factors (exposure to heavy metals, air pollution, arsenic and other toxins), dietary patterns (starvation, famine, contamination), and lifestyle habits (smoking, level of physical activity, and BMI) in populations has the prospect to significantly benefit future cancer prevention and treatment schemes.
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204
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205
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Shiota K, Yamada S. Intrauterine environment-genome interaction and children's development (3): Assisted reproductive technologies and developmental disorders. J Toxicol Sci 2009; 34 Suppl 2:SP287-91. [PMID: 19571482 DOI: 10.2131/jts.34.sp287] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In vitro fertilization (IVF) and other assisted reproductive technologies (ART) are widely used clinically as infertility treatments. Although ART procedures are generally considered safe, some studies have suggested an increase in the occurrence of major malformations and some other complications in babies conceived by ART. Further, it has recently been suggested that ART are associated with imprinting disorders in the offspring such as Beckwith-Wiedemann syndrome and Angelman syndrome. We review the human and animal studies investigating the outcome of ART pregnancies and discuss the potential risk of ART to pre- and perinatal development.
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Affiliation(s)
- Kohei Shiota
- Congenital Anomaly Research Center, Kyoto, Japan.
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206
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Abstract
Epigenetic mechanisms are essential for normal development and maintenance of tissue-specific gene expression patterns in mammals. Disruption of epigenetic processes can lead to altered gene function and malignant cellular transformation. Global changes in the epigenetic landscape are a hallmark of cancer. The initiation and progression of cancer, traditionally seen as a genetic disease, is now realized to involve epigenetic abnormalities along with genetic alterations. Recent advancements in the rapidly evolving field of cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer including DNA methylation, histone modifications, nucleosome positioning and non-coding RNAs, specifically microRNA expression. The reversible nature of epigenetic aberrations has led to the emergence of the promising field of epigenetic therapy, which is already making progress with the recent FDA approval of three epigenetic drugs for cancer treatment. In this review, we discuss the current understanding of alterations in the epigenetic landscape that occur in cancer compared with normal cells, the roles of these changes in cancer initiation and progression, including the cancer stem cell model, and the potential use of this knowledge in designing more effective treatment strategies.
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Affiliation(s)
- Shikhar Sharma
- Department of Urology, Biochemistry and Molecular Biology, USC/Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9181, USA
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207
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Abstract
Worldwide use of assisted reproductive technology (ART) accounts for an estimated 1 to 3% of births. Since 2002, a series of reports have suggested an increased risk of imprinting disorders (Beckwith-Wiedemann syndrome and Angelman syndrome) in children conceived by ART. Definitive conclusions are difficult to substantiate due to the rarity of imprinting disorders and the variability in ART protocols. Despite these limitations, there is biological plausibility for alteration in nongenomic inheritance caused by ART. Animal studies have shown that ART procedures can alter normal imprinting, specifically DNA methylation patterns. Collectively, studies suggest an association between ART and loss of maternal methylation. More recent reports examined a possible association between ART and global hypomethylation of DNA. Three other imprinting disorders (Silver-Russell syndrome, maternal hypomethylation syndrome, and retinoblastoma) have also been implicated, but there is insufficient evidence to establish an association of these syndromes with ART. Based on current evidence, the absolute risk of imprinting disorders after ART remains small and does not warrant routine screening. Large prospective studies are needed to better understand the risks associated with imprinting disorders, imprinting defects, and ART.
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Affiliation(s)
- Carter M Owen
- Reproductive Biology and Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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208
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Ohno M, Natsume A, Fujii M, Ito M, Wakabayashi T. Interferon-beta, MCNU, and conventional radiotherapy for pediatric patients with brainstem glioma. Pediatr Blood Cancer 2009; 53:37-41. [PMID: 19260101 DOI: 10.1002/pbc.21987] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Most children with brainstem glioma die within 2 years of diagnosis, and the median survival time for patients with this condition is less than 1 year. The role of chemotherapy in the treatment of children with brainstem glioma is not well defined. The primary aim of this study is to evaluate the effects of treatment with interferon-beta (IFN-beta), ranimustine (MCNU), and radiotherapy (IMR therapy) administered to brainstem glioma patients treated at our institution. We also determined patient response to IMR therapy by evaluating O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation in serum DNA. PROCEDURES We retrospectively reviewed 15 patients who were newly diagnosed to have brainstem tumors and were administered IFN-beta (1-2 MIU/day, days 1-7; 0.5-1 MIU/day, days 8-14) and MCNU (80 mg/m(2) on day 2) concurrently with conventional radiotherapy. Responses were assessed by MRI scan, and data on clinical course and toxicity were obtained from the medical records. The MGMT promoter methylation in serum DNA of five patients was assayed by methylation-specific PCR. RESULTS Of the 15 patients, partial response, stable disease, and progressive disease were noted in 5 patients each. The median overall survival time and the median progression-free survival time were 14.7 and 4.6 months, respectively. The protocol was not terminated in any of the patients because of hematological toxicity, nephrotoxicity, or neurotoxicity. The MGMT promoter methylation status in the serum appeared to correlate with a positive response to IMR therapy. CONCLUSIONS The IMR combination therapy is well tolerated and may be a promising treatment for brainstem glioma.
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Affiliation(s)
- Masasuke Ohno
- Department of Neurosurgery, Nagoya University, Nagoya, Japan
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209
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Abstract
Colorectal cancers (CRC)--and probably all cancers--are caused by alterations in genes. This includes activation of oncogenes and inactivation of tumor suppressor genes (TSGs). There are many ways to achieve these alterations. Oncogenes are frequently activated by point mutation, gene amplification, or changes in the promoter (typically caused by chromosomal rearrangements). TSGs are typically inactivated by mutation, deletion, or promoter methylation, which silences gene expression. About 15% of CRC is associated with loss of the DNA mismatch repair system, and the resulting CRCs have a unique phenotype that is called microsatellite instability, or MSI. This paper reviews the types of genetic alterations that can be found in CRCs and hepatocellular carcinoma (HCC), and focuses upon the epigenetic alterations that result in promoter methylation and the CpG island methylator phenotype (CIMP). The challenge facing CRC research and clinical care at this time is to deal with the heterogeneity and complexity of these genetic and epigenetic alterations, and to use this information to direct rational prevention and treatment strategies.
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Affiliation(s)
- Clement Richard Boland
- Division of Gastroenterology, Department of Internal Medicine, Sammons Cancer Center, Baylor Research Institute, Baylor University Medical Center, 3500 Gaston Avenue, Dallas, TX 75246, USA.
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210
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Iacobuzio-Donahue CA. Epigenetic changes in cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2009; 4:229-49. [PMID: 18840073 DOI: 10.1146/annurev.pathol.3.121806.151442] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cancer is as much an epigenetic disease as it is a genetic disease, and epigenetic alterations in cancer often serve as potent surrogates for genetic mutations. Normal epigenetic modifications of DNA encompass three types of changes: chromatin modifications, DNA methylation, and genomic imprinting, each of which is altered in cancer cells. This review addresses the various epigenetic modifications that are pervasive among human tumors and traces the history of cancer epigenetics from the first observations of altered global methylation content to the recently proposed epigenetic progenitor model, which provides a common unifying mechanism for cancer development.
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211
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Wakabayashi T, Natsume A, Hatano H, Fujii M, Shimato S, Ito M, Ohno M, Ito S, Ogura M, Yoshida J. p16 promoter methylation in the serum as a basis for the molecular diagnosis of gliomas. Neurosurgery 2009; 64:455-61; discussion 461-2. [PMID: 19240607 DOI: 10.1227/01.neu.0000340683.19920.e3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Deoxyribonucleic acid (DNA) methylation of tumor origin can be detected in the serum/plasma of cancer patients. The aim of this study was to detect aberrant p16 promoter methylation as a potential diagnostic marker in the serum of patients with diffuse glioma to differentiate between gliomas and, particularly, to differentiate those in the brainstem from others; this was done by using the modified methylation-specific polymerase chain reaction technique. METHODS The methylation-specific polymerase chain reaction was used to detect p16 methylation in the DNA extracted from 20 astrocytic tumors and 20 oligodendroglial tumors and the corresponding serum samples. Serum samples from 10 healthy individuals were used as controls. The association of p16 hypermethylation in the serum DNA of glioma patients with clinicopathological characteristics was analyzed. In addition, the serum DNA in 7 patients with a brainstem tumor (4 gliomas, 1 schwannoma, 1 cavernous angioma, and 1 ependymoma) was analyzed. RESULTS We found p16 methylation in 12 (60%) of the 20 tissues with astrocytoma, but in only 1 of the tissues with oligodendroglioma. Similar methylations were detected in the serum of 9 (75%) of the 12 patients with aberrant methylation in the tumor tissues. No methylated p16 sequences were detected in the peripheral serum of the patients having tumors without these methylation changes or in the 10 healthy controls. Additionally, p16 promoter methylation in the serum was observed in all brainstem astrocytoma cases, but not in other cases. CONCLUSION This assay has potential for use as a serum-based molecular diagnosis technique for diffuse glioma.
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Affiliation(s)
- Toshihiko Wakabayashi
- Center for Genetic and Regenerative Medicine, Nagoya University Hospital, Nagoya, Japan
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212
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Abstract
Recently, it has been shown that epigenetic changes are involved in early stages of tumorigenesis, and they may trigger the genetic events leading to tumor development. In cancer epidemiology, there are several epigenetic alterations involved, such as DNA hypermethylation, DNA hypomethylation, and chromatin modifications with critical roles in the initiation and progression of human neoplasms. This chapter discusses the hypermethylation profiles of several tumor types, including bladder, brain, breast, colorectal, ovarian, prostate, and other cancers as well as DNA hypomethylation phenomena together with the chromatin modifications and their role in the complex mechanism of epigenetic silencing. Moreover, the involvement of environmental exposures in cancer susceptibility is addressed. In conclusion, these epigenetic changes are important characteristics of human neoplasia, and a better understanding of these modifications and the link between these changes for each tumor type will be important in early diagnosis of cancer and cancer prevention.
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Affiliation(s)
- Ramona G Dumitrescu
- Georgetown University Medical Center, Lombardi Cancer Center, Washington, DC, USA
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213
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Malekzadeh K, Sobti RC, Nikbakht M, Shekari M, Hosseini SA, Tamandani DK, Singh SK. Methylation patterns of Rb1 and Casp-8 promoters and their impact on their expression in bladder cancer. Cancer Invest 2009; 27:70-80. [PMID: 19160091 DOI: 10.1080/07357900802172085] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aberrant methylation of the promoter CpG island of human genes is an alternative gene inactivation mechanisms that contributes to the carcinogenesis of human tumors. We tried to determine the methylation status and its impact on the expression of two tumor related genes Casp-8 and Rb1 in 103 bladder tumor tissues and 48 control paraffin-embedded tissues by using MSP-PCR and SQRT-PCR. Of the patients, 19.4% for Casp-8 and 28.2% for Rb1 showed methylation in bladder cancer. There were significant differences between patients and healthy controls in methylation of Rb1 (p = 0.001) and Casp-8 (p = 0.008) and especially when both genes methylated (p = 0.004). Methylation of Casp-8 has mostly been taken places in patients with age >60 years (p = 0.013) whereas methylation of Rb1 has taken place in age >60 (p = 0.018) as well as in patients age <60 (p = 0.027). Patients with methylated of both genes with stage T2 showed an increasing risk of 4.75 fold (95% CI = 2.87-7.85, p = 0.00) and for stage T3, 23.50 fold (95% CI = 6.05-91.21, p = 0.00) of bladder cancer. Smoking showed a high significant effect on methylation (p = 0.00 in compare to non-smoker patients), especially in those with pack-years more than 44.7 (OR = 3.53, 95% CI = 1.69-7.35, p = 0.001). The risk of bladder cancer was marginally associated in drinker patients (OR = 1.78, 95% CI = 1.42-2.24, p = 0.010) featuring both genes methylated, especially in those patients consumed alcohol units>30 per week (OR = 4.57, 95% CI = 2.38-8.80, p = 0.000). Significant reduction in expression has been detected in patients with methylated Rb1 (p = 0.00) and Casp-8 (p = 0.03). These results suggest that age, smoking and drinking will increase the probability of methylation of these genes and consequently increased risk of developing of bladder cancer to higher stages of disease. Interestingly, it has been deduced that methylation by itself maybe significantly have a role on reducing the expression ofRb1, but it seems that methylation along with risk factors lead to decrease the expression of Casp-8. Methylation of Rb1 can be considered as one of prognosis indicator for progression and development bladder cancer.
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214
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215
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Manipalviratn S, DeCherney A, Segars J. Imprinting disorders and assisted reproductive technology. Fertil Steril 2009; 91:305-15. [PMID: 19201275 PMCID: PMC3081604 DOI: 10.1016/j.fertnstert.2009.01.002] [Citation(s) in RCA: 253] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Accepted: 01/06/2009] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To review currently available literature on the association between imprinting disorders (Beckwith-Wiedemann syndrome [BWS], Angelman syndrome [AS] and retinoblastoma) and assisted reproductive technology (ART) in humans. DESIGN Publications related to imprinting/epigenetic disorders including BWS, AS, and retinoblastoma with ART, as well as articles publishing outcome of ART, including IVF and ICSI from July 1978 to February 2008, were identified using PubMed, Medline, and EMBASE. RESULT(S) Considerable evidence in animal studies has demonstrated alteration in gene imprinting of embryos cultured in vitro. Publications from Europe, the United States, and Australia have suggested an association between ART and BWS. Importantly, more than 90% of children with BWS that were born after ART had imprinting defects, compared with 40%-50% of children with BWS and conceived without ART. Moreover, there have been other reports suggesting an association between AS and ART. The majority of children with AS born after ART had an imprinting defect as the underlying etiology, specifically loss of methylation of the maternal allele. There was a single report suggesting an increased incidence of retinoblastoma in children conceived with ART. CONCLUSION(S) Because the absolute incidence of imprinting disorders is small (<1:12,000 births), routine screening for imprinting disorders in children conceived by ART is not recommended. Additional large cohort studies of children born after ART are needed to determine whether there is a genuine association between ART and imprinting disorders.
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Affiliation(s)
- Somjate Manipalviratn
- Reproductive Biology and Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Alan DeCherney
- Reproductive Biology and Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - James Segars
- Reproductive Biology and Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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216
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Hesson LB, Krex D, Latif F. Epigenetic markers in human gliomas: prospects for therapeutic intervention. Expert Rev Neurother 2008; 8:1475-96. [PMID: 18928342 DOI: 10.1586/14737175.8.10.1475] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gliomas represent the most common CNS cancers in adults. Prognosis for patients harboring malignant gliomas is particularly dismal and, despite current treatment strategies comprising surgery, radiotherapy and chemotherapy, the median survival time after diagnosis is still in the range of just 12 months. In recent years, there has been an increased effort to identify tumor biomarkers that can be used as diagnostic tools, or markers for predicting therapeutic response and prognosis. Investigation of genetic changes has identified several such markers that have shown some success in predicting the most effective therapy. In recent years, however, it has become apparent that the biology of many cancers of the CNS is determined not only by their genetic profile but also their epigenetic profile. Epigenetic biomarkers show great potential in effectively predicting patient prognosis and response to therapy. The eventual application of epigenetic profiling of tumors may help to indicate the most effective tailored therapy for individual patients.
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Affiliation(s)
- Luke B Hesson
- Department of Reproductive and Child Health, Institute of Biomedical Research, Medical School, University of Birmingham, Edgbaston, B15 2TT, UK.
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217
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Novak P, Jensen T, Oshiro MM, Watts GS, Kim CJ, Futscher BW. Agglomerative epigenetic aberrations are a common event in human breast cancer. Cancer Res 2008; 68:8616-25. [PMID: 18922938 DOI: 10.1158/0008-5472.can-08-1419] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Changes in DNA methylation patterns are a common characteristic of cancer cells. Recent studies suggest that DNA methylation affects not only discrete genes, but it can also affect large chromosomal regions, potentially leading to LRES. It is unclear whether such long-range epigenetic events are relatively rare or frequent occurrences in cancer. Here, we use a high-resolution promoter tiling array approach to analyze DNA methylation in breast cancer specimens and normal breast tissue to address this question. We identified 3,506 cancer-specific differentially methylated regions (DMR) in human breast cancer with 2,033 being hypermethylation events and 1,473 hypomethylation events. Most of these DMRs are recurrent in breast cancer; 90% of the identified DMRs occurred in at least 33% of the samples. Interestingly, we found a nonrandom spatial distribution of aberrantly methylated regions across the genome that showed a tendency to concentrate in relatively small genomic regions. Such agglomerates of hypermethylated and hypomethylated DMRs spanned up to several hundred kilobases and were frequently found at gene family clusters. The hypermethylation events usually occurred in the proximity of the transcription start site in CpG island promoters, whereas hypomethylation events were frequently found in regions of segmental duplication. One example of a newly discovered agglomerate of hypermethylated DMRs associated with gene silencing in breast cancer that we examined in greater detail involved the protocadherin gene family clusters on chromosome 5 (PCDHA, PCDHB, and PCDHG). Taken together, our results suggest that agglomerative epigenetic aberrations are frequent events in human breast cancer.
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Affiliation(s)
- Petr Novak
- Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724, USA
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218
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DNA methylation, epimutations and cancer predisposition. Int J Biochem Cell Biol 2008; 41:34-9. [PMID: 18835361 DOI: 10.1016/j.biocel.2008.09.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 09/09/2008] [Accepted: 09/10/2008] [Indexed: 12/11/2022]
Abstract
Hereditary cancer syndromes caused by germline mutations give rise to distinct spectra of cancers with characteristic clinico-pathological features. Many of these hereditary cancer genes are silenced by methylation in a similar spectrum of sporadic cancers. It is likely that the initiating event in some of those cases of sporadic cancer is the somatic epigenetic inactivation (epimutation) of the same hereditary cancer gene. Recently, it has been shown that epimutations of certain hereditary cancer genes can be constitutional i.e. present throughout the soma. These epimutations may be inherited or arise very early in the germline. The heritability of these epimutations is very low as in most cases they are erased by passage through the germline. In other cases, predisposition to epimutations rather than the epimutations themselves can be inherited. These cases are characterised by Mendelian inheritance and are likely to be associated with sequence variants. Other sequence variants and environmental influences may also affect methylation propensity at a global level.
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219
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Abstract
Deregulation of gene expression is a hallmark of cancer. Although genetic lesions have been the focus of cancer research for many years, it has become increasingly recognized that aberrant epigenetic modifications also play major roles in the tumorigenic process. These modifications are imposed on chromatin, do not change the nucleotide sequence of DNA, and are manifested by specific patterns of gene expression that are heritable through many cell divisions. We review these modifications in normal and cancer cells and the evolving approaches used to study them. Additionally, we outline advances in their potential use for cancer diagnostics and targeted epigenetic therapy.
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Affiliation(s)
- Einav Nili Gal-Yam
- Department of Urology, Biochemistry and Molecular Biology, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles 90089, USA
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220
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Goel A, Shin SK. CpG Island methylator phenotype in colorectal cancer: A current perspective. CURRENT COLORECTAL CANCER REPORTS 2008. [DOI: 10.1007/s11888-008-0014-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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221
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Hackenberg M, Matthiesen R. Annotation-Modules: a tool for finding significant combinations of multisource annotations for gene lists. Bioinformatics 2008; 24:1386-93. [PMID: 18434345 DOI: 10.1093/bioinformatics/btn178] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Michael Hackenberg
- Bioinformatics Group, CIC bioGUNE, CIBER-HEPAD, Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain.
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222
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Mulero-Navarro S, Esteller M. Epigenetic biomarkers for human cancer: the time is now. Crit Rev Oncol Hematol 2008; 68:1-11. [PMID: 18430583 DOI: 10.1016/j.critrevonc.2008.03.001] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 02/25/2008] [Accepted: 03/05/2008] [Indexed: 12/22/2022] Open
Abstract
The importance of epigenetic processes in the development of cancer is clear. The study of epigenetics is therefore bound to contribute to the improvement of human health. Aberrations in DNA methylation, post-translational modifications of histones, chromatin remodeling and microRNAs patterns are the main epigenetic alterations, and these are associated with tumorigenesis. Epigenetic technologies in cancer studies are helping increase the number of cancer candidate genes and allow us to examine changes in 5-methylcytosine DNA and histone modifications at a genome-wide level. In fact, all the various cellular pathways contributing to the neoplastic phenotype are affected by epigenetic genes in cancer. They are being explored as biomarkers in clinical use for early detection of disease, tumor classification and response to treatment with classical chemotherapy agents, target compounds and epigenetic drugs. Encouraging results have been obtained with histone deacetylase and DNA methyltransferase inhibitors, leading the US Food and Drug Administration to approve several of them for the treatment of hematological malignancies and lymphoproliferative disorders, such as myelodysplastic syndrome and cutaneous lymphoma. However, many tasks remains to be done, such as the clinical validation of epigenetic biomarkers to allow the accurate prediction of the outcome of cancer patients and their potential chemosensitivity to current pharmacological treatments.
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Affiliation(s)
- Sonia Mulero-Navarro
- Cancer Epigenetics and Biology Program (PEBC), Catalan Institute of Oncology (ICO), Hospital Duran i Reynals, Avinguda Gran Via s/n Km 2.7, E-08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain
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223
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Sun L, Huang L, Nguyen P, Bisht KS, Bar-Sela G, Ho AS, Bradbury CM, Yu W, Cui H, Lee S, Trepel JB, Feinberg AP, Gius D. DNA methyltransferase 1 and 3B activate BAG-1 expression via recruitment of CTCFL/BORIS and modulation of promoter histone methylation. Cancer Res 2008; 68:2726-35. [PMID: 18413740 PMCID: PMC2733164 DOI: 10.1158/0008-5472.can-07-6654] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In a previous genomic analysis, using somatic methyltransferase (DNMT) knockout cells, we showed that hypomethylation decreased the expression of as many genes as were observed to increase, suggesting a previously unknown mechanism for epigenetic regulation. To address this idea, the expression of the BAG family genes was used as a model. These genes were used because their expression was decreased in DNMT1(-/-), DNMT3B(-/-), and double knockout cells and increased in DNMT1-overexpressing and DNMT3B-overexpressing cells. Chromatin immunoprecipitation analysis of the BAG-1 promoter in DNMT1-overexpressing or DNMT3B-overexpressing cells showed a permissive dimethyl-H3-K4/dimethyl-H3-K9 chromatin status associated with DNA-binding of CTCFL/BORIS, as well as increased BAG-1 expression. In contrast, a nonpermissive dimethyl-H3-K4/dimethyl-H3-K9 chromatin status was associated with CTCF DNA-binding and decreased BAG-1 expression in the single and double DNMT knockout cells. BORIS short hairpin RNA knockdown decreased both promoter DNA-binding, as well as BAG-1 expression, and changed the dimethyl-H3-K4/dimethyl-H3-K9 ratio to that characteristic of a nonpermissive chromatin state. These results suggest that DNMT1 and DNMT3B regulate BAG-1 expression via insulator protein DNA-binding and chromatin dynamics by regulating histone dimethylation.
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Affiliation(s)
- Lunching Sun
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Lei Huang
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Phuongmai Nguyen
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Kheem S. Bisht
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Gil Bar-Sela
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Allen S. Ho
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - C. Matthew Bradbury
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Wenqiang Yu
- Department of Medicine and Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hengmi Cui
- Department of Medicine and Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sunmin Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Jane B. Trepel
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
| | - Andrew P. Feinberg
- Department of Medicine and Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David Gius
- Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland
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224
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Affiliation(s)
- Manel Esteller
- Cancer Epigenetics Laboratory, Spanish National Cancer Research Center, Madrid, Spain.
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225
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Yideng J, Zhihong L, Jiantuan X, Jun C, Guizhong L, Shuren W. Homocysteine-Mediated PPARα,γ DNA Methylation and Its Potential Pathogenic Mechanism in Monocytes. DNA Cell Biol 2008; 27:143-50. [PMID: 18004978 DOI: 10.1089/dna.2007.0658] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Jiang Yideng
- Department of Pathophysiology, Ningxia Medical College, Yinchuan, Ningxia, PR China.
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226
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Linhart HG, Lin H, Yamada Y, Moran E, Steine EJ, Gokhale S, Lo G, Cantu E, Ehrich M, He T, Meissner A, Jaenisch R. Dnmt3b promotes tumorigenesis in vivo by gene-specific de novo methylation and transcriptional silencing. Genes Dev 2007; 21:3110-22. [PMID: 18056424 PMCID: PMC2081977 DOI: 10.1101/gad.1594007] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Accepted: 10/11/2007] [Indexed: 01/28/2023]
Abstract
Increased methylation of CpG islands and silencing of affected target genes is frequently found in human cancer; however, in vivo the question of causality has only been addressed by loss-of-function studies. To directly evaluate the role and mechanism of de novo methylation in tumor development, we overexpressed the de novo DNA methyltransferases Dnmt3a1 and Dnmt3b1 in Apc Min/+ mice. We found that Dnmt3b1 enhanced the number of colon tumors in Apc Min/+ mice approximately twofold and increased the average size of colonic microadenomas, whereas Dnmt3a1 had no effect. The overexpression of Dnmt3b1 caused loss of imprinting and increased expression of Igf2 as well as methylation and transcriptional silencing of the tumor suppressor genes Sfrp2, Sfrp4, and Sfrp5. Importantly, we found that Dnmt3b1 but not Dnmt3a1 efficiently methylates the same set of genes in tumors and in nontumor tissues, demonstrating that de novo methyltransferases can initiate methylation and silencing of specific genes in phenotypically normal cells. This suggests that DNA methylation patterns in cancer are the result of specific targeting of at least some tumor suppressor genes rather than of random, stochastic methylation followed by clonal selection due to a proliferative advantage caused by tumor suppressor gene silencing.
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Affiliation(s)
- Heinz G. Linhart
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Haijiang Lin
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Yasuhiro Yamada
- Department for Tumor Pathology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Eva Moran
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Eveline J. Steine
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Sumita Gokhale
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Grace Lo
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Erika Cantu
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | - Timothy He
- Novartis Institutes for BioMedical Research, Inc., Cambridge, Massachusetts 02139, USA
| | - Alex Meissner
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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227
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Fujimura S, Matsui T, Kuwahara K, Maeda K, Sakaguchi N. Germinal center B-cell-associated DNA hypomethylation at transcriptional regions of the AID gene. Mol Immunol 2007; 45:1712-9. [PMID: 17996946 DOI: 10.1016/j.molimm.2007.09.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Accepted: 09/27/2007] [Indexed: 11/30/2022]
Abstract
T-cell-dependent antigen induces differentiation of germinal center (GC) B-cell in peripheral lymphoid follicles. We studied whether GC B-cell differentiation is associated with DNA methylation status by examining regulatory regions of mouse AID transcription that are essential for B-cell maturation. AID-negative cell lines of pre-B cells, immature B cells, mature B cells, plasmacytomas or T cells showed various hypermethylation profiles in the 5'-promoter and intronic regions. In contrast, AID-positive GC-type B cells were hypomethylated in these regions. Stimulation of splenic B cells with lipopolysaccharide and interleukin-4 caused DNA hypomethylation in the 5'-promoter and intronic CpG sites proportional to the increase in AID transcription. Mature GL7+Fas+ GC B cells were hypomethylated at these CpG sites, especially near the Pax5-consensus site and an intronic site. However, Syndecan-1+ plasma cells showed DNA hypermethylation, as seen in plasmacytomas. Methylation status of the transcriptional regulatory region might contribute to stage-dependent activation of AID transcription during GC B-cell differentiation.
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Affiliation(s)
- Satoru Fujimura
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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228
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Abstract
Genetic and epigenetic mechanisms contribute to the development of human tumors. However, the conventional analysis of neoplasias has preferentially focused on only one of these processes. This approach has led to a biased, primarily genetic view, of human tumorigenesis. Epigenetic alterations, such as aberrant DNA methylation, are sufficient to induce tumor formation, and can modify the incidence, and determine the type of tumor which will arise in genetic models of cancer. These observations raise important questions about the degree to which genetic and epigenetic mechanisms cooperate in human tumorigenesis, the identity of the specific cooperating genes and how these genes interact functionally to determine the diverse biological and clinical paths to tumor initiation and progression. These gaps in our knowledge are, in part, due to the lack of methods for full-scale integrated genetic and epigenetic analyses. The ultimate goal to fill these gaps would include sequencing relevant regions of the 3-billion nucleotide genome, and determining the methylation status of the 28-million CpG dinucleotide methylome at single nucleotide resolution in different types of neoplasias. Here, we review the emergence and advancement of technologies to map ever larger proportions of the cancer methylome, and the unique discovery potential of integrating these with cancer genomic data. We discuss the knowledge gained from these large-scale analyses in the context of gene discovery, therapeutic application and building a more widely applicable mechanism-based model of human tumorigenesis.
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Affiliation(s)
- Romulo M Brena
- Department of Molecular Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
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229
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Yideng J, Jianzhong Z, Ying H, Juan S, Jinge Z, Shenglan W, Xiaoqun H, Shuren W. Homocysteine-mediated expression of SAHH, DNMTs, MBD2, and DNA hypomethylation potential pathogenic mechanism in VSMCs. DNA Cell Biol 2007; 26:603-11. [PMID: 17688412 DOI: 10.1089/dna.2007.0584] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Homocysteine (Hcy) is a well-established risk factor for atherosclerosis and may cause dysregulation of gene expression, but the characteristics and the key links involved in its pathogenic mechanisms are still poorly understood. The aim of this study was to explore (i) the effects of Hcy on DNA methylation in vascular smooth muscle cells (VSMCs) and (ii) the underlying mechanism of Hcy-induced changes in DNA methylation patterns in relation to atherosclerosis. We examined the levels of gDNA methylation, namely, the Alu and line-1 element sequences, which can serve as a surrogate marker for gDNA methylation, and also investigated the effects of Hcy on the intracellular S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations as well as the expressions of SAH hydrolase (SAHH), DNA methyltransferase3a (DNMT3a), DNMT3b, and methyl-CpG-binding domain 2 (MBD2). We found that clinically relevant levels of Hcy (0-500 microM) induced elevation of SAH, declination of SAM and SAM/SAH ratio, and reduction in expression of SAHH and MBD2, but increased the activity of DNMT3a and DNMT3b compared to the control group (p < 0.05). We found also that the genome-wide hypomethylation is a common feature of gDNA in the VSMCs cultured with Hcy. In conclusion, these results suggest that Hcy-induced DNA methylation may be an important potential pathogenic mechanism in the development of atherosclerosis, and may become a therapeutic target for preventing Hcy-induced atherosclerosis.
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Affiliation(s)
- Jiang Yideng
- Department of Pathophysiology, West China College of Preclinical and Forensic Medical Sciences, Sichuan University, Chengdu, China
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230
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Moskalyov EA, Eprintsev AT, Hoheisel JD. DNA methylation profiling in cancer: From single nucleotides towards the methylome. Mol Biol 2007. [DOI: 10.1134/s0026893307050068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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231
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He X, Chang S, Zhang J, Zhao Q, Xiang H, Kusonmano K, Yang L, Sun ZS, Yang H, Wang J. MethyCancer: the database of human DNA methylation and cancer. Nucleic Acids Res 2007; 36:D836-41. [PMID: 17890243 PMCID: PMC2238864 DOI: 10.1093/nar/gkm730] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cancer is ranked as one of the top killers in all human diseases and continues to have a devastating effect on the population around the globe. Current research efforts are aiming to accelerate our understanding of the molecular basis of cancer and develop effective means for cancer diagnostics, treatment and prognosis. An altered pattern of epigenetic modifications, most importantly DNA methylation events, plays a critical role in tumorigenesis through regulating oncogene activation, tumor suppressor gene silencing and chromosomal instability. To study interplay of DNA methylation, gene expression and cancer, we developed a publicly accessible database for human DNA Methylation and Cancer (MethyCancer, http://methycancer.genomics.org.cn). MethyCancer hosts both highly integrated data of DNA methylation, cancer-related gene, mutation and cancer information from public resources, and the CpG Island (CGI) clones derived from our large-scale sequencing. Interconnections between different data types were analyzed and presented. Furthermore, a powerful search tool is developed to provide user-friendly access to all the data and data connections. A graphical MethyView shows DNA methylation in context of genomics and genetics data facilitating the research in cancer to understand genetic and epigenetic mechanisms that make dramatic changes in gene expression of tumor cells.
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Affiliation(s)
- Ximiao He
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Suhua Chang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Jiajie Zhang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Qian Zhao
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Haizhen Xiang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Kanthida Kusonmano
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Liu Yang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Zhong Sheng Sun
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Huanming Yang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
| | - Jing Wang
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300, China, Graduate University of the Chinese Academy of Sciences, Yuquan Road 19A, Beijing 100039, China, Bioinformatics Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand, Behavioral Genetics Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 101300, China and James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou 310007, China
- *To whom correspondence should be addressed.+86 10 80485492+86 10 80498676
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232
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Abstract
DNA methylation is the best known and most thoroughly studied epigenetic mechanism. Hypermethylation of CpG islands associated with silencing of tumour suppressor genes or tumour-related genes is a common hallmark of human cancer. The list of tumour-related genes with aberrant hypermethylation in their CpG islands has been increasing. There is also the potential for using DNA methylation profile data as markers for various types of human cancer. In this paper, we review the methylation profile of testicular germ cell tumours (TGCTs). We show that TGCTs have distinctive DNA methylation profiles that differ from those of somatic tissue-derived cancers or somatic tissues. We also discuss the methylation profile of TGCTs in terms of the DNA reprogramming that occurs in primordial germ cells or pre-implantation embryos. Finally, we describe the potential clinical utility of this unique methylation phenotype in TGCTs with regard to developing a novel tumour marker. These data suggest that unmethylated DNA fragments in TGCTs may have diagnostic implications. Further elucidation of epigenetic profiles in TGCTs is expected to provide a new insight into the biology of this disease.
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Affiliation(s)
- Keisei Okamoto
- Department of Urology, Shiga University of Medical Science, Shiga, Japan.
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233
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Yoo CB, Jeong S, Egger G, Liang G, Phiasivongsa P, Tang C, Redkar S, Jones PA. Delivery of 5-aza-2'-deoxycytidine to cells using oligodeoxynucleotides. Cancer Res 2007; 67:6400-8. [PMID: 17616700 DOI: 10.1158/0008-5472.can-07-0251] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The major goal of epigenetic therapy is to reverse aberrant promoter hypermethylation and restore normal function of tumor suppressor genes by the use of chromatin-modifying drugs. Decitabine, or 5-aza-2'-deoxycytidine (5-aza-CdR), is a well-characterized drug that is now Food and Drug Administration approved for the treatment of myelodysplastic syndrome. Although 5-aza-CdR is an extremely potent inhibitor of DNA methylation, it is subject to degradation by hydrolytic cleavage and deamination by cytidine deaminase. We show that short oligonucleotides containing a 5-aza-CdR can also inhibit DNA methylation in cancer cells at concentrations comparable with 5-aza-CdR. Detailed studies with S110, a dinucleotide, showed that it works via a mechanism similar to that of 5-aza-CdR after incorporation of its aza-moiety into DNA. Stability of the triazine ring in aqueous solution was not improved in the S110 dinucleotide; however, deamination by cytidine deaminase was dramatically decreased. This is the first demonstration of the use of short oligonucleotides to provide effective delivery and cellular uptake of a nucleotide drug and protection from enzymatic degradation. This approach may pave the way for more stable and potent inhibitors of DNA methylation as well as provide means for improving existing therapeutics.
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Affiliation(s)
- Christine B Yoo
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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234
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Abdelrazeq AS. Spontaneous regression of colorectal cancer: a review of cases from 1900 to 2005. Int J Colorectal Dis 2007; 22:727-36. [PMID: 17146588 DOI: 10.1007/s00384-006-0245-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/31/2006] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Spontaneous regression of cancer is an exceptional but well-documented biological event. Further understanding of this phenomenon and harnessing of the mechanisms involved will have significant preventative and therapeutic implications. DISCUSSION In this review, the literature of spontaneous regression of colon or rectal cancer is reviewed from 1965 to 2005 to update reviews by Everson et al., Boyd and Challis et al. By adding to these, the author reports the entire series of colorectal cancer, which underwent documented spontaneous regression from 1900 to 2005. The demographic and pathologic characteristics, the details of regression and the outcome of reported cases are presented and discussed. Special emphasis is placed on identifying possible causes hypothesized by authors for occurrence of regression. Possible mechanisms operating to affect these regressions are also discussed.
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Affiliation(s)
- Ayman S Abdelrazeq
- Colorectal Unit, Department of Surgery, Huddersfield Royal Infirmary, Huddersfield, UK.
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235
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Abstract
It is becoming clear that epigenetic changes are involved in human disease as well as during normal development. A unifying theme of disease epigenetics is defects in phenotypic plasticity--cells' ability to change their behaviour in response to internal or external environmental cues. This model proposes that hereditary disorders of the epigenetic apparatus lead to developmental defects, that cancer epigenetics involves disruption of the stem-cell programme, and that common diseases with late-onset phenotypes involve interactions between the epigenome, the genome and the environment. Increased understanding of epigenetic-disease mechanisms could lead to disease-risk stratification for targeted intervention and to targeted therapies.
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Affiliation(s)
- Andrew P Feinberg
- Department of Medicine and Center for Epigenetics, Institute for Basic Biomedical Sciences, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, Maryland 21205, USA.
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236
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Jiang Y, Zhang J, Xiong J, Cao J, Li G, Wang S. Ligands of peroxisome proliferator-activated receptor inhibit homocysteine-induced DNA methylation of inducible nitric oxide synthase gene. Acta Biochim Biophys Sin (Shanghai) 2007; 39:366-76. [PMID: 17492134 DOI: 10.1111/j.1745-7270.2007.00291.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Homocysteine (Hcy) is a risk factor for atherosclerosis. It is generally accepted that inducible nitric oxide synthase (iNOS) is a key enzyme in the regulation of vascular disease. The aim of the present study is to investigate the effects of peroxisome proliferator-activated receptor ligands on iNOS in the presence of Hcy in human monocytes. Foam cells, induced by oxidize low density lipoprotein (ox-LDL) and phorbol myristate acetate (PMA) in the presence of different concentrations of Hcy, clofibrate and pioglitazone in human monocytes for 4 d, were examined by oil red O staining. The activity of iNOS was detected by real-time quantitative reverse transcription-polymerase chain reaction and Western blot analysis. The capability of DNA methylation was measured by assaying endogenous C5 DNA methyltransferase (C5MTase) activity, and the iNOS promoter methylation level was determined by quantitative MethyLight assays. The results indicated that Hcy increased the activity of C5MTase and the level of iNOS gene DNA methylation, resulting in a decrease of iNOS expression. Clofibrate and pioglitazone could antagonize the hcy effect on iNOS expression through DNA methylation, resulting in attenuation of iNOS transcription. These findings suggested that Hcy decreased the expression of iNOS by elevating iNOS DNA methylation levels, which can repress the transcription of some genes. Peroxisome proliferator-activated receptor alpha/gamma ligands can down-regulate iNOS DNA methylation, and could be useful for preventing Hcy-induced atherosclerosis by repressing iNOS expression.
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Affiliation(s)
- Yideng Jiang
- Department of Pathology, Ningxia Medical College, Yinchuan 750004, China.
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237
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Fernández-Gonzalez R, Ramirez MA, Bilbao A, De Fonseca FR, Gutiérrez-Adán A. Suboptimal in vitro culture conditions: an epigenetic origin of long-term health effects. Mol Reprod Dev 2007; 74:1149-56. [PMID: 17474101 DOI: 10.1002/mrd.20746] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The foetal origins of adult diseases or Barker hypothesis suggests that there can be adverse in uterus effects on the foetus that can lead to certain diseases in adults. Extending this hypothesis to the early stages of embryo development, in particular, to preimplantation stages, it was recently demonstrated that, long-term programming of postnatal development, growth and physiology can be irreversibly affected during this period of embryo development by suboptimal in vitro culture (IVC). As an example, it was found in two recent studies that, mice derived from embryos cultured in suboptimal conditions can suffer from obesity, increased anxiety, and deficiencies on their implicit memory system. In addition, it was observed that suboptimal IVC can cause disease in mature animals by promoting alterations in their genetic imprinting during preimplantation development. Imprinting and other epigenetic mechanisms control the establishment and maintenance of gene expression patterns in the embryo, placenta and foetus. The previously described observations, suggest that the loss of epigenetic regulation during preimplantation development may lead to severe long-term effects. Although mostly tested in rodents, the hypothesis that underlies these studies can also fit assisted reproductive technology (ART) procedures in other species, including humans. The lack of information on how epigenetic controls are lost during IVC, and on the long-term consequences of ART, underscore the necessity for sustained epigenetic analysis of embryos produced in vitro and long-term tracking of the health of the human beings conceived using these procedures.
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238
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Abstract
Epigenetic gene inactivation in transformed cells involves many 'belts of silencing'. One of the best-known lesions of the malignant cell is the transcriptional repression of tumor-suppressor genes by promoter CpG island hypermethylation. We are in the process of completing the molecular dissection of the entire epigenetic machinery involved in methylation-associated silencing, such as DNA methyltransferases, methyl-CpG binding domain proteins, histone deacetylases, histone methyltransferases, histone demethylases and Polycomb proteins. The first indications are also starting to emerge about how the combination of cellular selection and targeted pathways leads to abnormal DNA methylation. One thing is certain already, promoter CpG island hypermethylation of tumor-suppressor genes is a common hallmark of all human cancers. It affects all cellular pathways with a tumor-type specific profile, and in addition to classical tumor-suppressor and DNA repair genes, it includes genes involved in premature aging and microRNAs with growth inhibitory functions. The importance of hypermethylation events is already in evidence at the bedside of cancer patients in the form of cancer detection markers and chemotherapy predictors, and in the approval of epigenetic drugs for the treatment of hematological malignancies. In the very near future, the synergy of candidate gene approaches and large-scale epigenomic technologies, such as methyl-DIP, will yield the complete DNA hypermethylome of cancer cells.
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Affiliation(s)
- Manel Esteller
- Cancer Epigenetics Laboratory, Spanish National Cancer Centre (CNIO), Melchor Fernandez Almagro 3, 28029 Madrid, Spain.
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239
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Wersäll PJ, Blomgren H, Pisa P, Lax I, Kälkner KM, Svedman C. Regression of non-irradiated metastases after extracranial stereotactic radiotherapy in metastatic renal cell carcinoma. Acta Oncol 2006; 45:493-7. [PMID: 16760190 DOI: 10.1080/02841860600604611] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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240
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Gutiérrez-Adán A, Perez-Crespo M, Fernandez-Gonzalez R, Ramirez MA, Moreira P, Pintado B, Lonergan P, Rizos D. Developmental Consequences of Sexual Dimorphism During Pre-implantation Embryonic Development. Reprod Domest Anim 2006; 41 Suppl 2:54-62. [PMID: 16984469 DOI: 10.1111/j.1439-0531.2006.00769.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Abnormalities of development potential arising from pre-implantation environment are not limited to in vitro culture (IVC) (for, i.e. in ruminants the large offspring syndrome produced by IVC), they may also be consequence of specific stress conditions experienced in vivo, like maternal diet, toxins, etc. A complex group of mechanisms (gene expression, epigenetic, metabolic, etc.) may operate to link early embryo environment with future health. Furthermore, during the pre-implantation period, in vitro produced male embryos have a higher metabolic rate, they grow faster than females, and they also have differential gene transcription of genes located in the Y-, X-, or in autosomal-chromosomes. As a consequence of these differences embryos may be affected differentially by natural or artificial environmental conditions, depending on their gender. It has been suggested that under some stress conditions male embryos are more vulnerable than females; however the biological fragility of male embryos is poorly understood. Evidences suggest that epigenetic differences produced by the presence of one or two X-chromosomes are the principal cause of the male and female pre-implantation differences, and we put forward the possible role of these early sex differences to control sex ratio of the offspring under different environmental conditions in Nature. By following the differences between male and female early embryos not only may be possible to manipulate sex ratio in farm animals, we can also gain further insight into aspects of early embryo development, X inactivation, and epigenetic and genetic processes related with early development that may have a long-term effect on the offspring.
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241
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Abstract
Epigenetics is the study of genes during development. Gene expression states are set by transcriptional activators and repressors and locked in by cell-heritable chromatin states. Inappropriate expression or repression of genes can change developmental trajectories and result in disease. Aberrant chromatin states leading to aberrant gene expression patterns (epimutations) have been detected in several recognizable syndromes as well as in cancer. They can occur secondary to a DNA mutation in a cis- or trans-acting factor, or as a "true" or primary epimutation in the absence of any DNA sequence change. Primary epimutations often occur after fertilization and lead to somatic mosaicism. It has been estimated that the rate of primary epimutations is one or two orders of magnitude greater than somatic DNA mutation. Therefore, the contribution of epimutations to human disease is probably underestimated.
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Affiliation(s)
- B Horsthemke
- Institut für Humangenetik, Universitätsklinikum Essen, Germany.
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242
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Abstract
Retinoblastoma is the most common primary intraocular tumor in childhood. Mutations in both the alleles of the RB1 gene represent the causative agent for the tumor to occur. It is becoming evident that, although these alterations represent key events in the genesis of retinoblastoma, they are not sufficient per se for the tumor to develop, and other additional genetic or epigenetic alterations must occur. A supportive role in the genesis of retinoblastoma has recently been proposed for the RB1-related gene RB2/p130. Additionally, several other genetic alterations involving different chromosomes have been described as relevant in the tumorigenic process. In this review we will analyse current knowledge about the molecular mechanisms involved in retinoblastoma, paying particular attention to the mechanisms of inactivation of the biological function of the retinoblastoma family of proteins.
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Affiliation(s)
- G De Falco
- Department of Human Pathology and Oncology, University of Siena, Siena, Italy
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243
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Albrecht P, Ansperger-Rescher B, Schüler A, Zeschnigk M, Gallie B, Lohmann DR. Spectrum of gross deletions and insertions in the RB1 gene in patients with retinoblastoma and association with phenotypic expression. Hum Mutat 2006; 26:437-45. [PMID: 16127685 DOI: 10.1002/humu.20234] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Quantitative multiplex PCR and genomic real-time PCR were used to complete an RB1 mutation analysis in 57 of 433 and 72 of 262 patients with hereditary and isolated unilateral retinoblastoma, respectively. These patients were selected because in previous analyses, which focused mainly on the identification of point mutations, no RB1 mutation was found. We identified gross deletions and insertions in peripheral blood DNA from 26 of 57 patients (46%) with hereditary retinoblastoma, and in six of 72 patients (8.3%) with isolated unilateral disease. In addition, we identified 32 somatic mutations in tumor DNA from 31 of 72 patients (43%) with isolated unilateral retinoblastoma. Together with our previous results, we found that gross RB1 alterations were present in the peripheral blood DNA from 65 of 433 (15%) and 17 of 262 (6.5%) patients with bilateral or familial and isolated unilateral retinoblastoma, respectively. Including reported gross deletions, an analysis of the frequency of breakpoints per intron length shows higher densities in introns 13, 16, 23, and 24. Genotype-phenotype analyses showed that on the whole, carriers of gross deletions develop fewer retinoblastomas compared to patients who are heterozygous for other types of RB1 null mutations. Specifically, carriers of cytogenetic and submicroscopic whole gene deletions often have unilateral tumors only. By contrast, almost all patients with gross deletions with one breakpoint in RB1 have bilateral retinoblastoma.
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Affiliation(s)
- P Albrecht
- Institut für Humangenetik, Universität Duisburg-Essen, Essen, Germany
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244
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Deng G, Nguyen A, Tanaka H, Matsuzaki K, Bell I, Mehta KR, Terdiman JP, Waldman FM, Kakar S, Gum J, Crawley S, Sleisenger MH, Kim YS. Regional hypermethylation and global hypomethylation are associated with altered chromatin conformation and histone acetylation in colorectal cancer. Int J Cancer 2006; 118:2999-3005. [PMID: 16425274 DOI: 10.1002/ijc.21740] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Regional DNA hypermethylation and global DNA hypomethylation are 2 epigenetic alterations associated with colorectal cancers. However, their correlation with microsatellite instability (MSI) and chromosomal instability (CIN) in colorectal cancer, and their relationship with chromatin conformation and histone modification are not clear. In this study, we analyzed regional and global methylation in 16 cell lines and 64 primary colorectal cancers. We found that MSI and CIN are 2 alternative events in most cell lines and tumors. Furthermore, regional hypermethylation and global hypomethylation are also alternative events in most cases. We also observed a strong correlation between MSI and regional hypermethylation and between CIN and global hypomethylation. We further analyzed chromatin conformation and histone acetylation in cell lines with CIN or MSI. CIN cancers had open chromatin conformation and enriched histone acetylation in repetitive as well as in gene-specific regions. MSI cancers, on the other hand, had closed chromatin conformation and low levels of histone acetylation. After a MSI cell line was treated with 5-aza-2'-deoxycytidine or trichostatin A, the closed chromatin conformation became open, and histone acetylation was enriched. These observations support our hypothesis that in colorectal cancer, regional hypermethylation and global hypomethylation are associated with altered chromatin conformation and histone acetylation, which might have a causal correlation with MSI and CIN, respectively.
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Affiliation(s)
- Guoren Deng
- Gastrointestinal Research Laboratory, Veteran Affairs Medical Center and Department of Medicine, University of California San Francisco, 94121, USA
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245
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Lin H, Yamada Y, Nguyen S, Linhart H, Jackson-Grusby L, Meissner A, Meletis K, Lo G, Jaenisch R. Suppression of intestinal neoplasia by deletion of Dnmt3b. Mol Cell Biol 2006; 26:2976-83. [PMID: 16581773 PMCID: PMC1446955 DOI: 10.1128/mcb.26.8.2976-2983.2006] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 12/22/2005] [Accepted: 01/11/2006] [Indexed: 12/31/2022] Open
Abstract
Aberrant gene silencing accompanied by DNA methylation is associated with neoplastic progression in many tumors that also show global loss of DNA methylation. Using conditional inactivation of de novo methyltransferase Dnmt3b in Apc(Min/+) mice, we demonstrate that the loss of Dnmt3b has no impact on microadenoma formation, which is considered the earliest stage of intestinal tumor formation. Nevertheless, we observed a significant decrease in the formation of macroscopic colonic adenomas. Interestingly, many large adenomas showed regions with Dnmt3b inactivation, indicating that Dnmt3b is required for initial outgrowth of macroscopic adenomas but is not required for their maintenance. These results support a role for Dnmt3b in the transition stage between microadenoma formation and macroscopic colonic tumor growth and further suggest that Dnmt3b, and by extension de novo methylation, is not required for maintaining tumor growth after this transition stage has occurred.
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Affiliation(s)
- Haijiang Lin
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02141, USA
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246
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Arce C, Segura-Pacheco B, Perez-Cardenas E, Taja-Chayeb L, Candelaria M, Dueñnas-Gonzalez A. Hydralazine target: from blood vessels to the epigenome. J Transl Med 2006; 4:10. [PMID: 16507100 PMCID: PMC1413557 DOI: 10.1186/1479-5876-4-10] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Accepted: 02/28/2006] [Indexed: 12/22/2022] Open
Abstract
Hydralazine was one of the first orally active antihypertensive drugs developed. Currently, it is used principally to treat pregnancy-associated hypertension. Hydralazine causes two types of side effects. The first type is an extension of the pharmacologic effect of the drug and includes headache, nausea, flushing, hypotension, palpitation, tachycardia, dizziness, and salt retention. The second type of side effects is caused by immunologic reactions, of which the drug-induced lupus-like syndrome is the most common, and provides clues to underscoring hydralazine's DNA demethylating property in connection with studies demonstrating the participation of DNA methylation disorders in immune diseases. Abnormalities in DNA methylation have long been associated with cancer. Despite the fact that malignant tumors show global DNA hypomethylation, regional hypermethylation as a means to silence tumor suppressor gene expression has attracted the greatest attention. Reversibility of methylation-induced gene silencing by pharmacologic means, which in turns leads to antitumor effects in experimental and clinical scenarios, has directed efforts toward developing clinically useful demethylating agents. Among these, the most widely used comprise the nucleosides 5-azacytidine and 2'deoxy-5-azacytidine; however, these agents, like current cytotoxic chemotherapy, causes myelosuppression among other side effects that could limit exploitation of their demethylating properties. Among non-nucleoside DNA demethylating drugs currently under development, the oral drug hydralazine possess the ability to reactivate tumor suppressor gene expression, which is silenced by promoter hypermethylation in vitro and in vivo. Decades of extensive hydralazine use for hypertensive disorders that demonstrated hydralazine's clinical safety and tolerability supported its testing in a phase I trial in patients with cancer, confirming its DNA demethylating activity. Hydralazine is currently being evaluated, along with histone deacetylase inhibitors either alone or as adjuncts to chemotherapy and radiation, for hematologic and solid tumors in phase II studies.
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Affiliation(s)
- Claudia Arce
- Division of Clinical Research, Instituto Nacional de Cancerología, Mexico City, Mexico
| | - Blanca Segura-Pacheco
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas (IIB)/Instituto Nacional de Cancerología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Enrique Perez-Cardenas
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas (IIB)/Instituto Nacional de Cancerología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Lucia Taja-Chayeb
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas (IIB)/Instituto Nacional de Cancerología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Myrna Candelaria
- Division of Clinical Research, Instituto Nacional de Cancerología, Mexico City, Mexico
| | - Alfonso Dueñnas-Gonzalez
- Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas (IIB)/Instituto Nacional de Cancerología, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
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247
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Oshiro MM, Futscher BW, Lisberg A, Wozniak RJ, Klimecki WT, Domann FE, Cress AE. Epigenetic regulation of the cell type-specific gene 14-3-3sigma. Neoplasia 2006; 7:799-808. [PMID: 16229802 PMCID: PMC1501934 DOI: 10.1593/neo.05274] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 05/18/2005] [Accepted: 05/20/2005] [Indexed: 11/18/2022] Open
Abstract
Epigenetic control participates in processes crucial in mammalian development, such as X-chromosome inactivation, gene imprinting, and cell type-specific gene expression. We provide evidence that the p53-inducible gene 14-3-3sigma is a new example of a gene important to human cancer, where epigenetic mechanisms participate in the control of normal cell type-specific expression, as well as aberrant gene silencing in cancer cells. Like a previously identified cell type-specific gene maspin, 14-3-3sigma is a p53-inducible gene; however, it participates in G2/M arrest in response to DNA-damaging agents. 14-3-3Sigma expression is restricted to certain epithelial cell types, including breast and prostate, whereas expression is absent in nonepithelial tissues such as fibroblasts and lymphocytes. In this report, we show that in normal cells expressing 14-3-3sigma, the 14-3-3sigma CpG island is unmethylated; associated with acetylated histones, unmethylated histone H3 lysine 9; and an accessible chromatin structure. By contrast, normal cells that do not express 14-3-3sigma have a methylated 14-3-3sigma CpG island with hypoacetylated histones, methylated histone H3 lysine 9, and an inaccessible chromatin structure. These findings extend the spectrum of cell type-specific genes controlled, partly, by normal epigenetic mechanisms, and suggest that this subset of genes may represent important targets of epigenetic dysregulation in human cancer.
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Affiliation(s)
- Marc M Oshiro
- Pharmacology and Toxicology, University of Arizona, Arizona Cancer Center, Tucson, AZ 85724, USA
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248
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Lee H, Yu H. Methylation of Stat1 promoter can contribute to squamous cell carcinogenesis. J Natl Cancer Inst 2006; 98:154-5. [PMID: 16449669 DOI: 10.1093/jnci/djj038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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249
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Rollins RA, Haghighi F, Edwards JR, Das R, Zhang MQ, Ju J, Bestor TH. Large-scale structure of genomic methylation patterns. Genes Dev 2006; 16:157-63. [PMID: 16365381 PMCID: PMC1361710 DOI: 10.1101/gr.4362006] [Citation(s) in RCA: 289] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 09/19/2005] [Indexed: 11/24/2022]
Abstract
The mammalian genome depends on patterns of methylated cytosines for normal function, but the relationship between genomic methylation patterns and the underlying sequence is unclear. We have characterized the methylation landscape of the human genome by global analysis of patterns of CpG depletion and by direct sequencing of 3073 unmethylated domains and 2565 methylated domains from human brain DNA. The genome was found to consist of short (<4 kb) unmethylated domains embedded in a matrix of long methylated domains. Unmethylated domains were enriched in promoters, CpG islands, and first exons, while methylated domains comprised interspersed and tandem-repeated sequences, exons other than first exons, and non-annotated single-copy sequences that are depleted in the CpG dinucleotide. The enrichment of regulatory sequences in the relatively small unmethylated compartment suggests that cytosine methylation constrains the effective size of the genome through the selective exposure of regulatory sequences. This buffers regulatory networks against changes in total genome size and provides an explanation for the C value paradox, which concerns the wide variations in genome size that scale independently of gene number. This suggestion is compatible with the finding that cytosine methylation is universal among large-genome eukaryotes, while many eukaryotes with genome sizes <5 x 10(8) bp do not methylate their DNA.
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Affiliation(s)
- Robert A Rollins
- Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, Columbia University, New York, NY 10032, USA
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250
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Abstract
Genetic, or genomic, instability refers to a series of observed spontaneous genetic changes occurring at an accelerated rate in cell populations derived from the same ancestral precursor. This is far from a new finding, but is one that has increasingly gained more attention in the last decade due to its plausible role(s) in tumorigenesis. The majority of genetic alterations contributing to the malignant transformation are seen in growth regulatory genes, and in genes involved in cell cycle progression and arrest. Genomic instability may present itself through alterations in the length of short repeat stretches of coding and non-coding DNA, resulting in microsatellite instability. Tumors with such profiles are referred to as exhibiting a mutator phenotype, which is largely a consequence of inactivating mutations in DNA damage repair genes. Genomic instability may also, and most commonly, results from gross chromosomal changes, such as translocations or amplifications, which lead to chromosomal instability. Telomere length and telomerase activity, important in maintaining chromosomal structure and in regulating a normal cell's lifespan, have been shown to have a function in both suppressing and facilitating malignant transformation. In addition to such direct sequence and structural changes, gene silencing through the hypermethylation of promoter regions, or increased gene expression through the hypomethylation of such regions, together, form an alternative, epigenetic mechanism leading to instability. Emerging evidence also suggests that dietary and environmental agents can further modulate the contribution of genetic instability to tumorigenesis. Currently, there is still much debate over the distinct classes of genomic instability and their specific roles in the initiation of tumor formation, as well as in the progressive transition to a cancerous state. This review examines the various molecular mechanisms that result in this genomic instability and the potential contribution of the latter to human carcinogenesis.
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Affiliation(s)
- Stavroula Raptis
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5 Canada.
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