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DNMT3B Expression Might Contribute to Abnormal Methylation of RASSF1A in Lager Colorectal Adenomatous Polyps. Gastroenterol Res Pract 2020; 2020:1798729. [PMID: 33061956 PMCID: PMC7547352 DOI: 10.1155/2020/1798729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 08/04/2020] [Accepted: 09/15/2020] [Indexed: 11/17/2022] Open
Abstract
Background It is pretty well known that DNA methyltransferases (DNMTs) are actively involved in abnormal cell growth. The goal of the current study is to explore the correlation between DNMT expression and colorectal adenomatous polyps (CAPs). Method Twenty pairs of CAP samples with a diameter ≥ 10 mm and corresponding normal colorectal mucosa (NCM) tissues from patients were used in the present study. The expression levels and activity of DNA methyltransferases (DNMTs) were measured in the CAP tissues. The global methylation and the promoter methylation level of 3 kinds of tumour suppressor gene were detected. Results mRNA and protein levels of DNMT3B were found to be elevated in the CAP tissues compared with the control tissue. Additionally, the methylation of long interspersed nuclear elements-1 (LINE-1/L1) was decreased in the CAP tissue. Furthermore, methylation of the promoter of a tumour suppressor gene Ras association domain family 1A (RASSF1A) was increased in the CAP tissues, while the mRNA levels of RASSF1A were decreased. Conclusions These results suggest that the overexpression of DNMT3B may contribute to a role in the genesis of CAPs through the hypomethylation of chromosomes in the whole cell and promoter hypermethylation of RASSF1A.
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Zeggar HR, How-Kit A, Daunay A, Bettaieb I, Sahbatou M, Rahal K, Adouni O, Gammoudi A, Douik H, Deleuze JF, Kharrat M. Tumor DNA hypomethylation of LINE-1 is associated with low tumor grade of breast cancer in Tunisian patients. Oncol Lett 2020; 20:1999-2006. [PMID: 32724446 PMCID: PMC7377197 DOI: 10.3892/ol.2020.11745] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 05/19/2020] [Indexed: 12/24/2022] Open
Abstract
DNA hypomethylation of long interspersed repetitive DNA retrotransposon (LINE-1) and Alu repeats elements of short interspersed elements family (SINEs) is an early event in carcinogenesis that causes transcriptional activation and leads to chromosomal instability. In the current study, DNA methylation levels of LINE-1 and Alu repeats were analyzed in tumoral tissues of invasive breast cancer in a Tunisian cohort and its association with the clinicopathological features of patients was defined. DNA methylation of LINE-1 and Alu repeats were analyzed using pyrosequencing in 61 invasive breast cancers. Median values observed for DNA methylation of LINE-1 and Alu repeats were considered as the cut-off (59.81 and 18.49%, respectively). The results of the current study demonstrated a positive correlation between DNA methylation levels of LINE-1 and Alu repeats (rho=0.284; P<0.03). DNA hypomethylation of LINE-1 was also indicated to be associated with low grade (P=0.023). To the best of our knowledge, the current study is the first study regarding DNA methylation of LINE-1 and Alu repeats element in breast cancer of the Tunisian population. The results of the current study suggest that, since hypomethylation of LINE-1 is associated with low grade, it could be used as a biomarker for prognosis for patients with breast cancer.
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Affiliation(s)
- Hayet Radia Zeggar
- University of Tunis El Manar, Faculty of Medicine of Tunis, LR99ES10 Human Genetics Laboratory, 1007 Tunis, Tunisia
| | - Alexandre How-Kit
- Laboratoire de Génomique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
| | - Antoine Daunay
- Laboratoire de Génomique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
| | - Ilhem Bettaieb
- Department of Immunohistocytology, Salah Azaïz Cancer Institute, 1006 Tunis, Tunisia
| | - Mourad Sahbatou
- Laboratoire de Biostatistique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
| | - Khaled Rahal
- Service de Chirurgie Carcinologique, Institut Salah Azaiz de Tunis, 1006 Tunis, Tunisia
| | - Olfa Adouni
- Department of Immunohistocytology, Salah Azaïz Cancer Institute, 1006 Tunis, Tunisia
| | - Amor Gammoudi
- Department of Immunohistocytology, Salah Azaïz Cancer Institute, 1006 Tunis, Tunisia
| | - Hayet Douik
- University of Tunis El Manar, Faculty of Medicine of Tunis, LR99ES10 Human Genetics Laboratory, 1007 Tunis, Tunisia
| | - Jean-François Deleuze
- Laboratoire de Génomique, Fondation Jean Dausset-CEPH, Centre d'Etude du Polymorphisme Humain, 75010 Paris, France
- Centre National de Recherche en Génomique Humaine, CEA, Le Commissariat à l'énergie atomique et aux énergies alternatives-Institut François Jacob, 92265 Evry, France
| | - Maher Kharrat
- University of Tunis El Manar, Faculty of Medicine of Tunis, LR99ES10 Human Genetics Laboratory, 1007 Tunis, Tunisia
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Rhee YY, Kim KJ, Kang GH. CpG Island Methylator Phenotype-High Colorectal Cancers and Their Prognostic Implications and Relationships with the Serrated Neoplasia Pathway. Gut Liver 2017; 11:38-46. [PMID: 27885175 PMCID: PMC5221859 DOI: 10.5009/gnl15535] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 03/29/2016] [Indexed: 12/20/2022] Open
Abstract
The concept of a CpG island methylator phenotype (CIMP) was first introduced by Toyota and Issa to describe a subset of colorectal cancers (CRCs) with concurrent hypermethylation of multiple CpG island loci. The concept of CIMP as a molecular carcinogenesis mechanism was consolidated by the identification of the serrated neoplasia pathway, in which CIMP participates in the initiation and progression of serrated adenomas. Distinct clinicopathological and molecular features of CIMP-high (CIMP-H) CRCs have been characterized, including proximal colon location, older age of onset, female preponderance, and frequent associations of high-level microsatellite instability and BRAF mutations. CIMP-H CRCs arise in sessile or traditional serrated adenomas and thus tend to display the morphological characteristics of serrated adenomas, including epithelial serration, vesicular nuclei, and abundant cytoplasm. Both the frequent association of CIMP and poor prognosis and different responses of CRCs to adjuvant therapy depending on CIMP status indicate clinical implications. In this review, we present an overview of the literature documenting the relevant findings of CIMP-H CRCs and their relationships with the serrated neoplasia pathway.
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Affiliation(s)
- Ye-Young Rhee
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
| | - Kyung-Ju Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
| | - Gyeong Hoon Kang
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
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Bae JM, Kim JH, Kang GH. Molecular Subtypes of Colorectal Cancer and Their Clinicopathologic Features, With an Emphasis on the Serrated Neoplasia Pathway. Arch Pathol Lab Med 2017; 140:406-12. [PMID: 27128298 DOI: 10.5858/arpa.2015-0310-ra] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CONTEXT -Colorectal cancer is a heterogeneous disease entity with 3 molecular carcinogenesis pathways and 2 morphologic multistep pathways. Right-sided colon cancers and left-sided colon and rectal cancers exhibit differences in their incidence rates according to geographic region, age, and sex. A linear tendency toward increasing frequencies of microsatellite instability-high or CpG island methylator phenotype-high cancers in subsites along the bowel from the rectum to the cecum or the ascending colon accounts for the differences in tumor phenotypes associated with these subsites. The molecular subtypes of colorectal cancers exhibit different responses to adjuvant therapy, which might be responsible for differences in subtype-specific survival. OBJECTIVES -To review the clinicopathologic and molecular features of the molecular subtypes of colorectal cancer generated by combined CpG island methylator phenotype and microsatellite statuses, to integrate these features with the most recent findings in the context of the prognostic implications of molecular subtypes, and to emphasize the necessity of developing molecular markers that enable the identification of adenocarcinomas involving the serrated neoplasia pathway. DATA SOURCES -Based on the authors' own experimental data and a review of the pertinent literature. CONCLUSIONS -Because colorectal cancers arise from 2 different morphologic multistep carcinogenesis pathways with varying contributions from 3 different molecular carcinogenesis pathways, colorectal cancer is a heterogeneous and complex disease. Thus, molecular subtyping of colorectal cancers is an important approach to characterizing their heterogeneity with respect to not only prognosis and therapeutic response but also biology and natural history.
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Affiliation(s)
| | | | - Gyeong Hoon Kang
- From the Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
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Bae JM, Rhee YY, Kim KJ, Wen X, Song YS, Cho NY, Kim JH, Kang GH. Are clinicopathological features of colorectal cancers with methylation in half of CpG island methylator phenotype panel markers different from those of CpG island methylator phenotype-high colorectal cancers? Hum Pathol 2015; 47:85-94. [PMID: 26520418 DOI: 10.1016/j.humpath.2015.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/28/2015] [Accepted: 09/04/2015] [Indexed: 12/23/2022]
Abstract
CpG island methylator phenotype (CIMP)-high (CIMP-H) colorectal cancer (CRC) is defined when a tumor shows methylation at greater than or equal to 60% of CIMP panel markers. Although CRCs with methylation at 50% of panel markers are classified as CIMP-low/CIMP-0 tumors, little is known regarding the clinicopathological and molecular features of CRCs with methylation at 4/8 panel markers (4/8 methylated markers) and whether they are akin to CIMP-H or CIMP-low/CIMP-0 CRCs in terms of their clinicopathological or molecular features. A total of 1164 cases of surgically resected CRC were analyzed for their methylation status in 8 CIMP panel markers, and the frequencies of various clinicopathological and molecular features were compared between CRCs with 0/8, 1/8 to 3/8, 4/8, and 5/8 to 8/8 methylated markers. CRCs with 4/8 methylated markers were closer to CRCs with 5/8 to 8/8 methylated markers in terms of sex distribution, mucin production, serration, nodal metastasis, CK7 expression, CK20 loss, and CDX2 loss frequencies and overall survival rate. CRCs with methylation at 4/8 markers were closer to CRCs with 1/8 to 3/8 methylated markers in terms of less frequent right colon location and poor differentiation. CRCs with 4/8 methylated markers showed the shortest overall survival time compared with CRCs with 0/8, 1/8 to 3/8, 4/8, or 5/8 to 8/8 methylated markers. In terms of clinicopathological and molecular features, CRCs with 4/8 methylated markers appeared to be closer to CIMP-H than to CIMP-low/CIMP-0 and would thus be better classified as CIMP-H if the CRCs require classification into either CIMP-H or CIMP-low/CIMP-0.
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Affiliation(s)
- Jeong Mo Bae
- Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
| | - Ye-Young Rhee
- Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
| | - Kyung Ju Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
| | - Xianyu Wen
- Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea.
| | - Young Seok Song
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea.
| | - Nam-Yun Cho
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea.
| | - Jung Ho Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea
| | - Gyeong Hoon Kang
- Department of Pathology, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea.
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Tiwawech D, Srisuttee R, Rattanatanyong P, Puttipanyalears C, Kitkumthorn N, Mutirangura A. Alu Methylation in Serum from Patients with Nasopharyngeal Carcinoma. Asian Pac J Cancer Prev 2014; 15:9797-800. [DOI: 10.7314/apjcp.2014.15.22.9797] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Park SY, Seo AN, Jung HY, Gwak JM, Jung N, Cho NY, Kang GH. Alu and LINE-1 hypomethylation is associated with HER2 enriched subtype of breast cancer. PLoS One 2014; 9:e100429. [PMID: 24971511 PMCID: PMC4074093 DOI: 10.1371/journal.pone.0100429] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 05/28/2014] [Indexed: 01/31/2023] Open
Abstract
The changes in DNA methylation status in cancer cells are characterized by hypermethylation of promoter CpG islands and diffuse genomic hypomethylation. Alu and long interspersed nucleotide element-1 (LINE-1) are non-coding genomic repetitive sequences and methylation of these elements can be used as a surrogate marker for genome-wide methylation status. This study was designed to evaluate the changes of Alu and LINE-1 hypomethylation during breast cancer progression from normal to pre-invasive lesions and invasive breast cancer (IBC), and their relationship with characteristics of IBC. We analyzed the methylation status of Alu and LINE-1 in 145 cases of breast samples including normal breast tissue, atypical ductal hyperplasia/flat epithelial atypia (ADH/FEA), ductal carcinoma in situ (DCIS) and IBC, and another set of 129 cases of IBC by pyrosequencing. Alu methylation showed no significant changes during multistep progression of breast cancer, although it tended to decrease during the transition from DCIS to IBC. In contrast, LINE-1 methylation significantly decreased from normal to ADH/FEA, while it was similar in ADH/FEA, DCIS and IBC. In IBC, Alu hypomethylation correlated with negative estrogen receptor (ER) status, and LINE-1 hypomethylation was associated with negative ER status, ERBB2 (HER2) amplification and p53 overexpression. Alu and LINE-1 methylation status was significantly different between breast cancer subtypes, and the HER2 enriched subtype had lowest methylation levels. In survival analyses, low Alu methylation status tended to be associated with poor disease-free survival of the patients. Our findings suggest that LINE-1 hypomethylation is an early event and Alu hypomethylation is probably a late event during breast cancer progression, and prominent hypomethylation of Alu and LINE-1 in HER2 enriched subtype may be related to chromosomal instability of this specific subtype.
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Affiliation(s)
- So Yeon Park
- Department of Pathology, Seoul National University College of Medicine, Jongno-gu, Seoul, Korea
- Department of Pathology, Seoul National University Bundang Hospital, Bundang-gu, Seongnam, Gyeonggi, Korea
| | - An Na Seo
- Department of Pathology, Seoul National University Bundang Hospital, Bundang-gu, Seongnam, Gyeonggi, Korea
| | - Hae Yoen Jung
- Department of Pathology, Seoul National University Bundang Hospital, Bundang-gu, Seongnam, Gyeonggi, Korea
| | - Jae Moon Gwak
- Department of Pathology, Seoul National University College of Medicine, Jongno-gu, Seoul, Korea
| | - Namhee Jung
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University, Jongno-gu, Seoul, Korea
| | - Nam-Yun Cho
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University, Jongno-gu, Seoul, Korea
| | - Gyeong Hoon Kang
- Department of Pathology, Seoul National University College of Medicine, Jongno-gu, Seoul, Korea
- Laboratory of Epigenetics, Cancer Research Institute, Seoul National University, Jongno-gu, Seoul, Korea
- * E-mail:
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Puttipanyalears C, Subbalekha K, Mutirangura A, Kitkumthorn N. Alu hypomethylation in smoke-exposed epithelia and oral squamous carcinoma. Asian Pac J Cancer Prev 2014; 14:5495-501. [PMID: 24175848 DOI: 10.7314/apjcp.2013.14.9.5495] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alu elements are one of the most common repetitive sequences that now constitute more than 10% of the human genome and potential targets for epigenetic alterations. Correspondingly, methylation of these elements can result in a genome-wide event that may have an impact in cancer. However, studies investigating the genome-wide status of Alu methylation in cancer remain limited. OBJECTIVES Oral squamous cell carcinoma (OSCC) presents with high incidence in South-East Asia and thus the aim of this study was to evaluate the Alu methylation status in OSCCs and explore with the possibility of using this information for diagnostic screening. We evaluated Alu methylation status in a) normal oral mucosa compared to OSCC; b) peripheral blood mononuclear cells (PBMCs) of normal controls comparing to oral cancer patients; c) among oral epithelium of normal controls, smokers and oral cancer patients. MATERIALS AND METHODS Alu methylation was detected by combined bisulfite restriction analysis (COBRA) at 2 CpG sites. The amplified products were classified into three patterns; hypermethylation ((m)C(m)C), partial methylation (uC(m)C+(m)C(u)C), and hypomethylation ((u)C(u)C). RESULTS The results demonstrate that the %(m)C(m)C value is suitable for differentiating normal and cancer in oral tissues (p=0.0002), but is not significantly observe in PBMCs. In addition, a stepwise decrease in this value was observed in the oral epithelium from normal, light smoker, heavy smoker, low stage and high stage OSCC (p=0.0003). Furthermore, receiver operating characteristic (ROC) curve analyses demonstrated the potential of combined %mC or %(m)C(m)C values as markers for oral cancer detection with sensitivity and specificity of 86.7% and 56.7%, respectively. CONCLUSIONS Alu hypomethylation is likely to be associated with multistep oral carcinogenesis, and might be developed as a screening tool for oral cancer detection.
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Shi X, Zhang Y, Cao B, Lu N, Feng L, Di X, Han N, Luo C, Wang G, Cheng S, Zhang K. Genes involved in the transition from normal epithelium to intraepithelial neoplasia are associated with colorectal cancer patient survival. Biochem Biophys Res Commun 2013; 435:282-8. [PMID: 23628414 DOI: 10.1016/j.bbrc.2013.04.063] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 04/18/2013] [Indexed: 01/31/2023]
Abstract
Whether the heterogeneity in tumor cell morphology and behavior is the consequence of a progressive accumulation of genetic alterations or an intrinsic property of cancer-initiating cells established at initiation remains controversial. The hypothesis of biological predetermination in human cancer was proposed many years ago and states that the biological potency of cancer cells is predestinated in the precancerous stage. The present study aimed to investigate whether the aberrant molecular events occurring in initial cancer stages could eventually influence colorectal cancer (CRC) progression. We analyzed the mRNA and miRNA expression profiles of colorectal normal mucosa, low-grade intraepithelial neoplasia (LIN), high-grade intraepithelial neoplasia (HIN), and adenocarcinoma tissues. Compared with the transitions from LIN to HIN to invasive carcinoma, the transition from normal epithelium to LIN appeared to be associated with greater changes in the number and expression levels of mRNAs and miRNAs, with a differential expression of 2322 mRNAs and 71 miRNAs detected. Utilizing these early molecular changes, a miRNA-hub network analysis showed that 166 genes were identified as targets regulated by 30 miRNAs. Among these genes, a 55-gene signature regulated by 5 miRNAs was shown to be associated with overall survival or disease-free survival in three independent sample sets. Thus, the molecular changes in the transcriptome associated with the transition from normal to intraepithelial neoplasm may influence CRC progression.
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Affiliation(s)
- Xiaoyu Shi
- State Key Laboratory of Molecular Oncology, Cancer Institute (Hospital), Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100021, PR China
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Sirivanichsuntorn P, Keelawat S, Danuthai K, Mutirangura A, Subbalekha K, Kitkumthorn N. LINE-1 and Alu hypomethylation in mucoepidermoid carcinoma. BMC Clin Pathol 2013; 13:10. [PMID: 23510117 PMCID: PMC3610265 DOI: 10.1186/1472-6890-13-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/26/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Mucoepidermoid carcinoma (MEC) can be classified into low-, intermediate-, and high-grade tumors based on its histological features. MEC is mainly composed of three cell types (squamous or epidermoid, mucous and intermediate cells), which correlates with the histological grade and reflects its clinical behavior. Most cancers exhibit reduced methylation of repetitive sequences such as Long INterspersed Element-1 (LINE-1) and Alu elements. However, to date very little information is available on the LINE-1 and Alu methylation status in MEC. The aim of this study was to investigate LINE-1 and Alu element methylation in MEC and compare if key differences in the methylation status exist between the three different cell types, and adjacent normal salivary gland cells, to see if this may reflect the histological grade. METHODS LINE-1 and Alu element methylation of 24 MEC, and 14 normal salivary gland tissues were compared using Combine Bisulfite Restriction Analysis (COBRA). Furthermore, the three different cell types from MEC samples were isolated for enrichment by laser capture microdissection (LCM), essentially to see if COBRA was likely to increase the predictive value of LINE-1 and Alu element methylation. RESULTS LINE-1 and Alu element methylation levels were significantly different (p<0.001) between the cell types, and showed a stepwise decrease from the adjacent normal salivary gland to the intermediate, mucous and squamous cells. The reduced methylation levels of LINE-1 were correlated with a poorer histological grade. In addition, MEC tissue showed a significantly lower level of LINE-1 and Alu element methylation overall compared to normal salivary gland tissue (p<0.001). CONCLUSIONS Our findings suggest that LINE-1 methylation differed among histological grade mucoepidermoid carcinoma. Hence, this epigenetic event may hold value for MEC diagnosis and prognostic prediction.
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Affiliation(s)
- Porntipa Sirivanichsuntorn
- Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330, Thailand.
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Flom JD, Ferris JS, Liao Y, Tehranifar P, Richards CB, Cho YH, Gonzalez K, Santella RM, Terry MB. Prenatal smoke exposure and genomic DNA methylation in a multiethnic birth cohort. Cancer Epidemiol Biomarkers Prev 2011; 20:2518-23. [PMID: 21994404 DOI: 10.1158/1055-9965.epi-11-0553] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Exposure to prenatal tobacco smoke (PTS) has been associated with a number of health outcomes in the offspring, including some childhood cancers. Lower levels of genomic DNA methylation have also been associated with several types of cancers. We investigated whether PTS was associated with global DNA methylation levels in the offspring. METHODS Our sample was drawn from a birth cohort of women born between 1959 and 1963 in New York City (n = 90). We measured methylation of repetitive elements (Sat2, Alu, LINE-1) from peripheral blood granulocytes. We combined prospectively collected data on PTS with adult epidemiologic data and blood samples collected in 2001 to 2007 (mean age, 43 years). We used linear regression to assess the association between PTS and repetitive element methylation. RESULTS Thirty-six percent of mothers smoked during pregnancy. We observed an inverse association between PTS and Sat2 methylation. This inverse association remained even after adjustment for potential mediators including child environmental tobacco smoke exposure, birth size, postnatal weight and height changes, and adult smoking status and alcohol intake (β = -0.22, 95% confidence interval = -0.40 to -0.03 for ever exposed to PTS vs. never exposed using models of log-transformed methylation levels). PTS exposure was not statistically significantly associated with LINE-1 or Alu methylation. CONCLUSIONS PTS exposure, measured at the time of pregnancy and not retrospectively reported, was associated with a decrease in Sat2 methylation but not LINE-1 or Alu methylation. IMPACT If replicated in larger studies, this study supports a persistent effect of PTS on DNA methylation levels, as measured by Sat2, in adulthood.
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Affiliation(s)
- Julie D Flom
- Department of Epidemiology, Columbia University Medical Center, New York, NY, USA
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Sunami E, de Maat M, Vu A, Turner RR, Hoon DSB. LINE-1 hypomethylation during primary colon cancer progression. PLoS One 2011; 6:e18884. [PMID: 21533144 PMCID: PMC3077413 DOI: 10.1371/journal.pone.0018884] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 03/24/2011] [Indexed: 01/12/2023] Open
Abstract
Background Methylation levels of genomic repeats such as long interspersed nucleotide elements (LINE-1) are representative of global methylation status and play an important role in maintenance of genomic stability. The objective of the study was to assess LINE-1 methylation status in colorectal cancer (CRC) in relation to adenomatous and malignant progression, tissue heterogeneity, and TNM-stage. Methodology/Principal Findings DNA was collected by laser-capture microdissection (LCM) from normal, adenoma, and cancer tissue from 25 patients with TisN0M0 and from 92 primary CRC patients of various TNM-stages. The paraffin-embedded tissue sections were treated by in-situ DNA sodium bisulfite modification (SBM). LINE-1 hypomethylation index (LHI) was measured by absolute quantitative analysis of methylated alleles (AQAMA) realtime PCR; a greater index indicated enhanced hypomethylation. LHI in normal, cancer mesenchymal, adenoma, and CRC tissue was 0.38 (SD 0.07), 0.37 (SD 0.09), 0.49 (SD 0.10) and 0.53 (SD 0.08), respectively. LHI was significantly greater in adenoma tissue compared to its contiguous normal epithelium (P = 0.0003) and cancer mesenchymal tissue (P<0.0001). LHI did not differ significantly between adenoma and early cancer tissue of Tis stage (P = 0.20). LHI elevated with higher T-stage (P<0.04), was significantly greater in node-positive than node-negative CRC patients (P = 0.03), and was significantly greater in stage IV than all other disease stages (P<0.05). Conclusion/Significance By using in-situ SBM and LCM cell selection we demonstrated early onset of LINE-1 demethylation during adenomatous change of colorectal epithelial cells and demonstrated that LINE-1 demethylation progression is linear in relation to TNM-stage progression.
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Affiliation(s)
- Eiji Sunami
- Department of Molecular Oncology, John Wayne Cancer Institute, Santa Monica, California, United States of America
| | - Michiel de Maat
- Department of Molecular Oncology, John Wayne Cancer Institute, Santa Monica, California, United States of America
| | - Anna Vu
- Department of Molecular Oncology, John Wayne Cancer Institute, Santa Monica, California, United States of America
| | - Roderick R. Turner
- Department of Surgical Pathology, Saint John's Health Center, Santa Monica, California, United States of America
| | - Dave S. B. Hoon
- Department of Molecular Oncology, John Wayne Cancer Institute, Santa Monica, California, United States of America
- * E-mail:
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Kitkumthorn N, Mutirangura A. Long interspersed nuclear element-1 hypomethylation in cancer: biology and clinical applications. Clin Epigenetics 2011; 2:315-30. [PMID: 22704344 PMCID: PMC3365388 DOI: 10.1007/s13148-011-0032-8] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 03/20/2011] [Indexed: 12/31/2022] Open
Abstract
Epigenetic changes in long interspersed nuclear element-1s (LINE-1s or L1s) occur early during the process of carcinogenesis. A lower methylation level (hypomethylation) of LINE-1 is common in most cancers, and the methylation level is further decreased in more advanced cancers. Consequently, several previous studies have suggested the use of LINE-1 hypomethylation levels in cancer screening, risk assessment, tumor staging, and prognostic prediction. Epigenomic changes are complex, and global hypomethylation influences LINE-1s in a generalized fashion. However, the methylation levels of some loci are dependent on their locations. The consequences of LINE-1 hypomethylation are genomic instability and alteration of gene expression. There are several mechanisms that promote both of these consequences in cis. Therefore, the methylation levels of different sets of LINE-1s may represent certain phenotypes. Furthermore, the methylation levels of specific sets of LINE-1s may indicate carcinogenesis-dependent hypomethylation. LINE-1 methylation pattern analysis can classify LINE-1s into one of three classes based on the number of methylated CpG dinucleotides. These classes include hypermethylation, partial methylation, and hypomethylation. The number of partial and hypermethylated loci, but not hypomethylated LINE-1s, is different among normal cell types. Consequently, the number of hypomethylated loci is a more promising marker than methylation level in the detection of cancer DNA. Further genome-wide studies to measure the methylation level of each LINE-1 locus may improve PCR-based methylation analysis to allow for a more specific and sensitive detection of cancer DNA or for an analysis of certain cancer phenotypes.
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