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Clinical, Pathological, and Molecular Characteristics of CpG Island Methylator Phenotype in Colorectal Cancer: A Systematic Review and Meta-analysis. Transl Oncol 2018; 11:1188-1201. [PMID: 30071442 PMCID: PMC6080640 DOI: 10.1016/j.tranon.2018.07.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/10/2018] [Accepted: 07/10/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND: CpG island methylator phenotype (CIMP) tumors, comprising 20% of colorectal cancers, are associated with female sex, age, right-sided location, and BRAF mutations. However, other factors potentially associated with CIMP have not been robustly examined. This meta-analysis provides a comprehensive assessment of the clinical, pathologic, and molecular characteristics that define CIMP tumors. METHODS: We conducted a comprehensive search of the literature from January 1999 through April 2018 and identified 122 articles, on which comprehensive data abstraction was performed on the clinical, pathologic, molecular, and mutational characteristics of CIMP subgroups, classified based on the extent of DNA methylation of tumor suppressor genes assessed using a variety of laboratory methods. Associations of CIMP with outcome parameters were estimated using pooled odds ratio or standardized mean differences using random-effects model. RESULTS: We confirmed prior associations including female sex, older age, right-sided tumor location, poor differentiation, and microsatellite instability. In addition to the recognized association with BRAF mutations, CIMP was also associated with PIK3CA mutations and lack of mutations in KRAS and TP53. Evidence of an activated immune response was seen with high rates of tumor-infiltrating lymphocytes (but not peritumoral lymphocytes), Crohn-like infiltrates, and infiltration with Fusobacterium nucleatum bacteria. Additionally, CIMP tumors were associated with advance T-stage and presence of perineural and lymphovascular invasion. CONCLUSION: The meta-analysis highlights key features distinguishing CIMP in colorectal cancer, including molecular characteristics of an active immune response. Improved understanding of this unique molecular subtype of colorectal cancer may provide insights into prevention and treatment.
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Zhou Z, Zhang H, Lai J, Diao D, Li W, Dang C, Song Y. Relationships between p14ARF Gene Methylation and Clinicopathological Features of Colorectal Cancer: A Meta-Analysis. PLoS One 2016; 11:e0152050. [PMID: 26999279 PMCID: PMC4801177 DOI: 10.1371/journal.pone.0152050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 03/08/2016] [Indexed: 12/31/2022] Open
Abstract
We conducted a meta-analysis to explore the relationships between p14ARF gene methylation and clinicopathological features of colorectal cancer (CRC). Databases, including Pubmed, Embase and Cochrane Library, were searched and, finally, a total of 18 eligible researches encompassing 1988 CRC patients were selected. Combined odds ratios (ORs) with 95% confidence intervals (95% CIs) were evaluated under a fixed effects model for absence of heterogeneity. Significant associations were observed between p14ARF gene methylation and tumor location (OR = 2.35, 95% CI: 1.55–3.55, P = 0.001), microsatellite instability (MSI) status (OR = 3.28, 95% CI: 2.12–5.07, P<0.0001). However, there were no significant associations between p14ARF gene methylation and tumor stage, tumor differentiation. We concluded that p14ARF gene methylation may be significantly associated with tumor location, and MSI status of CRC.
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Affiliation(s)
- Zhangjian Zhou
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Hao Zhang
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Jianguo Lai
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Dongmei Diao
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Wenhan Li
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Chengxue Dang
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
| | - Yongchun Song
- Division of Surgical Oncology, The First Affiliated Hospital, Xi'an Jiaotong University, 277 W, Yanta Road, Xi'an, 710061, Shaanxi, China
- * E-mail:
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Ladabaum U, Ford JM, Martel M, Barkun AN. American Gastroenterological Association Technical Review on the Diagnosis and Management of Lynch Syndrome. Gastroenterology 2015; 149:783-813.e20. [PMID: 26226576 DOI: 10.1053/j.gastro.2015.07.037] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Uri Ladabaum
- Division of Gastroenterology/Hepatology, Stanford University School of Medicine, Stanford, California
| | - James M Ford
- Division of Oncology, Department of Medicine, Stanford University School of Medicine, Stanford, California
| | - Myriam Martel
- Division of Gastroenterology, McGill University Health Center, McGill University, Montreal, Quebec, Canada
| | - Alan N Barkun
- Division of Gastroenterology, McGill University Health Center, McGill University, Montreal, Quebec, Canada; Division of Epidemiology and Biostatistics and Occupational Health, McGill University Health Center, McGill University, Montreal, Quebec, Canada
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IJspeert JEG, Medema JP, Dekker E. Colorectal neoplasia pathways: state of the art. Gastrointest Endosc Clin N Am 2015; 25:169-82. [PMID: 25839680 DOI: 10.1016/j.giec.2014.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Colorectal cancer (CRC) is a heterogeneous disease and each CRC possesses a unique molecular tumor profile. The main pathways of oncogenesis are the chromosomal instability, microsatellite instability and serrated neoplasia pathway. Sessile serrated adenomas/polyps (SSA/Ps) may be the precursor lesions of CRC arising via the serrated neoplasia pathway. This has led to a paradigm shift because all SSA/Ps should be detected and resected during colonoscopy. The ability to accurately detect and resect only those polyps with a malignant potential could result in safer and cost-effective practice. Optimization of the endoscopic classification systems is however needed to implement targeted prevention methods.
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Affiliation(s)
- Joep Evert Godfried IJspeert
- Department of Gastroenterology and Hepatology, Academic Medical Center, Meibergdreef 9, Room C2-231, Amsterdam 1105 AZ The Netherlands
| | - Jan Paul Medema
- Laboratory for Experimental Oncology and Radiobiology, Center for Experimental Molecular Medicine, Academic Medical Center (AMC), Meibergdreef 9, Room G2-131, Amsterdam 1105 AZ, The Netherlands
| | - Evelien Dekker
- Department of Gastroenterology and Hepatology, Academic Medical Center, Meibergdreef 9, Room C2-115, Amsterdam 1105 AZ, The Netherlands.
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Prognostic and predictive value of CpG island methylator phenotype in patients with locally advanced nonmetastatic sporadic colorectal cancer. Gastroenterol Res Pract 2014; 2014:436985. [PMID: 24822060 PMCID: PMC4005388 DOI: 10.1155/2014/436985] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 12/17/2013] [Indexed: 01/05/2023] Open
Abstract
Purpose. In the present study, the prognostic significance of CpG island methylator phenotype (CIMP) in stage II/III sporadic colorectal cancer was evaluated using a five-gene panel. Methods. Fifty stage II/III colorectal cancer patients who received radical resection were included in this study. Promoter methylation of p14ARF, hMLH1, p16INK4a, MGMT, and MINT1 was determined by methylation specific polymerase chain reaction (MSP). CIMP positive was defined as hypermethylation of three or more of the five genes. Impact factors on disease-free survival (DFS) and overall survival (OS) were analyzed using Kaplan-Meier method (log-rank test) and adjusted Cox proportional hazards model. Results. Twenty-four percent (12/50) of patients were characterized as CIMP positive. Univariate analysis showed stage III (P = 0.049) and CIMP positive (P = 0.014) patients who had significantly inferior DFS. In Cox regression analysis, CIMP positive epigenotype was independently related with poor DFS with HR = 2.935 and 95% CI: 1.193–7.220 (P = 0.019). In patients with CIMP positive tumor, those receiving adjuvant chemotherapy had a poor DFS than those without adjuvant chemotherapy (P = 0.023). Conclusions. CIMP positive was significantly correlated with decreased DFS in stage II/III colorectal cancer. Patients with CIMP positive locally advanced sporadic colorectal cancers may not benefit from 5-fluorouracil based adjuvant chemotherapy.
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Subsets of microsatellite-unstable colorectal cancers exhibit discordance between the CpG island methylator phenotype and MLH1 methylation status. Mod Pathol 2013; 26:1013-22. [PMID: 23370766 DOI: 10.1038/modpathol.2012.241] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 12/11/2012] [Accepted: 12/11/2012] [Indexed: 12/26/2022]
Abstract
Although the presence of MLH1 methylation in microsatellite-unstable colorectal cancer generally indicates involvement of the CpG island methylator phenotype (CIMP) in the development of the tumor, these two conditions do not always correlate. A minority of microsatellite-unstable colorectal cancers exhibit discordance between CIMP and MLH1 methylation statuses. However, the clinicopathological features of such microsatellite-unstable colorectal cancers with discrepant MLH1 methylation and CIMP statuses remain poorly studied. Microsatellite-unstable colorectal cancers (n=220) were analyzed for CIMP and MLH1 methylation statuses using the MethyLight assay. Based on the combinatorial CIMP and MLH1 methylation statuses, the microsatellite-unstable colorectal cancers were grouped into four subtypes (CIMP-high (CIMP-H) MLH1 methylation-positive (MLH1m+), CIMP-H MLH1 methylation-negative, CIMP-low/0 (CIMP-L/0) MLH1m+, and CIMP-L/0 MLH1 methylation-negative), which were compared in terms of their associations with clinicopathological and molecular features. The CIMP-L/0 MLH1 methylation-negative and CIMP-H MLH1m+ subtypes were predominant, comprising 63.6 and 24.1% of total microsatellite-unstable colorectal cancers, respectively. The discordant subtypes, CIMP-H MLH1 methylation-negative and CIMP-L/0 MLH1m+, were found in 5 and 7% of microsatellite-unstable colorectal cancers, respectively. The CIMP-H MLH1 methylation-negative subtype exhibited elevated incidence rates in male patients and was associated with larger tumor size, more frequent loss of MSH2 expression, increased frequency of KRAS mutation, and advanced cancer stage. The CIMP-L/0 MLH1m+ subtype was associated with onset at an earlier age, a predominance of MLH1 loss, and earlier cancer stage. None of the CIMP-L/0 MLH1m+ subtype patients succumbed to death during the follow-up. Our findings suggest that the discordant subtypes of colorectal cancers exhibit distinct clinicopathological and molecular features, although the proportion of discordant subtypes is low. The microsatellite-unstable colorectal cancers of the same CIMP status tended to exhibit different clinicopathological features depending on MLH1 methylation status.
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Li X, Yao X, Wang Y, Hu F, Wang F, Jiang L, Liu Y, Wang D, Sun G, Zhao Y. MLH1 promoter methylation frequency in colorectal cancer patients and related clinicopathological and molecular features. PLoS One 2013; 8:e59064. [PMID: 23555617 PMCID: PMC3612054 DOI: 10.1371/journal.pone.0059064] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 02/12/2013] [Indexed: 02/07/2023] Open
Abstract
Purpose To describe the frequency of MLH1 promoter methylation in colorectal cancer (CRC); to explore the associations between MLH1 promoter methylation and clinicopathological and molecular factors using a systematic review and meta-analysis. Methods A literature search of the PubMed and Embase databases was conducted to identify relevant articles published up to September 7, 2012 that described the frequency of MLH1 promoter methylation or its associations with clinicopathological and molecular factors in CRC. The pooled frequency, odds ratio (OR) and 95% confidence intervals (95% CI) were calculated. Results The pooled frequency of MLH1 promoter methylation in unselected CRC was 20.3% (95% CI: 16.8–24.1%). They were 18.7% (95% CI: 14.7–23.6%) and 16.4% (95% CI: 11.9–22.0%) in sporadic and Lynch syndrome (LS) CRC, respectively. Significant associations were observed between MLH1 promoter methylation and gender (pooled OR = 1.641, 95% CI: 1.215–2.215; P = 0.001), tumor location (pooled OR = 3.804, 95% CI: 2.715–5.329; P<0.001), tumor differentiation (pooled OR = 2.131, 95% CI: 1.464–3.102; P<0.001), MSI (OR: 27.096, 95% CI: 13.717–53.526; P<0.001). Significant associations were also observed between MLH1 promoter methylation and MLH1 protein expression, BRAF mutation (OR = 14.919 (95% CI: 6.427–34.631; P<0.001) and 9.419 (95% CI: 2.613–33.953; P = 0.001), respectively). Conclusion The frequency of MLH1 promoter methylation in unselected CRC was 20.3%. They were 18.7% in sporadic CRC and 16.4% in LS CRC, respectively. MLH1 promoter methylation may be significantly associated with gender, tumor location, tumor differentiation, MSI, MLH1 protein expression, and BRAF mutation.
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Affiliation(s)
- Xia Li
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Xiaoping Yao
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Yibaina Wang
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Fulan Hu
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Fan Wang
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Liying Jiang
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Yupeng Liu
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Da Wang
- Department of Science and Technology Administration, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Guizhi Sun
- Department of Surgery, Cancer Hospital of Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
| | - Yashuang Zhao
- Department of Epidemiology, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, P.R. China
- * E-mail:
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Abstract
Microsatellite instability (MSI) occurs in about 15% of gastrointestinal cancers and it is associated with specific clinic, pathologic, and molecular features of the tumors. MSI-high (MSI-H) carcinomas also follow specific tumor development pathways. This review is focused on the molecular profile of alterations in members of the KRAS signaling pathway (EGFR, KRAS, BRAF, PIK3CA, RASSF1A, and MLK3 genes) in MSI gastrointestinal carcinomas. Alterations in these genes characterize more than half of gastrointestinal cancers and frequently occur simultaneously in the same tumor, pinpointing the KRAS signaling pathway as one of the most frequently altered pathways in this subset of cancers. Nowadays, many and novel inhibitors targeting molecules of this signaling pathway are being described; therefore, it is worthwhile to test their efficacy in MSI gastrointestinal cancers in order to develop new and more directed targeted therapies for patients affected by this disease.
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Ali AHK, Kondo K, Namura T, Senba Y, Takizawa H, Nakagawa Y, Toba H, Kenzaki K, Sakiyama S, Tangoku A. Aberrant DNA methylation of some tumor suppressor genes in lung cancers from workers with chromate exposure. Mol Carcinog 2010; 50:89-99. [PMID: 21229606 DOI: 10.1002/mc.20697] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/25/2010] [Accepted: 09/28/2010] [Indexed: 12/16/2022]
Abstract
Our previous studies revealed a variety of genetic changes in lung cancers from chromate-exposed workers (chromate lung cancer). In the present study, we examined epigenetic changes in chromate lung cancers. Nested-methylation-specific PCR was employed in studying the methylation of CpG islands in the APC, MGMT, hMLH1 genes in 36 chromate lung cancers and 25 nonchromate lung cancers. Methylation in chromate lung cancers was detected at 86% for APC, 20% for MGMT, and 28% for hMLH1. Whereas, it occurred at lower frequencies in nonchromate lung cancers, particularly in APC (44%) and hMLH1 (0%) genes. Our previous study showed that methylation of p16 gene in chromate lung cancer and nonchromate lung cancer was 33% and 26%, respectively. The mean methylation index (MI), a reflection of the overall methylation status, was significantly higher in chromate lung cancers than nonchromate lung cancers (0.41 vs. 0.21, P=0.001). Methylation of multiple genes (particularly hMLH1, p16, and APC genes) had experienced more than 15 yr of chromate exposure in chromate lung cancer (MI: <15 yr; 0.19, ≥ 15 yr, 0.42). There is a significant correlation of p16 and hMLH1 methylation with the expressional decrease or loss of the corresponding gene products (P=0.037 and 0.024) respectively, and an inverse correlation between APC and MGMT methylation (P = 0.014). This study provides a novel evidence for the chromium carcinogenesis that chromate lung cancer is linked to the progressive methylation of some tumor suppressor genes, which may be related to genomic instability.
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Affiliation(s)
- Abdellah H K Ali
- Department of Respiratory Medicine, Sohag Faculty of Medicine, Sohag University, Sohag, Egypt
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Selection of patients with germline MLH1 mutated Lynch syndrome by determination of MLH1 methylation and BRAF mutation. Fam Cancer 2010; 9:167-72. [PMID: 19949877 DOI: 10.1007/s10689-009-9302-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Lynch syndrome is one of the most common hereditary colorectal cancer (CRC) syndrome and is caused by germline mutations of MLH1, MSH2 and more rarely MSH6, PMS2, MLH3 genes. Whereas the absence of MSH2 protein is predictive of Lynch syndrome, it is not the case for the absence of MLH1 protein. The purpose of this study was to develop a sensitive and cost effective algorithm to select Lynch syndrome cases among patients with MLH1 immunohistochemical silencing. Eleven sporadic CRC and 16 Lynch syndrome cases with MLH1 protein abnormalities were selected. The BRAF c.1799T> A mutation (p.Val600Glu) was analyzed by direct sequencing after PCR amplification of exon 15. Methylation of MLH1 promoter was determined by Methylation-Sensitive Single-Strand Conformation Analysis. In patients with Lynch syndrome, there was no BRAF mutation and only one case showed MLH1 methylation (6%). In sporadic CRC, all cases were MLH1 methylated (100%) and 8 out of 11 cases carried the above BRAF mutation (73%) whereas only 3 cases were BRAF wild type (27%). We propose the following algorithm: (1) no further molecular analysis should be performed for CRC exhibiting MLH1 methylation and BRAF mutation, and these cases should be considered as sporadic CRC; (2) CRC with unmethylated MLH1 and negative for BRAF mutation should be considered as Lynch syndrome; and (3) only a small fraction of CRC with MLH1 promoter methylation but negative for BRAF mutation should be true Lynch syndrome patients. These potentially Lynch syndrome patients should be offered genetic counselling before searching for MLH1 gene mutations.
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Hawkins NJ, Lee JHF, Wong JJL, Kwok CT, Ward RL, Hitchins MP. MGMT methylation is associated primarily with the germline C>T SNP (rs16906252) in colorectal cancer and normal colonic mucosa. Mod Pathol 2009; 22:1588-99. [PMID: 19734844 DOI: 10.1038/modpathol.2009.130] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
O(6)-methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that restores mutagenic O(6)-methylguanine to guanine. MGMT methylation is frequently observed in sporadic colorectal cancer and was recently correlated with the C>T allele at SNP rs16906252, within the transcriptional enhancer element of the promoter. MGMT methylation has also been associated with KRAS mutations, particularly G>A transitions. We studied 1123 colorectal carcinoma to define the molecular and clinicopathological profiles associated with MGMT methylation. Furthermore, we assessed factors contributing to MGMT methylation in the development of colorectal cancer by studying the allelic pattern of MGMT methylation using SNP rs16906252, and the methylation status of neighbouring genes within 10q26 in selected tumours and matched normal colonic mucosa. MGMT methylation was detected by combined bisulphite restriction analysis in 28% of tumours and was associated with a number of characteristics, including CDKN2A methylation, absent lymphovascular space invasion and KRAS mutations (but not specifically with KRAS G>A transitions). In a multivariate analysis adjusted for age and sex, MGMT methylation was associated with the T allele of SNP rs16906252 (P<0.0001, OR 5.5, 95% CI 3.8-7.9). Low-level methylation was detected by quantitative methylation-specific PCR in the normal colonic mucosa of cases, particularly those with a correspondingly methylated tumour, as well as controls without neoplasia, and this was also associated with the C>T SNP. We show that the T allele at SNP rs16906252 is a key determinant in the onset of MGMT methylation in colorectal cancer, whereas the association of methylation at MGMT and CDKN2A suggests that these loci may be targets of a common mechanism of epigenetic dysregulation.
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Alemayehu A, Sebova K, Fridrichova I. Redundant DNA methylation in colorectal cancers of Lynch-syndrome patients. Genes Chromosomes Cancer 2008; 47:906-14. [PMID: 18618713 DOI: 10.1002/gcc.20586] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Lynch syndrome is an inherited disease resulting predominantly in colorectal cancer (CRC). The crucial cause is DNA mismatch repair (MMR) malfunction that is associated mostly with MLH1 or MSH2 germline mutations. A significant hallmark of repair defects is a high level of instability in microsatellites (MSI-H). In many sporadic unstable CRCs, the MLH1 gene is inactivated by promoter hypermethylation in addition to extensive promoter methylation in many tumor-suppressor genes known as CpG island methylation phenotype (CIMP). To investigate the possible role of epigenetic alterations in causing MMR deficiency and thereby Lynch syndrome, we evaluated the MLH1 specific and global hypermethylation in hereditary CRCs. Of 22 Lynch-syndrome-related CRCs, 18 (81.8%) demonstrated various levels of DNA methylation; of these, 14 (63.6%) and 4 (18.2%) were methylated in distal and both distal and proximal regions of the MLH1 promoter, respectively. However, only 7/18 (38.9%) of results were confirmed by bisulfite sequencing. Similar methylation patterns in tumors and frequently in matched normal DNA were found in twelve and four patients with MLH1 and MSH2 alterations documented by the absence of protein or presence of germline mutation, respectively. Moreover, the same results were observed in five stable CRCs. None of 22 Lynch-syndrome-related tumors presented CIMP in contrast to 3/10 (30%) stable carcinomas. The rather randomly distributed weak methylation patterns in hereditary CRCs indicate that epigenetic events are redundant in Lynch-syndrome etiology, in contrast to the widespread DNA methylation in sporadic unstable CRCs. These methylation-profile differences can lead to more effective molecular diagnosis of Lynch syndrome.
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Affiliation(s)
- Aster Alemayehu
- Cancer Research Institute of Slovak Academy of Sciences, Bratislava, Slovakia
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Nagasaka T, Koi M, Kloor M, Gebert J, Vilkin A, Nishida N, Shin SK, Sasamoto H, Tanaka N, Matsubara N, Boland CR, Goel A. Mutations in both KRAS and BRAF may contribute to the methylator phenotype in colon cancer. Gastroenterology 2008; 134:1950-60, 1960.e1. [PMID: 18435933 PMCID: PMC2543132 DOI: 10.1053/j.gastro.2008.02.094] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 02/21/2008] [Accepted: 02/28/2008] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Colorectal cancers (CRCs) with the CpG island methylator phenotype (CIMP) often associate with epigenetic silencing of hMLH1 and an activating mutation in the BRAF gene. However, the current CIMP criteria are ambiguous and often result in an underestimation of CIMP frequencies in CRCs. Because BRAF and KRAS belong to same signaling pathway, we hypothesized that not only mutations in BRAF but mutant KRAS may also associate with CIMP in CRC. METHODS We determined the methylation status in a panel of 14 markers (7 canonical CIMP-related loci and 7 new loci), microsatellite instability status, and BRAF/KRAS mutations in a collection of 487 colorectal tissues that included both sporadic and Lynch syndrome patients. RESULTS Methylation analysis of 7 CIMP-related markers revealed that the mean number of methylated loci was highest in BRAF-mutated CRCs (3.6) vs KRAS-mutated (1.2, P < .0001) or BRAF/KRAS wild-type tumors (0.7, P < .0001). However, analyses with 7 additional markers showed that the mean number of methylated loci in BRAF mutant tumors (4.4) was the same as in KRAS mutant CRCs (4.3, P = .8610). Although sporadic microsatellite instability high tumors had the highest average number of methylated markers (8.4), surprisingly, Lynch syndrome CRCs also demonstrated frequent methylation (5.1). CONCLUSIONS CIMP in CRC may result from activating mutations in either BRAF or KRAS, and the inclusion of additional methylation markers that correlate with mutant KRAS may help clarify CIMP in future studies. Additionally, aberrant DNA methylation is a common event not only in sporadic CRC but also in Lynch syndrome CRCs.
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Affiliation(s)
- Takeshi Nagasaka
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Minoru Koi
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Matthias Kloor
- Institute of Molecular Pathology, University of Heidelberg, Heidelberg, Germany
| | - Johannes Gebert
- Institute of Molecular Pathology, University of Heidelberg, Heidelberg, Germany
| | - Alex Vilkin
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Naoshi Nishida
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Sung Kwan Shin
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Hiromi Sasamoto
- Department of Gastroenterological Surgery and Surgical Oncology, Okayama University Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Noriaki Tanaka
- Department of Gastroenterological Surgery and Surgical Oncology, Okayama University Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Nagahide Matsubara
- Department of Gastroenterological Surgery and Surgical Oncology, Okayama University Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - C. Richard Boland
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Ajay Goel
- Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center and Baylor Research Institute, Baylor University Medical Center, Dallas, TX 75246, USA
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Cai G, Xu Y, Lu H, Shi Y, Lian P, Peng J, Du X, Zhou X, Guan Z, Shi D, Cai S. Clinicopathologic and molecular features of sporadic microsatellite- and chromosomal-stable colorectal cancers. Int J Colorectal Dis 2008; 23:365-73. [PMID: 18193434 DOI: 10.1007/s00384-007-0423-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/07/2007] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND AIMS Chromosomal instability (CIN) and microsatellite instability (MSI) are two major causes of colorectal cancers. Recently, a percentage of colorectal cancers were found to be neither CIN nor MSI. This study was performed to explore whether microsatellite- and chromosomal-stable (MACS) colorectal cancers comprise a substantially distinct subtype. MATERIALS AND METHODS Sixty-nine sporadic colorectal cancers were classified into three subsets according to ploidy and microsatellite instability status: CIN+, MSI+, and MACS. Clinicopathologic, genetic, and epigenetic differences among these three groups were investigated by immunohistochemical analysis of p53, APC, hMLH1, and BAX and methylation study of pl4ARF, hMLH1, p161NK4a MGMT, and MINT1 with methylation-specific polymerase chain reaction. RESULTS The 69 cases included 49 CIN+, 7 MSI+, and 13 MACS. MACS were found to differ from CIN+ and MSI+ in three aspects. The clinicopathologic features of MACS were similar to MSI+ but distinguished from CIN+. Comparatively, MACS preferred proximal location and poor differentiation (p < 0.05). An immunohistochemical study demonstrated that MACS had a lower rate of loss of hMLH1 or BAX protein than MSI+ and less loss of APC protein than CIN+. In an epigenetic aspect, both MACS and MSI+ had a high rate of CpG island methylator phenotype (46.2 and 42.9%). However, they differed in the presence of hMLH1 methylation (7.7 vs 57.1%, p < 0.05). Otherwise, compared with CIN+, MACS had a more frequent CpG island methylator phenotype and MINT1 methylation (p < 0.05) and relatively more common p161IK4a methylation with marginal significance (p= 0 .056). CONCLUSION MACS sporadic colorectal cancers may compose a unique phenotype with distinct clinicopathologic and molecular characteristics.
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Affiliation(s)
- Guoxiang Cai
- Department of Abdominal Surgery, Cancer Hospital, Fudan University, 270 Dong An Road, Shanghai 200032, People's Republic of China
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15
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Imai K, Yamamoto H. Carcinogenesis and microsatellite instability: the interrelationship between genetics and epigenetics. Carcinogenesis 2008; 29:673-80. [PMID: 17942460 DOI: 10.1093/carcin/bgm228] [Citation(s) in RCA: 307] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
DNA mismatch repair (MMR) deficiency results in a strong mutator phenotype and high-frequency microsatellite instability (MSI-H), which are the hallmarks of tumors arising within Lynch syndrome. MSI-H is characterized by length alterations within simple repeated sequences, microsatellites. Lynch syndrome is primarily due to germline mutations in one of the DNA MMR genes; mainly hMLH1 or hMSH2 and less frequently hMSH6 and rarely hPMS2. Germline hemiallelic methylation of MLH1, termed epimutation, has been reported to be a new cause of Lynch syndrome. MSI-H is also observed in approximately 15% of colorectal, gastric and endometrial cancers and in lower frequencies in a minority of other tumors, where it is associated with the hypermethylation of the promoter region of hMLH1. MSI-H underlies a distinctive tumorigenic pathway because cancers with MSI-H exhibit many differences in genotype and phenotype relative to cancers without MSI-H, irrespective of their hereditary or sporadic origins. Genetic, epigenetic and transcriptomic differences exist between cancers with and those without the MSI-H. The BRAF V600E mutation is associated with sporadic MSI-H colorectal cancers (CRCs) harboring hMLH1 methylation but not Lynch syndrome-related CRCs. The differences in genotype and phenotype between cancers with and those without MSI-H are likely to be causally linked to their differences in biological and clinical features. Therefore, the diagnosis of MSI-H in cancers is thus considered to be of increasing relevance, because MSI-H is a useful screening marker for identifying patients with Lynch syndrome, a better prognostic factor and could affect the efficacy of chemotherapy. This review addresses recent advances in the field of microsatellite instability research.
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Affiliation(s)
- Kohzoh Imai
- Sapporo Medical University, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan.
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16
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Lee S, Cho NY, Choi M, Yoo EJ, Kim JH, Kang GH. Clinicopathological features of CpG island methylator phenotype-positive colorectal cancer and its adverse prognosis in relation to KRAS/BRAF mutation. Pathol Int 2008; 58:104-13. [PMID: 18199160 DOI: 10.1111/j.1440-1827.2007.02197.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
CpG island methylator phenotype (CIMP) is a recently described subset of colorectal cancers (CRC) with widespread methylation of multiple promoter CpG islands. But the prognostic implication of CIMP in CRC has not been clarified. Thus, the aim of the present study was to differentiate the unique characteristics of CIMP from those of microsatellite instability (MSI)-high CRC, especially with regard to prognosis. CIMP, MSI, and mutations of KRAS codons 12 and 13 and of BRAF codon 600 were evaluated in 134 sporadic CRC. Patient survival and other clinicopathological variables were correlated with CIMP or genetic changes. High CIMP, high MSI, and mutations in KRAS or BRAF were detected in 31.3%, 14.2%, 33.6%, and 4.5% of overall CRC, respectively. High CIMP was closely associated with MSI and BRAF mutation but not with KRAS mutation. CIMP-high, microsatellite-stable (MSS) CRC were significantly associated with proximal location and nodal metastasis and had close but non-significant associations with liver metastasis. A worse clinical outcome was found for CIMP-high, MSS CRC with KRAS/BRAF mutation but not for those lacking KRAS/BRAF mutation. The findings support the contention that CIMP-high CRC have distinct clinicopathological and epidemiological features and suggest that the alleged poor clinical outcome of CIMP-high CRC patients is closely associated with the presence of KRAS/BRAF mutation.
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Affiliation(s)
- Sun Lee
- Department of Pathology, Kyung Hee University College of Medicine, Seoul, Korea
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17
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Herceg Z, Hainaut P. Genetic and epigenetic alterations as biomarkers for cancer detection, diagnosis and prognosis. Mol Oncol 2007; 1:26-41. [PMID: 19383285 PMCID: PMC5543860 DOI: 10.1016/j.molonc.2007.01.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 01/31/2007] [Accepted: 01/31/2007] [Indexed: 02/06/2023] Open
Abstract
The development of cancer is driven by the accumulation of scores of alterations affecting the structure and function of the genome. Equally important in this process are genetic alterations and epigenetic changes. Whereas the former disrupt normal patterns of gene expression, sometimes leading to the expression of abnormal, constitutively active proteins, the latter deregulate the mechanisms such as transcriptional control leading to the inappropriate silencing or activation of cancer-associated genes. Both types of changes are inheritable at the cellular level, thus contributing to the clonal expansion of cancer cells. In this review, we summarize current knowledge on how genetic alterations in oncogenes or tumour suppressor genes, as well as epigenetic changes, can be exploited in the clinics as biomarkers for cancer detection, diagnosis and prognosis. We propose a rationale for identifying alterations that may have a functional impact within a background of "passenger" alterations that may occur solely as the consequence of deregulated genetic and epigenetic stability. Such functional alterations may represent candidates for targeted therapeutic approaches.
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Affiliation(s)
- Zdenko Herceg
- Group of Molecular Carcinogenesis and Biomarkers, International Agency for Research on Cancer, 150 Cours Albert Thomas, Lyon Cedex F-69008, Rhone-Alpes, France.
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18
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Kaz A, Kim YH, Dzieciatkowski S, Lynch H, Watson P, Kay Washington M, Lin L, Grady WM. Evidence for the role of aberrant DNA methylation in the pathogenesis of Lynch syndrome adenomas. Int J Cancer 2007; 120:1922-9. [PMID: 17278092 DOI: 10.1002/ijc.22544] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Colorectal cancer (CRC) forms through a series of histologic steps that are accompanied by mutations and epigenetic alterations, which is called the polyp-cancer sequence. The role of epigenetic alterations, such as aberrant DNA methylation, in the polyp-cancer sequence in sporadic CRC and particularly in hereditary colon cancer is not well understood. Consequently, we assessed the methylation status of CDKN2A/p16, MGMT, MLH1 and p14(ARF) in adenomas arising in the Lynch syndrome, a familial colon cancer syndrome caused by MLH1 and MSH2 mutations, to determine if DNA methylation is a "second hit" mechanism in CRC and to characterize the role of DNA methylation in the polyp phase of the Lynch syndrome. We found MLH1 and p14(ARF) are methylated in 53 and 60% of the Lynch syndrome adenomas and in 4 and 20% of sporadic adenomas, whereas CDKN2A/p16 and MGMT are methylated in 6 and 14% of the Lynch syndrome adenomas versus 50 and 64% of sporadic adenomas. Therefore, the frequency and pattern of gene methylation varies between the Lynch syndrome and sporadic colon adenomas, implying differences in the molecular pathogenesis of the tumors. MLH1 methylation in the Lynch syndrome adenomas suggests gene methylation might have a role in the initiation of these neoplasms.
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Affiliation(s)
- Andrew Kaz
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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19
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Iacopetta B, Grieu F, Li W, Ruszkiewicz A, Caruso M, Moore J, Watanabe G, Kawakami K. APC gene methylation is inversely correlated with features of the CpG island methylator phenotype in colorectal cancer. Int J Cancer 2006; 119:2272-8. [PMID: 16981189 DOI: 10.1002/ijc.22237] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The notion of a CpG island methylator phenotype (CIMP) was proposed to describe a subset of colorectal cancers (CRC) displaying frequent and concordant methylation of CpG islands located within gene promoter regions. Some workers have failed to observe associations between CIMP and specific clinicopathological features of CRC, possibly because of the choice of genes used to define this phenotype. The aim of the current study was to determine whether the aberrant methylation of 6 genes implicated in CRC development was associated with the same phenotypic features of this tumour type. The MethyLight assay was used to provide quantitative estimates of MLH1, P16, TIMP3, P14, DAPK and APC methylation levels in 199 unselected colorectal tumours. The methylation of MLH1, P16, TIMP3 and P14 was highly concordant (p < 0.0001 for each pair) but that of DAPK and APC was not. An inverse association was observed between the methylation of APC and TIMP3 (p = 0.004). Methylation of the MLH1, P16, TIMP3 and P14 genes was associated with tumour infiltrating lymphocytes (p < 0.05), microsatellite instability (p < 0.001), BRAF mutation (p < 0.0001) and elevated concentrations of the methyl group carriers tetrahydrofolate (THF) and 5,10-methylene THF (p < 0.05). In contrast, APC methylation was associated with wildtype BRAF (p = 0.003) and with lower concentrations of methyl group carriers (p < 0.05). These findings highlight the importance of gene selection in studies that aim to characterize the biological features and clinical behaviour of CIMP+ tumours.
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Affiliation(s)
- Barry Iacopetta
- School of Surgery and Pathology, University of Western Australia, Nedlands, Australia.
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20
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Campan M, Weisenberger DJ, Laird PW. DNA Methylation Profiles of Female Steroid Hormone-Driven Human Malignancies. Curr Top Microbiol Immunol 2006; 310:141-78. [PMID: 16909910 DOI: 10.1007/3-540-31181-5_8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tumor DNA contains valuable clues about the origin and pathogenesis of human cancers. Alterations in DNA methylation can lead to silencing of genes associated with distinct tumorigenic pathways. These pathway-specific DNA methylation changes help define tumor-specific DNA methylation profiles that can be used to further our understanding of tumor development, as well as provide tools for molecular diagnosis and early detection of cancer. Female sex hormones have been implicated in the etiology of several of the women's cancers including breast, endometrial, ovarian, and proximal colon cancers. We have reviewed the DNA methylation profiles of these cancers to determine whether the hormonal regulation of these cancers results in specific DNA methylation alterations. Although subsets of tumors in each of these four types of cancers were found to share some DNA methylation alterations, we did not find evidence for global hormone-specific DNA methylation alterations, suggesting that female sex hormones may participate in different tumorigenic pathways that are associated with distinct DNA methylation-based molecular signatures. One such pathway may include MLH1 methylation in the context of the CpG island methylator phenotype.
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Affiliation(s)
- M Campan
- Department of Surgery and Department of Biochemistry and Molecular Biology, Keck School of Medicine, USC/Norris Comprehensive Cancer Center, University of Southern California, Los Angeles 90089-9176, USA
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21
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Oda S, Zhao Y, Maehara Y. Microsatellite instability in gastrointestinal tract cancers: a brief update. Surg Today 2006; 35:1005-15. [PMID: 16341479 DOI: 10.1007/s00595-005-3125-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 10/01/2004] [Indexed: 01/18/2023]
Abstract
Microsatellite instability (MSI) was initially reported in colorectal cancer and, particularly, in hereditary nonpolyposis colorectal cancer (HNPCC). Since mutations in the genes functioning in DNA mismatch repair (MMR) were found in HNPCC kindred, this phenotype has been connected to a deficiency in MMR. The MSI(+) phenotype is associated with various human malignancies. As MSI(+) tumors appear to form a unique clinicopathological and molecular entity that is clearly distinct from that of classical colorectal tumors, which are accompanied by chromosomal instability (CIN), an exclusive pathway of tumorigenesis has been proposed in colorectal cancer. However, this scheme, comprising two mutually exclusive pathways, is now being reexamined, in light of a series of evidence accumulating in the literature, which relates to (a) distinction between high-level MSI (MSI-H) and low-level MSI (MSI-L), (b) heterogeneity in MSI-H, particularly in the sporadic and hereditary settings, (c) molecular mechanisms underlying the MSI(+) phenotypes, and (d) relationships between the MSI(+) and CIN phenotypes. Several molecular mechanisms may underlie repeat instability in eukaryotic cells. The relationship between MSI and defective MMR may be more complicated than has been suspected. The role of MMR deficiency in tumorigenesis in the digestive tract appears to be diverse and is not simple, even in the colorectum.
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Affiliation(s)
- Shinya Oda
- Institute for Clinical Research, National Kyushu Cancer Center, Fukuoka, 811-1395, Japan
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22
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Takahashi T, Shigematsu H, Shivapurkar N, Reddy J, Zheng Y, Feng Z, Suzuki M, Nomura M, Augustus M, Yin J, Meltzer SJ, Gazdar AF. Aberrant promoter methylation of multiple genes during multistep pathogenesis of colorectal cancers. Int J Cancer 2006; 118:924-31. [PMID: 16108009 DOI: 10.1002/ijc.21453] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Aberrant methylation of 5'gene promoter regions associated with gene silencing is an epigenetic phenomenon responsible for silencing of tumor suppressor genes in many cancer types. The aims of our study were to study the role of methylation of a large panel of genes during multistage pathogenesis and to correlate our findings with patient age and other clinico-pathological features. We investigated the aberrant promoter methylation profile of 19 genes in 92 colorectal cancers (CRCs) and corresponding nonmalignant epithelia (NME) (n = 57), and selected 15 genes for studying 26 colorectal adenomas (CAs). On the Basis of our results, the genes could be divided into 3 groups. Group 1 consisted of 13 genes whose methylation was tumor-specific. For 8 of these genes, the methylation frequencies in CAs were similar to those of CRCs, but significantly different from the frequencies in NME. Group 2, consisting of 2 genes demonstrating little or no methylation, were present in any sample type. In Group 3, consisting of 4 genes, relatively frequent methylation was present in both CRCs and NME, and the differences between these specimen types were not significant. Methylation of Group 1 genes were tightly correlated with each other, and these genes demonstrated increased methylation frequencies in CRCs with increasing age. Methylation was not correlated with other clinico-pathological features. In general, methylation frequencies of CAs were intermediate between CRCs and NME. Our study constitutes the most comprehensive methylation profile of CRCs, demonstrates that methylation commences early during CRC pathogenesis and is an age-related phenomenon.
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Affiliation(s)
- Takao Takahashi
- Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-8593, USA
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23
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Kaup S, Grandjean V, Mukherjee R, Kapoor A, Keyes E, Seymour CB, Mothersill CE, Schofield PN. Radiation-induced genomic instability is associated with DNA methylation changes in cultured human keratinocytes. Mutat Res 2006; 597:87-97. [PMID: 16417911 DOI: 10.1016/j.mrfmmm.2005.06.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 06/01/2005] [Accepted: 06/03/2005] [Indexed: 01/24/2023]
Abstract
The mechanism by which radiation-induced genomic instability is initiated, propagated and effected is currently under intense scrutiny. We have investigated the potential role of altered genomic methylation patterns in the cellular response to irradiation and have found evidence for widespread dysregulation of CpG methylation persisting up to 20 population doublings post-irradiation. Similar effects are seen with cells treated with medium from irradiated cells (the 'bystander effect') rather than subjected to direct irradiation. Using an arbitrarily primed methylation sensitive PCR screening method we have demonstrated that irradiation causes reproducible alterations in the methylation profile of a human keratinocyte cell line, HPV-G, and have further characterised one of these sequences as being a member of a retrotransposon element derived sequence family on chromosome 7; MLT1A. Multiple changes were also detected in the screen, which indicate that although the response of cells is predominantly hypermethylation, specific hypomethylation occurs as well. Sequence specific changes are also reported in the methylation of the pericentromeric SAT2 satellite sequence. This is the first demonstration that irradiation results in the induction of heritable methylation changes in mammalian cells, and provides a link between the various non-radiological instigators of genomic instability, the perpetuation of the unstable state and several of its manifestations.
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Affiliation(s)
- Sahana Kaup
- Laboratory of Stem Cell biology, Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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24
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Losi L, Di Gregorio C, Pedroni M, Ponti G, Roncucci L, Scarselli A, Genuardi M, Baglioni S, Marino M, Rossi G, Benatti P, Maffei S, Menigatti M, Roncari B, Ponz de Leon M. Molecular genetic alterations and clinical features in early-onset colorectal carcinomas and their role for the recognition of hereditary cancer syndromes. Am J Gastroenterol 2005; 100:2280-7. [PMID: 16181381 DOI: 10.1111/j.1572-0241.2005.00223.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Colorectal cancer (CRC) occurs rarely in young individuals (<45 yr) and represents one of the criteria for suspecting hereditary cancer families. In this study we evaluated clinical features and molecular pathways (chromosomal instability [CIN] and microsatellite instability [MSI]) in early-onset CRC of 71 patients. METHODS Detailed family and personal history were obtained for each patient. Expression of APC, beta-catenin, p53, MLH1, MSH2, and MSH6 genes was evaluated by immunohistochemistry. MSI analysis was performed and constitutional main mutations of the mismatch repair (MMR) genes were searched by gene sequencing. RESULTS Fourteen (19.7%) out of the 71 cases showed both MSI and altered expression of MMR proteins. In the 57 MSI-negative (MSI-) lesions altered expression of APC, beta-catenin, and p53 genes were found more frequently than in MSI-positive(MSI+) tumors. Seven (50%) out of the 14 patients with MSI+ tumors presented clinical features of Lynch syndrome (hereditary non-polyposis colorectal cancer [HNPCC]) and in all but one, constitutional mutations in MLH1 or MSH2 genes could be detected. The same mutations were also found in other family members. CONCLUSIONS Our study demonstrates the involvement of CIN in a majority of early-onset colorectal tumors. Furthermore, we identified Lynch syndromes in seven cases (50%) of early-onset colorectal carcinomas with impairment of the MMR system. These results suggest that patients with early-onset CRC should be screened for hereditary cancer syndrome through clinical and molecular characterizations.
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Affiliation(s)
- Lorena Losi
- Department of Pathology, University of Modena and Reggio, Emilia, Italy
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25
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Lawes DA, Pearson T, SenGupta S, Boulos PB. The role of MLH1, MSH2 and MSH6 in the development of multiple colorectal cancers. Br J Cancer 2005; 93:472-7. [PMID: 16106253 PMCID: PMC2361590 DOI: 10.1038/sj.bjc.6602708] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
There is increased incidence of microsatellite instability (MSI) in patients who develop multiple primary colorectal cancers (CRC), although the association with hereditary nonpolyposis colon cancer (HNPCC) is unclear. This study aims to evaluate the underlying genetic cause of MSI in these patients. Microsatellite instability was investigated in 111 paraffin-embedded CRCs obtained from 78 patients with metachronous and synchronous cancers, and a control group consisting of 74 cancers from patients with a single CRC. Tumours were classified as high level (MSI-H), low level (MSI-L) or stable (MSS). MLH1, MSH2 and MSH6 gene expression was measured by immunohistochemistry. Methylation of the MLH1 promoter region was evaluated in MSI-H cancers that failed to express MLH1, and mutational analysis performed in MSI-H samples that expressed MLH1, MSH2 and MSH6 proteins. The frequency of MSI-H was significantly greater in the multiple, 58 out of 111 (52%), compared to the single cancers, 10 out of 74 (13.5%), P < 0.01. Of the 32 patients from whom two or more cancers were analysed, eight (25%) demonstrated MSI-H in both cancers, 13 (41%) demonstrated MSI-H in one cancer and 11 (34%) failed to demonstrate any MSI-H. MSI-H single cancers failed to express MLH1 or MSH2 in seven out of nine (78%) cases and MSI-L/MSS cancers failed to express MLH1 or MSH2 in one out of 45 (2.2%) cases, all cancers expressed MSH6. MSI-H multiple cancers failed to express MLH1 or MSH2 in 21 out of 43 (48%) cases and MSI-L/MSS cancers failed to express MLH1 or MSH2 in four out of 32 (12.5%) cases. MSH6 expression was lost in five MSI-H multiple cancers, four of which also failed to express MLH1 or MSH2. Loss of expression of the same mismatch repair (MMR) gene was identified in both cancers from six out of 19 (31%) patients. Methylation was identified in 11 out of 17 (65%) multiple and three out of six (50%) single MSI-H cancers that failed to express MLH1. Mutational analysis of 10 MSI-H multiple cancers that expressed MLH1, MSH2 and MSH6 failed to demonstrate mutations in the MLH1 or MSH2 genes. We suggest that, although MSI-H is more commonly identified in those with multiple colorectal cancers, this does not commonly arise from a classical HNPCC pathway.
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Affiliation(s)
- D A Lawes
- Department of Surgery, Royal Free and University College London, 2nd Floor 67-73 Riding House Street, London, W1W 7EJ, UK
| | - T Pearson
- Department of Surgery, Royal Free and University College London, 2nd Floor 67-73 Riding House Street, London, W1W 7EJ, UK
| | - S SenGupta
- Department of Surgery, Royal Free and University College London, 2nd Floor 67-73 Riding House Street, London, W1W 7EJ, UK
| | - P B Boulos
- Department of Surgery, Royal Free and University College London, 2nd Floor 67-73 Riding House Street, London, W1W 7EJ, UK
- Department of Surgery, Royal Free and University College London, 2nd Floor 67-73 Riding House Street, London, W1W 7EJ, UK. E-mail:
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26
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Wang Y, Yu Q, Cho AH, Rondeau G, Welsh J, Adamson E, Mercola D, McClelland M. Survey of differentially methylated promoters in prostate cancer cell lines. Neoplasia 2005; 7:748-60. [PMID: 16207477 PMCID: PMC1501885 DOI: 10.1593/neo.05289] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 04/15/2005] [Accepted: 04/22/2005] [Indexed: 12/31/2022]
Abstract
DNA methylation and copy number in the genomes of three immortalized prostate epithelial and five cancer cell lines (LNCaP, PC3, PC3M, PC3M-Pro4, and PC3M-LN4) were compared using a microarray-based technique. Genomic DNA is cut with a methylation-sensitive enzyme HpaII, followed by linker ligation, polymerase chain reaction (PCR) amplification, labeling, and hybridization to an array of promoter sequences. Only those parts of the genomic DNA that have unmethylated restriction sites within a few hundred base pairs generate PCR products detectable on an array. Of 2732 promoter sequences on a test array, 504 (18.5%) showed differential hybridization between immortalized prostate epithelial and cancer cell lines. Among candidate hypermethylated genes in cancer-derived lines, there were eight (CD44, CDKN1A, ESR1, PLAU, RARB, SFN, TNFRSF6, and TSPY) previously observed in prostate cancer and 13 previously known methylation targets in other cancers (ARHI, bcl-2, BRCA1, CDKN2C, GADD45A, MTAP, PGR, SLC26A4, SPARC, SYK, TJP2, UCHL1, and WIT-1). The majority of genes that appear to be both differentially methylated and differentially regulated between prostate epithelial and cancer cell lines are novel methylation targets, including PAK6, RAD50, TLX3, PIR51, MAP2K5, INSR, FBN1, and GG2-1, representing a rich new source of candidate genes used to study the role of DNA methylation in prostate tumors.
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Affiliation(s)
- Yipeng Wang
- Sidney Kimmel Cancer Center, 10835 Road to the Cure, San Diego, CA 92121, USA
| | - Qiuju Yu
- Sidney Kimmel Cancer Center, 10835 Road to the Cure, San Diego, CA 92121, USA
| | - Ann H Cho
- Sidney Kimmel Cancer Center, 10835 Road to the Cure, San Diego, CA 92121, USA
| | - Gaelle Rondeau
- Sidney Kimmel Cancer Center, 10835 Road to the Cure, San Diego, CA 92121, USA
| | - John Welsh
- Sidney Kimmel Cancer Center, 10835 Road to the Cure, San Diego, CA 92121, USA
| | - Eileen Adamson
- The Burnham Institute, Cancer Research Center, La Jolla, CA, USA
| | - Dan Mercola
- Department of Pathology, University of California at Irvine, Irvine, CA 92697, USA
| | - Michael McClelland
- Sidney Kimmel Cancer Center, 10835 Road to the Cure, San Diego, CA 92121, USA
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27
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Castagnola P, Giaretti W. Mutant KRAS, chromosomal instability and prognosis in colorectal cancer. Biochim Biophys Acta Rev Cancer 2005; 1756:115-25. [PMID: 16112461 DOI: 10.1016/j.bbcan.2005.06.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Revised: 06/14/2005] [Accepted: 06/29/2005] [Indexed: 12/23/2022]
Abstract
The RAS gene family provides a global effect on gene expression by encoding small GTP-binding proteins which act as molecular switches connecting extracellular signals with nuclear transcription factors. While wild type RAS proteins are switched off shortly after activation, mutant RAS proteins remain constitutively activated leading to complex interactions among their downstream effectors. For some human tumor types, these interactions were shown to contribute to cancer genesis and progression by inducing changes in cell survival, apoptosis, angiogenesis, invasion and metastasis. This review addresses the controversial link of KRAS mutations in colorectal cancer with chromosomal instability and patient prognosis.
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Affiliation(s)
- Patrizio Castagnola
- National Institute for Cancer Research, Largo R. Benzi, 10, 16132-Genoa, Italy
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Gologan A, Sepulveda AR. Microsatellite Instability and DNA Mismatch Repair Deficiency Testing in Hereditary and Sporadic Gastrointestinal Cancers. Clin Lab Med 2005; 25:179-96. [PMID: 15749237 DOI: 10.1016/j.cll.2004.12.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reference cancers associated with DNA mismatch repair (MMR)deficiency are the adenocarcinomas of patients with hereditary nonpolyposis colorectal cancer, also known as Lynch syndrome. Sporadic gastrointestinal (GI) carcinomas, most commonly colorectal and gastric carcinomas, may also be associated with deficiencies of DNA mismatch repair. Deficiency in cellular MMR leads to wide-spread mutagenesis and neoplastic development and progression. An important diagnostic feature of MMR-deficient tumors is the high rate of mutations that accumulate in repetitive nucleotide regions, and these mutations are known as microsatellite instability(MSI). A standard panel of markers to test for MSI in tumors has been recommended and efficiently separates tumors into those with high, low, or no microsatellite instability (MSI-H, MSI-L, or MSS). Tumors characterized by MSI-H characteristically show loss of one of the main DNA MMR proteins, mLH1 or MSH2, and rarely MSH6 and PMS2, detected by immunohistochemistry (IHC). The combination of MSI testing and IHC for MMR proteins in tumors tissues is used to identify underlying DNA MMR deficiency andis clinically relevant screen patients who might have hereditary non-polyposis colorectal cancer for DNA repair gene germline testing. Increasing evidence demonstrates that tumors with a positive MSI status have lower lymph node metastases burden, and these patients have an overall improved survival, suggesting that the MSI and MMR status may contribute to decision making regarding treatment approaches. Updated guidelines for MSI and IHC for DNAMMR testing, and the biological and potential clinical implications of MMR deficiency and microsatellite instability in GI polyps and cancers are reviewed.
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Affiliation(s)
- Adrian Gologan
- Department of Pathology, University of Pittsburgh, PUH-A610, 100 Lothrop Street, Pittsburgh, PA 15213-2582, USA
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Abstract
DNA hypermethylation in CpG-rich promoters is now recognized as a common feature of human neoplasia. However, the pathophysiology of hyper-methylation (why, when, where) remains obscure. Cancers can be classified according to their degree of methylation, and those cancers with high degrees of methylation (the CpG island methylator phenotype, or CIMP) represent a clinically and aetiologically distinct group that is characterized by 'epigenetic instability'. Furthermore, CIMP-associated cancers seem to have a distinct epidemiology, a distinct histology, distinct precursor lesions and distinct molecular features.
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Affiliation(s)
- Jean-Pierre Issa
- Jean-Pierre Issa is at the Department of Leukemia, M. D. Anderson Cancer Center, Unit 425, 1515 Holcombe, Houston, Texas 77030, USA.
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McGivern A, Wynter CVA, Whitehall VLJ, Kambara T, Spring KJ, Walsh MD, Barker MA, Arnold S, Simms LA, Leggett BA, Young J, Jass JR. Promoter hypermethylation frequency and BRAF mutations distinguish hereditary non-polyposis colon cancer from sporadic MSI-H colon cancer. Fam Cancer 2004; 3:101-7. [PMID: 15340260 DOI: 10.1023/b:fame.0000039861.30651.c8] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Colorectal cancers resulting from defective DNA mismatch repair can occur in both hereditary non-polyposis colon cancer (HNPCC) and in the sporadic setting. They are characterised by a high level of microsatellite instability (MSI-H) and superficially resemble each other in that they are frequently located in the proximal colon and share features such as circumscribed tumour margins and tumour-infiltrating lymphocytes. However, significant differences can be demonstrated at the molecular level including widespread promoter hypermethylation and BRAF -activating mutations which occur significantly less often in HNPCC. AIMS In this study, we sought to determine whether the presence of widespread promoter hypermethylation and BRAF mutations would exclude HNPCC. MATERIALS AND METHODS We investigated the methylation status of four methylated in tumour markers (MINTs 1,2,12 and 31), and the promoter regions of 5 genes hMLH1, HPP1, MGMT, p16INK4A and p14ARF, in 21 sporadic MSI-H colorectal cancers and compared these with 18 cancers from HNPCC patients. The methylation status of CpG islands were determined by either methylation specific PCR (MSP) or combined bisulfite restricton analysis (COBRA). In addition we considered the BRAF mutation status of 18 HNPCC tumours and 19 sporadic MSI-H cancers which had been previously determined by RFLP analysis and confirmatory sequencing. RESULTS Methylation of the promoter regions in target genes occurred less frequently within the HNPCC tumours (27% of analyses), compared with the sporadic MSI-H tumours (59% of analyses) (P < 0.001). Methylation of MINTs 1, 2, 12 and 31 occurred in 4% of analyses for HNPCC tumours contrasted with 73% for sporadic MSI-H tumours (P < 0.001). BRAF mutations were detected in 74% of sporadic tumours but none of the HNPCC cancers tested. CONCLUSIONS The total number of genes and MINTs methylated in HNPCC was lower than in MSI-H colorectal tumours. No HNPCC tumour showed evidence of widespread promoter hypermethylation or BRAF mutation suggesting this feature could be used as a discriminator between familial and sporadic cases.
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Affiliation(s)
- A McGivern
- Conjoint Gastroenterology Laboratory, Bancroft Centre, Herston, Brisbane, Queensland, Australia
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Westra JL, Plukker JT, Buys CH, Hofstra RM. Genetic Alterations in Locally Advanced Stage II/III Colon Cancer: A Search for Prognostic Markers. Clin Colorectal Cancer 2004; 4:252-9. [PMID: 15555207 DOI: 10.3816/ccc.2004.n.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Heterogeneity in advanced colon cancer leads to different results from adjuvant chemotherapy. To identify groups of patients who may need adjuvant treatment, molecular staging and correlation with clinical data may be helpful in classifying histologically similar tumors. Colon cancer develops through a multistep process with an accumulation of multiple genetic alterations that are often the cause of a form of genomic instability. The 2 best known mechanisms of genomic instability are chromosomal instability (CIN) and microsatellite instability (MSI). The CIN phenotype is found in approximately 85% of sporadic colon cancers and is characterized by aneuploidy, multiple chromosomal rearrangements, and an accumulation of somatic mutations in oncogenes such as K-ras and tumor suppressor genes such as TP53 and APC. The MSI phenotype is associated with small insertions and deletions mainly in repetitive sequences (microsatellites) and is found in approximately 15% of cases. This instability, often referred to as high-frequency MSI (MSI-H), is caused by defects of the mismatch repair system, which is involved in repairing DNA errors that arise during DNA replication. Clear-cut correlations between the somatic genetic alterations in tumors and the clinical behavior of the tumor are rare. Only a few markers, such as MSI-H and TP53, seem to have a prognostic value. Mutations in the TP53 gene are associated with an aggressive tumor growth and subsequent reduced survival, whereas MSI-H seems to be correlated with a favorable outcome. In general, predicting biologic behavior of in particular stage III colon cancers is difficult and remains a great clinical problem.
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Lind GE, Thorstensen L, Løvig T, Meling GI, Hamelin R, Rognum TO, Esteller M, Lothe RA. A CpG island hypermethylation profile of primary colorectal carcinomas and colon cancer cell lines. Mol Cancer 2004; 3:28. [PMID: 15476557 PMCID: PMC526388 DOI: 10.1186/1476-4598-3-28] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Accepted: 10/11/2004] [Indexed: 12/23/2022] Open
Abstract
Background Tumor cell lines are commonly used as experimental tools in cancer research, but their relevance for the in vivo situation is debated. In a series of 11 microsatellite stable (MSS) and 9 microsatellite unstable (MSI) colon cancer cell lines and primary colon carcinomas (25 MSS and 28 MSI) with known ploidy stem line and APC, KRAS, and TP53 mutation status, we analyzed the promoter methylation of the following genes: hMLH1, MGMT, p16INK4a (CDKN2A α-transcript), p14ARF (CDKN2A β-transcript), APC, and E-cadherin (CDH1). We compared the DNA methylation profiles of the cell lines with those of the primary tumors. Finally, we examined if the epigenetic changes were associated with known genetic markers and/or clinicopathological variables. Results The cell lines and primary tumors generally showed similar overall distribution and frequencies of gene methylation. Among the cell lines, 15%, 50%, 75%, 65%, 20% and 15% showed promoter methylation for hMLH1, MGMT, p16INK4a, p14ARF, APC, and E-cadherin, respectively, whereas 21%, 40%, 32%, 38%, 32%, and 40% of the primary tumors were methylated for the same genes. hMLH1 and p14ARF were significantly more often methylated in MSI than in MSS primary tumors, whereas the remaining four genes showed similar methylation frequencies in the two groups. Methylation of p14ARF, which indirectly inactivates TP53, was seen more frequently in tumors with normal TP53 than in mutated samples, but the difference was not statistically significant. Methylation of p14ARF and p16INK4a was often present in the same primary tumors, but association to diploidy, MSI, right-sided location and female gender was only significant for p14ARF. E-cadherin was methylated in 14/34 tumors with altered APC further stimulating WNT signaling. Conclusions The present study shows that colon cancer cell lines are in general relevant in vitro models, comparable with the in vivo situation, as the cell lines display many of the same molecular alterations as do the primary carcinomas. The combined pattern of epigenetic and genetic aberrations in the primary carcinomas reveals associations between them as well as to clinicopathological variables, and may aid in the future molecular assisted classification of clinically distinct stages.
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Affiliation(s)
- Guro E Lind
- Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, 0310 Oslo, Norway
| | - Lin Thorstensen
- Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, 0310 Oslo, Norway
| | - Tone Løvig
- Institute of Forensic Medicine, The National Hospital, University of Oslo, Norway
| | - Gunn I Meling
- The University Hospital of Akershus, Akershus, Norway
| | | | - Torleiv O Rognum
- Institute of Forensic Medicine, The National Hospital, University of Oslo, Norway
| | - Manel Esteller
- Cancer Epigenetics Laboratory, the Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Ragnhild A Lothe
- Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, 0310 Oslo, Norway
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Huang J, Zheng S, Jin SH, Zhang SZ. Somatic mutations of APC gene in carcinomas from hereditary non-polyposis colorectal cancer patients. World J Gastroenterol 2004; 10:834-6. [PMID: 15040027 PMCID: PMC4727021 DOI: 10.3748/wjg.v10.i6.834] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To investigate the mutational features of adenomatous polyposis coli (APC) gene and its possible arising mechanism in hereditary non-polyposis colorectal cancers (HNPCC).
METHODS: PCR-based In Vitro Synthesized Protein Test (IVSP) assay and sequencing analysis were used to confirm somatic mutations of whole APC gene in 19 HNPCC cases.
RESULTS: Eleven cases with 13 mutations were determined to harbor APC mutations. The prevalence of APC mutation was 58%(11/19). The mutations consisted of 9 frameshift and 4 nonsense ones, indicating that there were more frameshift mutations (69%). The frameshift mutations all exhibited deletion or insertion of 1-2 bp and most of them (7/9) happened at simple nucleotide repeat sequences, particularly within (A)n tracts (5/9). All point mutations presented C-to-T transitions at CpG sites.
CONCLUSION: Mutations of APC gene were detected in more than half of HNPCC, indicating that its mutation was a common molecular event and might play an important role in the tumorigenesis of HNPCC. Locations of frameshift mutations at simple nucleotide repeat sequences and point mutations at CpG sites suggested that many mutations probably derived from endogenous processes including mismatch repair (MMR) deficiency. Defective MMR might affect the nature of APC mutations in HNPCC and likely occur earlier than APC mutational inactivation in some patients.
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Affiliation(s)
- Jian Huang
- Department of Oncology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang Province, China.
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Sarrió D, Moreno-Bueno G, Hardisson D, Sánchez-Estévez C, Guo M, Herman JG, Gamallo C, Esteller M, Palacios J. Epigenetic and genetic alterations of APC and CDH1 genes in lobular breast cancer: relationships with abnormal E-cadherin and catenin expression and microsatellite instability. Int J Cancer 2003; 106:208-15. [PMID: 12800196 DOI: 10.1002/ijc.11197] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The causes and functional consequences of E-cadherin (E-CD) loss in breast cancer are poorly understood. E-CD loss might act in concert with alterations in the APC/beta-catenin pathway to permit oncogenic beta-catenin signaling. To test this hypothesis, we have analyzed the presence of genetic and epigenetic alterations affecting E-CD (CDH1), APC and beta-catenin (CTNNB1) genes and the immunohistochemical expression of E-CD, beta- and gamma-catenin in a series of 46 infiltrating lobular breast carcinomas (ILCs). Since 80% of ILCs featured complete loss of E-CD expression, we analyzed the molecular alterations responsible for E-CD inactivation in these tumors. We found that 10 of 46 (22%) cases harbored mutations in CDH1, including 1 case with 2 different mutations (1 of which was germline). CDH1 was also inactivated by loss of heterozygosity (LOH; 30/41, 73%) and promoter hypermethylation (19/46, 41%). Interestingly, LOH and mutations were also detected in the corresponding in situ lesions of the ILCs, implying that these alterations are early events in lobular cancer tumorogenesis. Additionally, the presence of a polymorphism in the CDH1 promoter was found to be inversely correlated with CDH1 mutations, but not with E-CD levels. We next examined whether alterations in the APC/beta-catenin pathway also occurred in the same series of ILCs. Although no CTNNB1 or APC mutations were detected, promoter methylation (25/46, 52%) and LOH (7/30, 23%) of APC were found. Moreover, methylation of APC and CDH1 occurred concordantly. However, beta- and gamma-catenin were severely reduced or absent in 90% of these tumors, implying that alterations in CDH1 and APC genes do not promote beta-catenin accumulation in ILC. These molecular alterations were not associated with microsatellite instability. In summary, several different mechanisms (mutations, LOH, methylation) are involved in the frequent CDH1 inactivation in invasive and in situ lobular breast cancer. The same tumors also show genetic and epigenetic alterations of APC gene. However, altered CDH1 and APC genes do not promote beta-catenin accumulation in this tumor type.
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Affiliation(s)
- David Sarrió
- Laboratory of Breast and Gynecological Cancer, Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas, Madrid, Spain
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Fang DC, Wang RQ, Yang SM, Yang JM, Liu HF, Peng GY, Xiao TL, Luo YH. Mutation and methylation of hMLH1 in gastric carcinomas with microsatellite instability. World J Gastroenterol 2003; 9:655-9. [PMID: 12679904 PMCID: PMC4611422 DOI: 10.3748/wjg.v9.i4.655] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To appraise the correlation of mutation and methylation of hMSH1 with microsatellite instability (MSI) in gastric cancers.
METHODS: Mutation of hMLH1 was detected by Two-dimensional electrophoresis (Two-D) and DNA sequencing; Methylation of hMLH1 promoter was measured with methylation-specific PCR; MSI was analyzed by PCR-based methods.
RESULTS: Sixty-eight cases of sporadic gastric carcinoma were studied for mutation and methylation of hMLH1 promoter and MSI. Three mutations were found, two of them were caused by a single bp substitution and one was caused by a 2 bp substitution, which displayed similar Two-D band pattern. Methylation of hMLH1 promoter was detected in 11 (16.2%) gastric cancer. By using five MSI markers, MSI in at least one locus was detected in 17/68 (25%) of the tumors analyzed. Three hMLH1 mutations were all detected in MSI-H (≥ 2 loci, n = 8), but no mutation was found in MSI-L (only one locus, n = 9) or MSS (tumor lacking MSI or stable, n = 51). Methylation frequency of hMLH1 in MSI-H (87.5%, 7/8) was significantly higher than that in MSI-L (11.1%, 1/9) or MSS (5.9%, 3/51) (P < 0.01-0.001), but no difference was found between MSI-L and MSS (P > 0.05).
CONCLUSION: Both mutation and methylation of hMLH1 are involved in the MSI pathway but not related to the LOH pathway in gastric carcinogenesis.
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Affiliation(s)
- Dian-Chun Fang
- Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
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Suter CM, Norrie M, Ku SL, Cheong KF, Tomlinson I, Ward RL. CpG island methylation is a common finding in colorectal cancer cell lines. Br J Cancer 2003; 88:413-9. [PMID: 12569385 PMCID: PMC2747532 DOI: 10.1038/sj.bjc.6600699] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Tumour cell lines are commonly used in colorectal cancer (CRC) research, including studies designed to assess methylation defects. Although many of the known genetic aberrations in CRC cell lines have been comprehensively described, no studies have been performed on their methylation status. In this study, 30 commonly used CRC cell lines as well as seven primary tumours from individuals with hereditary nonpolyposis colorectal cancer (HNPCC) were assessed for methylation at six CpG islands known to be hypermethylated in colorectal cancer: hMLH1, p16, methylated in tumour (MINT-)-1, -2, -12 and -31. The cell lines were also assessed for microsatellite instability (MSI), ploidy status, hMLH1 expression, and mutations in APC and Ki-ras. Methylation was frequently observed at all examined loci in most cell lines, and no differences were observed between germline-derived and sporadic cell lines. Methylation was found at MINT 1 in 63%, MINT 2 in 57%, MINT 12 in 71%, MINT 31 in 53%, p16 in 71%, and hMLH1 in 30% of cell lines. Overall only one cell line, SW1417, did not show methylation at any locus. Methylation was found with equal frequency in MSI and chromosomally unstable lines. MSI was over-represented in the cell lines relative to sporadic CRC, being detected in 47% of cell lines. The rate of codon 13 Ki-ras mutations was also over three times that expected from in vivo studies. We conclude that CpG island hypermethylation, whether acquired in vivo or in culture, is a ubiquitous phenomenon in CRC cell lines. We suggest that CRC cell lines may be only representative of a small subset of real tumours, and this should be taken into account in the use of CRC cell lines for epigenetic studies.
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Affiliation(s)
- C M Suter
- Department of Medical Oncology, St Vincent's Hospital, Victoria St, Darlinghurst, NSW 2010, Australia
| | - M Norrie
- Department of Medical Oncology, St Vincent's Hospital, Victoria St, Darlinghurst, NSW 2010, Australia
- School of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
| | - S L Ku
- Department of Medical Oncology, St Vincent's Hospital, Victoria St, Darlinghurst, NSW 2010, Australia
| | - K F Cheong
- Department of Medical Oncology, St Vincent's Hospital, Victoria St, Darlinghurst, NSW 2010, Australia
| | - I Tomlinson
- Molecular and Population Genetics Laboratory, Cancer Research UK, London WC2A 3PX, UK
| | - R L Ward
- Department of Medical Oncology, St Vincent's Hospital, Victoria St, Darlinghurst, NSW 2010, Australia
- School of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
- Department of Medical Oncology, St Vincent's Hospital, Victoria St, Darlinghurst, NSW 2010, Australia. E-mail:
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Bae SI, Lee HS, Kim SH, Kim WH. Inactivation of O6-methylguanine-DNA methyltransferase by promoter CpG island hypermethylation in gastric cancers. Br J Cancer 2002; 86:1888-92. [PMID: 12085181 PMCID: PMC2375420 DOI: 10.1038/sj.bjc.6600372] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2001] [Revised: 04/05/2002] [Accepted: 04/22/2002] [Indexed: 12/17/2022] Open
Abstract
Promoter hypermethylation of CpG islands in tumour suppressor genes can lead to transcriptional inactivation. To investigate the association between methylation and expression at O6-methylguanine-DNA methyltransferase, we performed methylation-specific PCR and immunohistochemistry in 149 gastric carcinomas. Promoter methylation was found in 14.1% of tumours and loss of expression was detected in 11.4% of tumours. To examine correlation between the O6-methylguanine-DNA methyltransferase expression and the clinical data, we investigated O6-methylguanine-DNA methyltransferase expression in 315 consecutive gastric carcinomas. A similar frequency of loss of O6-methylguanine-DNA methyltransferase expression was confirmed in these cases. The loss of O6-methylguanine-DNA methyltransferase expression was significantly associated with pTNM stage (P=0.037), tumour invasion (P=0.02), microsatellite instability (P=0.041) and overall survival (P=0.01). Among 11 gastric cancer cell lines, SNU-620 showed the loss of O6-methylguanine-DNA methyltransferase expression as well as promoter methylation. After treatment with 5-aza-2-deoxycytidine, a demethylating agent, SNU-620 re-expressed O6-methylguanine-DNA methyltransferase mRNA. In summary, we suggest that during gastric carcinogenesis, the loss of O6-methylguanine-DNA methyltransferase expression frequently occurs via the hypermethylation of the CpG islands of the promoter region, and that this is significantly associated with the clinicopathological characteristics.
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Affiliation(s)
- S I Bae
- Department of Pathology, Seoul National University College of Medicine, 28 Yongon-dong, Seoul 110-799, Korea
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