| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Regular Articles |
From the Departments of Pathology,*
Leukemia,
andBiostatistics,
University of Texas M. D.Anderson Cancer Center, Houston, Texas
 |
Abstract |
|---|
 Top Abstract Materials and MethodsResultsDiscussionReferences |
|---|
CpG islands are 0.5- to 2-kb regions rich in cytosine-guanine dinucleotides and are present in the 5' region of approximately half of all human genes.6 Methylation of cytosine within CpG islands is associated with loss of gene expression and is observed in physiological conditions, such as X chromosome inactivation7 and aging,8 and in neoplasia.9 Transcriptional repression by methylation in colorectal cancers inactivates the p16 cell-cycle regulator,10 the estrogen receptor growth suppressor,8 the THBS1 angiogenesis inhibitor,11 the TIMP3 metastasis suppressor,12 the O6-methylguanine DNA methyltransferase DNA repair gene,13 and the hMLH1 nucleotide mismatch repair gene.14 The recently discovered CpG island methylator phenotype (CIMP) is a novel pathway characterized by methylation of multiple CpG islands in colorectal carcinomas and adenomas.15-17 CIMP-high adenomas and carcinomas have a distinct genetic profile with frequent mutations of the K-ras gene, but lack of p53 mutations.16 CIMP status is not correlated among multiple adenomas from the same patient.17 The mechanism of methylation of multiple CpG islands is postulated to be either aberrant de novo methylation because of mutation in a DNA-methyltransferase or loss of protection against de novo methylation through the loss of a trans-activating factor.18-20
Hyperplastic polyps (HPs) are usually present in the left colon, small in size, and considered to be benign in nature. However, patients with hyperplastic polyposis, characterized by the presence of numerous HPs and/or large HPs, have increased risk of colorectal cancer.21-28 A HP-serrated adenoma-carcinoma sequence is proposed as an alternative pathway to the adenoma-carcinoma sequence.28-31
We investigated the possibility that CpG island methylation is a major molecular defect in patients with multiple/large HPs or hyperplastic polyposis, and report a high degree of patient-specific concordant methylation in HPs and other lesions, representing a hypermethylator phenotype.
|
Materials and Methods |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
The patients and specimens have been described in detail previously.28 The patients were classified into three groups based on the number and size of HPs: multiple HPs (patients with 5 to 10 HPs), hyperplastic polyposis (patients with >20 HPs), and large HPs (patients with HP >1 cm), as described previously.28 Predominance of HPs in the right colon and predominance of HPs in the left colorectum were defined by the location of the majority of HPs in the right colon or in the left colon and rectum, respectively. We initially studied 129 HPs from 23 patients. All histological sections had limited quantities of DNA extracted from tissue in paraffin-embedded specimens. Twenty-seven HPs, eight tubular adenomas, and three carcinomas from three patients with familial hyperplastic polyposis and three patients with hyperplastic polyposis from the previous study were excluded because of insufficient DNA for further analysis. Thus, we studied 102 HPs, 8 serrated adenomas, 19 tubular adenomas, and 9 carcinomas from 17 patients with hyperplastic polyposis. Histologically normal mucosa was available from 13 patients.
Sixteen sporadic HPs from 14 patients undergoing resection of colorectal cancer at the MD Anderson Cancer Center, Houston, TX, were also analyzed. All patients had given informed consent for the collection of specimens according to institutional guidelines.
Bisulfite Treatment of DNA and Methylation-Specific Polymerase Chain Reaction
The methylation status of p16, MINT1, MINT2, MINT31, and hMLH1 was determined by bisulfite treatment of DNA followed by methylation-specific polymerase chain reaction, as described with modification.32 These loci were chosen based on a previous study that showed that they offered excellent discrimination for CIMP and that they were unmethylated (<10% methylation) in normal tissues.15
In brief, 2 µg of microdissected genomic DNA was denatured with 2 mol/L NaOH at 37°C for 10 minutes, followed by incubation with 3 mol/L sodium bisulfite (pH 5.0) at 50°C for 16 hours in the dark. DNA was then purified using the DNA Cleanup Kit (Promega, Madison, WI) as recommended by the manufacturer, incubated with 3 mol/L of NaOH at room temperature for 5 minutes, precipitated with 10 mol/L of ammonium acetate and 100% ethanol, washed with 70% ethanol, and finally resuspended in 20 µl of distilled water.
The primers and polymerase chain reaction (PCR) conditions for p16 were the same as reported by Herman and colleagues.32 The primers for MINT1 were 5'-AATTTTTTTATATATATTTTCGAAGC-3' and 5'-AAAAACCTCAACCCCGCG-3' for methylated alleles; and 5'-AATTTTTTTATATATATTTTTGAAGTGT-3' and 5'-AACAAAAAACCTCAACCCCACA-3' for unmethylated alleles. The cycling conditions for MINT1 were 95°C for 10 minutes and 37 cycles of 95°C for 30 seconds and 55°C for 45 seconds. The primers for MINT2 were 5'-TTGTTAAAGTGTTGAGTTCGTC-3' and 5'-AATAACGACGATTCCGTACG-3' for methylated alleles; and 5'-GATTTTGTTAAAGTGTTGAGTTTGTT-3' and 5'-CAAAATAATAACAACAATTCCATACA-3' for unmethylated alleles. The cycling conditions for MINT2 were 95°C for 10 minutes and 40 cycles of 95°C for 30 seconds and 60°C for 45 seconds. The primers for MINT31 were 5'-TGTTGGGGAAGTGTTTTTCGGC-3' and 5'-CGAAAACGAAACGCCGCG-3' for methylated alleles; and 5'-TAGATGTTGGGGAAGTGTTTTTTGGT-3' and 5'-TAAATACCCAAAAACAAAACACCACA-3' for unmethylated alleles. The cycling conditions for MINT31 were 95°C for 10 minutes and 38 cycles of 95°C for 30 seconds and 60°C for 45 seconds. The primers for hMLH1 were 5'-GATAGCGATTTTTAACGC-3' and 5'-TCTATAAATTACTAAATCTCTTCG-3' for methylated alleles; and 5'-AGAGTGGATAGTGATTTTTAATGT-3' and 5'-ACTCTATAAATTACTAAATCTCTTCA-3' for unmethylated alleles. The cycling conditions for hMLH1 were 95°C for 10 minutes and 40 cycles of 95°C for 30 seconds and 53°C for 45 seconds.
In brief, 2 µl of bisulfite-treated DNA was used as template for PCR
reactions using primers specific for methylated and unmethylated
alleles. RKO, a colon cancer cell line (American Type Culture
Collection, Manassas, VA), was used as a positive control, and PCR
reaction without DNA was used as the negative control in each batch of
reaction. PCR products from methylated and unmethylated reactions were
electrophoresed on 6% acrylamide gels and visualized by ethidium
bromide staining (examples in Figure 1
).
For quantitation of methylated and unmethylated alleles, gel
photographs were digitized using a BioRad imager (Bio-Rad, Richmond,
CA) and evaluated by densitometry using the manufacturer’s software.
The results were expressed as percentage of methylation by determining
the density of the methylated band relative to the sum of the
methylated and unmethylated bands. The loci used in this study are
unmethylated (<10% methylated) in normal tissues. Therefore, any
locus showing 
10% methylation was considered positive.
|
HPs, SAs, adenomas, and carcinomas were classified as CIMP-negative if none of the loci were methylated; CIMP-low, if one locus was methylated; and CIMP-high, if two or more loci were methylated.
K-ras Mutations, Loss of Heterozygosity of Chromosome 1p, and Microsatellite Instability-High (MSI-High)
K-ras mutations, loss of heterozygosity of chromosome 1p, and MSI in HPs and SAs from patients with hyperplastic polyposis were reported previously.28 MSI-high was defined by presence of allelic shift in comparison with control DNA in at least 30% of evaluated markers.
Statistical Analysis
The primary statistical endpoint of this study was the determination of factors associated with CIMP status of HPs. Patients with more than one HP were represented multiple times in this data set. Each HP was represented by a methylation index (number of loci methylated/number of loci evaluated). To model correctly the within-polyp and between-polyp correlation as well as simultaneously partition out the effects of the various factors considered, marginal logistic regression models for correlated binary data were used to assess associations between CIMP status and the various polyp and patient characteristics. Estimates were obtained using the generalized estimating equation approach of Zeger and Liang.33 An appropriate correlation structure was chosen to account for possible correlations both between HPs within patients and within HPs between observations from different loci. Both patient and polyp characteristics were tested for association with methylation status. The factor locus was also included in the model to account for locus-specific methylation rates. Relationships between HPs within patients and within HPs between loci were represented as odds ratios, in which an odds ratio of greater than one suggests positive correlation in CIMP status within patients and within polyps, respectively.
|
Results |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
. The sporadic HPs were from 11 men and
3 women, with a mean age of 64 ± 11 years (range, 48 to 80
years). The mean size of the polyp in this group was 0.3 cm (range, 0.1
to 0.7 cm). There were 2 HPs from the right colon and 14 from the left
colon.
|
None of the sporadic HPs were methylated at any of the four loci
(Figure 2, A and B)
and were classified
as CIMP-negative.
|
Nonlesional Mucosa
The apparently normal colorectal mucosa was analyzed for
methylation in 16 samples from 13 patients (Figure 3)
. Only three patients had methylation
(patients 4, 9, and 15) in the mucosa taken adjacent to a neoplasm:
methylation of p16 was present in mucosa adjacent to a
tubular adenoma in patient 15, MINT1 was methylated in mucosa adjacent
to a tubular adenoma in patient 9, and p16 and MINT1 were
methylated in mucosa adjacent to a carcinoma in patient 4. The
methylation at the normal mucosae in these three patients was
concordant with the adjacent adenoma or carcinoma. No methylation was
present in seven samples from mucosa of the resection margins or in six
additional samples of mucosa adjacent to a lesion. Thus, 6% (1 of 16)
of normal mucosae were classified CIMP-high, 12% (2 of 16) were
CIMP-low, and 81% (13 of 16) were CIMP-negative.
|
Forty-three percent (44 of 102) of HPs from these patients were
classified as CIMP-high, 14% (14 of 102) were CIMP-low, and 43% (44
of 102) were CIMP-negative (P = 0.00001
versus sporadic HPs, and P = 0.0045
versus nonlesional mucosa; Figure 2, A and B
; Figure 3
).
The methylation statuses of different loci in the same HP were
positively correlated (odds ratio, 3.41; P = 0.002;
Figure 3
), suggesting that some HPs from patients with multiple/large
HPs, or hyperplastic polyposis, have CIMP-high.15
In
addition, CIMP statuses for different HPs within the same patient were
positively correlated (odds ratio, 5.92; P = 0.0001),
suggesting concordance of methylation in multiple HPs within individual
patients.
The methylation status of HPs was tested for associations with patient
characteristics, with age, the site and size of HPs, and with other
genetic alterations in HPs (Table 2)
.
There was no association between methylation and age. Patients with the
three phenotypic groups of multiple HPs, large HPs, and hyperplastic
polyposis had overlapping CIMP status in HPs from the same patient
(P = 0.8; Figure 2C
). HPs from patients with
large HPs were invariably methylated, but HPs from patients with
hyperplastic polyposis and multiple HPs as defined in the previous
study28
were heterogeneous for methylation status. HPs
were more commonly methylated in patients with SAs, predominance of HPs
in right colon, or both SAs and predominance of HPs in right colon
(P = 0.0009; Figure 3
and Table 2
). Methylation
was present in 22% (10 of 46) of HPs in patients with predominance of
HPs in left colorectum without SAs (odds ratio, 1.00), 100% (23 of 23)
of HPs from patients with predominance of HPs in right colon without
SAs (odds ratio, 27.55; 95% confidence limit, 7.33 to 103.60), 83%
(10 of 12) of HPs from patients with predominance of HPs in left
colorectum with SAs (odds ratio, 9.55; 95% confidence limit, 3.72 to
24.53), and 76% (16 of 21) of HPs from patients with predominance of
HPs in right colon with SAs (odds ratio, 4.60; 95% confidence limit,
1.54 to 13.68).
|
and Table 2
). K-ras mutations were present in 0% (0 of 44) of CIMP-high HPs,
21% (3 of 14) of CIMP-low HPs, and 16% (7 of 44) of CIMP-negative HPs
(odds ratio, 5.08; P = 0.03). Similarly, loss of
heterozygosity of chromosome 1p was present in 2% (1 of 44) of
CIMP-high HPs, 7% (1 of 14) of CIMP-low HPs, and 11% (5 of 44) of
CIMP-negative HPs (not significant). HPs in the left colon and rectum
were less methylated than HPs in the right colon, and larger HPs were
more frequently methylated. The site and size of HPs were not
independently associated with methylation status but were dependent on
patient characteristics. Serrated Adenomas
Most of the SAs were methylated: 75% (6 of 8) of SAs were
CIMP-high, 12% (1 of 8) were CIMP-low, and 12% (1 of 8) were
CIMP-negative (Figures 2B and 3)
.
Tubular Adenomas and Carcinomas
The CIMP status of adenomas and carcinomas was more heterogeneous
(Figures 2B and 3)
. CIMP-high was present in 32% (6 of 19) of
adenomas, CIMP-low in 32% (6 of 19), and CIMP-negative in 37% (7 of
19). CIMP-high was present in 44% (4 of 9) of carcinomas, CIMP-low in
11% (1 of 9), and CIMP-negative in 44% (4 of 9) (Figures 2B and 3)
.
All three right-sided colonic carcinomas were CIMP-high (patients 4,
11, and 17) as contrasted with one of six left-sided colorectal
carcinomas (patient 12, P = 0.05). K-ras mutation was
present in 5% (1 of 19) adenomas and in none of nine carcinomas.
MSI-High and Methylation of hMLH1
All HPs from patients with multiple/large HPs or hyperplastic
polyposis were MSI-negative, but MSI-high was present in one SA, four
tubular adenomas, and two carcinomas from four patients (patients 3, 4,
12, and 17; Figure 3
). CIMP, MSI-high, and methylation of
hMLH1 status were compared in multiple lesions from the four
patients with MSI-high SA, tubular adenomas, or colorectal carcinomas
(Figure 4)
. Concordant methylation of
hMLH1, CIMP-high, and MSI-high was present in an adenoma and
carcinoma from one patient, and a carcinoma from another patient
(patients 4 and 17), but methylation of hMLH1 was not
present in all other MSI-negative HPs, SAs, adenomas, or carcinomas.
Methylation of hMLH1 was not present in one CIMP-high,
MSI-high SA from one patient (patient 12); and one CIMP-high and two
CIMP-negative, MSI-high adenomas from another patient (patient 3).
|
|
Discussion |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
A high degree of concordance was observed among HPs within the same patient with multiple/large HPs, or hyperplastic polyposis, in our study. In contrast, CIMP status was not correlated among sporadic adenomas within the same patient in another study.17 These findings suggest that some of the patients with multiple/large HPs, or hyperplastic polyposis, may have a hypermethylator phenotype either because of genetic predisposition to develop methylated HPs and related lesions, or because of an environmental exposure that results in development of multiple methylated HPs. Effects of carcinogen exposures on CpG island methylation of estrogen receptor in lung carcinomas have previously been described.34 This, together with the fact that most patients in the present study had no family history of colonic neoplasms, tends to favor the latter hypothesis.
Methylation was more common in patients with predominance of HPs in the right colon and/or SAs. We have previously described differences in topographic expression of p21Waf1/Cip1 cyclin-dependent kinase inhibitor and Ki-67 proliferation marker in right- and left-sided HPs from these patients.28
The genetic alterations in sporadic HPs differ from genetic alterations in HPs from patients with multiple HPs, large HPs, or hyperplastic polyposis. Sporadic HPs have frequent K-ras mutations and loss of chromosome 1p,35-39 but lack CpG island methylation. In contrast, HPs from patients with multiple/large HPs, or hyperplastic polyposis, have infrequent K-ras mutations, and loss of chromosome 1p in a small percentage of HPs,28 but frequent CpG island methylation. Furthermore, K-ras mutation or loss of chromosome 1p was predominantly present in HPs from patients with predominance of HPs in the left colorectum without serrated adenomas, a set of patients who lack CIMP-high HPs or carcinomas. These results suggest that either K-ras mutations and loss of chromosome 1p are a late event or two alternative sets of early genetic events occurring in HPs, one characterized by CpG island methylation and the other by K-ras mutations or loss of chromosome 1p. The latter is further corroborated by lack of K-ras mutations in adenomas and carcinomas in these patients.
CIMP-high colorectal carcinomas and adenomas have frequent methylation of the p16 gene and mutations of the K-ras gene, but lack p53 gene mutation.16,40 HPs with CIMP-high from the present study had frequent methylation of the p16 gene, but lacked K-ras mutations and p53 overexpression of the type seen with p53 gene mutation.28 These data provide additional evidence that progression of colorectal carcinogenesis in patients with hyperplastic polyposis is distinct from sporadic CIMP-negative and CIMP-high carcinomas. There is evidence for two CIMP-positive pathways of colorectal carcinogenesis: one characterized by methylation of O6-methylguanine DNA methyltransferase DNA repair gene is associated with MSI-low, and G to A K-ras and p53 gene mutations;13,41,42 and an another characterized by CIMP-high, paucity of K-ras gene mutation, and with or without MSI-high dependent on methylation status of hMLH1.14-17,41
MSI-high SA, tubular adenomas, or carcinomas were present in four patients in our study. Concordant methylation of hMLH1, CIMP-high, and MSI-high was present in one tubular adenoma and two carcinomas from two patients. Another patient had MSI-high, CIMP-high SA without methylation of hMLH1. All of these three patients had CIMP-high HPs without MSI. In contrast, one patient had MSI-high in three adenomas without CIMP-high in the majority of adenomas or HPs. There was no MSI-positive, CIMP-high HPs in our study. This data suggest that methylation of hMLH1 marks a genetic and histological progression in CIMP-high lesions that develop MSI-high and undergo adenomatous or carcinomatous transformation in a few patients: CIMP-high tubular adenomas and carcinomas develop in patients with CIMP-high HPs because of methylation of hMLH1. This corroborates loss of expression of hMLH1 in MSI-high dysplastic and malignant foci in hyperplastic polyposis noted by Jass and colleagues.31
Thus, some patients with multiple/large HPs, or hyperplastic polyposis, have concordant methylation of multiple CpG islands in HPs. The patient factors that we determined to be important for the development of heavy methylation were the presence of SA(s) and the predominance of HPs in right colon. The role of HPP1 gene methylation in the development of HPs corroborates our findings.43 A CpG island methylation-independent pathway to hyperplastic polyposis also exists, as documented by four patients with loss of chromosome 1p or K-ras mutations in the majority of their HPs. Neoplastic progression because of microsatellite instability is also present in multiple/large HPs, or hyperplastic polyposis.28-31
A high degree of concordance of methylation is observed among HPs in multiple/large HPs or hyperplastic polyposis within the same patient, supporting the existence of a hypermethylator phenotype. Patients with a hypermethylator phenotype will be invaluable in studying and understanding the causes of aberrant methylation in cancer.
|
Footnotes |
|---|
Accepted for publication October 25, 2001.
|
References |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  P. Karpinski, D. Ramsey, Z. Grzebieniak, M. M. Sasiadek, and N. Blin The CpG Island Methylator Phenotype Correlates with Long-Range Epigenetic Silencing in Colorectal Cancer Mol. Cancer Res., April 1, 2008; 6(4): 585 - 591. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Al-Ghnaniem, J. Peters, R. Foresti, N. Heaton, and M. Pufulete Methylation of estrogen receptor {alpha} and mutL homolog 1 in normal colonic mucosa: association with folate and vitamin B-12 status in subjects with and without colorectal neoplasia Am. J. Clinical Nutrition, October 1, 2007; 86(4): 1064 - 1072. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Young, M. Jenkins, S. Parry, B. Young, D. Nancarrow, D. English, G. Giles, and J. Jass Serrated pathway colorectal cancer in the population: genetic consideration Gut, October 1, 2007; 56(10): 1453 - 1459. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Ogino, T. Kawasaki, G. J. Kirkner, M. Loda, and C. S. Fuchs CpG Island Methylator Phenotype-Low (CIMP-Low) in Colorectal Cancer: Possible Associations with Male Sex and KRAS Mutations J. Mol. Diagn., November 1, 2006; 8(5): 582 - 588. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Young and J. R. Jass The case for a genetic predisposition to serrated neoplasia in the colorectum: hypothesis and review of the literature. Cancer Epidemiol. Biomarkers Prev., October 1, 2006; 15(10): 1778 - 1784. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P Minoo, K Baker, R Goswami, G Chong, W D Foulkes, A R Ruszkiewicz, M Barker, D Buchanan, J Young, and J R Jass Extensive DNA methylation in normal colorectal mucosa in hyperplastic polyposis Gut, October 1, 2006; 55(10): 1467 - 1474. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S Ogino, M Cantor, T Kawasaki, M Brahmandam, G J Kirkner, D J Weisenberger, M Campan, P W Laird, M Loda, and C S Fuchs CpG island methylator phenotype (CIMP) of colorectal cancer is best characterised by quantitative DNA methylation analysis and prospective cohort studies Gut, July 1, 2006; 55(7): 1000 - 1006. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. O. Chan, A. S. Soliman, Q. Zhang, A. Rashid, A. Bedeir, P. S. Houlihan, N. Mokhtar, N. Al-Masri, U. Ozbek, R. Yaghan, et al. Differing DNA Methylation Patterns and Gene Mutation Frequencies in Colorectal Carcinomas from Middle Eastern Countries Clin. Cancer Res., December 1, 2005; 11(23): 8281 - 8287. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. D. Ramsey, W. Burke, L. Pinsky, L. Clarke, P. Newcomb, and M. J. Khoury Family History Assessment to Detect Increased Risk for Colorectal Cancer: Conceptual Considerations and a Preliminary Economic Analysis Cancer Epidemiol. Biomarkers Prev., November 1, 2005; 14(11): 2494 - 2500. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Shen, Y. Kondo, G. L. Rosner, L. Xiao, N. S. Hernandez, J. Vilaythong, P. S. Houlihan, R. S. Krouse, A. R. Prasad, J. G. Einspahr, et al. MGMT Promoter Methylation and Field Defect in Sporadic Colorectal Cancer J Natl Cancer Inst, September 21, 2005; 97(18): 1330 - 1338. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Beach, A. O.-O. Chan, T.-T. Wu, J. A. White, J. S. Morris, S. Lunagomez, R. R. Broaddus, J.-P. J. Issa, S. R. Hamilton, and A. Rashid BRAF Mutations in Aberrant Crypt Foci and Hyperplastic Polyposis Am. J. Pathol., April 1, 2005; 166(4): 1069 - 1075. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z. Petko, M. Ghiassi, A. Shuber, J. Gorham, W. Smalley, M. K. Washington, S. Schultenover, S. Gautam, S. D. Markowitz, and W. M. Grady Aberrantly Methylated CDKN2A, MGMT, and MLH1 in Colon Polyps and in Fecal DNA from Patients with Colorectal Polyps Clin. Cancer Res., February 1, 2005; 11(3): 1203 - 1209. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P Zauber, M Sabbath-Solitare, S Marotta, A Zauber, and T Bishop Comparative molecular pathology of sporadic hyperplastic polyps and neoplastic lesions from the same individual J. Clin. Pathol., October 1, 2004; 57(10): 1084 - 1088. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. J. Belshaw, G. O. Elliott, E. A. Williams, D. M. Bradburn, S. J. Mills, J. C. Mathers, and I. T. Johnson Use of DNA from Human Stools to Detect Aberrant CpG Island Methylation of Genes Implicated in Colorectal Cancer Cancer Epidemiol. Biomarkers Prev., September 1, 2004; 13(9): 1495 - 1501. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T Higuchi and J R Jass My approach to serrated polyps of the colorectum J. Clin. Pathol., July 1, 2004; 57(7): 682 - 686. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C V A Wynter, M D Walsh, T Higuchi, B A Leggett, J Young, and J R Jass Methylation patterns define two types of hyperplastic polyp associated with colorectal cancer Gut, April 1, 2004; 53(4): 573 - 580. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Kopelovich, J. A. Crowell, and J. R. Fay The Epigenome as a Target for Cancer Chemoprevention J Natl Cancer Inst, December 3, 2003; 95(23): 1747 - 1757. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. L. Frazier, L. Xi, J. Zong, N. Viscofsky, A. Rashid, E. F. Wu, P. M. Lynch, C. I. Amos, and J.-P. J. Issa Association of the CpG Island Methylator Phenotype with Family History of Cancer in Patients with Colorectal Cancer Cancer Res., August 15, 2003; 63(16): 4805 - 4808. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. L. Chan, W. Zhao, Cancer Genome Project, S. Y. Leung, and S. T. Yuen BRAF and KRAS Mutations in Colorectal Hyperplastic Polyps and Serrated Adenomas Cancer Res., August 15, 2003; 63(16): 4878 - 4881. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y Kaneko, S Sakurai, M Hironaka, S Sato, S Oguni, Y Sakuma, K Sato, K Sugano, and K Saito Distinct methylated profiles in Helicobacter pylori dependent and independent gastric MALT lymphomas Gut, May 1, 2003; 52(5): 641 - 646. [Abstract] [Full Text]
|
|
|
|
|
|
C. Bariol, C. Suter, K. Cheong, S.-L. Ku, A. Meagher, N. Hawkins, and R. Ward The Relationship between Hypomethylation and CpG Island Methylation in Colorectal Neoplasia Am. J. Pathol., April 1, 2003; 162(4): 1361 - 1371. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. E. MOORE, W.-Y. HUANG, J. CHUNG, and R. B. HAYES Epidemiologic Considerations to Assess Altered DNA Methylation from Environmental Exposures in Cancer Ann. N.Y. Acad. Sci., March 1, 2003; 983(1): 181 - 196. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Jass Serrated Adenoma of the Colorectum: A Lesion with Teeth Am. J. Pathol., March 1, 2003; 162(3): 705 - 708. [Full Text] [PDF]
|
|
|
|
|
|
S.-J. Park, A. Rashid, J.-H. Lee, S. G. Kim, S. R. Hamilton, and T.-T. Wu Frequent CpG Island Methylation in Serrated Adenomas of the Colorectum Am. J. Pathol., March 1, 2003; 162(3): 815 - 822. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. O.-O. Chan, R. R. Broaddus, P. S. Houlihan, J.-P. J. Issa, S. R. Hamilton, and A. Rashid CpG Island Methylation in Aberrant Crypt Foci of the Colorectum Am. J. Pathol., May 1, 2002; 160(5): 1823 - 1830. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||
