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Published online before print May 3, 2007
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From the Departments of Pathology
* and Medicine,
Brigham and Women’s Hospital, Boston; the Department of Medical Oncology,
Dana-Farber Cancer Institute, Boston; Harvard Medical School,
Boston; and the Department of Epidemiology and Biostatistics,
¶ Harvard School of Public Health, Boston, Massachusetts
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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6/8 or 5/8 methylated promoters, based on tumor distribution and BRAF/KRAS mutation frequencies. All but two very specific markers [MLH1 (98% specific) and SOCS1 (93% specific)] demonstrated 85% sensitivity and 80% specificity, indicating overall good concordance in methylation patterns and good performance of these markers. Based on sensitivity, specificity, and false positives and negatives, the eight markers were ranked in order as: RUNX3, CACNA1G, IGF2, MLH1, NEUROG1, CRABP1, SOCS1, and CDKN2A. In conclusion, a panel of markers including at least RUNX3, CACNA1G, IGF2, and MLH1 can serve as a sensitive and specific marker panel for CIMP-high. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In this study using quantitative DNA methylation analysis (MethyLight) and a large number of population-based colorectal cancer specimens, we have evaluated performance characteristics of eight methylation markers including CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1 as well as CDKN2A (p16), CRABP1, and MLH1. The latter three markers have also been selected from screening of the 195 CpG islands to be good markers for CIMP.11 MethyLight assays can reliably distinguish high from low levels of DNA methylation, the latter of which likely have little or no biological significance.19
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Genomic DNA Extraction and Whole Genome Amplification
Genomic DNA was extracted using QIAmp DNA Mini Kit (Qiagen, Valencia, CA) according to the manufacturer’s instructions as previously described.11
Whole genome amplification of genomic DNA was performed by poly-merase chain reaction (PCR) using random 15-mer primers26
for subsequent MSI analysis and KRAS and BRAF sequencing. Previous studies by us and others showed that whole genome amplification did not significantly affect KRAS mutation detection or microsatellite analysis.26, 27
Real-Time PCR (MethyLight) for Quantitative DNA Methylation Analysis
Sodium bisulfite treatment on genomic DNA was performed as previously described.19
For DNA methylation analysis, we typically used one to two tissue sections (10 µm thick) when large tumor sections were available. Real-time PCR to measure DNA methylation (MethyLight) was performed as previously described.28, 29, 30
Using ABI 7300 (Applied Biosystems, Foster City, CA) for quantitative real-time PCR, we amplified eight CIMP-specific promoters [CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1]. COL2A1 (the collagen 2A1 gene) was used to normalize for the amount of input bisulfite-converted DNA.19, 30
Primers and probes were previously described as follows: CACNA1G, CRABP1, and NEUROG111, 12
; CDKN2A and COL2A130
; MLH119
; and IGF2, RUNX3, and SOCS1.12
The percentage of methylated reference (PMR, ie, degree of methylation) at a specific locus was calculated by dividing the GENE:COL2A1 ratio of template amounts in a sample by the GENE:COL2A1 ratio of template amounts in SssI-treated human genomic DNA (presumably fully methylated) and multiplying this value by 100.31
A PMR cutoff value of 4 was based on previously validated data.19, 30, 31
Based on the distribution of PMR values at the CRABP1 and IGF2 loci, we raised PMR cutoff to 6 for CRABP1 and IGF2. Precision and performance characteristics of bisulfite conversion and subsequent MethyLight assays have been previously evaluated, and the assays have been validated.19
MSI Analysis
Methods to determine MSI status have been previously described.32
In addition to the recommended MSI panel consisting of D2S123, D5S346, D17S250, BAT25, and BAT26,33
we also used BAT40, D18S55, D18S56, D18S67, and D18S487 (ie, 10-marker panel).32
A high degree of MSI (MSI-H) was defined as the presence of instability in 30% of the markers. A low degree of MSI (MSI-L) was defined as the presence of instability in <30% of the markers, and microsatellite stable (MSS) tumors were defined as tumors without an unstable marker. Among 889 tumors with MSI status determined, 131 tumors (15%) were MSI-H.
Sequencing of KRAS and BRAF
Methods of PCR and sequencing targeted for KRAS codons 12 and 13, and BRAF codon 600 have been previously described.24, 26
Among 874 tumors with both KRAS and BRAF genes sequenced, KRAS and BRAF mutations were present in 321 tumors (37%) and 116 tumors (13%), respectively.
Statistical Analysis
For statistical analysis, the 
2 test (or Fisher’s exact test for categories with an N value of less than 10) was performed on categorical data, using the SAS program (version 9.1; SAS Institute, Cary, NC). All P values were two-sided, and statistical significance was set at P values of 
0.05.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Table 1
shows the distributions of the number of methylated promoters (from 0 to 8) in all 920 colorectal cancers. We confirmed the associations between CIMP-high and female sex, and between CIMP-low and male sex as we previously reported using five-marker CIMP panel.24
Table 1
also shows distributions of microsatellite instability-high (MSI-H), MSI-low (MSI-L), and MSS tumors according to the number of methylated promoters. Among 131 MSI-H tumors in this study, we observed a striking bimodal distribution with only one tumor (0.8%) exhibiting 4/8 to 5/8 methylated promoters. Thus, it is reasonable to assume that a cutoff for CIMP-high is either 6/8, 5/8, or 4/8 methylated promoters, at least in MSI-H tumors. Distributions of the number of methylated promoters in MSI-L and MSS tumors did not significantly differ, justifying analysis of the combined MSI-L/MSS category.
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, BRAF mutations were more common in extensively methylated tumors (6/8 methylated promoters) than in tumors with less extensive methylation (4/8 methylated promoters). KRAS mutations were less common in tumors with 6/8 methylated promoters than in tumors with 4/8 methylated promoters. Tumors with 5/8 methylated promoters showed intermediate features between 6/8 methylated tumors and 4/8 methylated tumors. Figure 1B
shows a clear separation between MSI-H tumors with 6/8 methylated promoters and tumors with 3/8 methylated promoters. As shown in Figure 1C
, MSI-L/MSS tumors could be separated into CIMP-high (6/8 methylated promoters) and CIMP-low/CIMP-0 (4/8 methylated promoters) categories based on the frequencies of KRAS and BRAF mutations. Tumors with 5/8 methylated promoters showed intermediate features between 6/8 methylated tumors and 4/8 methylated tumors. Thus, the cutoff for CIMP-high could be narrowed, either 6/8 or 5/8 methylated promoters, resulting in the CIMP-high frequency of 15% (=136 of 920) or 18% (=163 of 920), respectively, in our large sample.
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6/8 and 5/8 methylated promoters) (Table 2)
. With either cutoff for CIMP-high, CRABP1, IGF2, and NEUROG1 demonstrated very good sensitivity (95%), whereas CACNA1G, MLH1, RUNX3, and SOCS1 showed superior specificity (90%). We did not examine how bimodal was the distribution of tumors according to different marker combinations, as a previous study did to select the best set of markers.12
This is because bimodal distribution was observed in MSI-H tumors but not in MSI-L/MSS tumors (Table 1)
. We rather assessed sensitivity and specificity of each marker, which reflected how concordant methylation patterns were.
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. Although sensitivity or specificity is important in a setting where there are some characteristic samples (eg, sensitivity is important when testing only MSI-H tumors), the latter (the number of false-positive and false-negative cases) is important in a relatively unbiased clinical setting because it directly reflects the number of misdiagnosed cases. We assigned rank order numbers for individual markers according to the sum of sensitivity and specificity from the largest to the smallest. We also assigned rank order numbers for individual markers according to the sum of false-positive/-negative cases from the smallest to the largest. The sum of these rank order numbers for both CIMP-high cutoffs (6/8 and 5/8 methylated promoters) was an overall score for each marker (smaller, the better) (Table 3)
. We admit that there is no established method to evaluate methylation markers using a large sample; however, our method took into account the parameters commonly assessed for other clinical laboratory markers. As a result, RUNX3 seemed to be the best marker, followed by CACNA1G and IGF2. MLH1 ranked fourth by virtue of its best specificity (98%). NEUROG1, CRABP1, SOCS1, and CDKN2A ranked fifth, sixth, seventh, and eighth, respectively.
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. For instance, to assess sensitivity and specificity of CACNA1G, CIMP status was determined by seven markers excluding CACNA1G. In this way, we could avoid confounding effect of CACNA1G status on diagnosing the CIMP status by the eight markers including CACNA1G. For this analysis, CIMP-high was defined as the presence of 5/7 methylated promoters. As in Table 4
, each marker still exhibited good sensitivity and/or specificity for the diagnosis of CIMP-high, indicating good overall concordance of methylation status in the eight markers. The eighth ranked marker CDKN2A demonstrated 85% sensitivity and 81% specificity. Table 5
shows the methylation frequency of each marker in colorectal cancers with a specific BRAF/KRAS status. The methylation frequencies of the eight markers were high in the BRAF-mutated tumors and low in the BRAF/KRAS wild-type tumors and the KRAS-mutated tumors.
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80% for CIMP-high (Tables 2
and 4)
. Then, we could consider that a classification based on all of the eight markers was more accurate in reflecting true CIMP status (global epigenomic status) than any other marker combinations. Thus, we designated the eight-marker panel (panel 8) as the gold standard. BRAF and KRAS mutation frequency spectra indicated that a separation between CIMP-high and CIMP-low by the five markers of Weisenberger and colleagues12
was not perfect with more borderline cases (40 cases showing 3/5 methylated promoters, 43% KRAS-mutated, and 28% BRAF-mutated) and that, although still not perfect, CIMP panel 8 served as a superior gold standard panel (with 27 cases showing 5/8 methylated promoters, 44% KRAS-mutated, and 33% BRAF-mutated). The overall high sensitivities and specificities of the eight markers indicated that methylation of these markers was reasonably linked and any of these markers could serve as a good surrogate marker for the CIMP status. We further attempted to find the best combination of a relatively small number of markers for an accurate classification of the CIMP status.
We compared three combinations of markers, which were designated as follows: panel 8, panel 5A (RUNX3, CACNA1G, IGF2, NEUROG1, and SOCS1) described by Weisenberger and colleagues,12
and panel 5B (CACNA1G, MLH1, NEUROG1, CRABP1, and CDKN2A) described by Ogino and colleagues,11
and panel 4 (including the four best markers; RUNX3, CACNA1G, IGF2, and MLH1). For each CIMP panel, we examined the BRAF and KRAS mutation frequencies according to the number of methylated promoters (as in Figure 1
) to determine a cutoff for CIMP-high (data not shown). In general, CIMP-high was defined as >65 to 70% of promoters methylated.
An example of assessment of cross-panel classification errors is shown in Table 6
. Tumors were classified as CIMP-high or non-CIMP-high, by one panel (eg, panel 5A) versus the other panel (eg, panel 8). We counted the number of tumors for which classifications (CIMP-high versus non-CIMP-high) were discordant by the two panels. In the example of panel 5A versus panel 8 (Table 6)
, the cross-panel classification error rate was 13/920 = 1.4%. Table 7
shows the cross-panel classification error rates for all pairwise comparisons of the four CIMP panels (8, 5A, 5B, and 4). Remarkably, no pairwise comparison showed the error rate greater than 3.2%, implying that, for a vast majority of tumors, it made no difference to determine the CIMP status by any of these panels. Even panel 4 with only a half of the number of markers in panel 8 showed an excellent concordance rate (98%) with panel 8.
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. CIMP-high was defined as follows, based on the BRAF and KRAS mutation frequencies (data not shown): 2/2 methylated promoters for panel 2, 3/3 methylated promoters for panel 3, 3/4 methylated promoters for panel 4, 4/5 methylated promoters for panel 5, 5/6 methylated promoters for panel 6, 5/7 methylated promoters for panel 7, and 6/8 methylated promoters for panel 8. There was a trend toward higher specificity with a larger number of markers. Sensitivity depended on both CIMP-high cutoff and the number of markers. Panel 4 showed excellent sensitivity and specificity, which were almost as high as those by panel 7. With regard to the classification error rates, there was a trend toward a lower error rate with a larger number of markers. The error rate by panel 4 was 2.0%. Thus, it seemed that panel 4 was almost as good as panel 8, which included twice as many markers.
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50% mucinous component) in relation to combined MSI/CIMP status determined by either CIMP panel 8 or panel 4 (Figure 3)
. Both MSI-H and CIMP-high (determined by either panel) were correlated with proximal (right) location, poor differentiation, and mucinous tumors, and there was no substantial difference between classifications by panel 8 and panel 4.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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We have shown that all of the eight methylation markers evaluated exhibit good sensitivity and specificity for overall CIMP status and that the best individual marker to predict the CIMP status is RUNX3, followed by CACNA1G, IGF2, MLH1, NEUROG1, CRABP1, SOCS1, and last, CDKN2A. CDKN2A still exhibits more than 80% sensitivity and specificity for the prediction of CIMP status determined by the other seven markers. The four best markers we proposed are slightly different from the five markers proposed by Weisenberger and colleagues,12
presumably because of a difference in the sources and sizes of samples; however, we emphasize that all of the eight markers tested have shown good concordance of methylation patterns. Lower sensitivity of SOCS1 and lower specificity of NEUROG1 (compared with RUNX3, CACNA1G, and IGF2) have previously been shown by Weisenberger and colleagues (see Figures 4 and 5 in Weisenberger et al12
). However, various marker combinations in CIMP panels do not misclassify substantial numbers of tumors, especially when RUNX3 is included in a CIMP panel. The validity of the eight markers was also shown by a striking bimodal distribution of MSI-H tumors according to the number of methylated markers (Table 1
and Figure 1
). However, we failed to observe such bimodality in MSI-L/MSS tumors. In addition, although we could separate CIMP-high from CIMP-low by the frequencies of BRAF and KRAS mutations, the difference between CIMP-high and CIMP-low in MSI-L/MSS tumors was not as clear-cut as in MSI-H tumors (Figure 1)
. It remains to be seen whether there exists a different set of markers that can even more clearly separate the rare MSS CIMP-high subtype (
5% of all colorectal cancers) from the MSS CIMP-low subtype.
Weisenberger and colleagues12 examined 195 CpG islands throughout the human genome (including MINT1, MINT2, MINT31, and THBS1, which were described by Toyota and colleagues4 ) and five selected markers including CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1. CDKN2A, CRABP1, and MLH1 were also shown to be good predictors for CIMP status by the initial screening of the 195 loci.11 Using a limited number of samples (40 MSS tumors and 10 sporadic MSI-H tumors), Weisenberger and colleagues12 compared the five markers with the classic methylation markers including CDKN2A, MINT1, MINT2, MINT31, and MLH1. Their data have shown that methylation in CDKN2A and MLH1 is correlated well with BRAF mutations as the new five markers, whereas methylation in MINT1, MINT2, and MINT31 is not specific for BRAF-mutated CIMP tumors (see Figures 4 and 5 in Weisenberger and colleagues12 ). That is why MINT1, MINT2, and MINT31 were excluded from the current study. Nonetheless, we emphasize that our data do not necessarily indicate that these MINT markers or other CpG islands are inappropriate for assessment of CIMP in colorectal cancer, because it remains a possibility that a difference in primer designs and PCR conditions may substantially change sensitivity and specificity of a particular marker for the detection of CIMP in colorectal cancer.
We propose the use of (at least) four markers, including RUNX3, CACNA1G, IGF2, and MLH1, as a cost-effective CIMP-specific promoter panel. Some investigators have suggested that MLH1 may be eliminated from a CIMP panel because the CIMP status of MSS tumors is primarily determined by methylation markers other than MLH1.8 However, in our previous study including MLH1 in the CIMP promoter panel, there were very similar BRAF mutation frequencies in CIMP-high versus non-CIMP-high tumors, regardless of MSI status.11 Thus, we cannot justify exclusion of MLH1 from a CIMP panel solely because of its tight association with MSI phenotype. In the current study, MLH1 proved to be the most specific marker for CIMP-high (ie, 98% specificity). Besides an important role in our proposed CIMP-specific panel, MLH1 methylation testing is clinically useful because most, although not all, MSI-H tumors in Lynch syndrome (a major form of hereditary nonpolyposis colorectal cancer, HNPCC) show no evidence of MLH1 methylation.34, 35 Thus, MLH1 methylation positivity would favor against a diagnosis of Lynch syndrome, in which hereditary colorectal cancer is typically caused by germline and somatic mutations in one of mismatch repair genes including MSH2, MLH1, MSH6, and PMS2.34, 35 However, we emphasize that MLH1 methylation is not a diagnostic test for Lynch syndrome because not all MSI-H tumors without MLH1 methylation are related to Lynch syndrome and because MLH1 methylation positivity cannot completely exclude the possibility of Lynch syndrome.
MSI-H CIMP-low/0 colorectal cancer is an interesting subtype that warrants discussion. As discussed above, most colorectal cancers arising in a background of Lynch syndrome/HNPCC exhibit MSI-H, but no evidence of MLH1 methylation or CIMP-high. Thus, most HNPCCs belong to the MSI-H CIMP-low/0 group. However, HNPCCs probably constitute only a minority in the MSI-H CIMP-low/0 group because the population frequency of Lynch syndrome/HNPCC among all colorectal cancers is estimated to be 1 to 3%,35
and the population frequency of MSI-H CIMP-low/0 colorectal cancers is estimated to be 4.3% (=38 of 889, Table 1
). These data imply the presence of MSI-H CIMP-low/0 tumors unrelated to Lynch syndrome/HNPCC, in contrast to Weisenberger and colleagues12
who state that MSI-H tumors arise either through CIMP pathway or in a background of Lynch syndrome/HNPCC. There is probably a different pathway (CIMP-low/0 unrelated to HNPCC) to MSI-H tumors.
We have previously shown that CIMP-low is associated with male sex and KRAS mutations.24 In the current study, we have confirmed that these associations still persist with increases in both the number of cases and the number of methylation markers in a CIMP panel. However, differences between CIMP-low (1/8 to 5/8 methylated promoters) and CIMP-0 (0/8 methylated promoters) are still not large. Further studies are necessary to assess whether CIMP-low represents a distinct phenotype in colorectal cancer and, if the hypothesis is true, to determine reasonably good markers for the detection of CIMP-low. We recognize that the markers we have chosen are sensitive and specific for the detection of CIMP-high, rather than the identification of CIMP-low.
In summary, we have evaluated CIMP-specific DNA methylation markers and criteria for CIMP-high by a large population-based colorectal cancer sample. Our findings indicate that all of the eight markers evaluated are reasonably good surrogate markers to determine the CIMP status and that (at least) four markers including RUNX3, CACNA1G, IGF2, and MLH1 constitute a sensitive and specific CIMP panel for the purpose of research and clinical use.
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Acknowledgments |
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Footnotes |
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Supported by the National Institutes of Health (grants P01 CA87969 and P01 CA55075).
Accepted for publication December 29, 2006.
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 S. Ogino, A. Hazra, G. J. Tranah, G. J. Kirkner, T. Kawasaki, K. Nosho, M. Ohnishi, Y. Suemoto, J. A. Meyerhardt, D. J. Hunter, et al. MGMT germline polymorphism is associated with somatic MGMT promoter methylation and gene silencing in colorectal cancer Carcinogenesis, September 1, 2007; 28(9): 1985 - 1990. [Abstract] [Full Text] [PDF]
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W. S. Samowitz The CpG Island Methylator Phenotype in Colorectal Cancer J. Mol. Diagn., July 1, 2007; 9(3): 281 - 283. [Full Text] [PDF]
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