Dataset Information

CpG island methylator phenotype (CIMP) of colorectal cancer is best characterised by quantitative DNA methylation analysis and prospective cohort studies.

ABSTRACT:

Background

The concept of CpG island methylator phenotype (CIMP) is not universally accepted. Even if specific clinicopathological features have been associated with CIMP, investigators often failed to demonstrate a bimodal distribution of the number of methylated markers, which would suggest CIMP as a distinct subtype of colorectal cancer. Previous studies primarily used methylation specific polymerase chain reaction which might detect biologically insignificant low levels of methylation.

Aim

To demonstrate a distinct genetic profile of CIMP colorectal cancer using quantitative DNA methylation analysis that can distinguish high from low levels of DNA methylation.

Materials and methods

We developed quantitative real time polymerase chain reaction (MethyLight) assays and measured DNA methylation (percentage of methylated reference) of five carefully selected loci (promoters of CACNA1G, CDKN2A (p16), CRABP1, MLH1, and NEUROG1) in 460 colorectal cancers from large prospective cohorts.

Results

There was a clear bimodal distribution of 80 microsatellite instability-high (MSI-H) tumours according to the number of methylated promoters, with no tumours showing 3/5 methylated loci. Thus we defined CIMP as having >or=4/5 methylated loci, and 17% (78) of the 460 tumours were classified as CIMP. CIMP was significantly associated with female sex, MSI, BRAF mutations, and wild-type KRAS. Both CIMP MSI-H tumours and CIMP microsatellite stable (MSS) tumours showed much higher frequencies of BRAF mutations (63% and 54%) than non-CIMP counterparts (non-CIMP MSI-H (0%, p<10(-5)) and non-CIMP MSS tumours (6.6%, p<10(-4)), respectively).

Conclusion

CIMP is best characterised by quantitative DNA methylation analysis. CIMP is a distinct epigenotype of colorectal cancer and may be less frequent than previously reported.

SUBMITTER: Ogino S

PROVIDER: S-EPMC1856352 | biostudies-literature | 2006 Jul

REPOSITORIES: biostudies-literature

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Publications

CpG island methylator phenotype (CIMP) of colorectal cancer is best characterised by quantitative DNA methylation analysis and prospective cohort studies.

Ogino S S Cantor M M Kawasaki T T Brahmandam M M Kirkner G J GJ Weisenberger D J DJ Campan M M Laird P W PW Loda M M Fuchs C S CS

Gut 20060111 7

<h4>Background</h4>The concept of CpG island methylator phenotype (CIMP) is not universally accepted. Even if specific clinicopathological features have been associated with CIMP, investigators often failed to demonstrate a bimodal distribution of the number of methylated markers, which would suggest CIMP as a distinct subtype of colorectal cancer. Previous studies primarily used methylation specific polymerase chain reaction which might detect biologically insignificant low levels of methylatio ...[more]

PMID: 16407376

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Project description:Background:Hypermethylation of promoter CpG islands [CpG island methylator phenotype (CIMP)] represents a unique pathway for the development of colorectal cancer (CRC), characterized by lack of chromosomal instability and a low rate of adenomatous polyposis coli (APC) mutations, which have both been correlated with taxane resistance. Similarly, small bowel adenocarcinoma (SBA), a rare tumor, also has a low rate of APC mutations. This phase II study evaluated taxane sensitivity in SBA and CIMP-high CRC. Patients and methods:The primary objective was Response Evaluation Criteria in Solid Tumors version 1.1 response rate. Eligibility included Eastern Cooperative Oncology Group performance status 0/1, refractory disease, and SBA or CIMP-high metastatic CRC. Nab-paclitaxel was initially administered at a dose of 260?mg/m2 every 3?weeks but was reduced to 220?mg/m2 owing to toxicity. Results:A total of 21 patients with CIMP-high CRC and 13 with SBA were enrolled from November 2012 to October 2014. The efficacy-assessable population (patients who received at least three doses of the treatment) comprised 15 CIMP-high CRC patients and 10 SBA patients. Common grade 3 or 4 toxicities were fatigue (12%), neutropenia (9%), febrile neutropenia (9%), dehydration (6%), and thrombocytopenia (6%). No responses were seen in the CIMP-high CRC cohort and two partial responses were seen in the SBA cohort. Median progression-free survival was significantly greater in the SBA cohort than in the CIMP-high CRC cohort (3.2?months compared with 2.1?months, P?=?0.03). Neither APC mutation status nor CHFR methylation status correlated with efficacy in the CIMP-high CRC cohort. In vivo testing of paclitaxel in an SBA patient-derived xenograft validated the activity of taxanes in this disease type. Conclusion:Although preclinical studies suggested taxane sensitivity was associated with chromosomal stability and wild-type APC, we found that nab-paclitaxel was inactive in CIMP-high metastatic CRC. Nab-paclitaxel may represent a novel therapeutic option for SBA.

Dataset Information

CpG island methylator phenotype (CIMP) of colorectal cancer is best characterised by quantitative DNA methylation analysis and prospective cohort studies.

Background

Aim

Materials and methods

Results

Conclusion

Publications

CpG island methylator phenotype (CIMP) of colorectal cancer is best characterised by quantitative DNA methylation analysis and prospective cohort studies.

Similar Datasets

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