Open Access

Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data

  • Authors:
    • Teow Kok-Sin
    • Norfilza Mohd Mokhtar
    • Nur Zarina Ali Hassan
    • Ismail Sagap
    • Isa Mohamed Rose
    • Roslan Harun
    • Rahman Jamal
  • View Affiliations

  • Published online on: May 19, 2015     https://doi.org/10.3892/or.2015.3993
  • Pages: 22-32
  • Copyright: © Kok-Sin et al. This is an open access article distributed under the terms of Creative Commons Attribution License [CC BY_NC 3.0].

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Abstract

Apart from genetic mutations, epigenetic alteration is a common phenomenon that contributes to neoplastic transformation in colorectal cancer. Transcriptional silencing of tumor‑suppressor genes without changes in the DNA sequence is explained by the existence of promoter hypermethylation. To test this hypothesis, we integrated the epigenome and transcriptome data from a similar set of colorectal tissue samples. Methylation profiling was performed using the Illumina InfiniumHumanMethylation27 BeadChip on 55 paired cancer and adjacent normal epithelial cells. Fifteen of the 55 paired tissues were used for gene expression profiling using the Affymetrix GeneChip Human Gene 1.0 ST array. Validation was carried out on 150 colorectal tissues using the methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) technique. PCA and supervised hierarchical clustering in the two microarray datasets showed good separation between cancer and normal samples. Significant genes from the two analyses were obtained based on a ≥2‑fold change and a false discovery rate (FDR) p-value of <0.05. We identified 1,081 differentially hypermethylated CpG sites and 36 hypomethylated CpG sites. We also found 709 upregulated and 699 downregulated genes from the gene expression profiling. A comparison of the two datasets revealed 32 overlapping genes with 27 being hypermethylated with downregulated expression and 4 hypermethylated with upregulated expression. One gene was found to be hypomethylated and downregulated. The most enriched molecular pathway identified was cell adhesion molecules that involved 4 overlapped genes, JAM2, NCAM1, ITGA8 and CNTN1. In the present study, we successfully identified a group of genes that showed methylation and gene expression changes in well-defined colorectal cancer tissues with high purity. The integrated analysis gives additional insight regarding the regulation of colorectal cancer-associated genes and their underlying mechanisms that contribute to colorectal carcinogenesis.
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July-2015
Volume 34 Issue 1

Print ISSN: 1021-335X
Online ISSN:1791-2431

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Spandidos Publications style
Kok-Sin T, Mokhtar NM, Ali Hassan NZ, Sagap I, Mohamed Rose I , Harun R and Jamal R: Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data. Oncol Rep 34: 22-32, 2015
APA
Kok-Sin, T., Mokhtar, N.M., Ali Hassan, N.Z., Sagap, I., Mohamed Rose, I. ., Harun, R., & Jamal, R. (2015). Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data. Oncology Reports, 34, 22-32. https://doi.org/10.3892/or.2015.3993
MLA
Kok-Sin, T., Mokhtar, N. M., Ali Hassan, N. Z., Sagap, I., Mohamed Rose, I. ., Harun, R., Jamal, R."Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data". Oncology Reports 34.1 (2015): 22-32.
Chicago
Kok-Sin, T., Mokhtar, N. M., Ali Hassan, N. Z., Sagap, I., Mohamed Rose, I. ., Harun, R., Jamal, R."Identification of diagnostic markers in colorectal cancer via integrative epigenomics and genomics data". Oncology Reports 34, no. 1 (2015): 22-32. https://doi.org/10.3892/or.2015.3993