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Cellular Oncology
Volume 28 (2006), Issue 5-6, Pages 259-272
http://dx.doi.org/10.1155/2006/949506

ADAMTS1, CRABP1, and NR3C1 Identified as Epigenetically Deregulated Genes in Colorectal Tumorigenesis

Guro E. Lind,1 Kristine Kleivi,2 Gunn I. Meling,3 Manuel R. Teixeira,4 Espen Thiis-Evensen,5 Torleiv O. Rognum,6 and Ragnhild A. Lothe1,7

1Department of Cancer Prevention, Institute for Cancer Research, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway
2Department of Genetics, Institute for Cancer Research, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway
3Surgical Department, Faculty Division Akershus University Hospital, University of Oslo, Oslo, Norway
4Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
5Medical Department, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway
6Institute of Forensic Medicine, Institute for Cancer Research, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway
7Department of Molecular Biosciences, University of Oslo, Oslo, Norway

Copyright © 2006 Hindawi Publishing Corporation and the authors. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: Gene silencing through CpG island hypermethylation is a major mechanism in cancer development. In the present study, we aimed to identify and validate novel target genes inactivated through promoter hypermethylation in colorectal tumor development. Methods: With the use of microarrays, the gene expression profiles of colon cancer cell lines before and after treatment with the demethylating agent 5-aza-2′-deoxycytidine were identified and compared. The expression of the responding genes was compared with microarray expression data of primary colorectal carcinomas. Four of these down-regulated genes were subjected to methylation-specific PCR, bisulphite sequencing, and quantitative gene expression analysis using tumors (n=198), normal tissues (n=44), and cell lines (n=30). Results: Twenty-one genes with a CpG island in their promoter responded to treatment in cell lines, and were simultaneously down-regulated in primary colorectal carcinomas. Among 20 colon cancer cell lines, hypermethylation was subsequently identified for three of four analyzed genes, ADAMTS1 (85%), CRABP1 (90%), and NR3C1 (35%). For the latter two genes, hypermethylation was significantly associated with absence or reduced gene expression. The methylation status of ADAMTS1, CRABP1, and NR3C1 was further investigated in 116 colorectal carcinomas and adenomas. Twenty-three of 63 (37%), 7/60 (12%), and 2/63 (3%) adenomas, as well as 37/52 (71%), 25/51 (49%), and 13/51 (25%) carcinomas were hypermethylated for the respective genes. These genes were unmethylated in tumors (n=82) from three other organs, prostate, testis, and kidney. Finally, analysis of normal colorectal mucosa demonstrated that the observed promoter hypermethylation was cancer-specific. Conclusion: By using a refined microarray screening approach we present three genes with cancer-specific hypermethylation in colorectal tumors, ADAMTS1, CRABP1, and NR3C1.