title: No SMAD4 hypermethylation in colorectal cancer.
abstract: The chromosome region 18q21 is frequently deleted in colorectal cancers. Three candidate tumour suppressor genes, DCC, SMAD4 and SMAD2, map to this region. The SMAD4(DPC4) gene was recently identified as a candidate pancreatic cancer suppressor gene. It is also a gene for juvenile polyposis tumour predisposition syndrome. Somatic SMAD4 mutations have been detected in some colorectal carcinomas. However, the frequency of these mutations is relatively low, and whether SMAD4 plays a key role in colorectal tumorigenesis is still unclear. In addition to loss of chromosomal material and intragenic mutations there is a third mechanism, DNA methylation, which may have an important role in gene inactivation. In the present study, we examined whether promoter hypermethylation could be a mechanism for SMAD4 inactivation. In total, 42 colorectal tumours were selected for the methylation analysis and no evidence of promoter hypermethylation was found. Our result suggests that hypermethylation of the SMAD4 promoter region is not a frequent event in colorectal tumorigenesis.
authors.affiliation: Department of Medical Genetics, Haartman Institute, University of Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Roth
authors.forename: P
authors.initials: P
authors.lastname: Laiho
authors.forename: R
authors.initials: R
authors.lastname: Salovaara
authors.forename: V
authors.initials: V
authors.lastname: Launonen
authors.forename: L A
authors.initials: LA
authors.lastname: Aaltonen
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D001483:Base Sequence; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D002887:Chromosomes, Human, Pair 18; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics*; D016147:Genes, Tumor Suppressor; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011401:Promoter Regions, Genetic; D051901:Smad4 Protein; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D015534:Trans-Activators