5 '-cytosine DNA-methyltransferase mRNA levels in hereditary colon carcinoma

DNA methylation plays an important part in the regulation of gene expressio n. Alterations in DNA methylation in tumours have been reported and have be en used to generate hypotheses about mutagenesis and silencing of tumour su ppressor genes. However, the underlying mechanism is still poorly understoo d, and conflicting data on the levels of overexpression of 5'-cytosine DNA methyltransferase in sporadic colon carcinoma have been published. We used a competitive RT-PCR assay for quantification of mRNA of 5'-cytosine DNA me thyltransferase in colon biopsies obtained from patients with hereditary co lon carcinoma syndromes and compared the results with those obtained ill a control group. No significant difference was found between the flat mucose of FAP patients and the mucosa of the control group. In FAP and HNPCC patie nts, the 5'-cytosine DNA methyltransferase mRNA levels of adenomas were sig nificantly higher (P<0.05) than of flat mucosa in the same group, but both showed great variability from patient to patient. Our findings suggest that the mRNA levels of methyltransferase cannot be used as predictive marker f or screening in families affected by hereditary colon carcinoma.