HYPOMETHYLATION IN THE C-MYC ONCOGENE IN COLON-CARCINOMA

The methylation state of the third exon of c-myc oncogene was studied in ten human colon carcinomas and adjacent normal tissue. DNA methylat ion was studied by means of two restriction endonuclease isoschizomers Msp I and Hpa II which recognize the sequence 5'-CCGG-3'. In 80% of t he cases digested with Hpa IIit was observed the presence of two bands of 2.2 Kb and 3.4 Kb. Taking into account the behaviour of this enzim e an hypomethylation in the CCGG site in the third exon was present. I n normal DNA a higher molecular weigh band (5.6 Kb) was observed indic atI ing a complete methylation in this site. The inverse correlation b etween gene expression and DNA SS methylation can be related with the oncogene activation in tumoral development.