In the last few years, numerous studies have dealt with the hypermethylation of CpG islands in promoters that is frequently observed in cancer cell lines. Promoter hypermethylation is capable of repressing the expression of genes, a process which may contribute to carcinogenesis especially if the promoters of tumor suppressor genes are affected.
A recent study published in Human Molecular Genetics (Smiraglia et al., Hum. Mol. Genet., 2001, Vol. 10, No. 13, 1413-1419) reveals that the hypermethylation of CpG islands observed in cancer lines seems to be an intrinsic property specific of these cell lines. Using a method called restriction landmark genomic scanning to measure the extent of hypermethylation, the authors could show that cancer cell lines exhibited a significantly higher level of CpG island hypermethylation compared to the primary malignancies from which they originated. Furthermore, 70% of hypermethylated loci were found to be hypermethylated in cancer cell lines of different type. This observation reinforces the idea that hypermethylated loci may be less representative of a special tumor type than of a stage in the establishment of a tumourous phenotype.
Dominic J. Smiraglia
The Ohio State University
Division of Human Cancer Genetics
phone +1 614 292 6478
fax +1 614 688 4761
Message posted by: Ulrike Sattler