Change in methylation status of DNA of remaining allele in human lung cancers with loss of heterozygosity on chromosomes 3p and 13q.

Loss of heterozygosity at several chromosomal loci is frequently observed in human cancers and loss of one allele is supposed to affect expression of the gene(s) in the remaining allele. As DNA methylation is known to be closely related to gene expression in vertebrates, we are interested in the methylation status of the regions of alleles remaining after loss of their counterparts. In this work we investigated the methylation status of DNA from human lung carcinoma in which heterozygosity was lost at 3p and 13q and found that the remaining allele at these loci was preferentially demethylated. In contrast, tumor DNAs without allele loss tended to retain highly methylated states. These results suggest that in tumors, change of the DNA methylation status is closely related with allele loss, and vice versa.