[Screening of hypermethylated DNA fragments in tumor tissue derived from patients with lung cancer].

The investigations on the role of DNA methylation in carcinogenesis have been mainly focused on promoter hypermethylation of tumor suppressor genes. As a number of genes associated with cancer development may be influenced by DNA methylation, identification of these genes is of great importance for understanding the epigenetic alteration in carcinogenesis. In this study, hypermethylated regions of genomic DNA from Chinese lung cancer patients were identified by a modified methylation-sensitive arbitrarily primed PCR (MS-AP-PCR). Eight hypermethylated DNA fragments (HMDF) were separated from a PCR product region between 300 and 500bp in size. After cloning, sequencing and searching with Blast and NewCpGseek programs,the result showed that all of them were typical CpG island sequences, four fragments had 99% approximately 100% homology to regions on human chromosome 2, 7, 9 and 10, respectively,but only one revealed to be known gene. Neural Network Promoter Prediction, TSSG and TSSW programs were run to analyze possible functions of the rest 7 fragments, of which 4 were identified as candidate promoter regions, indicating that they might belong to new genes. The hypermethylated DNA fragments identified in this study might be specific epigenetic alterations in the Chinese lung cancer.