AIM:Aberrant DNA methylation of CpG site is among theearliest and most frequent alterations in cancer.Severalstudies suggest that aberrant methylation of the CpG sitesof the tumor suppressor gene is closely associated withcarcinogenesis.However,large-scale analysis of candidategenes has so far been hampered by the lack of high-throughput approach for analyzing DNA methylation.Theaim of this study was to describe a microarray-based methodfor detecting changes of DNA methylation in cancer.METHODS:This method used bisulfite-modified DNA as atemplate for PCR amplification,resulting in conversion ofunmethylated cytosine,but not methylated cytosine,intothymine within CpG islands of interest.Therefore,the amplifiedproduct might contain a pool of DNA fragments with alterednucleotide sequences due to differential methylation status.Nine sets of oligonucleotide probes were designed tofabricate a DNA microarray to detect the methylation changesof p16 gene CpG islands in gastric carcinomas.The resultswere further validated by methylation-specific PCR(MSP).RESULTS:The experimental results showed that themicroarray assay could successfully detect methylationchanges of p16 gene in 18 gastric tumor samples.Moreover,it could also potentially increase the frequency of detectingp16 methylation from tumor samples than MSP.CONCLUSION:Microarray assay could be applied as a usefultool for mapping methylation changes in multiple CpG lociand for generating epigenetic profiles in cancer. AIM: Aberrant DNA methylation of CpG site is among the mostar and the most frequent alterations in cancer. Severalstudies suggest that aberrant methylation of the CpG sitesof the tumor suppressor gene is closely associated withcarcinogenesis.However, large-scale analysis of candidate genes has so far been been hampered by the lack of high-throughput approach for analyzing DNA methylation. aim of this study was to describe a microarray-based method for detecting changes of DNA methylation in cancer. METHODS: This method used bisulfite-modified DNA as atemplate for PCR amplification, resulting in conversion ofunmethylated cytosine, but not methylated cytosine, intothymine within CpG islands of interest. Therefore, the amplified product may contain a pool of DNA fragments with altered nucleotide sequences due to differential methylation status. Nine sets of oligonucleotide probes were designed tofabricate a DNA microarray to detect the methylation changesof p16 gene CpG islands in gastric carcinomas. the res The results showed that theyicroarray assay could successfully detect methylationchanges of p16 gene in 18 gastric tumor samples. More than that it could also potentially increase the frequency of detecting p16 methylation from tumor samples than MSP. CONCLUSION: Microarray assay could be applied as a usefultool for mapping methylation changes in multiple CpG lociand for generating epigenetic profiles in cancer.