Methylation and mutation analysis of p16 gene in gastric cancer

AIM To study methylation,frequencies of homozygousdeletion and mutation of p16 gene in gastric carcinoma.METHODS:The methylation pattern in exon 1 and exon 2of p16 gene was studied with polymerase chain reaction(PCR),using methylation sensitive restriction endonucleaseHpall and methylation insensitive restriction endonucleaseMspl.PCR technique was used to detect homozygousdeletions of exon 1 and exon 2 of p16 gene and singlestrand conformation polymorphism(SSCP)technique wasused to detect the mutation of the gene.RESULTS:Hypermethylation changes in exon 1 and exon2 of p16 gene were observed in 25 % and 45 % of 20gastric cancer tissues,respectively,while no methylationabnormality was found in normal tissues.The homozygousdeletion frequency of exon 1 and exon 2 of p16 gene in 20gastric cancer tissues was 20 % and 10 %,respectively.Nomutation was found in exon 1 of p16 gene,while abnormalsingle strands were found in 2(10 %)cases in exon 2 asdetected by SSCP.CONCLUSION:The results suggest that hypermethylationand abnormality of p16 gene may play a key role in theprogress of gastric cancer.Hypermethylation of exon 2 ofp16 gene may have effects on the carcinogenesis of gastricmucosa and may be a later event.