High methylation of Ptchl gene involved in hedgehog signal pathway in human gastric carcinoma / 中华消化杂志

ABSTRACT

Objective To investigate the expression and aberrant methylation of Ptchl gene in hedgehog signal pathway in carcinogenesis of human gastric cancer.Methods The total RNA and genomic DNA were extracted from 10 human gastric carcinoma tissues,adjacent tissues(＞3 cm from cancerous tissue)and gastric cancer eell line AGS.Ptchl mRNA expression was detected by real-time quantitative reverse transcription PCR.The pattern of CpG island in Ptchl gene 5'regulation sequence was analyzed by software and its methylation extent was tested by bisulfite sequencing PCR.Results The analysis of CpG island(starting-3950 bases upstream of the Ptchl mRNAla transcription start site and ending 2050 bases downstream)revealed that there were two CpG islands in Ptchl gene 5' regulation sequence(first CpG-1139 bp～+860 bp;second CpG+875 bp～+1692 bp).Bisulfite sequencing PCR analysis of 19 CpG sites included in the first CpG island(-870 bp～+229 bp)showed that there was methylation present in all cell lines and the average extent of the methylation of these CpG sites was significantly higher in cancerous tissues(64%±32%,ranged 16%～100%)than that in adjacent tissues(13%±14%,ranged 0%～42%,P＜0.05).There was a negative correlation of the Ptchl methylation with its expression.Conclusion The high methylation of Ptchl gene that involves in the carcinogenesis of human gastric carcer will be a new biomarker for gastric carcer.