Analysis To DNA Methylation Status Of The Promoter Of Human Telomerase Reverse Transcriptase (hTERT) In Gastric Carcinogenesis

ObjectiveWe analyze the specific methylation status of hTERT promoter in gastric carcinogenesis and analyze the relationship among the methylation status of hTERT promoter,the expression of hTERT and telomerase activity.We hope this study may provide experimental data and academic information for the early diagnosis of gastric cancer.MethodsGenomic DNAs were extracted from normal gastric mucosa samples,precancerous lesion samples and gastric cancer samples.Genomic DNAs were modified using sodium bisulfite.After the modification the unmethylated cytosine in the CpG sites of hTERT promoter were changed to uracil.The modified gemomic DNAs were amplified by PCR with primers that did not contain CpG sites.After PCR amplification,each PCR product was sequenced.Via matching the sequencing results and the original sequence,the staus of each samples were obtained.PCR were carried to identify the expression of hTERT.TRAP was carried to test the activity of telomerase among the three groups.Results1.The promoter region of hTERT in gastric cancer was more methylated than in the precancerous lesions and normal gastric mucosa..The differences have statistic significance.(P＜0.05)2.hTERT was absent in normal gastric mucosa and its positive rate was higher in gastric cancer than that in precancerous lesions.The differences have statistic significance.(P＜0.05)3.The activity of telomerase was not detected in normal gastric mucosa and its positive rate was higher in gastric cancer than that in precancerous lesions.The differences have statistic significance.(P＜0.05)ConclusionThe promoter region of hTERT in gastric cancer was more methylated than in the precancerous lesions and normal gastric mucosa.This may suggest that the degree of methylation status of hTERT promoter was increased gradually during gastric carcinogenesis and it may be a potential biological maker in early diagnosis of gastriccancer.During the gastric carcinogenesis the expression of hTERT and the telomerase activity was increased.This may suggest that the methylation of hTERT may have influence on the expression of hTERT and the activity of telomerase.