Detection Of CpG Island Methylation Status Of Caveolin-1 Gene Exon 2 And Caveolin-2 Gene In Gastric Carcinoma

AIM: To detect methylation status of 5'CpG island in the promoter region of Caveolin-1 gene exon-2 and Caveolin-2 gene in gastric carcinoma and to analyze the role of methylation of 5'CpG island in the promoter region of caveolin-1 gene and Caveolin-2 gene in genesis, development and biological behaviour in gastric carcinoma.Methods: Tissues of gastric carcinoma and normal gastric tissues which exceed 5 cm apart from tumour were collected. Genomic DNA of tissues was extracted by a standard proteinase K digestion and a phenol/chloroform extraction protocol. After the treatment with CpGenome DNA Modification Kit, extracted DNA was amplified using primers either methylated or unmethylated. The PCR products were analyzed by both agarose gel electrophoresis and sequencing.Results:1. There were no methylation of the 5'CpG island in the promoter region of Caveolin-1 gene exon-2 examined in all 6 samples of normal gastric tissues. In 30 samples of tissues of gastric carcinoma, the methylation positive rate of 5'CpG island in the promoter region of Caveolin-1 gene exon-2 was 90%, among which there were 16 cases (53.3%) were only amplified by methylated primers, and 11 cases (36.7%) were amplified both by methylated and unmethylated primers. The result of statistics showed the methylation rate of the promoter region of Caveolin-1 gene exon-2 in gastric carcinoma was obviously higher than normal gastric tissues.2. The Fisher's exact test showed that the methylation status of 5'CpG island in the promoter region of Caveolin-1 gene exon-2 was not related with differentiation level of tissues of gastric carcinoma, patients' age, gender, the size of tumor, invasion depths, lymph node metastasis and vessel invasion (p>0.05). 3. There were no methylation of the 5'CpG island in the promoter region of Caveolin-2 gene examined in all 5 samples of normal gastric tissues. In 33 samples of tissues of gastric carcinoma, the methylation positive rate of promoter region of Caveolin-2 gene was 87.9%, among which there were 20 cases (60.6%) showed complete methylation, and 9 cases (27.3%) were partial methylation. 4 samples of tissues of gastric carcinoma were no methylation of the 5'CpG island in the promoter region of Caveolin-2 gene. The result of statistics showed the methylation rate of the promoter region of Caveolin-2 gene in gastric carcinoma was obviously higher than normal gastric tissues.4. The Fisher's exact test showed that the methylation status of 5'CpG island in the promoter region of caveolin-2 gene was not related with differentiation level of tissues of gastric carcinoma, patients' age, gender, the size of tumor, invasion depths, lymph node metastasis and vessel invasion (p>0.05).Conclusion:1. The methylation of the 5'CpG island in the promoter region of caveolin-1 gene is existed in gastric carcinoma and may be involved in the early process of gastric carcinogenesis.2. The methylation positive rate of the 5'CpG island in the promoter region of Caveolin-2 gene in gastric carcinoma is high, and methylation of Caveolin-2 gene may be related to genesis of gastric carcinoma.