Study On Demethylation State Of Mage-1 Gene B'B Promoter In Gastric Carcinoma

After the surgery, radiotherapy and chemiotherapy, the biological therapy has become the fourth kind of therapies of malignant tumors. The antigenicity of tumor cells, the induced antibody which can react with the tumor antigens and the specific immune responses have piay an important role in tumor immunotherapy.MAGE-1 which encodes one of tumor-rejection antigens associated with melanoma can not be expressed in normal tissues except for testis and placenta. In many kinds of tumor cells, it can be transcribed and translated, then the functional products can be produced to accelerate the development of tumor. The products of MAGE-1 has been regarded as a kind of tumor specific antigen that can be identified by cytotoxic T lymphocytes of the tumor patients, which suggests that MAGE-1 gene products are appropriate target molecules for immune system. They can induce the organism to produce the specific cellular mediated immune responses and humoral immune responses, so that the growth diffusion recurrence of tumor can be inhabited. We studied the methylation state within MAGE-1 B'B promoter in gastric carcinoma and the association between demeth-ylation and pathological differentiation, as well as demethylation and clinical stage.Using methylation-sensitive restriction analysis followed by polymerase chain reaction (PCR),we studied 80 specimen that were obtained from surgical samples(including 40 gastric carcinoma and 40 matched adjacent normal gastric mucosae). Each specimen was stored at-70 until used. Disease stages were determined using the TNM classification according to UIGC criteria.Then we obtained the results; An demethylation state was identified in DNA from gastric carcinoma specimens. The demethvlation rate is 25% (10/40). In contrast, no demethylation state was identified in DNA from matched adjacent normal gastric mucosae. The differences were significant statistically. In our study, the demethylation in poorly, moderately, and well differentiated glandulous-cell carcinoma were detected at frequencies of 50%, 18. 7%, and 8. 3%, respectively. The differences were significant statistically(P<0. 05). The demethylation rate in early, late tumor stage was 16. 7% and 28. 6%, respectively, The differences were significant statistically(P<0. 05).This study suggested that the demethylation in MAGE-1 B'B promoter is anomalous in gastric carcinoma, and was related to the expression of MAGE-1 gene in gastric carcinoma. The demethylation rate was related to the pathological and disease stages differentiation.