人肝癌组织GGT基因甲基化状态与酶蛋白异常表达关系的研究

Relationship between methylation status of γ-glutamyl transpeptidase (GGT) genes and abnormal expressionof its enzyme proteins in tissues of human hepatomas

目的探讨肝癌发生过程中γ－谷氨酰转肽酶（ＧＧＴ）的表达及其改变机制。方法将肝癌、癌旁及远癌组织总ＧＧＴ和ＲＮＡ纯化，观察总ＧＧＴ、膜结台和可溶性ＧＧＴ的表达，并以逆转录巢式ＰＣＲ扩增ＧＧＴ非编码区基因片段，分析Ｍ３位点的甲基化状态。结果肝癌、癌旁和远癌组总ＲＮＡ浓度呈明显的梯度升高趋势（Ｐ＜０．０５）；癌组织总ＧＧＴ、膜结合和可溶性ＧＧＴ均高于癌周和远癌组织（Ｐ＜０．０５）；在癌、癌旁和远癌组织中，特定基因片段的扩增检出率分别为１００％，８５％和７５０／０，Ｍ３位点低甲基化频率分别为７５％，５５％和５０％。结论肝癌组织中ＧＧＴ呈异常表达与基因低甲基化状态有关，分析ＧＧＴ基因可望成为监测肝细胞癌变的灵敏方法。

Objective To explore the mechanism of expression and alteration of γ-glutamyltranspeptidase (GGT) gmes during the development of human hepatomas. Methods The total GGT proteinand total RNA were purified in human hepatomas, adjacent paracancerous and distal cancerous tissues.The speific activities of total GGT, membrane--combine GGT and soluble GGT were investigated, the GGTgene of 5-NC region was amplified by using a nest RT-PCR assay, and methylation status of GGT aceM3 site were analyzed in the present study. Results An increasing tendency (P<0.05) of total RNAconcentrations was found from cancer in distal cancerous tissues; the speCific aCtivities (U/g) of total GGT,membrane-combine GGT and soluble GGT were significantly higher (P<0.05) in hepatomas than those inadjacent paracancerous or and that distal cancerous tissues; and the fmpuencies of amplified fragment andhypomethylated M3 site of GGT 5-NC region gmes were 100% and 75% in hepatomas, 85% and 55% inadjacent cancerous, and 75% and 50% in distal cancerous tissues, respectively. Conclusions The presentdata snareSt that the abnormal expression of GGT proteins in hepatomas was related to hypomethylatiollstatus of GGT g6nes, and that the fragment analysis of the GGT g6nes might be a sensitive assay tomonitor the hepatic cell canceration.