微囊藻毒素促肝癌过程中肝细胞bcl-2及bax基因表达研究

目的 探讨微囊藻毒素（MC）促肝癌的分子机制。方法 采用二阶段致癌理论建立中期试验动物模型,γ－谷氨酰转肽酶（γ－GT）染色检验MC的促癌作用,并以免疫组化法结合图像分析技术精确测定大鼠肝脏bcl－2和bax基因的表达情况。结果 MC在促大鼠肝癌过程中能显著增加γ－GT阳性率,γ－GT染色的阳性率纯毒素组为100％,显著高于二乙基亚硝胺（DEN）对照组的22．22％。MC在促大鼠肝癌过程中能显著降低大鼠肝脏bax基因的表达强度和面积,bax表达的强度和面积纯毒素组分别为0．0283和0．0073,显著高于强度和面积分别为0．0655和0．0244的DEN对照组。MC在促大鼠肝癌过程中有显著增加大鼠肝脏bcl－2基因表达强度和面积,bcl－2表达的强度和面积纯毒素组分别为0．0977和0．0315,显著高于强度和面积分别为0．0460和0．0205的DEN对照组。结论 进一步证明了MC具有促肝癌作用。调节与细胞凋亡相关的癌基因和抑癌基因表达可能是MC促癌过程的重要机制之一。

The expression of bcl-2 and bax genes during microcystin induced liver tumorigenesis

OBJECTIVE: To study the molecular mechanism of microcystin (MC) induced liver tumorigenesis in rats. METHODS: The two-stage-medium-term tumorigenesis theory was applied to establish the animal model, and the effect of MC in liver tumor formation was evaluated by the Albert gamma-GT methods, and then, the immunohistochemical technique and image analysis were used to study the expression of the bcl-2 and bax genes during tumorigenesis. RESULTS: (1) MC enhanced the formation of gamma-GT foci in liver (100%), which was significantly higher than the diethylnitrosamine (DEN) control group (22.22%) (P < 0.05). (2) MC decreased the expression of bax gene. The intensity and area of bax gene expression in the pure MC toxin group were 0.028 3 AODV and 0.007 3 ( micro m(2)/ micro m(2)) and in the DEN control group were 0.065 5 AODV and 0.024 4 ( micro m(2)/ micro m(2)), respectively. The intensity and areas of bax gene expression in the pure MC toxin group were significantly lower than those in the DEN control group (P < 0.05). (3) MC increased the expression of bcl-2 gene. The intensity and area of bcl-2 gene expression in the pure MC toxin group wee 0.097 7 AODV and 0.031 5 ( micro m(2)/ micro m(2)), respectively, and in the DEN control group were 0.046 0 AODV and 0.020 5 ( micro m(2)/ micro m(2)) respectively (P < 0.05). CONCLUSION: (1) MC can strongly promote liver tumorigenesis. (2) The changes of bcl-2 and bax gene expression possibly play an important role in the MC induced liver tumor formation.