线粒体凋亡途径在TA2小鼠自发性乳腺癌中的作用

Effects of Mitochondrial Apoptosis Pathway on the Oncogenesis of Spontaneous Breast Cancer in TA2 Mice

目的:比较TA2小鼠正常乳腺、乳腺癌前病变和乳腺癌组织中细胞增殖和凋亡的情况,通过检测线粒体凋亡途径中Bcl-2、Bax、Caspase-3和Caspasee-9在乳腺组织中的表达,初步确定线粒体凋亡途径在ITA2小鼠自发乳腺癌中可能发挥的作用.方法:收集正常TA2成年雌鼠的乳腺组织(NC组)和TA2自发性乳腺癌癌前病变组织(SBC-b组)和乳腺癌组织(SBC-t组),采用免疫组化方法检测各组乳腺上皮细胞中PCNA、Bcl-2、Bax、Caspase-3和Caspase-9的表达并计算增殖指数(PI);采用TUNEL方法检测细胞凋亡并计算凋亡指数(AI);采用Rea[-★me PCR和Westem blot方法检测组织中Bcl-2、Bax、Caspase-3和Caspase-9蛋白表达及mRNA相对表达水平.结果:免疫组化染色,Real-tinmePCR以及Western blot结果一致显示,SBC-b组Bcl-2,Bax,Cas-pase-3和Ca[sPase-9表达均明显高于NC(P<0.0l或P<0.05);SBC-t组中除Bcl-2高于NC外,其余蛋白表达均明显低于NC(fJ<0.01),但hcl-2,bax和Caspase-3 mRNA表达均显著高于NC(P<0.01),Caspase-9mRNA略高于NC,但无统计学意义(P>0.05)。结论:线粒体途径可能参与了TA2鼠自发性乳腺癌的发生,其通过刺激部分乳腺上皮细胞凋亡,破坏了TA2小鼠乳腺上皮细胞增殖和凋亡的平衡,以致乳腺癌发生.

Objective： To compare the cell proliferation and apoptosis in normal breast tissues, precancerous lesions of the breast, and breast cancer tissues of TA2 mice as well as to ascertain the effects of mitochondrial apoptosis pathway on the oncogenesis of spontaneous breast cancer in TA2 mice by detecting the expression of Bcl-2, Bax, Caspase-3, and Caspase-9 proteins in the breast tissues during the mitochondrial apoptosis pathway. Methods： Normal breast tissues were obtained from adult female TA2 mice （ NC ）. Precancerous breast tissues （ SBC-b ） and breast cancer tissues （SBC-t） were obtained from female TA2 mice with spontaneous breast cancer. PCNA, Bcl-2, Bax, Caspase-3, and Caspase-9 expression was determined by immunohistochemistry, whereas cell apoptosis was determined by TUNEL assay. Proliferation （PI） and apoptosis （AI） indices were calculated. The relative expression of Bcl-2, Bax, caspase-3, and caspase-9 mRNA and protein were determined by real-time PCR and Western blot. Results： Immunohistochemistry, real-time PCR, and Westem blot assays indicated that the AI, PI, and the expression of Bcl-2, Bax, caspase-3, and caspase-9 mRNA and protein were higher in the SBC-b group compared with those in the NC group （ P 〈 0.01 or P 〈 0.05 ）. The expression of all proteins, except for Bcl-2, was significantly lower in the SBC-t group compared with that in the NC group （ P 〈 0.01 ）. However, the expression of bcl-2, bax, and caspase-3 mRNA was evidently higher in the SBC-t group, compared with that in the NC （ P 〈 0.01 ）. The expression of caspase-9 mRNA was slightly higher in the SBC-t than in the NC, which was not statistically significant （ P 〉 0.0 5）. Conclusion： Mitochondrial apoptosis pathways may contribute to the genesis of spontaneous breast cancer in TA2 mice by inducing the apoptosis of mammary epithelium as well as by destroying the balance of proliferation and apoptosis in mammary epithelium.