甲状腺激素受体βΔ对大鼠乳腺癌SHZ-88细胞增殖及凋亡的影响

目的 探讨甲状腺激素受体βΔ（thyroid hormone receptor βΔ, TRβΔ）对大鼠乳腺癌SHZ-88细胞增殖、凋亡的影响及其作用机制。方法 将真核表达载体pcDNA3.1-TrβΔ及空载体pcDNA3.1分别转染体外培养的SHZ-88细胞，并给予10 nmol/L T3干预。CCK-8（Cell Counting Kit-8）法分析细胞的增殖活力；Annexin V/PI和JC-1荧光染色，流式细胞仪检测细胞凋亡及细胞线粒体膜电位变化；ELISA法检测细胞组蛋白/DNA碎片；定量PCR检测细胞半胱氨酸天冬氨酸特异性蛋白酶-9（Cysteinylaspartate specific proteinase-9, Caspase-9）、Caspase-3基因表达；比色法检测Caspase-9和Caspase-3活性。结果 与空载体pcDNA3.1转染组相比，pcDNA3.1-TrβΔ转染组明显抑制SHZ-88细胞的增殖、增加细胞组蛋白/DNA碎片和凋亡细胞百分比、降低线粒体膜电位、上调Caspase-9、Caspase-3基因的表达并促进Caspase-9及Caspase-3的活化（P<0.05）；给予T3后可明显增强上述作用（P<0.05）。结论 TRβΔ可抑制SHZ-88细胞的增殖并促进其发生凋亡，该作用可能通过降低线粒体膜电位，激活Caspase-9及Caspase-3蛋白, 启动内源性细胞凋亡途径实现，且该作用受T3调节。

Effect of Thyroid Hormone Receptor βΔ on Proliferation and Apoptosis of Rat Breast Cancer Cells SHZ-88

Objective To investigate the effect of thyroid hormone receptor βΔ(TRβΔ) on the proliferation and apoptosis of rat breast cancer cell line SHZ-88 in vitro and related mechanism. Methods The expression plasmid pcDNA3.1-TrβΔ and empty vector pcDNA3.1 were compared in the presence or absence of 10 nmol/L T3. Cell Counting Kit-8 was used to measure SHZ-88 cells activity. The apoptotic rate and mitochondrial transmembrane potential were analyzed by flow cytometry. Histone/DNA fragment was assayed by ELISA. The levels of Cysteinyl aspartate specific proteinase-9(Caspase-9), Caspase-3 mRNA were detected by quantitative RT-qPCR. The activity of Caspase-9 and caspase-3 were measured using colorimetry. Results Compared with empty vector pcDNA3.1 transfection group, pcDNA3.1-TrβΔ transfection group significantly inhibited the cell proliferation, increased the level of histone/DNA fragment and the percentage of apoptotic cells, up-regulated Caspase-9, Caspase-3 expression and activity, and reduced the mitochondrial transmembrane potential in SHZ-88 cells(P<0.05). These effects could be significantly strengthened by T3(P<0.05). Conclusion TRβΔ could inhibit the proliferation of SHZ-88 cells and enhance cell apoptosis, which might be via reducing the mitochondrial transmembrane potential, activating Caspase-9 and Caspase-3 protein, and starting endogenous apoptotic pathway, moreover, these effect could be regulated by T3.