新型Topo I抑制剂CPUY013对胃腺癌细胞BGC823的体内外作用

探讨CPUY013在体内外对人胃腺癌BGC823细胞的抗肿瘤活性及其机制。采用MTT法、克隆原形成法检测CPUY013对BGC823细胞增殖的抑制作用；体外实验以pBR322 DNA为底物，依据质粒的松弛和超螺旋形式在琼脂糖电泳上泳动度对药物抑制解旋的作用进行定性分析。用AO/EB荧光染色技术、DNA凝胶电泳及JC-1线粒体膜电位检测试剂盒检测细胞凋亡。口服给药CPUY013后观察其对裸鼠移植瘤的生长抑制作用；用流式细胞术观察CPUY013对BGC823细胞周期的影响；采用Western blotting分别检测CPUY013处理后的BGC823细胞中Topo I及凋亡相关蛋白表达的改变。结果表明，CPUY013呈明显的剂量依赖性抑制BGC823细胞的增殖。随着剂量的增加，CPUY013对Topo I松弛活性的抑制趋势增强。100 μmol·L^-1 CPUY013 和拓扑替康(TPT)对Topo I松弛活性的抑制呈现相似的变化趋势。CPUY013可使大部分BGC823细胞阻滞在S期，并诱导细胞凋亡；出现DNA片段化，亚G1峰显著增加，线粒体膜电位降低，荧光染色后出现凋亡细胞的特征性改变等。同时，CPUY013能明显抑制BGC823裸鼠移植瘤的生长，150 mg·kg^-1剂量组的瘤重抑制率为62.1%。CPUY013使BGC823细胞内Topo I和bcl-2蛋白表达均有所下调， p53和bax蛋白表达有明显上调趋势， bcl-2/bax比值明显降低， caspase-3蛋白表达增高。新型Topo I抑制剂CPUY013在体内明显抑制移植瘤的生长， 体外可诱导细胞凋亡从而抑制BGC823细胞增殖， 其机制可能与抑制Topo I， 从而下调bcl-2，上调bax和p53蛋白的表达有关。

Effects of CPUY013, a novel Topo I inhibitor, on human gastric adenocarcinoma BGC823 cells in vitro and in vivo

Antitumor activity and the mechanism of CPUY013, a novel Topo I inhibitor, on gastric adenocarcinoma BGC823 cells were studied in vitro and in vivo. The proliferation was investigated by MTT assay and colony formation assay. Apoptosis was determined by both dual fluorescence staining with AO and EB and DNA agarose gel electrophoresis analysis methods. Nude mice model of BGC823 xenograft tumor was established by subcutaneous inoculation. The suppression activity of the CPUY013 by intragastric administration on xenograft mice model was detected. The change of cell cycle was studied by flow cytometry assay. The expressions of Topo I, widetype p53, active caspase-3, bcl-2 and bax proteins were analyzed by Western blotting assay. Results showed that CPUY013 could inhibit BGC823 cell proliferation at a certain range of dose. The flow cytometry analysis showed that CPUY013 and topoecan (TPT) led to a decrease in the proportion of G1 phase cells and an increase in the proportion of S phase cells, suggesting that they arrested the transition of tumor cells from S phase to G2 phase. The sub-G1 group was analyzed by flow cytometry. Compared with control, after 48 h treatment with CPUY013 or TPT, the sub-G1 group significantly increased in a dose-dependent manner. CPUY013 and TPT induced apoptosis in tumor cells. Cells treated with CPUY013 for 48 h were stained with AO/EB mixture. Then the cells were observed under fluorescence microscope. And it was found that early and late apoptosis cells were identified by perinuclear condensation of chromatin stained by AO/EB, respectively. Necrotic cells were identified by uniform labeling with EB. With the increase of concentration of CPUY013 and TPT, these morphological changes under the fluorescence microscope become clearer, indicating that the proportion of apoptosis cells increased gradually. By using JC-1 kit, loss of ΔΨm was also detected in BGC823 cells treated with CPUY013 and TPT, which represent mitochondria function. And characteristic DNA ladder was observed apparently in BGC823 cells treated with CPUY013.When the xenograft tumor mice were treated with 150 mg·kg^-1 CPUY013, the tumor growth inhibition rate was 62.1%. The expression of bax and p53 proteins increased significantly and bcl-2 and bcl-2/bax decreased after the treatment of the CPUY013. The CPUY013 down-regulated Topo I protein expression and up-regulated active caspase-3 protein expression. The novel Topo I inhibitor CPUY013 can significantly suppress the growth of BGC823 xenograft tumor in vivo and inhibit the proliferation by inducing apoptosis of BGC823 cells in vitro.