中文摘要：

目的通过研究土槿乙酸衍生物PB—LY对肿瘤细胞的影响，探讨PB—LY的抗肿瘤活性及其作用机制。方法采用MTr法和绘制细胞生长曲线等方法检测PB—LY对多种肿瘤细胞的抑制作用；采用荧光染色、DNA ladder和流式细胞术等方法检测PB-LY诱导肿瘤细胞凋亡的作用；采用RT—PCR法检测PB-LY对肿瘤细胞相关凋亡基因Caspase-3、Bcl-2和Bax的mRNA表达的影响。结果PB-LY作用于多种肿瘤细胞的IC50在1．35μmol·L^-1～3．68μmol·L^-1之间，且有明显的量效关系，能够诱发肿瘤细胞产生凋亡小体、DNA ladder和细胞凋亡峰，上调相关促凋亡基因Caspase-3和Bax的表达，同时协同下调抑凋亡基因Bcl-2的表达。结论PB-LY能抑制肿瘤细胞的生长，同时影响肿瘤细胞内相关促凋亡和抑凋亡基因的表达，从而诱导肿瘤细胞发生凋亡。

英文摘要：

Aim To determine the antitumor activity of PB-LY and investigate its anticancer mechanism in vitro. Methods MTT and cell growth curve were used to study antitumor activity of PB-LY. Morphological study, DNA gel electrophoresis and flow cytometric analysis were used to determine tumor cell apoptosis induced by PB-LY. RT-PCR investigated the expression of Caspase-3 mRNA, Bax mRNA and Bcl-2 mRNA in Hela cells exposed to PB-LY. Results MTF showed that IC50 was 1.35 μmol · L^-1 - 3. 68 μmol · L^-1. After tumor cells were treated with PB-LY, morphological characteristic of apoptosis was detected. Agarose gel electrophoresis showed typical DNA ladder. Flow cytometric analysis showed apoptotic ＂Sub-G1 peak＂. RT-PCR showed that Caspase-3 mRNA and Bax mRNA levels increased, meanwhile the expression of Bcl-2 mRNA decreased. Conclusion PB-LY exerted obvious anticancer activity, which induced apoptosis by upregulating Caspase-3 and Bax, and downregulating Bcl-2.