去甲斑蝥素衍生物Nd3对人卵巢癌细胞SKOV3增殖的作用及机制初步探讨

Effect of Norcantharidin's Derivative Nd3 on Proliferation of Human Ovarian Cancer Cell Line SKOV3 and Its Possible Mechanisms

背景与目的:去甲斑蝥素(norcantharidin,NCTD)是斑蝥素(cantharidin)的衍生物,对多种肿瘤细胞的生长均有抑制作用,但其药效较同类化疗药物小。本研究探讨NCTD衍生物Nd3对人卵巢癌细胞SKOV3的体外抗增殖作用,同时与NCTD的作用进行比较,并初步探讨Nd3的作用机制。方法:采用增殖抑制实验分别测定Nd3和NCTD对SKOV3细胞增殖的抑制作用,流式细胞术分析Nd3对SKOV3细胞周期和细胞凋亡的改变。Westernblot方法检测Nd3对SKOV3细胞周期和凋亡相关蛋白Cdc2、CyclinB1、Bax和Bcl-2表达的影响。结果:2.5、5、10、20、30和40μmol/L的Nd3作用SKOV3细胞48h后,细胞抑制率依次为27.3%、34.1%、53.3%、64.3%、83.3%和96.7%,与阴性对照组比较差异有显著性(P<0.001)。Nd3作用24h、36h和48h的IC50分别为(25.1±2.3)!mol/L、(21.8±2.8)!mol/L和(20.4±3.3)!mol/L。细胞周期分析证实,10、20、30、40μmol/LNd3作用48h后,G2/M期细胞百分数为14.3%、20.2%、26.2%和27.9%;同时30μmol/L的Nd3作用12、24、36、48h后,G2/M期的细胞比例分别为19.8%、26.6%、27.8%和32.0%,呈现G2/M期阻滞。此外Nd3可以诱导SKOV3细胞凋亡,40μmol/L的Nd3作用48h后细胞凋亡率高于对照组30%以上。Westernblot结果表明,Nd3可使Bax蛋白的表达增高,而Cdc2、CyclinB1和Bcl-2的表达则相应减少。结论:Nd3能明显抑制SKOV3细胞的增殖,其作用比NCTD强,且可阻断SKOV3细胞周期于G2/M期并诱导细胞凋亡,其作用机制与Cdc2、CyclinB1、Bcl-2和Bax蛋白的表达变化有关。

BACKGROUND ＆ OBJECTIVE： Norcantharidin （NCTD）, the demethylated form of cantharidin, can inhibit the proliferation of many kinds of cancer cells, but its effect is milder than those of other drugs. This study was to explore the inhibitory effect of Nd3, a derivative of norcantharidin, on the proliferation of human ovarian cancer cell line SKOV3, compare its antitumor effect with that of norcantharidin, and investigate its possible molecular mechanisms. METHODS： SKOV3 cells were treated with Nd3 and norcantharidin, separately. Cell proliferation was evaluated by sulforhodamine B（SRB） assay. Cell cycle distribution and apoptosis were detected by flow cytometry. The expression of Cdc2, Cyclin B1, Bax, and Bcl-2 was detected by Western blot. RESULTS： When treated with 2.5, 5, 10, 20, 30, and 40 μmol/L Nd3 for 48 h, the inhibition rates of SKOV3 cells were 27.3%, 34.1%, 53.3%, 64.3%, 83.3%, and 96.7%, respectively, which were significantly higher than that of negative control cells （P〈0.001）. The 50% inhibition concentration of Nd3 was （25.1±2.3） μmol/L at 24 h, （21.8±2.8） μmol/L at 36 h, and （20.4±3.3） μmol/L at 48 h. When treated with 10, 20, 30, and 40 μmol/L Nd3 for 48 h, SKOV3 cells were arrested at G2/M phase at rates of 14.3%, 20.2%, 26.2%, and 27.9%; when treated with 30 μmol/L Nd3 for 12, 24, 36, and 48 h, the proportions of SKOV 3 cells at G2/M phase were 19.8%, 26.6%, 27.8%, and 32.0%. When treated with 40 μmol/L Nd3 for 48 h, the apoptosis rate of SKOV3 cells was significantly higher than that of control cells [（17.9±4.4）% vs. （2.5±2.8）%, P〈0.01]. After treatment of Nd3, the expression of Cdc2, Cyclin B1, and Bcl-2 were down-regulated, and the expression of Bax was up-regulated. CONCLUSIONS： Nd3 inhibits SKOV3 cell proliferation more than norcantharidin does, blocks cell cycle at G2/M phase, and induces apoptosis. The antitumor mechanism of Nd3 is related to the changes of Cdc2, Cyclin B1, Bax, and Bcl-2 expression.