熊果酸体外抑制胃癌细胞SGC7901增殖及机制探讨

Mechanism of proliferative inhibition caused by ursolic acid in human gastric cancer cell lines SGC7901 in vitro

目的探讨熊果酸（Ursolic Acid,UA）体外抑制胃癌细胞SGC7901 增殖的作用机制.方法：人胃癌细胞株SGC7901 常规培养于RPMI 1640 培养基中,MTT 法观察加入外源性PGE2 前后UA 对细胞增殖的影响;不同浓度UA 处理SGC7901 细胞24h后,倒置显微镜观察细胞形态变化;流式细胞仪检测细胞周期变化及凋亡率;Westernblotting 法检测环氧合酶-2（Cyclooxygenase-2,COX-2）蛋白表达;放射免疫分析法测定COX-2 催化产物前列腺素E2（Prostaglandin E2,PGE2）.结果：20 ～ 40mmol/L UA 可抑制SGC7901 的增殖,并呈浓度和时间依赖性,其作用24h 的半数抑制浓度（IC50）为（34.28±2.05）mmol/L;外源性PGE2 能够部分逆转UA 对SGC7901 细胞的增殖抑制作用;20 ～ 40mmol/L UA 作用24h 后,SGC7901 细胞变圆,出现不同程度的漂浮;20 ～ 40mmol/L UA 作用24h 后,SGC7901 细胞被阻滞于G0/G1 期,并发生凋亡,凋亡率随药物浓度升高而增加;同时COX-2 蛋白表达减少,其催化生成产物PGE2 浓度下降.结论：熊果酸对SGC7901 细胞具有增殖抑制作用,其机制可能与直接的细胞毒作用、干扰细胞周期、下调COX-2 表达、减少PGE2 合成进而诱导凋亡有关.

Objective To investigate the potential mechanism of proliferative inhibition of ursolic acid in human gastric cancercell lines SGC7901 in vitro. Methods： SGC7901 cells were cultured in vitro; MTT assay was applied to observe the influence ofUA on cell proliferation before and after adding exogenous PGE2. SGC7901 cells were treated by 0~40mmol/L UA for 24h, thenmorphological changes were observed by inverted microscope. Apoptotic rate and phase distribution of cell cycle were analyzed byFCM. Expression of COX-2 was determined by western blotting. The level of PGE2 was detected by RIA. Results： 20~40mmol/LUA could significantly inhibit the proliferation of SGC7901 cells in a dosage and time-dependent manner; the IC50 value of UA forSGC7901 cells for 24h was （34.28±2.05） mmol/L; The growth inhibition of SGC7901 cells that caused by UA was partly reversedby treatment with PGE2. After 20~40 mmol/L UA treatment for 24h, SGC7901 cells turned round and floated; SGC7901 cells werearrested at G0/G1 phase and apoptosis was induced, and the apoptotic rate was increased along with increase of UA concentration;Meanwhile an obvious decline in expression of COX-2 protein was found, and PGE2 level decreased. Conclusion： UA could inhibitproliferation of SGC7901 cells. Cytotoxic effects, cell cycle arrest, COX-2 inhibition, the reduced production of PGE2 and apoptosismay be involved in these effects of UA.