雷帕霉素与PD98059联合抑制小鼠结直肠癌雷帕霉素靶蛋白信号转导通路

Rapamycin and PD98059 collaborative inhibit mammalian target of rapamycin pathway in the prevention and treatment of mouse colorectal cancer

目的探讨雷帕霉素靶蛋白（mTOR）抑制剂雷帕霉素（rapamycin）与丝裂原激活蛋白激酶／细胞外信号调节激酶的激酶（MEK）抑制剂PD98059对小鼠结直肠癌的联合作用及机制。方法将二甲基肼注射于小鼠颈后20周，建立小鼠结直肠癌模型。从第16周起给予雷帕霉素、PD98059和雷帕霉素＋PD98059腹腔注射，共8周；至24周处死实验动物，测算肿瘤体积，以HE染色判断肿瘤发生率；应用免疫组化法检测肿瘤组织mTOR、p70s6K、4E-BP1蛋白的磷酸化水平。结果雷帕霉素、PD98059及雷帕霉素＋PD98059干预组小鼠结直肠癌发生率显著低于模型组（44．44％、38．89％、6．67％比77．78％，P均〈0．05）；肿瘤体积显著小于模型组[分别为（6．153±2．192）、（8．85±3．983）、（2．917±0．191）比（16．136±6．855）mm^3，P值均〈0．05]；蛋白磷酸化水平显著低于模型组，mTOR蛋白磷酸化水平分别为69．584％±3．600％、72．381％±8．561％、14．430％±2．413％比91．689％±1．994％；p70s6K分别为84．315％±3．132％、81．183％±3．980％、12．135％±2．382％比91．451％±2．160％；4E-BP1分别为65．288％±4．259％、66．641％±4．296％、19．119％±6．297％比75．999％±4．417％（P均〈0．05）。且在降低肿瘤发生率、缩小肿瘤体积以及抑制mTOR信号通路活性方面，雷帕霉素＋PD98059干预组的效果显著优于雷帕霉素及PD98059单独用药，差异有统计学意义（P均〈0．05）。结论雷帕霉素与PD98059可联合抑制小鼠结直肠癌的发生和生长，其作用机制可能涉及对mTOR信号转导通路相关蛋白磷酸化水平的抑制。

Objective To investigate the combined inhibition effect and the potential mechanism of rapamycin （mammalian target of rapamycin inhibitor） and PD98059 （mitogen-activated protein kinase/extracellular signal-regulated kinase kinase （MEK） inhibitor） on mouse colorectal cancer （CRC）. Methods S-ICR mice were subcutaneously injected with 20 mg/kg of 1,2-dimethylhydrazine dihydrochloride in the nape for 20 weeks to induce CRC. From the 16th week, the mice were treated with alone or combined injection with 0. 25 mg/kg rapamycin and 2. 5 mg/kg PD98059. The drugs were administered for 8 weeks. Subsequently, the animals were sacrificed and dissected, the tumor （6.15±2. 192）, （8.85±3. 983）, （2.917±0. 191）, （16.36±6.855） mm^3 respectively （P〈0.05）. The anti-cancer effect of the combination treatment was substantially significant. The proteins of phospho mTOR, phospho-p70s6K and phospho-4E-BP1 were significantly down-regulated after treatments （all P values d0.05）. Conclusions Combined treatment was more effective than single- drug treatments of rapamycin or PD98059 alone for the prevention and treatment of mouse CRC. The mTOR signal pathway might be involved in the inhibitory mechanism.