mTORC1信号通路在小鼠化疗胃黏膜损伤中的作用

摘要

目的 探讨mTORC1信号通路在使用化疗药物白消安(BU)+环磷酰胺(CY)后小鼠胃黏膜损伤中的作用.方法 将60只C57BL/6雄性小鼠随机分为4组,即正常对照组,BU+CY组,Rapamycin组和BU+CY+Rapamycin组,每组15只.各组分别于造模后2、6和14 d处死小鼠后取胃体进行常规HE染色观察病理变化,采用免疫组织化学方法检测小鼠胃黏膜的BrdU阳性细胞和PS6阳性蛋白的表达,用Tunnel方法检测细胞凋亡,用图像分析仪进行体视学测量和图像分析.结果 BU+CY组小鼠胃黏膜损伤明显,并有大量炎症细胞浸润;BU+CY+Rapamycin组小鼠上述损伤明显减轻.与正常对照组比较,BU+CY组胃黏膜BrdU阳性细胞数密度显著降低(P<0.01),BU+CY+Rapamycin组则基本恢复至正常值;BU+CY组胃黏膜凋亡细胞显著增加(P<0.01),BU+CY+Rapamycin组则明显恢复;BU+CY组PS6免疫阳性蛋白的积分光密度明显增高(P<0.05),提示mTORC1通路被激活,BU+CY+Rapamycin组则显著减少,mTORC1通路受到强烈抑制;Rapamycin组可出现BrdU阳性细胞数密度降低、凋亡细胞增加.结论 化疗药物BU+CY可激活mTORC1信号通路、抑制胃黏膜上皮干细胞增殖和促进胃黏膜上皮细胞凋亡引起胃黏膜损伤,且这种损伤可被Rapamycin 逆转.%Objective To explore the role of mTORC1 signaling pathway in gastric mucosal injury caused by chemotherapy drugs busulfan(BU) and cyclophosphamide(CY).Methods Sixty male C57BL/6 mice were randomly divided into four groups: control group,BU+CY group,rapamycin group,and BU+CY+rapamycin group,with 15 mice in each group.Mice were executed 2,6 and 14 days after modeling,and pathological changes in gastric body mucosa were observed by HE staining.The number density of BrdU-positive cells and the expression of PS6 in gastric mucosa were detected by immunohistochemistry.Cell apoptosis was measured using Tunnel staining.Stereological measurement was done with an image analyzer.Results Obvious gastric mucosal injury and inflammatory cell infiltration were observed in BU+CY group,while the injury was significantly reduced in BU+CY+rapamycin group.Compared with control group,the number density of BrdU-positive cells decreased and the number of apoptotic cells increased in BU+CY group(P<0.01),but they were significantly restored in BU+CY+rapamycin group.Furthermore,compared with control group,the integral optical density of PS6 increased in BU+CY group but decreased in BU+CY+rapamycin group(P<0.05),indicating that mTORC1 pathway was activated in BU+CY group but was inhibited in BU+CY+rapamycin group.In addition,the decrease in BrdU-positive cells and the increase in apoptotic cells could be observed in rapamycin group.Conclusion Chemotherapy drugs BU and CY can activate mTORC1 signaling pathway,inhibit epithelial stem cell proliferation,promote epithelial cell apoptosis,and thus result in gastric mucosal injury.However,the injury caused by chemotherapy can be reversed by rapamycin.