PPIs抑制P13K/Akt／mTOR信号通路逆转胃癌细胞的化疗多药耐药

背景：前期实验显示质子泵抑制剂（PPIs）可抑制空泡型质子泵（V-H＋-ATPases）和多药耐药蛋白P—gP、MRP1表达，增强胃癌细胞的化疗敏感性。目的：探讨PPIs抑制空泡型质子泵逆转胃癌细胞化疗多药耐药与P13K／Akt／mTOR信号通路的关系。方法：应用不同浓度埃索美拉唑或泮托拉唑预处理人胃腺癌细胞敏感株SGC7901和多药耐药株SGC7901／MDR，或以V—H＋-ATPasessiRNA干扰SGC7901／MDR细胞内的V-H＋-ATPases表达，或以雷帕霉素阻断mTOR表达，以蛋白质印迹法检测经不同方式处理的细胞内V—H＋ATPases、P—SP、MRPl蛋白表达以及P13K／Akt/mT0R／HIF—1α信号通路及其信号旁路TSCl／2-Rheb中的相关蛋白表达；以免疫荧光法检测经埃索美拉唑预处理的SGC7901／MDR细胞内的V-H＋ATPases、P—gP蛋白表达和定位。结果：PPIs可呈浓度依赖性地抑制SGC7901／MDR细胞内的V—H＋ATPases、P13K、Akt、roTOR、HIF-1仅、TSCI、TSC2、Rheb、P—gP、MRP1表达以及Akt底物和TSC2磷酸化，改变V-H＋ATPases、P—gP的胞内定位，对SGC7901细胞则无上述影响。以V—H＋-ATPasessiRNA抑制SGC7901／MDR细胞内的V—H＋-ATPases表达，作用与PPIs预处理相似。以雷帕霉素阻断mTOR可呈浓度依赖性地抑制SGC7901／MDR细胞内的HIF-1α、P—gP表达。结论：PPIs抑制空泡型质子泵逆转胃癌细胞化疗多药耐药的机制与抑制P13K／Akt／mTOR信号通路有关。

PPIs Reverse Multidrug Resistance of Gastric Cancer Cells to Chemotherapy by Inhibiting PI3K/Akt/mTOR Signaling Pathway

Background： Preliminary studies revealed that proton pump inhibitors （PPIs） pretreatment could inhibit vacuolar H ＋ -ATPases （V-H ＋ -ATPases） activity, down-regulate multidrug resistance proteins P-gp and MRP1, and sensitize gastric cancer cells to chemotherapy. Aims： To study whether the reversal of multidrug resistance of gastric cancer cells to chemotherapy mediated by PPIs-induced V-H＋-ATPases inhibition is through PI3K/Akt/mTOR signaling pathway. Methods： Sensitive and muhidrug resistance human gastric adenocareinoma cell lines （SGC7901 and SGC7901/MDR） were pretreated with esomeprazole and pantoprazole at different concentrations. In addition, SGC7901/MDR cells were transfeeted with V-H ~ -ATPases siRNA to inactivate V-H ＋ -ATPases, or treated with rapamycin to block mTOR expression. Western blotting was used to assess the expressions of V-H ＋ -ATPases, P-gp and MRP1 protein, as well as the proteins associated with PI3K/Akt/mTOR/HIF-1α signaling pathway or its alternative pathway TSC1/2-Rheb in cells treated with various reagents. Immunofluorescence was used to determine the protein expressions and intracellular distributions of V- H＋ -ATPases and P-gp in esomeprazole-treated SGC7901/MDR cells. Results： In SGC7901/MDR cells, PPIs inhibited the expressions of V-H＋-ATPases, PI3K, Akt, roTOR, HIF-lct, TSC1, TSC2, Rheb, P-gp and MRP1 in a dosedependent manner; the phosphorylation levels of Akt substrate and TSC2 were also inhibited, and the intracellular distributions of V-H＋ -ATPases and P-gp were changed. However, SGC7901 cells were not affected by PPIs pretreatment in these aspects. Effect of V-H ~ -ATPases siRNA on SGC7901/MDR cells was similar to that induced by PPIs pretreatment. Blockage of mTOR by rapamycin inhibited the expressions of HIF-lc~ and P-gp in a dose-dependent manner in SGC7901/ MDR ceils. Conclusions： Reversal of multidrug resistance of gastric cancer cells to chemotherapy mediated by PPls- induced V-I-I ~ -ATPases inhibition is related to the inhibition of PI3K/Akt/mTOR signaling pathway.