20(S)-ginsenoside-Rg3 Reverses Temozolomide Resistance By Inhibiting MGMT And Restrains Epithelial-mesenchymal Transition Progression In Glioblastoma

?Background and Objective?Glioblastoma(Glioblastoma multiforme,GBM)is the most common primary malignant tumor in the adult central nervous system.the prognosis of glioblastoma is very poor.the annual incidence of glioblastoma is about 3-4/100000 people.At present,the standard treatment for patients with glioblastoma is surgery combined with postoperative radiotherapy and chemotherapy.Among them,alkylating agent temozolomide(TMZ)is the first choice for patients with GBM,but it has little effect on GBM tumor patients with positive expression of O~6-methylguanine DNA-methyltransferase(MGMT).This is closely related to the fact that MGMT can mediate the formation of chemotherapy resistance to temozolomide in tumor cells.The purpose of this study was to study the effect of 20(S)-ginsenoside Rg3(20(S)-Rg3)on reversal of temozolomide resistance and restriction of epithelial-mesenchymal transformation in MGMT-positive human glioblastoma cells.Meanwhile,we elucidated the pathway mechanism of 20(S)-Rg3,and expected to provide a new method and idea for improving the therapeutic effect of glioblastoma patients with MGMT positive expression.?Materials and Methods?CCK8,Western blot,qRT-PCR,Immunohistochemical staining,Flow cytometry,Tumor xenograft experiment,Wound healing assay,Transwell assay,Immunofluorescence assay and Tumor peritoneal metastasis experiment were used in exploring the effect of 20(S)-Rg3 on the reversal of temozolomide resistance in MGMT positive glioblastoma cells and its pathway mechanism.In addition,the effect of 20(S)-Rg3 on epithelial-mesenchymal transformation of glioblastoma cells was also explored.?Results?The mRNA level and protein expression of MGMT gene in glioblastoma T98G,U118 cell lines and primary cultured GBM-XX cell lines which treated with 20(S)-Rg3(100?mol/L)were significantly lower than those in the control group.At the same time,it was found that the expression of?-catenin(the key protein of Wnt/?-catenin signaling pathway)and the expression of key transcription factors LEF1 and TCF1/TCF7 in T98G,U118 and GBM-XX cells were significantly down-regulated.Furthermore,the expression level of several target gene proteins downstream of Wnt/?-catenin signaling pathway decreased significantly.The results in vitro and in vivo showed that the cell activity of tumor cells treated with 20(S)-Rg3 combined with TMZ were significantly lower than those treated with TMZ or 20(S)-Rg3 alone.And on the contrary,the apoptosis rate was significantly increased.In addition,it was found that20(S)-Rg3 could restrains the epithelial-mesenchymal transformation process of glioblastoma cells by up-regulating E-cadherin and down-regulating N-cadherin and vimentin in vitro and in vivo.?Conclusions?The results showed that 20(S)-ginsenoside Rg3 could effectively reverse the chemotherapy resistance of MGMT positive glioblastoma to temozolomide,and 20(S)-Rg3 could significantly inhibit the epithelial-mesenchymal transformation of glioblastoma cells.