布雷菲德菌素A通过激活IRE1-XBP1信号通路增强顺铂诱导的人肺癌GLC-82细胞凋亡

Brefeldin A Enhances Cisplatin-induced Apoptosis of Human Lung Cancer GLC-82 Cells by Activating IIER1-XBP1 Signaling

长时间剧烈的内质网应激(endoplasmic reticulum stress,ERS)可启动ERS相关通路诱导细胞凋亡;而IREl-XBP1(肌醇需求蛋白1α-X盒结合蛋白1)为高度保守的ERS基本通路。它是最有前景的肿瘤治疗靶点之一。我们研究已证明,布雷菲德菌素A(brefeldin A,BFA)能增强顺铂(cisdichlorodiamine platinum,CDDP)的肺癌细胞杀伤作用,但其分子机制尚不清楚。本研究证明了IRE1-XBP1通路在该协同效应中的作用。Annexin V/PI双染结合流式细胞分析显示,与BFA或CDDP单独处理比较,BFA联合CDDP处理能增强人肺癌GLC-82细胞的凋亡。RT-q PCR和Western印迹揭示,与单独处理比较,BFA联合CDDP处理能增强GLC-82细胞的procaspase3转录本(mRNA)和蛋白质的表达,以及procaspase3的裂解激活,进一步证明了BFA联合CDDP处理可增强GLC-82细胞凋亡。最重要的是,RT-q PCR和Western印迹结果证明,与单独CDDP处理比较,BFA处理的GLC-82细胞中IRE1、XBP1水平明显上调(P<0.05),而BFA+CDDP处理的细胞中IRE1、XBP1水平进一步上调,超过BFA组(P<0.01)。结果提示BFA和BFA+CDDP处理细胞可激活ERS的IRE1-XBP1通路。这些结果证明,BFA可通过激活ERS中的IRE1-XBP1通路增强顺铂诱导的肿瘤细胞凋亡。本研究结果为IREl-XBP1是颇具前景的肿瘤治疗靶点提供了新的证据。

Long term and severe endoplasmic reticulum stress（ ERS） can induce cellular apoptosis.Inositol-requiring protein 1α（ IRE1α）-X-box binding protein 1（ XBP1） signaling is the most common ERS-related pathway that may be the most promising target for tumor therapy. We have previously demonstrated that brefeldin A（ BFA） enhances the cis-dichlorodiamine platinum（ CDDP）-induced apoptosis in human lung cancer cells,however,its mechanism is unclear. In the study,we demonstrated the involvement of IREl-XBP1 pathway in the synergistic anti-cancer effects of BFA and CDDP on the apoptosis of human lung cancer GLC-82 cells. Annexin V/PI double staining and flow cytometry showed that compared to BFA or CDDP single exposure,combined BFA and CDDP exposure increased GLC-82 cell apoptosis. Further evidences by RT-q PCR and Western blotting revealed that BFA plus CDDP exposure increased the transcript（ mRNA） and protein levels of procaspase3 and the cleavage/activation of procaspase3 when compared to single exposure. Importantly, RT-q PCR and Western blotting demonstrated that BFA increased IRE1α and XBP1 expression significantly when compared to CDDP exposure（ P 0. 05）. BFA plus CDDP exposure increased IRE1α and XBP1 expression markedly than BFA single treatment（ P 0. 01）. These findings indicate that BFA and BFA ＋ CDDP both can activate IRE1α-XBP1 pathway under ERS and BFA enhances cisplatin-induced lung cancer cell apoptosis via activating IIER1-XBP1 signaling. Our data provide new evidence for IREl-XBP1 signaling as a promising target for chemotherapy.