The Role Of BAG-1Protein In ERS And The Sensitivity Enhancement To Cispiatin In Tuncamyin-induced Lung Cancer A549Cells

ObjectiveTo observe the induced effect of low dose of tunicamycin on endoplasmicreticulum stress（ERS）in human lung adenocarcinoma A549cell line in vitro,and during which the change of Bcl-2associated athanogene-1(BAG-1) proteinexpression; as well as explore whether A549cells pretreated with tunicamycinwould bring about a change of sensitivity to cisplatin, and to detect the changeof BAG-1protein expression during the treatment of cisplatin in A549cells withor without ERS.Methods（1）SP immunohistochemistry method was taken to tested the expressionof BAG-1Protein in normal A549cells.（2）Expressions of GRP78and BAG-1proteins in A549cell treated with low does of tunicamycin were detected byWestern Blotting.（3）The half maximal inhibitory concentrations (IC50) of cis-platin to A549cells with or without pretreatment of tunicamycin were measuredby MTT assay.（4）Apoptosis of A549cells induced by cisplaitn with or withoutpretreatment of tunicamycin was assayed by flow cytometry (FCM).（5）Western blotting was carried out to detect the expressions of BAG-1and Pro-caspase-12proteins in A549cells induced by cisplatin with or without pre-treatment of tunicamycin. Results（1）BAG-1protein expressed both in Nuclei and cytoplasm of A549cells.（2）ERS could be induced by1.25μg/mL tunicamycin in A549cells for8h, andthe ERS marker GRP78protein expression was upregulated (P＜0.05), whileBAG-1protein expression was also upregulated (P＜0.05).（3） ERS couldincrease the sensitivity of A549cells to cisplatin (P＜0.05).（4）Before ERS,1.25、2.5and5μg/mL cisplatins upregulated the expression of BAG-1protein (P＜0.05), but the amount of upregulation induced by2.5and5μg/mL cisplatinswas less than that induced by1.25μg/mL cisplatin. When A549cells were un-dergoing ERS,1.25、2.5and5μg/mL cisplatin downregulated the expression ofBAG-1protein as compared with the group just undergoing ERS but not treatedwith cisplatin, and the amount of downregulation was proportionable to theconcentration of cisplatin.（5）2.5and5μg/mL cisplatins could induce cellapoptosis by ERS pathway, during which the expressions of Procaspase-12andBAG-1proteins were downregulated (P＜0.05).ConclusionBAG-1may be one of the critical factors in the both processes of ERS andcisplatin-induced apoptosis of lung cancer cells. ERS related apoptotic pathwaymay be one of the important ways of cisplatin-induced apoptosis in lung cancercells.