Fig. 4

Combination therapy of TMZ and ABX enhanced DNA damage by disturbing expression and nuclear translocation of DNA repair proteins ERCC1 and XPC. a The schematic diagram illustrates the proteomics design and analysis process, which aims to further explore the potential molecular mechanisms of drug combination treatment. b The analysis of total number and subcellular components of proteins identified in proteomics. c The schematic diagram of downstream target proteins selection. To explore the potential molecular mechanism of enhanced DNA damage in drug combination treatment group, we mainly focused on nuclear localization proteins and DNA damage repair related proteins. A total of 51 potential target proteins were identified. Furthermore, in order to investigate the down-regulated DNA damage-related proteins underlying combination therapy, data screening was conducted based on a fold change standard (TMZ + ABX vs. TMZ) of less than 0.5. Finally, we screened out ERCC1 protein. d The total expression of ERCC1 protein in GBM cells from each group with the indicated drug treatment was assessed by western blotting. e Western blotting analysis was performed to examine the expression of ERCC1 and XPC proteins in cytoplasmic (C) and nuclear (N) fractions of GBM cells after drug treatments. GAPDH and Histone H3 were used as internal loading controls. f Immunofluorescence staining was performed to detect the localization of XPC protein in GBM cells treated with TMZ (400 µM for U87-MG and G353 cells; 800 µM for LN229 and G393 cells) and ABX (12 nM)