Fig. 4

VHL mediated the degradation of BRD4 through the ubiquitin-proteasome pathway. a Mechanism of action diagram for MZ1. b U87 and LN229 cells were treated with MZ1 at the concentrations indicated in the figure for 48 h (- represented 1% DMSO, + represented MZ1). Subsequently, cells were further treated with MG-132 at the concentrations shown in the figure for 8 h (- represents 1% DMSO). Western blot analysis was performed to measure the protein levels of BRD4, with GAPDH serving as an internal reference. c Based on the grayscale values of the bands in (B), the ratio of BRD4 protein to the corresponding GAPDH protein was calculated for each group. d Western blot was performed to assess the overexpression of VHL in U87 and LN229 cells. PLVX-NC represented the empty vector group, PLVX-VHL represented the VHL overexpression group, and β-actin was used as an internal reference. e Treatment of U87 and LN229 cells overexpressing empty vector or VHL with the concentrations of MZ1 as shown in the figure for 72 h. Cell viability compared to 0 μM (1% DMSO) was assessed using CCK-8. Green dots represented the empty vector group, and red squares represented the VHL overexpression group. f Western blot was performed to assess the knockdown of VHL in U87 and LN229 cells. sh-NC represented the negative control group, sh-VHL represented the VHL knockdown group, and β-actin was used as an internal reference. g U87 and LN229 cells with negative control or VHL knockdown were treated with the concentrations of MZ1 as shown in the figure for 72 h. Cell viability compared to 0 μM (1% DMSO) was assessed using CCK-8. Green dots represented the negative control group, and red squares represented the VHL knockdown group. Data was presented as Mean ± SD. Student’s t-test, *p < 0.05, **p < 0.01; ns, non-significant