EBNA3C expressing B-cells are more sensitive to apoptotic cell death induced by proteasome inhibitors.

(A) ~0.5 × 10⁵ BJAB cells stably harboring vector or EBNA3C expressing plasmid plated into each well of six-well plates were either left untreated (DMSO control) or treated with increasing concentrations (0–20 μM) of MG132 or bortezomib for 3 days. Viable cells from each well were measured by Trypan blue exclusion method using an automated cell counter. (B-D) ~10 × 10⁵ BJAB-vector or BJAB-EBNA3C cells were treated with DMSO, or 5 μM of MG132 or bortezomib for 24 h were subjected to (B) apoptosis assay using annexin V/propidium iodide (PI) staining, (C) western blot analyses using indicated antibodies and (D) soft agar colony formation assay as described in the “Materials and Methods” section. GAPDH blot was used as loading control in western blot analyses. Protein bands were quantified by Odyssey imager software and indicated as bar diagrams at the bottom of corresponding lanes. Error bars represent standard deviations of duplicate assays of two independent experiments. *, **, *** = p-value < 0.01, 0.005 and 0.001 respectively.