Figure 5

BU-32 upregulates apoptosis and downregulates NF-κB expression. BU-32 exposure induces accumulation of proapoptotic markers, cell-cycle-dependent kinase inhibitors and the p53 tumor suppressor gene, and downregulates NF-κB expression in breast cancer cells. Western blot analysis of total cell extracts of all three breast cancer cell lines shows the effect of treatment with Bortezomib and BU-32 on the expression level of the cyclin-dependent kinase inhibitor proteins p21 and p27, tumor suppressor p53, proapoptotic genes Bid and Bax, anti-apoptotic NF-κB, and cell cycle regulatory protein p44/42, phospho p44/42. Breast cancer cell lines were examined after 24 hours of exposure to the proteasome inhibitors (5 nM) and a series of western blots using specific antibodies was performed to detect relative levels of proteins. Results are the average of three independent measurements.