Capzimin can be used as a therapeutic for cancer treatment.[1]
Capzimin dimer is the stable precursor form of capzimin. Capzimin is a selective inhibitor of proteasome isopeptidase Rpn11, a proteasomal deubiquitinase that is part of the proteosome 19S regulatory particle subunit that removes the polyubiquitin chain from substrates in preparation for degradation. Capzimin was shown to have an IC50 value of 340 nM and have selectivity over related enzymes with 80-fold selectivity for Rpn11 over Csn5, ten-fold over AMSH and six-fold over BRCC36. It stabilized proteasome substrates that would otherwise have been degraded, induced an unfolded protein response, and blocked the proliferation of cancer cells, including some that had become resistant to bortezomib. Capzimin dimer will be quickly reduced to capzimin by glutathione in cell-based systems; DTT should be added to in vitro assays to reduce the disulfide.
