[CAS NO. 1211877-36-9]  MG132

MG-132 displays >1000 times more activity than ZLLal in inhibiting the ZLLL-MCA-degrading activity of 20S proteasome with IC50 of 100 nM versus 110 μM. MG-132 also inhibits calpain with IC50 of 1.2 μM. MG-132 induces neurite outgrowth in PC12 cells at an optimal concentration of 20 nM, displaying 500 times more potency than ZLLal. MG-132 (10 μM) potently inhibits TNF-α-induced NF-κB activation, interleukin-8 (IL-8) gene transcription, and IL-8 protein release in A549 cells by inhibition of proteasome-mediated IκBα degradation. MG-132 treatment potently induces p53-dependent apoptosis in KIM-2 cells by 26S proteasome inhibition. Unlike BzLLLCOCHO or PS-341, MG-132 treatment results in weak inhibition of the chymotrypsinlike (CT-L) and peptidylglutamyl peptide hydrolysing (PGPH) activities of the 26S proteasome, whereas multiple myeloma cells (U266 and OPM-2) are more sensitive to induction of apoptosis by MG-132 than BzLLLCOCHO. MG-132 (1 μM) sensitizes TRAIL-resistant prostate cancer cells by activating the AP-1 family members c-Fos and c-Jun, which, in turn, repress the antiapoptotic molecule c-FLIP(L). MG-132 significantly enhances the ability of inositol hexakisphosphate (IP6) to reduce cellular metabolic activity in both PC3 and DU145 androgen-independent prostate cancer (AIPCa) cell lines.