b-AP15 DUB inhibitor

Not a general deubiquitinase inhibitor. Has minimal inhibition on recombinant and cytosolic nonproteasomal cysteine deubiquitinases.

b-AP15 inhibits the activity of two 19S regulatory-particle-associated deubiquitinases, Ubiquitin C-terminal hydrolase 5 (UCHL5) and ubiquitin-specific peptidase 14 (USP14), resulting in accumulation of polyubiquitin. This compound results in a dose-dependent accumulation of the UbG76V-YFP reporter with IC50 of 0.8 μM, indicating impaired proteasome degradation. It (1 μM) results in rapid accumulation of polyubiquitinated proteins in human colon carcinoma HCT-116 cells. This chemical (2.2 μM) increases the amounts of the cyclin-dependent kinases CDKN1A and CDKNIB and the tumour suppressor TP53 in a dose-dependent manner without altering the amounts of ornithine decarboxylase 1 (ODC1) in HCT-116 cells. It (1 μM) results in G2/M phase cell-cycle arrest in HCT-116 cells, consistent with the accumulation of cell-cycle inhibitors. This compound treatment increases the number of hypodiploid cells and is associated with increased amounts of apoptotic markers, including activated caspase-3, caspase-cleaved poly-ADP ribose polymerase (PARP) and cytokeratin-18 (CK18). It is more toxic to HCT-116 cells as compared to immortalised epithelial cells (hTERT-RPE1) or peripheral blood mononuclear cells. This inhibitor inhibits DUB activity using a variety of substrates, including Ub-AMC, Ub-GFP22, ubiquitinated p53-binding protein homolog (HDM2), and K48- and K63-linked Ubiquitin tetramer chains. [1] It is an inhibitor of the UPS that induced cell death via induction of the lysosomal apoptosis pathway in a cathepsin-D dependent manner. This compound elicits characteristic UPS defects including the accumulation of Ubiquitin conjugates and cell cycle inhibitors such as p21, p27 and the tumour suppressor p53. It inhibits the DUB activity of both cysteine DUBs, with USP14 being slightly more sensitive than UCHL5. This chemical induces apoptosis in cells over-expressing the anti-apoptotic Bcl-2 protein and in cells lacking the p53 gene. [2] It (1 μM) inhibits ATP-induced IL-1β release from LPS-primed peritoneal macrophages. This compound (1 μM) reduces the levels of cell death induced by nigericin treatment in THP-1 cells. It (1 μM) significantly reduces the numbers of ASC specks formed after nigericin treatment in LPS-primed THP-1 cells. [3]

b-AP15 (5 mg/kg) shows significant antitumour activity in severe combined immunodeficiency (SCID) mice with FaDu squamous carcinoma xenografts. This compound significantly delays tumour onset in mice with HCT-116 colon carcinoma xenografts. [1]