Notes: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) tends to cause apoptosis in tumor cells over normal cells, and so the TRAIL ligand and signaling pathway is an attractive pathway for developing cancer therapeutics. Bortezomib is a proteasome inhibitor that is used for therapy in many cancers. Studies indicate that it can sensitize tumor cells to the apoptotic effects of TRAIL. In this study, the authors investigated the ability of bortezomib on renal cell carcinoma (RCC). Growth inhibition of RCC in response to treatment with bortezomib followed by TRAIL treatment in the presence or absence of caspase inhibitors was assessed using the CellTiter® 96 AQ_ueous Non-Radioactive Cell Proliferation Assay. They assessed caspase activity in bortezomib/TRAI- treated RCC using the Caspase-Glo® 8 Assay. The effect of bortezomib on the proteasome of the RCCs was investigated using the Proteasome-Glo™ Chymotrypsin-Like Cell-Based Assay. Their studies suggest that bortezomib can sensitize some RCC to TRAIL signaling. (4169)

Notes: The authors of this study investigated the mechanism of action of syringolin A (SylA), which is secreted by virulent strains of the plant pathogen Pseudomonas syringae. They show that SylA inhibits all three activities of the proteasome in vitro. They also used the Proteasome-Glo™ Chymotrypsin-Like Cell-Based Assay to show that SylA inhibits the chymotrypsin-like activity of the proteasome in SK-N-HS neuroblastoma cells. (3846)

Notes: The authors of this review article highlight the use of bioluminescence as a readout for high-throughput ADME/Tox assays. They discuss three strategies for designing bioluminescent assays, using either luciferase, ATP or luciferin substrates as the limiting reagents for a luciferase-catalyzed reaction. Reporter gene assays limit the production of luciferase by tying it to a promoter or DNA regulatory region of interest. Such assays can be used to study genes that are regulated by drugs and other xenobiotics. Bioluminescent assays in which ATP is the limiting reagent of the luciferase reaction can be designed to monitor cell viability or the activity kinases. Bioluminescent assays in which the substrate is limiting can be designed so that the activity of a particular enzyme results in the production of a luciferin substrate that can, in turn, be acted upon by luciferase. (3926)

Notes: The authors of this study used the gene module map method to identify genotype-specific therapies for human cancers. They studied breast cancer cell lines that expressed the "mitochondria" and "wound signatures". These cell lines, which are associated with tumors that have poor prognosis, were also shown to have a "proteasome signature" and were sensitive to the proteasome inhibitor bortezomib. The authors used the Proteasome-Glo™ Chymotrypsin-Like Cell-Based Assay to show that genotype-specific killing of "wound signature" cells was not due to differential degrees of proteasome inhibition, since 1 and 1µmol/L of bortezomib completely inhibited the ability of the wound signature and control cells to cleave the luminogenic substrate. More likely, the wound signature genotype conferred increased susceptibility to death from proteasome inhibition. (3870)

Notes: The authors of this study investigated the effects of betulinic acid (BA) and its chemical derivatives on the proteasome in vitro and in cells. They used the Proteasome-Glo™ Chymotrypsin-Like Cell-Based Assay to assess the effects of BA derivatives on proteasome activity in MT4 cells. (3871)

Notes: Endosomal sorting complexes required for transport (ESCRTs) are necessary for sorting membrane proteins into the intralumenal vesicles of the multivesicular body for eventual degradation by the lysosome/vacuole. Mutations in at least one subunit of the ESCRTs are associated with frontotemporal dementia and ALS. In this study, the authors demonstrate that ESCRTs are required for autophagy and prevention of protein aggregation. They address the question of whether loss of ESCRTs might interfere with proteasome activity. Using the Proteasome-Glo™ Chymotrypsin-Like Cell-Based Assay, they show that proteasome activity is minimally affected in ESCRT-depleted cells. (3847)