Late stage results from the probe development effort to identify inhibitors of Retinoblastoma Binding Protein 9 (RBBP9): Luminescence-based counterscreen assay to identify cytotoxic compounds
Name: Late stage results from the probe development effort to identify inhibitors of Retinoblastoma Binding Protein 9 (RBBP9): Luminescence-based counterscreen assay to identify cytotoxic compounds ..more
Data Source (MLPCN Center Name): The Scripps Research Institute Molecular Screening Center (SRIMSC)
Center Affiliation: The Scripps Research Institute, TSRI
Assay Provider: Benjamin Cravatt, TSRI
Network: Molecular Libraries Probe Production Center Network (MLPCN)
Grant Proposal Number: 1 2 R01 CA087660-05 Fast Track
Grant Proposal PI: Benjamin Cravatt, TSRI
External Assay ID: HEK 293T VIABILITY_INH_LUMI_96_CC50
Name: Late stage results from the probe development effort to identify inhibitors of Retinoblastoma Binding Protein 9 (RBBP9): Luminescence-based counterscreen assay to identify cytotoxic compounds
The retinoblastoma (RB) tumor suppressor protein controls cell cycle progression by regulating the activity of the transcription factor E2F (1), which activates genes essential for DNA replication. Due to the critical role of RB in regulating the cell cycle, factors that bind and regulate RB activity are considered valuable targets for preventing tumorigenesis. One such protein, RB binding protein 9 (RBBP9), is widely expressed in different tissues and upregulated in certain tumors (2, 3). The RBBP9 protein contains an alpha/beta hydrolase fold, which belongs to the DUF1234 domain superfamily of unknown function. Although an enzymatic activity of RBBP9 has not been reported, this protein does react with activity-based probes that target serine hydrolases, suggesting that it is a functional enzyme. Also consistent with this premise, the crystal structure of RBBP9 was recently solved and revealed a well-structured active site with a properly arranged catalytic triad (4). A role for RBBP9 in cellular transformation is supported by studies showing that RBBP9 mRNA expression is increased in transformed rat liver cell lines and human liver tumor biopsies (3). Furthermore, RBBP9-overexpressing cells form tumors when implanted into immuno-deficient mice (3), and RBBP9 overexpression confers resistance to TGF-β1-induced growth inhibition through its interaction with Rb and displacement of E2F (3, 5). RBBP9 is also suggested to play a role in gender-related differential responses to radiation-induced cell proliferation (6). As a result, the identification of compounds that selectively inhibit RBBP9 activity may provide valuable probes for the study of apoptosis, cell cycle, and tumorigenesis.
This cytotoxicity counterscreen was performed as part of a probe development effort to identify inhibitor probes of RBBP9 belonging to the oxime ester scaffold.
1. Nevins, J.R., E2F: a link between the Rb tumor suppressor protein and viral oncoproteins. Science, 1992. 258(5081): p. 424-9.
2. Chen, J.Z., Yang, Q.S., Wang, S., Meng, X.F., Ying, K., Xie, Y., and Ma, Y.M., Cloning and expression of a novel retinoblastoma binding protein cDNA, RBBP10. Biochem Genet, 2002. 40(7-8): p. 273-82.
3. Woitach, J.T., Zhang, M., Niu, C.H., and Thorgeirsson, S.S., A retinoblastoma-binding protein that affects cell-cycle control and confers transforming ability. Nat Genet, 1998. 19(4): p. 371-4.
4. Vorobiev, S.M., Su, M., Seetharaman, J., Huang, Y.J., Chen, C.X., Maglaqui, M., Janjua, H., Proudfoot, M., Yakunin, A., Xiao, R., Acton, T.B., Montelione, G.T., and Tong, L., Crystal structure of human retinoblastoma binding protein 9. Proteins, 2009. 74(2): p. 526-9.
5. Woitach, J.T., Hong, R., Keck, C.L., Zimonjic, D.B., Popescu, N.C., and Thorgeirsson, S.S., Assignment of the Bog gene (RBBP9) to syntenic regions of mouse chromosome 2G1-H1 and human chromosome 20p11.2 by fluorescence in situ hybridization. Cytogenet Cell Genet, 1999. 85(3-4): p. 252-3.
6. Cassie, S., Koturbash, I., Hudson, D., Baker, M., Ilnytskyy, Y., Rodriguez-Juarez, R., Weber, E., and Kovalchuk, O., Novel retinoblastoma binding protein RBBP9 modulates sex-specific radiation responses in vivo. Carcinogenesis, 2006. 27(3): p. 465-74.
7. Bachovchin, D.A., Brown, S.J., Rosen, H., and Cravatt, B.F., Identification of selective inhibitors of uncharacterized enzymes by high-throughput screening with fluorescent activity-based probes. Nat Biotechnol, 2003. 27(4): p. 387-94.
Late stage, HEK 293T cells, cytotoxicity, luminescence, viability, Probes, RBBP9, retinoblastoma binding protein 9, BOG, cell cycle, cancer, fluorescence polarization, fluorophosphonate rhodamine, FP-Rh, antagonist, inhibitor, primary, confirmation, gel-based ABPP, HTS, 1536, Scripps, Scripps Florida, Scripps Research Institute Molecular Screening Center, SRIMSC, Molecular Libraries Probe Production Centers Network, MLPCN.
Please see AIDs 1515 and 1537, Summary AID 1790, and below for all protocols performed in this probe development effort. The purpose of this assay is to determine cytotoxicity of inhibitor compounds belonging to the oxime ester scaffold. In this assay, HEK cells are incubated with test compounds, followed by determination of cell viability. The assay utilizes the CellTiter-Glo luminescent reagent to measure intracellular ATP in viable cells. Luciferase present in the reagent catalyzes the oxidation of beetle luciferin to oxyluciferin and light in the presence of cellular ATP. Well luminescence is directly proportional to ATP levels and cell viability. As designed, compounds that reduce cell viability will reduce ATP levels, luciferin oxidation and light production, resulting in decreased well luminescence. Compounds were tested in triplicate in a 10-point 1:3 dilution series starting at a nominal test concentration of 40 micromolar.
This assay was started by dispensing 5 x 10E3 HEK 293T cells/well into a 96-well plate. Compound (0.001-100 mM) or DMSO was added to each well, and after 48h cell viability was determined by the CellTitre assay (Promega).
The PubChem Activity Score is assigned a value of 100 for probe compounds, 50 for active compounds, and 0 for inactive compounds.
Compounds with a CC50 value of >20uM were considered inactive and <20uM were considered active.
List of Reagents:
HEK cells (provided by Assay Provider)
Cell Titer-Glo (Promega, part G75729)
This assay was performed in the laboratory of the Assay Provider with compounds ordered as powders. Probes were identified for this project. Details of protocols, compound structures, and results from the original assays can be found in PubChem at the respective AIDs listed in the Related Bioassays section. Please also see Summary AID 1790. The results of our probe development efforts can be found at http://mlpcn.florida.scripps.edu/index.php/probes/probe-reports.html. One paper has been published detailing the emetine probe (7).
Categorized Comment - additional comments and annotations
* Activity Concentration.
Data Table (Concise)