Reversible inhibitor of p97, DBeQ, impairs both ubiquitin-dependent and autophagic protein clearance pathways
A specific small-molecule inhibitor of p97 would provide an important tool to investigate diverse functions of this essential ATPase associated with diverse cellular activities (AAA) ATPase and to evaluate its potential to be a therapeutic target in human disease. We carried out a high-throughput screen to identify inhibitors of p97 ATPase activity. Dual-reporter cell lines that simultaneously express p97-dependent and p97-independent proteasome substrates were used to stratify inhibitors that emerged from the screen. N^2,N^4-dibenzylquinazoline-2,4-diamine (DBeQ) was identified as a selective, potent, reversible, and ATP-competitive p97 inhibitor. DBeQ blocks multiple processes that have been shown by RNAi to depend on p97, including degradation of ubiquitin fusion degradation and endoplasmic reticulum-associated degradation pathway reporters, as well as autophagosome maturation. DBeQ also potently inhibits cancer cell growth and is more rapid than a proteasome inhibitor at mobilizing the executioner caspases-3 and -7. Our results provide a rationale for targeting p97 in cancer therapy.
Additional Information© 2011 National Academy of Sciences. Edited by Randy King, Harvard University, Cambridge, MA, and accepted by the Editorial Board February 4, 2011 (received for review October 12, 2010). Published online before print March 7, 2011. We thank A. Brunger for providing plasmids; G. Georg for a useful suggestion regarding high-throughput screen validation; C. Weihl for helpful discussions; P. Baillargeon and L. DeLuca for compound management; F. Parlati for critical reading of the manuscript; and H. Park, R. Oania, and D. Shimoda for technical assistance. National Institutes of Health (NIH) U54 Grant MH074404 funded Scripps personnel. The University of Kansas was supported by Award U54 HG005031-02 administered by the National Human Genome Research Institute on behalf of the NIH Roadmap Molecular Libraries Program. A.C.J. was supported by NIH Grant F32GM082000. T.-F.C. was supported by a 2008 Fellows Grant Program Award from the Multiple Myeloma Research Foundation, the Howard Hughes Medical Institute (HHMI), and the Weston Havens Foundation. R.J.D. is an HHMI Investigator, and this work was funded in part by HHMI and in part by NIH R03 Grant MH085687. Author contributions: T.-F.C., B.M.S., F.J.S., M.P.P., P.H., H.R., and R.J.D. designed research; T.-F.C., S.J.B., D.M., B.E.N., K.L., A.C.J., P.C., and P.R.P. performed research; T.-F.C. and R.J.D. analyzed data; and T.-F.C. and R.J.D. wrote the paper.
Published - Chou2011p13345P_Natl_Acad_Sci_Usa.pdf
Supplemental Material - pnas.201015312SI.pdf
Supplemental Material - sd01.xls