Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 2013 | Supplemental Material
Journal Article Open

Structure–Activity Relationship Study Reveals ML240 and ML241 as Potent and Selective Inhibitors of p97 ATPase


To discover more potent p97 inhibitors, we carried out a structure–activity relationship study of the quinazoline scaffold previously identified from our HTS campaigns. Two improved inhibitors, ML240 and ML241, inhibit p97 ATPase with IC_(50) values of 100 nM. Both compounds inhibited degradation of a p97-dependent but not a p97-independent proteasome substrate in a dual-reporter cell line. They also impaired the endoplasmic-reticulum-associated degradation (ERAD) pathway. Unexpectedly, ML240 potently stimulated accumulation of LC3-II within minutes, inhibited cancer cell growth, and rapidly mobilized the executioner caspases 3 and 7, whereas ML241 did not. The behavior of ML240 suggests that disruption of the protein homeostasis function of p97 leads to more rapid activation of apoptosis than is observed with a proteasome inhibitor. Further characterization revealed that ML240 has broad antiproliferative activity toward the NCI-60 panel of cancer cell lines, but slightly lower activity toward normal cells. ML240 also synergizes with the proteasome inhibitor MG132 to kill multiple colon cancer cell lines. Meanwhile, both probes have low off-target activity toward a panel of protein kinases and central nervous system targets. Our results nominate ML240 as a promising starting point for the development of a novel agent for the chemotherapy of cancer, and provide a rationale for developing pathway-specific p97 inhibitors.

Additional Information

© 2013 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim. Received: November 8, 2012. Revised: December 7, 2012. Published online on January 11, 2013. We thank B. E. Nordin and M. P. Patricelli (ActivX Biosciences La Jolla, CA, USA) for analyzing the ACJI-47 positive control free of charge in the kinase profiling experiments. Ki determinations and receptor binding profiles were generously provided by the National Institute of Mental Health's Psychoactive Drug Screening Program, Contract no. HHSN-271-2008-00025-C (NIMH PDSP). The NIMH PDSP is Directed by Bryan L. Roth, MD PhD (University of North Carolina, Chapel Hill, NC, USA) and Project Officer Jamie Driscol (NIMH, Bethesda MD, USA). The NCI 60-cell-line screen was performed by the Developmental Therapeutics Program at the NCI. We thank Jeffrey Aubé (University of Kansas, Lawrence, KS, USA) for helpful discussions, P. Porubsky (University of Kansas) for compound management, Ben Neuenswander (University of Kansas) for compound purification and high-resolution mass determination, Justin Douglas and Sarah Neuenswander (University of Kansas) for NMR assistance, R. Weinberg (Massachusetts Institute of Technology, Cambridge, MA, USA) via H. Chang (Stanford University, CA, USA) for providing PHMLEB and PHMLER cells, K. S. Osthoff (Eberhard Karls University, Tübingen, Germany) via G. M. Cohen (University of Leicester, UK) for caspase 9-/- cells, G. Salvesen (Sanford-Burnham Medical Research Institute) for caspase 8-/- cells, and H. Park, R. Oania, and D. Shimoda for technical assistance. This work was supported by a grant from the NIH Molecular Libraries Probe Production Centers Network to Jeffrey Aubé (PI) (5U54HG005031). R.J.D. and T.-F.C. were supported by the Howard Hughes Medical Institute, of which R.J.D. is an Investigator.

Attached Files

Supplemental Material - cmdc_201200520_sm_miscellaneous_information.pdf

Supplemental Material - cmdc_201200520_sm_supporting_information.xls


Files (4.2 MB)
Name Size Download all
86.0 kB Download
4.1 MB Preview Download

Additional details

August 19, 2023
October 23, 2023