Small-molecule p21-activated kinase inhibitor PF-3758309 is a potent inhibitor of oncogenic signaling and tumor growth.

Abstract

Despite abundant evidence that aberrant Rho-family GTPase activation contributes to most steps of cancer initiation and progression, there is a dearth of inhibitors of their effectors (e.g., p21-activated kinases). Through high-throughput screening and structure-based design, we identify PF-3758309, a potent (K(d) = 2.7 nM), ATP-competitive, pyrrolopyrazole inhibitor of PAK4. In cells, PF-3758309 inhibits phosphorylation of the PAK4 substrate GEF-H1 (IC(50) = 1.3 nM) and anchorage-independent growth of a panel of tumor cell lines (IC(50) = 4.7 +/- 3 nM). The molecular underpinnings of PF-3758309 biological effects were characterized using an integration of traditional and emerging technologies. Crystallographic characterization of the PF-3758309/PAK4 complex defined determinants of potency and kinase selectivity. Global high-content cellular analysis confirms that PF-3758309 modulates known PAK4-dependent signaling nodes and identifies unexpected links to additional pathways (e.g., p53). In tumor models, PF-3758309 inhibits PAK4-dependent pathways in proteomic studies and regulates functional activities related to cell proliferation and survival. PF-3758309 blocks the growth of multiple human tumor xenografts, with a plasma EC(50) value of 0.4 nM in the most sensitive model. This study defines PAK4-related pathways, provides additional support for PAK4 as a therapeutic target with a unique combination of functions (apoptotic, cytoskeletal, cell-cycle), and identifies a potent, orally available small-molecule PAK inhibitor with significant promise for the treatment of human cancers.

• Authors: Brion W Murray, Chuangxing Guo, Joseph Piraino, John K Westwick, Cathy Zhang, Jane Lamerdin, Eleanor Dagostino, Daniel Knighton, Cho-Ming Loi, Michael Zager, Eugenia Kraynov, Ian Popoff, James G Christensen, Ricardo Martinez, Susan E Kephart, Joseph Marakovits, Shannon Karlicek, Simon Bergqvist, Tod Smeal
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 107 Issue 20 Pg. 9446-51 (May 18 2010) ISSN: 1091-6490 [Electronic] United States
• PMID: 20439741 (Publication Type: Journal Article)

Chemical References

• ARHGEF2 protein, human
• Guanine Nucleotide Exchange Factors
• PF 3758309
• Pyrazoles
• Pyrroles
• Rho Guanine Nucleotide Exchange Factors
• PAK4 protein, human
• p21-Activated Kinases

Topics

• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cell Survival (drug effects)
• Crystallography
• Guanine Nucleotide Exchange Factors (metabolism)
• Humans
• Models, Molecular
• Neoplasms (drug therapy, metabolism)
• Phosphorylation (drug effects)
• Pyrazoles (chemistry, metabolism, pharmacology)
• Pyrroles (chemistry, metabolism, pharmacology)
• Rho Guanine Nucleotide Exchange Factors
• Signal Transduction (drug effects)
• p21-Activated Kinases (antagonists & inhibitors)