Small-molecule p21-activated kinase inhibitor PF-3758309 is a potent inhibitor of oncogenic signaling and tumor growth.
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.
Murray
Brion W
BW
Pfizer Oncology, Pfizer, San Diego, CA 92121, USA. brion.murray@pfizer.com
Guo
Chuangxing
C
Piraino
Joseph
J
Westwick
John K
JK
Zhang
Cathy
C
Lamerdin
Jane
J
Dagostino
Eleanor
E
Knighton
Daniel
D
Loi
Cho-Ming
CM
Zager
Michael
M
Kraynov
Eugenia
E
Popoff
Ian
I
Christensen
James G
JG
Martinez
Ricardo
R
Kephart
Susan E
SE
Marakovits
Joseph
J
Karlicek
Shannon
S
Bergqvist
Simon
S
Smeal
Tod
T
D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D003461:Crystallography; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011720:Pyrazoles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011758:Pyrroles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D064067:Rho Guanine Nucleotide Exchange Factors; D015398:Signal Transduction / Q000187:drug effects*; D054462:p21-Activated Kinases / Q000037:antagonists & inhibitors*
C577356:ARHGEF2 protein, human; D020662:Guanine Nucleotide Exchange Factors; C550923:PF 3758309; D011720:Pyrazoles; D011758:Pyrroles; D064067:Rho Guanine Nucleotide Exchange Factors; C116367:PAK4 protein, human; D054462:p21-Activated Kinases