In Vitro | In vitro activity: PF-3758309 is a potent (Kd = 2.7 nM), ATP-competitive inhibitor of PAK4 with Ki of 18.7 nM. In cells, PF-3758309 inhibits phosphorylation of the PAK4 substrate GEF-H1 (IC50 = 1.3 nM) and anchorage-independent growth of a panel of tumor cell lines (IC50 = 4.7 nM). PF-3758309 also inhibits endogenous pGEF-H1 accumulation in HCT116 cells. PF-3758309 potently inhibits cellular proliferation (IC50 = 20 nM) and anchorage-independent growth (IC50 = 27 nM) of A549 cells.
Kinase Assay: TR-293-KDG cells are constructed from HEK293 cells stably transfected with tetracycline-inducible PAK4-kinase domain (amino acids 291-591) and constitutively expressed HA-tagged GEFH1ΔDH (amino acids 210-921). TR-293-KDG cells are incubated for 3 h with PF-3758309, captured on an anti-HA antibody-coated plate, detected with an anti-phospho-S810-GEF-H1 antibody, and quantified with a horseradish peroxidase-goat anti-rabbit antibody conjugate.
Cell Assay: A panel of cancer cell lines is used to test the potency of PF-3758309. On day 1, cells are plated on 384-well plates. Onday2, compounds are added to the cell culture. The cells are incubated with the compound for 3 days. On day 5, all media are aspirated from the wells. Dose-dependent effects of PF-3758309 on cell proliferation are quantified via the CellTiter-Glo Luminescent Cell Viability Assay(a,b,c), which is a homogeneous method of determining the number of viable cells in culture based on quantitation of the ATP present, an indicator of metabolically active cells. Proliferation data displayed for HEK293T, HCT116, and SKOV3 cells are measured using the Cyquant NF assay as specified by the manufacturer. Briefly, 24 h after seeding on 384-well plates, cells are treated with vehicle or PF-3758309, Dasatinib, or the positive control, Bleomycin (60 mU/ mL).72 hours after drug treatment, cell proliferation is measured. Results for each drug are normalized to vehicle control and expressed as a percentage of maximum assay inhibition relative to Bleomycin. Error bars represent the SD from at least three experiments. |
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