| In Vitro | In vitro activity: GW788388 shows anti-TGF-β activity with IC50 of 93 nM in cellular assay. GW788388 shows some inhibitory to activin type II receptor (ActRII) but no inhibitory to bone morphogenic protein (BMP) type II receptor. GW788388 shows no toxicity in Namru murine mammary gland (NMuMG), MDA-MB-231, renal cell carcinoma (RCC)4, and U2OS cells at 4 nM to 15 μM. GW788388 blocks TGF-β-induced Smad activation and target gene expression, while decreasing epithelial-mesenchymal transitions and fibrogenesis. GW788388 inhibits ALK5, ALK4, ALK7 and TGF-β-mediated growth arrest.
Kinase Assay: GW788388 binding to ALK5 is tested on purified recombinant GST–ALK5 (residues 198-503). Displacement of rhodamine green fluorescently labeled ATP competitive inhibitor by different concentrations of GW788388 is used to calculate a binding pIC50. GST–ALK5 is added to a buffer containing 62.5 mM N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (Hepes), pH 7.5, 1 mM dithiothreitol (DTT), 12.5 mM MgCl2, 1.25 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS), and 1 nM rhodamine green-labeled ligand so that the final ALK5 concentration is 10 nM based on active-site titration of the enzyme. The enzyme/ligand reagent (40 μL) is added to 384-well assay plates containing 1 μL of different concentrations of GW788388. The plates are read immediately on a LJL Acquest fluorescence reader with excitation, emission, and dichroic filters of 485, 530, and 505 nm, respectively. The fluorescence polarization for each well is calculated by the Acquest and is then imported into curve-fitting software for construction of concentration–response curves.
Cell Assay: Cell viability/proliferation assays (Namru murine mammary gland (NMuMG), MDA-MB-231, renal cell carcinoma (RCC)4, and U2OS cells) are done according to the manufactures instructions (CellTiter 96 Aqueous One Solution Cell Proliferation Assay). Viability and proliferation are measured after 72 hours GW788388 treatment in the presence or absence of TGF-β. |
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