LY-364947 (HTS466284) is a potent ATP-competitive inhibitor of TGFβR-I.

TGFβRI:59 nM, MLK7K:1.4 μM, TGFβRII:0.4 μM, RIPK2:0.11 μM, CK1δ:0.22 μM

Administering 1 mg/kg i.p. of LY364947 significantly enhances the LYVE-1-positive regions within the tumor tissues in a BxPC3 pancreatic cancer xenograft model. Similarly, 25 mg/kg i.p. of LY364947 markedly increases LYVE-1-positive areas in a chronic peritonitis mouse model, indicating accelerated lymphangiogenesis. Additionally, LY364947 (25 mg/kg) increases p-Akt levels and decreases nuclear Foxo3a in leukemia-initiating cells in mice infected with CML.

At a concentration as low as 0.25 μM, LY364947 enhances the xVent2-lux BMP4 response in NMuMG cells by 30%. At 2 μM, it prevents TGF-β-induced epithelial-mesenchymal transition (EMT) in NMuMG cells. A 3 μM dose of LY364947, after 24 hours of treatment, induces the expression of Prox1 and LYVE-1 in nearly all HDLECs. LY364947 promotes the nuclear export of Foxo3a and is characterized by low Smad2/3 and high Akt phosphorylation levels in leukemia-positive cells. When co-cultured with OP-9 stromal cells, LY364947 (at concentrations <20 μM) inhibits the colony-forming ability of leukemia-initiating cells. Acting as an ATP-competitive, tight-binding inhibitor, LY364947 inhibits P-Smad3 phosphorylation through TGFβR-I kinase with a Ki of 28 nM and inhibits Smad2 phosphorylation in NMuMG cells in vivo with an IC50 of 135 nM.

The IC50 of LY-364947 at different enzyme concentrations are determined by the filter-binding assay. Typically, 40 μL reactions in 50 mM HEPES at pH 7.5, 1 mM NaF, 200 μM pKSmad3(-3), and 50 mM ATP containing a titration of each inhibitor with concentrations of 1600, 800, 400, 200, 100, 50, 25, and 0 nM are incubated at 30°C for 30 min. The IC50 is calculated using a nonlinear regression method with GraphPad Prism software. The binding type is determined by plotting the correlation between enzyme concentrations and IC50 values.