Description

Cancer

Description

SB 525334 is a potent and selective inhibitor of TGF-β1 (ALK5) with IC50 of 14.3 nM.

Targets

IC₅₀

In Vitro

SB 525334 shows no inhibition in the enzymes ALK2, 3, and 6, with IC50 values > 10 μM. SB 525334 blocks phosphorylation induced by TGF-β1 and nuclear translocation of Smad2/3 in renal proximal tubule cells. SB 525334 also inhibits the increased mRNA expression levels of plasminogen activator inhibitor-1 (PAI-1) and procollagen α1(I) induced by TGF-β1 in A498 renal epithelial carcinoma cells at 1 μM). ^[1]SB 525334 (1 μM) attenuates the heightened sensitivity to TGF-β1 exhibited by pulmonary artery smooth muscle cells (PASMCs) from patients with familial forms of idiopathic pulmonary arterial hypertension (PAH). ^[2]

In Vivo

SB 525334 (10 mg/kg/day) decreases the renal mRNA levels of PAI-1, procollagen α1(I), and procollagen α1(III) in a nephritis-induced renal fibrosis rat model. Furthermore, PAN-induced proteinuria is significantly inhibited by SB 525334 (10 mg/kg/day). ^[1]SB 525334 may also be efficacious in mesenchymal tumors. SB 525334 (10 mg/kg/day) significantly decreases uterine mesenchymal tumor incidence, multiplicity, and size in Eker rats. ^[3]SB 525334 significantly reverses pulmonary arterial pressure and inhibits right ventricular hypertrophy in a rat model of PAH. This is revealed by a significant reduction in pulmonary arteriole muscularization induced by monocrotaline (used to induce PAH) after treatment with SB 525334 (3 or 30 mg/kg). ^[2]In a Bleomycin-induced pulmonary fibrosis mice model, SB 525334 (10 mg/kg or 30 mg/kg) attenuates the histopathological alterations in the lung, and significantly decreased mRNA expression of Type I and III procollagen and fibronectin. SB 525334 also attenuates Smad2/3 nuclear translocation, myofibroblast proliferation, deposition of Type I collagen, and decreases CTGF-expressing cells. ^[4]

Clinical Trials

Features

Kinase assay to determine the potency and selectivity of SB 525334

In order to determine the potency of SB 525334, purified GST-tagged kinase domain of ALK5 is incubated with purified GST-tagged full-length Smad3 in the presence of ³³P-γATP and different concentrations of SB 525334. The readout is radioactively labeled Smad3.To determine the selectivity of SB 525334, purified GST-tagged kinase domain of ALK2 and ALK4 are incubated with GST-tagged full-length Smad1 and Smad3, respectively, in the presence of different concentrations of SB 525334. IC50 values are calculated.

Cell Lines

Human renal proximal tubule epithelial (RPTE) cells

Concentrations

1 μM

Incubation Time

1 hour

Methods

RPTE cells are seeded on microscope slides. The following day, the cells are starved for 24 hours to dosing by removal of the serum and epidermal growth factor. Cells are treated with either 10 ng/mL TGF-β1, 1 μM SB 525334, or a combination of both. Slides are pretreated with SB 525334 or starve media for 3 hours prior to a 1-hour incubation at 37 °C with TGF-β1 or starve media.The cells are then fixed and permeabilized. The slides are blocked with BSA, incubated with a mouse anti-Smad2/3 primary antibody followed by an anti-mouse IgG fluorescein secondary antibody. The slides are then viewed in a confocal microscope and nuclear signal intensity is analyzed.

Animal Models

Bleomycin-induced pulmonary fibrosis in female Eker rats

Formulation

200 mg/L in drinking water

Doses

Estimated dose of 10 mg/kg/day

Administration

Oral (in drinking water)