BMS-3 is a potent LIMK inhibitor with IC50s of 5 nM and 6 nM for LIMK1 and LIMK2, respectively.

LIMK2:6 nM, LIMK1:5 nM

BMS-3 (Compound 2) causes a dose-dependent reduction in cell count and induces mitotic arrest by increases in total nuclear DNA intensity and histone H3 phosphorylation after 24 h treatment in A549 human lung cancer cells. BMS-3 inhibits A549 human lung cancer cells with EC50 value of 154 nM[1]. BMS-3 is used to demonstrate the direct participation of LIMK1 in the phosphorylation of Cofilin. Inhibition of p-LIMK with 1-50 μM of BMS-3 results in a dose-dependent decrease of p-Cofilin after 10 min incubation in capacitating conditions. As a control, sperm are also incubated for 10 min under non-capacitating conditions which result in low levels of p-Cofilin. In the presence of 1 or 50 μM of BMS-3, actin polymerization levels are significantly lower compared to controls (DMSO). Mouse sperm are incubated under capacitating conditions for 90 min in the presence or absence of increasing concentrations of pLIMK inhibitor BMS-3 (0, 1, 10 and 50 μM). The increasing concentrations of BMS-3 result in a strong decrease on the percentage of sperm that undergoes acrosomal exocytosis after stimulation with 20 μM of Progesterone[2] .

The protein kinase domains of human LIMK1 and LIMK2 are expressed as glutathione S-transferase fusion proteins using the Bac-to-Bac system in Sf9 cells. Compounds 1 to 6 (e.g., BMS-3) are assayed for inhibition of LIMK1 and LIMK2 protein kinase activity by radioactive phosphate incorporation into biotinylated full-length human destrin. Reactions are done with a concentration series of compound in 25 mM HEPES, 100 mM NaCl, 5 mM MgCl2, 5 mM MnCl2, 1 μM total ATP, 83 μg/mL biotinylated destrin, 167 ng/mL glutathione S-transferase-LIMK1, or 835 ng/mL glutathione S-transferase-LIMK2 in a total volume of 60 μL at room temperature for 30 min (LIMK1) or 60 min (LIMK2). Reactions are terminated by addition of 140 μL of 20% TCA/100 mM sodium pyrophosphate, and the precipitates are harvested onto GF/C unifilter plates. The radioactivity incorporated is determined using a TopCount after addition of 35 μL Microscint scintillation fluid[1]