OTSSP167 (OTS167) is an orally available inhibitor of maternal embryonic leucine zipper kinase (MELK) with potential antineoplastic activity.

MELK:0.41 nM

OTSSP167 inhibited the phosphorylation of PSMA1 and DBNL, novel MELK substrates that are essential for stem cell characterization and invasiveness.OTSSP167 inhibited sphere formation in breast cancer cells by inhibiting PSMA1 phosphorylation.OTSSP167 inhibited high levels of MELK expression in A549, T47D, DU4475 and 22Rv1 cancer cells with IC50 of 6.7, 4.3, 2.3 and 6.0 nM, respectively.

OTSSP167 inhibited the phosphorylation of PSMA1 and DBNL, novel MELK substrates that are essential for stem cell characterization and invasiveness.OTSSP167 inhibited sphere formation in breast cancer cells by inhibiting PSMA1 phosphorylation.OTSSP167 inhibited high levels of MELK expression in A549, T47D, DU4475 and 22Rv1 cancer cells with IC50 of 6.7, 4.3, 2.3 and 6.0 nM, respectively.

in vitro kinase assay: MELK recombinant protein (0.4 μg) is mixed with 5 μg of each substrate in 20 μL of kinase buffer containing 30 mM Tris-HCl (pH), 10 mM DTT, 40 mM NaF, 10 mM MgCl2, 0.1 mM EGTA with 50 μM cold-ATP and 10 Ci of [γ-32P]ATP for 30 min at 30 °C. The reaction is terminated by addition of SDS sample buffer and boiled for 5 min prior to SDS-PAGE. The gel is dried and autoradiographed with intensifying screens at room temperature. OTSSP167 (final concentration of 10 nM) is dissolved in DMSO and added to kinase buffer before the incubation.

Cell Counting Kit-8(Only for Reference)