Catalog No.S7159 Synonyms: OTS167

OTSSP167 Chemical Structure

Molecular Weight(MW): 487.42

Purity & Quality Control

Choose Selective MELK Inhibitors

Biological Activity

Description OTSSP167 is a highly potent MELK (maternal embryonic leucine zipper kinase) inhibitor with IC50 of 0.41 nM.
Features MELK-selective inhibitor.
MELK [1]
0.41 nM
In vitro

OTSSP167 inhibits A549, T47D, DU4475, and 22Rv1 cancer cells, in which MELK is highly expressed, with IC50 values of 6.7, 4.3, 2.3, and 6.0 nM, respectively. OTSSP167 inhibited the phosphorylation of PSMA1 (proteasome subunit alpha type 1) and DBNL (drebrin-like), which are novel MELK substrates and are important for stem-cell characteristics and invasiveness. OTSSP167 suppresses mammosphere formation of breast cancer cells through the inhibition of PSMA1 phosphorylation. [1]

In vivo OTSSP167 exhibits significant tumor growth suppression in xenograft studies using breast, lung, prostate, and pancreas cancer cell lines in mice by both intravenous and oral administration. In MDA-MB-231 model, intravenous administration of OTSSP167 at 20 mg/kg once every two days results in TGI of 73% The oral administration at 10 mg/kg once a day reveals TGI of 72%. OTSSP167 for multiple cancer types in dose-dependent and MELK-dependent manners with no or a little body-weight loss. [1]


Kinase Assay:[1]
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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 Research:[1]
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  • Cell lines: A549, T47D, DU4475, and 22Rv1, HT1197
  • Concentrations: 0.005-0.1 μM
  • Incubation Time: 72 h
  • Method: Cell Counting Kit-8
    (Only for Reference)
Animal Research:[1]
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  • Animal Models: MDA-MB-231, A549, DU145 xenografts
  • Formulation: 0.5% methylcellulose
  • Dosages: 1 mg/kg , 5mg/kg ,10 mg/kg, 20 mg/kg
  • Administration: oral
    (Only for Reference)

Solubility (25°C)

In vitro DMSO 0.5 mg/mL warmed (1.02 mM)
Water slightly soluble or insoluble
Ethanol slightly soluble or insoluble
In vivo

* 1 mg/ml means slightly soluble or insoluble.
* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Chemical Information

Molecular Weight 487.42


CAS No. 1431697-89-0
Storage powder
in solvent
Synonyms OTS167

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID