Catalog No.S7159

OTSSP167 is a highly potent MELK (maternal embryonic leucine zipper kinase) inhibitor with IC50 of 0.41 nM.

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OTSSP167 Chemical Structure

OTSSP167 Chemical Structure
Molecular Weight: 487.42

Validation & Quality Control

Quality Control & MSDS

Product Information

Product Description

Biological Activity

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

Protocol(Only for Reference)

Kinase Assay: [1]

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 Assay: [1]

Cell lines A549, T47D, DU4475, and 22Rv1, HT1197
Concentrations 0.005-0.1 μM
Incubation Time 72 h
Method Cell Counting Kit-8

Animal Study: [1]

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

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

SpeciesMouseRatRabbitGuinea pigHamsterDog
Weight (kg)
Body Surface Area (m2)0.0070.0250.
Km factor36128520
Animal A (mg/kg) = Animal B (mg/kg) multiplied by  Animal B Km
Animal A Km

For example, to modify the dose of resveratrol used for a mouse (22.4 mg/kg) to a dose based on the BSA for a rat, multiply 22.4 mg/kg by the Km factor for a mouse and then divide by the Km factor for a rat. This calculation results in a rat equivalent dose for resveratrol of 11.2 mg/kg.

Rat dose (mg/kg) = mouse dose (22.4 mg/kg) ×  mouse Km(3)  = 11.2 mg/kg
rat Km(6)


[1] Chung S, et al. Oncotarget, 2012, 3(12), 1629-1640.

Chemical Information

Download OTSSP167 SDF
Molecular Weight (MW) 487.42


CAS No. 1431697-89-0
Storage 3 years -20℃powder
2 years -80℃in solvent
Synonyms OTS167
Solubility (25°C) * In vitro DMSO 0.5 mg/mL warming (1.02 mM)
Water <1 mg/mL
Ethanol <1 mg/mL
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 Name 1-(6-(3,5-dichloro-4-hydroxyphenyl)-4-((1r,4r)-4-((dimethylamino)methyl)cyclohexylamino)-1,5-naphthyridin-3-yl)ethanone

Tech Support

Answers to questions you may have can be found in the inhibitor handling instructions. Topics include how to prepare stock solutions, how to store inhibitors, and issues that need special attention for cell-based assays and animal experiments.

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID
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