MLN8054 is a potent and selective Aurora A kinase inhibitor with an IC50 of 4 nM.

MLN8054 is an ATP-competitive, reversible inhibitor of recombinant Aurora A kinase with an IC50 of 4 nM, which shows >40-fold more selective inhibitory activity for Aurora A compared with Aurora B. [1] In vitro, MLN8054 exhibits the activity of growth inhibition across various cell lines from diverse tissue origins with IC50 values ranging from 0.11 μM to 1.43 μM. In addition, MLN8054 selectively inhibits Aurora A over Aurora B in cultured cells, and inhibits cell proliferation by promoting G2/M accumulation and spindle defects in multiple cultured human tumor cells lines. [1] A recent study shows that MLN8054 sensitizes androgen-resistant prostate cancer to radiation by inhibiting Aurora A kinase, which is associated with sustained DNA double-strand breaks. [2]

In the HCT-116 tumor-bearing mice, MLN8054, administered orally at 3 mg/kg, 10 mg/kg, and 30 mg/kg once a day, leads to dose-dependent tumor growth inhibition (TGI: 76% and 84% for 10 mg/kg and 30 mg/kg). MLN8054 also shows similar antitumor activity in the PC-3 tumor xenograft in nude mice. [1] In the HCT-116 xenograft-bearing animals, MLN8054 induces DNA and tubulin staining of tumor tissue in nuclear and cell body area, consistent with a senescent phenotype by increasing senescence-associated beta-galactosidase activity. [3]

Enzyme Assays : Recombinant murine Aurora A and Aurora B protein are expressed in Sf9 cells and purified with GST affinity chromatography. The peptide substrate for Aurora A is conjugated with biotin (Biotin-GLRRASLG). Aurora A kinase (5 nM) is assayed in 50 mM Hepes (pH 7.5)/10 mM MgCl2/5 mM DTT/0.05% Tween 20/2 μM peptide substrate/3.3 μCi/ml [γ-33P]ATP at 2 μM by using Image FlashPlates. Aurora B kinase (2 nM) is assayed with 10 μM biotinylated peptide Biotin-TKQTARKSTGGKAPR in 50 mM Tricine (pH 8.0)/2.5 mM MgCl2/5 mM DTT/10% glycerol/2% BSA/40 μCi/ml [γ-33P]ATP at 250 μM. The conditions for all other in vitro kinase assays are available upon request. MLN8054 is run in a 226 kinase screen at a 1 μM compound concentration with an ATP concentration of 10 μM for all assays.

Human tumor cell lines are grown in 96-well cell culture dishes according to the distributor's recommendations. MLN8054, diluted in DMSO, is added to the cells in 2-fold serial dilutions to achieve final concentrations ranging from 10 mM to 0.04 mM. MLN8054 at each dilution is added in triplicate with each replicate on a separate plate. Cells treated with DMSO (n = 6 wells per plate; 0.2% final concentration) serves as the untreated control. The cells are treated with MLN8054 for 96 hours at 37 °C in a humidified cell culture chamber. Cell viability in each cell line is measured by using the Cell Proliferation ELISA, BrdU colorimetric kit according to the manufacturer's recommendation(Only for Reference)