MLN120B is a selective and ATP competitive IKKβ inhibitor (IC50: 60 nM).

IKKβ:60 nM

MLN120B almost completely blocks the stimulation of MM.1S, U266, and INA6 cell growth, as well as IL-6 secretion from BMSCs, induced by multiple myeloma cell adherence to BMSCs [1]. MLN120B shows an inhibitory effect on LPS induced NF-κB activation in RAW267.4 cells. The IC50 values of MLN120B is 1.4, 14.8 or 27.3 μM for NF-κB2-luc2, IL8-luc2 or TNF-AIP3-luc2 reporter transfected cells, respectively [3].

MLN120B (50 mg/kg, p.o.) inhibits human multiple myeloma cell growth in vivo [1]. MLN120B (12 mg/kg twice daily, p.o.) inhibits paw swelling in a dose-dependent manner and offers significant protection against arthritis-induced weight loss as well as cartilage and bone erosion [2].

Multiple myeloma cells are cultured with MLN120B, harvested, washed, and lysed using lysis buffer [50 mM Tris-HCl (pH 7.4), 150 mM NaCl, 1% NP40, 5 mM EDTA, 5 mM NaF, 2 mM Na3VO4, 1 mM phenylmethylsulfonyl fluoride, 5 μg/mL leupeptin, 5 μg/mL aprotinin]. Whole-cell lysates are subjected to Western blotting using phosphorylated IκBα, IκBα, phosphorylated p65 NF-κB, and p65 NF-κB antibodies [1].

Human fetal long bone grafts are implanted into SCID mice (SCID-hu mice). Approximately 4 weeks following bone implantation, 2.5×10^6 INA6 multiple myeloma cells in 50 μL PBS is injected directly into human bone within SCID-hu hosts. Soluble human IL-6 receptor (shuIL-6R) released from INA6 cells is assessed in mouse sera by ELISA as in our prior studies. Mice are treated orally with vehicle alone or MLN120B 50 mg/kg (twice daily) for 3 weeks after the detection of measurable shuIL-6R in mouse sera [1].