SKI II

SKI II is a nonlipid inhibitor of sphingosine kinase. SKI II s orally bioavailable and has shown significant inhibition of tumor growth in mice.

Selective non-lipid inhibitor of sphingosine kinase (IC 50 = 0.5 μ M); does not act at ATP-binding site. Displays no inhibition of ERK2, PI 3-kinase, or PKC α at concentrations up to 60 μ M. Reduces levels of sphingosine-1-phosphate in MDA-MB-231 breast cancer cells. Induces apoptosis and inhibits proliferation in several other tumor cell lines in vitro (IC 50 = 0.9-4.6 μ M).

Sphingosine kinase (SK) plays a pivotal role in regulating tumor growth and SK can act as an oncogene. Expression of SK RNA is significantly elevated in a variety of solid tumors, compared with normal tissue from the same patient. A number of novel inhibitors of human SK were identified, and several representative compounds were characterized in detail. These compounds demonstrated activity at sub- to micromolar concentrations, making them more potent than any other reported SK inhibitor, and were selective toward SK compared with a panel of human lipid and protein kinases. Kinetic studies revealed that the compounds were not competitive inhibitors of the ATP-binding site of SK. 4-[4-(4-chloro-phenyl)-thiazol-2-ylamino]-phenol (SKI-II) inhibitor is orally bioavailable, detected in the blood for at least 8 h, and showed a significant inhibition of tumor growth in mice with IC50 = 0.5 μM; SKI II does not act at ATP-binding site. Displays no inhibition of ERK2, PI 3-kinase, or PKCa at concentrations up to 60 μM.SKI II induces apoptosis and inhibits proliferation in several other tumor cell lines in vitro (IC50 = 0.9-4.6 μM).