K145

K145 is a selective inhibitor of Sphingosine Kinase-2 (SphK2) with IC50 value of 4.3μM [1].

K145 is an analogue of sphingosine. It competes with the substrate of SphK2 and shows Ki value of 6.4μM in the in vitro assay. K145 is selective against SphK2 over SphK1 and CERK. In U937 cells, K145 decreases total cellular S1P and inhibits the phosphorylation of FTY720 (Both S1P and FTY720 are substrates of SphK2). Meanwhile, K145 suppresses cell growth and induces late apoptosis significantly. It is also found to inhibit the phosphorylation of ERK and Akt in this cell line [1].

In the U937 xenograft model in mice, K145 inhibits tumor growth with a TGI value of 44.2% and has less toxicity than tamibarotene. In BALB/c mice bearing the JC xenograft, K145 also shows potent inhibitory effects on tumor growth. Moreover, in BALB/c-nu mice bearing U937 xenograft, oral administration of K145 exerts better antitumor activity than tamibarotene [1].

References:
[1] Liu K, Guo T L, Hait N C, et al. Biological characterization of 3-(2-amino-ethyl)-5-[3-(4-butoxyl-phenyl)-propylidene]-thiazolidine-2, 4-dione (K145) as a selective sphingosine kinase-2 inhibitor and anticancer agent. PloS one, 2013, 8(2): e56471.