F-12509A

The inhibitory effects of two novel sphingosine (SPH) kinase inhibitors, F-12509A and B-5354c, on recombinant human SPH kinase isoforms (hSPHK1 and hSPHK2) were evaluated and compared with N,N-dimethylsphingosine (DMS), a well-characterized SPH kinase inhibitor.SPH kinase assay was performed using recombinant enzymes prepared from HEK293 cells transfected with vectors containing hSPHK1 or hSPHK2 constructs.The specific activities of the recombinant hSPHK1 and hSPHK2 preparations were 1225 and 225 pmol sphingosine-1-phosphate/min/mg protein, resp.These activities were satisfactory and substantially higher than the control preparation (8 pmol SPP/min/mg protein) from vector alone-transfected HEK293 cells.All the compounds inhibited both SPH kinase isoforms in a dose-dependent manner.DMS inhibited hSPHK1 competitively, while it inhibited hSPHK2 noncompetitively.The inhibitory potencies of F-12059A and B-5354c for hSPHK1 were almost the same as that of DMS.However, those for hSPHK2 were about two and four times more potent than DMS, resp.