PF 543

Общее описание

A cell-permeable hydroxymethylpyrrolidine compound that acts as a high affinity (K_d = 5 nM, k_offt_1/2 = 8.5 min), but poor, sphingosine kinase-1/SphK1 substrate (1/1,500 of sphingosine processivity) and potently inhibits against SphK1-catalyzed sphingosine-to-S1P conversion (IC₅₀ = 2.0 nM; [sphingosine] = 3 μM) in a reversible, sphingosine-, but not ATP-, competitive manner (K_i = 3.6 nM), exhibiting 132-fold selectivity over SphK2, no affinity toward S1P receptors (S1P1, S1P2, S1P3, S1P5), and much reduced or no inhibitory activity against a panel of 46 other lipid and protein kinases (IC₅₀ >10 μM), including the structurally related diacylglyerol kinase α/DAGKα (3.7% inhibition at 10 μM). PF-543 exposure in 1483 squamous cultures is reported to result in intracellular S1P depletion (by 90% upon 1 h 200 nM or 7 d 1 μM drug exposure) with concomitant elevation of sphingosine level and no detectable cytotoxicity (1 μM for 7 to 9 d in 1483, A549, Jurkat, LN229, MCF7, or U937 cultures). Also active in human whole blood assays in the presence human & bovine serum proteins (IC₅₀ = 26.7 nM against cellular C₁₇-S1P formation from exogenously added 20 μM C₁₇-sphingosine in 10 min with 30 min drug preincubation).

Биохимия/физиол Действия

PF-543 hydrochloride is a novel, cell-permeable, potent and selective inhibitor of sphingosine kinase-1 (SphK1). PF-543 inhibits SphK1 with a Ki of 3.6 nM, is sphingosine competitive and is more than 100-fold selective for SphK1 over the SphK2 isoform. PF-543 decreased the level of endogenous S1P by 10-fold with proportional increase of the level of sphingosine.