S32826, A Nanomolar Inhibitor of Autotaxin: Discovery, Synthesis and Applications as a Pharmacological Tool

Abstract

Autotaxin catalyzes the transformation of lyso-phosphatidylcholine in lyso-phosphatidic acid (LPA). LPA is a phospholipid possessing a large panel of activity, in particular as a motility factor or as a growth signal, through its G-protein coupled seven transmembrane receptors. Indirect evidence strongly suggests that autotaxin is the main, if not the only source of circulating LPA. Because of its central role in pathologic conditions, such as oncology and diabetes/obesity, the biochemical properties of autotaxin has attracted a lot of attention, but confirmation of its role in pathology remains elusive. One way to validate and/or confirm its central role, is to find potent and selective inhibitors. A systematic screening of several thousand compounds using a colorimetric assay and taking advantage of the phosphodiesterase activity of autotaxin that requires the enzymatic site than for LPA generation, led to the discovery of a potent nanomolar inhibitor, [4-(tetradecanoylamino)benzyl]phosphonic acid (S32826). This compound was inhibitory toward the various autotaxin isoforms, using an assay measuring the [ 14 C]lyso-phosphatidylcholine conversion into [ 14 C]LPA. We also evaluated the activity of S32826 in cellular models of diabesity and oncology. Nevertheless, the poor in vivo stability and/or bioavailability of the compound did not permit to use it in animals. S32826 is the first reported inhibitor of autotaxin with an IC 50 in the nanomolar range that can be used to validate the role of autotaxin in various pathologies in cellular models.

Autotaxin protects MCF-7 breast cancer and MDA-MB-435 melanoma cells against Taxol-induced apoptosis

“…Blocking ATX activity with 1 mM of the inhibitors VPC8a202, or S32826 (Ferry et al, 2008), or heating at 70 1C abolished the protective effect of recombinant ATX. Furthermore, concentrated medium from MCF-7 cells that contained no significant ATX activity failed to provide any significant protection with LPC against Taxol-induced apoptosis (Figures 5a-c).…”

“…However, in our work, LPC alone did not antagonize Taxolinduced apoptosis unless concentrated medium from MDA-MB-435 cells or recombinant ATX was added. This protective effect was blocked by VPC8a202 and S32826, two ATX inhibitors (Cui et al, 2007;Ferry et al, 2008), or by heat inactivation of ATX activity. The MDA-MB-435 medium, compared with that produced by MCF-7 cells, contained abundant ATX.…”

Boronic acid-based inhibitor of autotaxin reveals rapid turnover of LPA in the circulation

“…Direct targeting of LPA receptors seems to be a less attractive strategy, since LPA acts on multiple receptors that show overlapping activities (2 and 6). Since the initial finding that ATX is subject to product inhibition by LPA and sphingosine 1-phosphate (S1P) (22), various synthetic phospho-and phosphonate lipids have been explored as ATX inhibitors (23)(24)(25)(26). However, such lipid inhibitors have the inherent danger of inadvertently activating downstream LPA/S1P receptors, thereby inducing the opposite of the intended effect.…”

Dendrimer Conjugate of [4-(Tetradecanoylamino)benzyl]phosphonic Acid (S32826) as an Autotaxin Inhibitor

“…One of the most potent LPA analogues described to date is S32826 (Figure 1). 18 This compound exhibited nanomolar inhibition of autotaxin in vitro and reduced the amount of LPA present in plasma and ascites ex vivo. However, when tested in vivo, no inhibition of LPA production in plasma was observed a few minutes after administration.…”

“…18 Nonetheless, S32826 offers the opportunity to develop autotaxin inhibitors lacking affinity for LPA receptors. 18 More recently there have been a number of nonlipid autotaxin inhibitors identified, of which two, HA150 and PF8380, have been shown to lower LPA levels in vivo. 19,20 However, the effect of these compounds on LPA receptors has not yet been fully investigated.…”