Abstract 16349: A Novel Class of Inhibitors That Are Specific to Human NPP1 Prevent Pathologic Mineralization of Valve Interstitial Cells

Abstract

BACKGROUND: Ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) is an ectoenzyme, which plays a role into several disorders including calcific aortic valve disease (CAVD). So far, compounds that have been developed as inhibitors of NPP1 lack of potency and specificity. Quinazolin-4-piperidin-4-methyl sulfamide (QPS) derivatives have been described as potent inhibitors of NPP1. However, their mode of inhibition as well as their selectivity and capacity to modify biological processes have not been investigated. METHOD: We have investigated the potency and selectivity of QPS derivatives in inhibiting NPP1 by enzymatic activities. The biological effect of QPS derivatives was documented on the mineralization of valve interstitial cell cultures, apoptosis assay, as well as quantitative polymerase chain reaction. RESULTS: We documented that QPS1 derivative is a potent (67.9 ±5.3 nM) and selective non-competitive inhibitor of human NPP1. Moreover, QPS1 also significantly inhibited the K121Q NPP1 gene variant (ki 51.9±9.8 nM), which is prevalent in the general population. QPS1 did not significantly alter the activity of other nucleotide metabolising enzymes expressed at the cell surface, namely NPP3, NTPDases (1-3), ecto-5’-nucleotidase and ALP. Importantly, QPS1 in the low micromolar range (≤10μM) prevented phosphate-induced mineralization of VICs and lowered the rise of osteogenic genes as expected for NPP1 inhibition. CONCLUSION: We provide evidence that QPS1 is a potent and selective non-competitive inhibitor of NPP1 that prevents pathologic mineralization in a cellular model.