An Efficient Strategy for the Exploration of Specific Inhibitors of Sialyltransferases

Abstract

The characteristic changes of glycan composition detected in the process of cell transformation are often caused by the alteration of sialyltransferase (SiaT) activities, as shown in, for example, human colorectal cancer and breast carcinoma.

To develop potent inhibitors of SiaTs, a novel and efficient approach was established by combining the use of two types of cytidine monophosphate N-acetylneuraminic acid (CMP-NANA)-based compound libraries and a matrix assisted laser desorption adsorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based high-throughput screening system. “Click chemistry” between two CMP-NANA-based precursors bearing an azide group at the C-9 or C-5 position and commercially available alkynes afforded more than 70 novel compounds quickly.

Aminooxy-functionalized peptides (N ^α-((aminooxy)acetyl)tryptophanyl arginine methyl ester (aoWR) reagent) conjugated with an acceptor substrate of SiaTs enabled a high-throughput and quantitative inhibition assay of the compound libraries, using common MALDI-TOF MS equipment. It was clearly demonstrated, by using an α2,3- and an α2,6-SiaT, that the present protocol allowed for high-throughput screening, showing the inhibitory activities of newly synthesized compounds. Some compounds exhibited specific and strong inhibitory effects on α2,3-SiaT. On the other hand, interestingly, the inhibitors of α2,3-SiaT turned out to be donor substrates in the presence of α2,6-SiaT.