Inhibition of XPO-1 Mediated Nuclear Export through the Michael-Acceptor Character of Chalcones.

Marta Gargantilla,Dirk Daelemans,María-Jesús Pérez-Pérez,Maria-Jose Camarasa,José López-Fernández,Eva-Maria Priego,Leentje Persoons

doi:10.3390/ph14111131

Abstract

The nuclear export receptor exportin-1 (XPO1, CRM1) mediates the nuclear export of proteins that contain a leucine-rich nuclear export signal (NES) towards the cytoplasm. XPO1 is considered a relevant target in different human diseases, particularly in hematological malignancies, tumor resistance, inflammation, neurodegeneration and viral infections. Thus, its pharmacological inhibition is of significant therapeutic interest. The best inhibitors described so far (leptomycin B and SINE compounds) interact with XPO1 through a covalent interaction with Cys528 located in the NES-binding cleft of XPO1. Based on the well-established feature of chalcone derivatives to react with thiol groups via hetero-Michael addition reactions, we have synthesized two series of chalcones. Their capacity to react with thiol groups was tested by incubation with GSH to afford the hetero-Michael adducts that evolved backwards to the initial chalcone through a retro-Michael reaction, supporting that the covalent interaction with thiols could be reversible. The chalcone derivatives were evaluated in antiproliferative assays against a panel of cancer cell lines and as XPO1 inhibitors, and a good correlation was observed with the results obtained in both assays. Moreover, no inhibition of the cargo export was observed when the two prototype chalcones 9 and 10 were tested against a XPO1-mutated Jurkat cell line (XPO1C528S), highlighting the importance of the Cys at the NES-binding cleft for inhibition. Finally, their interaction at the molecular level at the NES-binding cleft was studied by applying the computational tool CovDock.

Highlights

IntroductionExportin-1 (XPO1, known as chromosome region maintenance 1, CRM1) is the best-characterized nuclear transporter that mediates the traffic of high molecular weight molecules (i.e., proteins or RNA) from the nucleus to the cytoplasm [1,2]
The synthesized compounds were tested for their antiproliferative activity against a panel of cancer cell lines using KPT-330 as a reference compound (Table 1)
Most of the synthesized compounds inhibited XPO1 function in a reporter cell line, and this inhibition nicely correlated with their antiproliferative activity in cell culture assays, with compounds 9, 10, 24 and 34 as the most potent

Summary

Introduction

Exportin-1 (XPO1, known as chromosome region maintenance 1, CRM1) is the best-characterized nuclear transporter that mediates the traffic of high molecular weight molecules (i.e., proteins or RNA) from the nucleus to the cytoplasm [1,2]. Exportin-1 recognizes specific leucine-rich peptide stretches, known as nuclear export signals (NES) in cargo proteins, and forms a ternary complex with RanGTP. When this exportin-RanGTP-cargo complex reaches the cytoplasm, GTP is hydrolyzed to GDP, disrupting the ternary complex and releasing the cargo [2]

Methods

Results

Conclusion