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

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.

Pooled multicolour tagging for visualizing subcellular protein dynamics

“…Here, we identify a set of compounds that show similar behaviour in vpCell pools to the known exportin inhibitors selinexor, verdinexor and leptomycin B. One class of these compounds (exemplified by Z346481166, Z362571812 and Z608351286) strongly resembles Michael acceptors, previously described as covalent XPO1 inhibitors 50 . Notably, only the most potent of these compounds also leads to nuclear accumulation of XPO1 cargo proteins, and also only at later time points when XPO1 is already degraded and its antiproliferative effect is independent of the selinexor resistance mutation XPO1 C528S .…”

Chalcone: A Promising Bioactive Scaffold in Medicinal Chemistry

“…Furthermore, heterocyclic chalcones ( 173, 175, 176, 181 , and 184 ) showed lower to larger IC 50 values, and chalcones with extended hetero functionality ( 177, 178, 179, 182, 183, and 186 ) were found to be the best in the broad-spectrum cancer cell lines, as indicated in the table. Moreover, chalcones with nitrogen- and sulfur-containing heterocycles and with methoxy substitutions have been reported to be active against microbes, leukemia, prostate cancer, and colon cancer [ 218 , 219 , 220 , 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 , 229 , 230 , 231 , 232 , 233 , 234 , 235 ].…”

Identification of Novel Covalent XPO1 Inhibitors Based on a Hybrid Virtual Screening Strategy

“…Since there is no protein-based evaluation model for XPO1, researchers commonly use a model based on MM.1S survival to evaluate the activity of XPO1 inhibitors [39]. The selected compounds were subjected to an anti-proliferation test using MM.1S cells to confirm the activities of the identified compounds.…”