A method for quantification of exportin-1 (XPO1) occupancy by Selective Inhibitor of Nuclear Export (SINE) compounds
Selective Inhibitor of Nuclear Export (SINE) compounds really are a group of small-molecules that hinder nuclear export through covalent binding to cysteine 528 (Cys528) within the cargo-binding pocket of Exportin 1 (XPO1/CRM1) and promote cancer cell dying. Selinexor may be the lead SINE compound presently in phase I and II numerous studies for advanced solid and hematological malignancies. In order to understand selinexor-XPO1 interaction and also to establish whether cancer cell fact is the purpose of drug-target engagement, we created a quantitative XPO1 occupancy assay. Biotinylated leptomycin B (b-LMB) was applied like a tool compound to determine SINE-free XPO1. Binding to XPO1 was quantitated from SINE compound treated adherent and suspension cells in vitro, dosed ex vivo human peripheral bloodstream mononuclear cells (PBMCs), and PBMCs from rodents dosed orally with Verdinexor drug in vivo. Look at a panel of selinexor sensitive and resistant cell lines says resistance wasn’t related to XPO1 occupancy by selinexor. Administration of merely one dose of selinexor bound XPO1 for minimally 72 hrs in vitro as well as in vivo. While XPO1 inhibition directly correlates with selinexor pharmacokinetics, the biological results of this inhibition depends upon modulation of pathways downstream of XPO1, which ultimately determines cancer cell responsiveness.