Selinexor

Selinexor binds to and inhibits exportin-1 (XPO1). XPO1 is a nuclear exporter protein which contains a pocket to which nuclear proteins can bind. When complexed with these proteins and Ran, activated through guanosine triphosphate (GTP) binding, the XPO1-protein-Ran-GTP complex is able to exit the nucleus through a nuclear pore. Once outside, GTP is hydrolyzed and the complex dissociates. The inhibition of this process in cancer cells allows the targets of XPO1, many of which are tumor suppressors, to collect in the nucleus and result in increased transcription of tumor suppressor genes. Tumor suppressor proteins known to be affected by XPO1 inhibition include p53, p73, adenomatous polyposis coli, retinoblastoma, forkhead box protein O, breast cancer 1, nucleophosmin, and merlin. Regulators of cell cycle progression are also affected, namely p21, p27, galectin-3, and Tob. Inhibitor of NFκB also collects in the nucleus as a result leading to reduced activity of NFκB, a known contributor to cancer. XPO1 participates in the formation of a complex with eukaryotic initiation factor 4E and contributes to the transport of messenger RNA for several oncegenes including cell cycle promotors, cyclin D1, cyclin E, and CDK2/4/6, as well as antiapoptotic proteins, Mcl-1 and Bcl-xL. These wide ranging changes in protein expression and gene transcription culminate in cell cycle arrest and the promotion of apoptosis in cancer cells.