Structure‐Activity Relationship of NF023 Derivatives Binding to XIAP‐BIR1

Abstract

Inhibitors of Apoptosis Proteins (IAPs) are conserved E3‐ligases that ubiquitylate substrates to prevent apoptosis and activate the NF‐kB survival pathway, often deregulated in cancer. IAPs‐mediated regulation of NF‐kB signaling is based on the formation of protein complexes by their type‐I BIR domains. The XIAP‐BIR1 domain dimerizes to bind two TAB1 monomers, leading to downstream NF‐kB activation. Thus, impairment of XIAP‐BIR1 dimerization could represent a novel strategy to hamper cell survival in cancer. To this aim, we previously reported NF023 as a potential inhibitor of XIAP‐BIR1 dimerization. Here we present a thorough analysis of NF023 binding to XIAP‐BIR1 through biochemical, biophysical and structural data. The results obtained indicate that XIAP‐BIR1 dimerization interface is involved in NF023 binding, and that NF023 overall symmetry and the chemical features of its central moiety are essential for an efficient interaction with the protein. Such strategy provides original hints for the development of novel BIR1‐specific compounds as pro‐apoptotic agents.

Structure-based identification of a new IAP-targeting compound that induces cancer cell death inducing NF-κB pathway

“…S1 ). We demonstrated that FC2 binds to the isolated BIR1 domains of XIAP and cIAP2 in vitro with low micromolar affinity and does not interfere with the dimerization of XIAP-BIR1 [12] , [13] ( Table S3 ). We tried to obtain a 3D structure of cIAP2-BIR1 bound to FC2 (Supplemental Fig.…”

“…The cIAP2-BIR1 and XIAP-BIR1 domains were expressed and purified as already described [11] , [12] , [13] . In brief, plasmids for cIAP2-BIR1 or XIAP-BIR1 expression were used to transform Escherichia coli strain BL21-CodonPlus (DE3)-RP competent cells (Agilent®).…”

“…This remarkable common feature in XIAP- and cIAP2-BIR1 domains can be exploited to identify new classes of wide spectrum molecules for the modulation of the BIR1-mediated interactions. In this context, we already characterized the compound NF023, resulting from virtual screening of the LOPAC® library [11] , [12] , [13] . This candidate was found to disrupt cIAP2-BIR1/TRAF2 assembly and to interfere with the dimerization of XIAP-BIR1, a crucial event for activation of NF-κB.…”

Reprogramming enriches for somatic cell clones with small-scale mutations in cancer-associated genes

“…Similarly, the E3 ubiquitin-protein ligase XIAP harbors a putatively actionable mutation within its BIR1 domain, which is crucial for homodimerization with TAB1, and recruitment of TAK1, an important regulatory component of the NF-κB canonical pathway promoting cell survival (Lu et al, 2007;Sorrentino et al, 2019). Moreover, mutation in the BIR1 domain (Pfam) might reduce SMAC binding, caspase release from XIAP, and induction of cell death (Attaran- Bandarabadi et al, 2017;Lu et al, 2007).…”

Reprogramming enriches for somatic cell clones with small scale mutations in cancer-associated genes

“…Similarly, the E3 ubiquitin-protein ligase XIAP harbors a putatively actionable mutation within its BIR1 domain, which is crucial for homodimerization with TAB1, and recruitment of TAK1, an important regulatory component of the NF-κB canonical pathway promoting cell survival (Lu et al, 2007;Sorrentino et al, 2019). Moreover, mutation in the BIR1 domain (Pfam) might reduce SMAC binding, caspase release from XIAP, and induction of cell death (Attaran-Bandarabadi et al, 2017;Lu et al, 2007).…”