In Silico Screening Reveals Structurally Diverse, Nanomolar Inhibitors of NQO2 That Are Functionally Active in Cells and Can Modulate NF-κB Signaling

Abstract

The National Cancer Institute chemical database has been screened using in silico docking to identify novel nanomolar inhibitors of NRH:quinone oxidoreductase 2 (NQO2). The inhibitors identified from the screen exhibit a diverse range of scaffolds and the structure of one of the inhibitors, NSC13000 cocrystalized with NQO2, has been solved. This has been used to aid the generation of a structure-activity relationship between the computationally derived binding affinity and experimentally measured enzyme inhibitory potency. Many of the compounds are functionally active as inhibitors of NQO2 in cells at nontoxic concentrations. To show this, advantage was taken of the NQO2-mediated toxicity of the chemotherapeutic drug CB1954. The toxicity of this drug is substantially reduced when the function of NQO2 is inhibited, and many of the compounds achieve this in cells at nanomolar concentrations. The NQO2 inhibitors also attenuated TNFa-mediated, NF-kB-driven transcriptional activity. The link between NQO2 and the regulation of NF-kB was confirmed by using short interfering RNA to NQO2 and by the observation that NRH, the cofactor for NQO2 enzyme activity, could regulate NF-kB activity in an NQO2-dependent manner. NF-kB is a potential therapeutic target and this study reveals an underlying mechanism that may be usable for developing new anticancer drugs.

Integrated systems‐genetic analyses reveal a network target for delaying glioma progression

“…Currently, the highest known affinity of resveratrol is toward quinone reductase NQO2 ( K d = 35 nmol/L). Inhibition of NQO2 has been shown to attenuate NF‐κB activity, which promotes tumor cell proliferation . Down‐regulation of module M2 genes and the subsequent decrease in cell division could therefore be mediated by reduced NF‐κB signaling.…”

The Unusual Cosubstrate Specificity of NQO2: Conservation Throughout the Amniotes and Implications for Cellular Function

“…Cell culture media was supplemented with 100 units/mL penicillin and 0.1 mg/ml streptomycin. To assess the ability of NQO2 to catalyze redox reactions in cells, activation of CB1954 by NRH was used as a reporter of NQO2 activity ( Nolan et al, 2012 ). HCT116 or HCT116ΔNQO2 cells were seeded at 1,000 cells per well in 96-well plates and were allowed to attach overnight.…”

Molecular Pharmacology of NRH:Quinone Oxidoreductase 2: A Detoxifying Enzyme Acting as an Undercover Toxifying Enzyme

“…In addition, strong binding and selectivity for NQO2 likely depend on both the size of the molecules and the subsequent interactions that result (Foster et al, 1999;Buryanovskyy et al, 2004;Calamini et al, 2008;Pegan et al, 2011). In addition, the crystal structures of NQO2 in complex with its inhibitors have led to the rational design and development of more potent and selective NQO2 mechanismbased inhibitors (Nolan et al, 2010a(Nolan et al, , 2012Dunstan et al, 2011). Finally, the intriguing possibility that NQO2 might work as a flavin switch that is dependent on the redox state of the cells and on the presence of certain biologically active ligands opens the possibility of a nonenzymatic role for NQO2 and implicates NQO2 in regulation of cellular signaling (Khutornenko et al, 2010;Hsieh et al, 2012;Nolan et al, 2012).…”