NAD(P)H:Quinone Oxidoreductase 1 and NRH:Quinone Oxidoreductase 2 Activity and Expression in Bladder and Ovarian Cancer and Lower NRH:Quinone Oxidoreductase 2 Activity Associated with an NQO2 Exon 3 Single-Nucleotide Polymorphism

Abstract

Purpose: NRH:quinone oxidoreductase 2 (NQO2) is a homologue of NAD(P)H:quinone oxidoreductase 1 (NQO1). Despite 54% homology with human NQO1, NQO2 has little endogenous enzymatic activity. However, NQO2 has potential as a therapeutic target because the addition of the nonbiogenic electron donor dihydronicotinamide riboside (NRH) selectively potentiates the bioactivation of the alkylating agent tretazicar (CB 1954). The NQO activity of ovarian and bladder tumors was determined and the effect of NQO polymorphisms on NQO activity was investigated. Experimental Design: Intraperitoneal ovarian metastases and bladder tumor clinical samples were analyzed for NQO1and NQO2 activity, mRNA expression by semiquantitative reverse transcription-PCR, and genotype by RFLP analysis. Results: NQO1activity was higher in the bladder cohort than in the ovarian cohort (0-283 and 0-30 nmol/min/mg, respectively; P < 0.0001). In contrast, NQO2 activity was higher in the ovarian tissue than in the bladder samples (0.15-2.27 and 0-1.14 nmol/min/mg, respectively; P = 0.0004). In both cohorts, the NQO1C609T single-nucleotide polymorphism (SNP) was associated with f7-fold lower NQO1activity. The NQO2 exon 3 T14055C SNP was associated with lower NQO2 activity relative to wild-type [median values of 0.18 and 0.37 nmol/min/mg in the bladder samples (P = 0.007) and 0.82 and1.16 nmol/min/mgin the ovarian cohort (P = 0.034)]. Conclusion: This is the first observation reporting an apparent association between an NQO2 exon 3 SNP and lower enzymatic activity. The high NQO2 activity of intraperitoneal ovarian metastases relative to other tissues indicates a potential for tretazicar therapy in the treatment of this disease. In contrast, the low level of NQO1 activity and expression relative to other tissues suggests that NQO1-directed therapies would not be appropriate. NAD(P)H:quinone oxidoreductase 1 (NQO1, EC 1.6.5.2) is a quinone reductase implicated in protection against carcinogenesis and exploited in cancer chemotherapy (1). NRH:quinone oxidoreductase 2 (NQO2, EC 1.10.99.2) is a homologue of the more fully characterized NQO1 (2). Whereas the two proteins retain similar substrate specificities, structural differences result in differences in affinity for electron donating cofactors. NQO1 can use either NADH or NADPH. In contrast, NQO2 can use neither NADH nor NADPH efficiently and instead requires the nonbiogenic compound dihydronicotinamide riboside (NRH) or related molecules to reveal what can be considered a latent enzymatic activity (3). Both proteins have also been implicated in stabilization of p53 (4, 5) and, in the case of NQO1, this has been shown to result from a direct protein:protein interaction (6).Polymorphisms have been described for both NQO1 and NQO2. A well-characterized single-nucleotide polymorphism (SNP) in the NQO1 gene (C609T) results in a proline to serine substitution and ubiquitination with rapid degradation of the variant protein (7). Numerous polymorphisms have been reported in NQO2, mostly in the promoter reg...

Sulforaphane and α-Lipoic Acid Upregulate the Expression of the π Class of Glutathione S-Transferase through c-Jun and Nrf2 Activation

“…The ethacrynate-glutathione conjugate formed was measured at 270 nm. The GST activity was measured with 1-chloro-2,4dinitrobenzene, whereas NQO-1 activity was determined using 2,6dichloroindophenol as the substrate (33).…”

The NQO1 rs1800566 Polymorphism and Risk of Bladder Cancer: Evidence from 6,169 Subjects

“…After further retrieved, 12 articles were excluded because of the following reasons: three were for review or meta-analysis articles (Gonzalez, 1997;Chao et al, 2006;Ersoy Tunali et al, 2011); one did not focus on the NQO1 rs1800566 polymorphism but on NQO2 (exon 3, T14055C) polymorphism (Wen et al, 2009); two were for the correlation between the NQO1 rs1800566 polymorphism and NQO1 activity (Basu et al, 2004;Jamieson et al, 2007); two were for the correlation between the NQO1 rs1800566 polymorphism and p53 mutations (Martone et al, 2000;Ryk et al, 2006); one was for the correlation between the NQO1 rs1800566 polymorphism and clinical course of bladder cancer (Sanyal et al, 2007); Three studies did not report gene frequencies (Vineis et al, 2007;Dhaini et al, 2012;Ersoy Tunali et al, 2012). Therefore, 12 studies (Schulz et al, 1997;Choi et al, 2003;Park et al, 2003;Hung et al, 2004;Moore et al, 2004;Sanyal et al, 2004;Broberg et al, 2005;Terry et al, 2005;Figueroa et al, 2008;Wang et al, 2008;Paonessa et al, 2009;Pandith et al, 2011) were included in our meta-analysis.…”

Population study of genetic polymorphisms and superficial bladder cancer risk in Han-Chinese smokers in Shanghai

“…The NQO2 exon 3 T14055C SNP was associated with lower NQO2 activity relative to wild-type in bladder samples. There are no observations reporting an apparent association between an NQO2 exon 3 SNP and superficial bladder cancer risk [26,27].…”