Human FAD-dependent NAD(P)H diaphorase

Edwards, Yvonne H.; Potter, Jon; Hopkinson, D. A.

doi:10.1042/bj1870429

Cited by 73 publications

(37 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In 1980, Edwards et al, showed that NQOl was lacking in 4% of a British population (Edwards et al, 1980). We characterized a point mutation in the BE colon carcinoma cell line that led to a loss of enzymatic activity consistent with the absence of enzymatic activity observed in the previous studies (Traver et al, 1992).…”

supporting

confidence: 53%

Characterization of a polymorphism in NAD(P)H: quinone oxidoreductase (DT-diaphorase)

Traver

Siegel²,

Beall³

et al. 1997

Br J Cancer

282

174

View full text Add to dashboard Cite

Summary NAD(P)H:quinone oxidoreductase (NQO1, EC 1.6.99.2) is an obligate two-electron reductase that can either bioactivate or detoxify quinones and has been proposed to play an important role in chemoprevention. We have previously characterized a homozygous point mutation in the BE human colon carcinoma cell line that leads to a loss of NOO1 activity. Sequence analysis showed that this mutation was at position 609 of the NQO1 cDNA, conferring a proline to serine substitution at position 187 of the NQO1 enzyme. Using polymerase chain reaction (PCR) analysis, we have found that the H596 human non-small-cell lung cancer (NSCLC) cell line has elevated NQO1 mRNA, but no detectable enzyme activity. Sequencing of the coding region of NQO1 from the H596 cells showed the presence of the identical homozygous point mutation present in the BE cell line. Expression and purification of recombinant wild-type and mutant protein from E. coli showed that mutant protein could be detected using immunoblot analysis and had 2% of the enzymatic activity of the wild-type protein. PCR and Northern blot analysis showed moderate to low levels of expression of the correctly sized transcript in the mutant cells. Immunoblot analysis also revealed that recombinant mutant protein was immunoreactive; however, the mutant protein was not detected in the cytosol of either BE or H596 cells, suggesting that the mutant proteins were either not translated or were rapidly degraded. The absence of any detectable, active protein, therefore, appears to be responsible for the lack of NQO1 activity in cells homozygous for the mutation. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis for the mutation at position 609 conducted on 90 human lung tissue samples (45 matched sets of tumour and uninvolved tissue) revealed a 7% incidence of individuals homozygous for the mutation, and 42% heterozygous for the mutation. These data suggest that the mutation at position 609 represents a polymorphism in an important xenobiotic metabolizing enzyme, which has implications for cancer therapy, chemoprevention and chemoprotection.

show abstract

supporting

confidence: 53%

Characterization of a polymorphism in NAD(P)H: quinone oxidoreductase (DT-diaphorase)

Traver

Siegel²,

Beall³

et al. 1997

Br J Cancer

282

174

View full text Add to dashboard Cite

show abstract

“…In tumour tissue from patient 3, higher protein expression than activity was measured. There is little information available on substrate specificities of the different forms of NQOs; the NQO2-encoded protein is 43 amino acids shorter at the carboxy terminal end, and several authors have suggested distinct affinities of diaphorases (NQOs) for the metabolism of several substrates, including menadione (Edwards et al, 1980; Segura-Aguilar and Lind, 1987). The NQO2 cDNA-encoded protein was found to be 50-fold to 100-fold less active at reducing the menadione readily metabolized by NQOl protein (Jaiswal et al, 1990), so we cannot discard the theory that patient 3 had this isoenzyme.…”

Section: Resultsmentioning

confidence: 99%

DT-diaphorase and cytochrome B5 reductase in human lung and breast tumours

Marín

Ceráin²,

Hamilton³

et al. 1997

Br J Cancer

100

View full text Add to dashboard Cite

Summary The level of expression of enzymes that can activate or detoxify bioreductive agents within tumours has emerged as an important feature in the development of these anti-tumour compounds. The levels of two such reductase enzymes have been determined in 19 human non-small-cell lung tumours and 20 human breast tumours, together with the corresponding normal tissue. DT-diaphorase (DTD) enzyme levels (both expression and activity) were determined in these samples. Cytochrome b5 reductase (Cytb5R) activity was also assessed. With the exception of six patients, the levels of DTD activity were below 45 nmol min-1 mg-' in the normal tissues assayed. DTD tumour activity was extremely variable, distinguishing two different groups of patients, one with DTD activity above 79 nmol min-1 mg-1 and the other with levels that were in the same range as found for the normal tissues. In 53% of the lung tumour samples, DTD activity was increased with respect to the normal tissue by a factor of 2.-90.3 (range 79-965 nmol min-1 mg-1). In 70% of the breast tumour samples, DTD activity was over 80 nmol min-1 mg-1 (range 83-267 nmol min-' mg-'). DTD expression measured by Western blot correlated well with the enzyme activity measured in both tumour and normal tissues. The levels of the other reductase enzyme, Cytb5R, were not as variable as those for DTD, being in the same range in both tumour and normal tissue or slightly higher in the normal tissues. The heterogeneous nature of DTD activity and expression reinforces the need to measure enzyme levels in individual patients before therapy with DTD-activated bioreductive drugs.

show abstract

“…The mutant allele frequency was 0.188, which is consistent with previous reports in whites and the Hardy-Weinberg formula, as well as the first report of null NQO1 activity in 4% of the British population. 20 Acute leukemia cases had the following distribution: 58% CC; 38% CT; 4% TT.…”

Section: Resultsmentioning

confidence: 99%

Low NAD(P)H:quinone oxidoreductase 1 activity is associated with increased risk of acute leukemia in adults

Smith

Wang

Kane

et al. 2001

Blood

130

View full text Add to dashboard Cite

NAD(P)H:quinone oxidoreductase 1 (NQO1)is an enzyme that detoxifies quinones and reduces oxidative stress. A cysteineto-threonine (C 3 T) substitution polymorphism at nucleotide 609 of the NQO1 complementary DNA (NQO1 C609T ) results in a lowering of NQO1 activity. Individuals homozygous for this mutation have no NQO1 activity, and heterozygotes have low to intermediate activity compared with people with wild type. DNA samples from 493 adult de novo acute leukemia patients and 838 matched controls were genotyped for NQO1 C609T. The majority of cases were diagnosed as acute myeloid leukemia (AML) (n ‫؍‬ 420); 67 as acute lymphoblastic leukemia (ALL); and 6 as other forms of acute leukemia. The frequency of cases with low or null NQO1 activity (heterozygote ؉ homozygous mutant) was significantly higher among total acute leukemia case subjects compared with their matched controls (odds ratio [ IntroductionClues to the etiology of leukemia may be gained through the study of genetic susceptibility in candidate genes. NAD(P)H:quinone oxidoreductase 1 (NQO1; EC 1.6.99.2), originally called DTdiaphorase, 1 is an enzyme that is able to detoxify a number of natural and synthetic compounds, including quinones and their derivatives. 2,3 It is induced by synthetic antioxidants and cruciferous vegetables 4,5 and protects cells against oxidative stress.A single nucleotide polymorphism (cysteine-to-threonine, [C 3 T]) at position 609 in the NQO1 gene has been identified in a human colon cancer cell line with very low NQO1 activity. 6 This variant produces a proline-to-serine substitution that inactivates the enzyme. People who are homozygous for the variant allele completely lack NQO1 activity, and heterozygotes have low to intermediate activity compared with people with the wild type. 7 The incidence of the polymorphism varies widely by race, 8 and associations have been made between the presence of variant alleles and lung and urological cancers. [9][10][11] Evidence that the NQO1 variant allele may be significantly overrepresented in therapy-related myeloid leukemias and in those with specific chromosome aberrations has been recently presented. 12 In addition, it has been reported that infant leukemias with MLL gene rearrangements have a significantly increased frequency of the NQO1 C609T allele. 13 The NQO1 C609T polymorphism has also been shown to be associated with a greater risk of leukopenia (low white blood cell counts) in benzene-exposed individuals. 14 Lack of, or low, NQO1 activity may therefore predispose individuals exposed to chemotherapy drugs and benzene to a greater risk of leukemia. These studies led us to ask whether low NQO1 activity may play a role in the etiology of adult acute leukemia in the general population. In the present study, we have applied a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay to survey the distribution of mutant NQO1 alleles in white patients with de novo acute leukemia and more than 800 control subjects. Patients and methods Case-control study p...

show abstract

Human FAD-dependent NAD(P)H diaphorase

Cited by 73 publications

References 11 publications

Characterization of a polymorphism in NAD(P)H: quinone oxidoreductase (DT-diaphorase)

Characterization of a polymorphism in NAD(P)H: quinone oxidoreductase (DT-diaphorase)

DT-diaphorase and cytochrome B5 reductase in human lung and breast tumours

Low NAD(P)H:quinone oxidoreductase 1 activity is associated with increased risk of acute leukemia in adults

Contact Info

Product

Resources

About