Abstract

NAD(P)H:quinone oxidoreductase (NQO1) converts benzene-derived quinones to less toxic hydroquinones and has been implicated in benzene-associated hematotoxicity. A point mutation in codon 187 (Pro to Ser) results in complete loss of enzyme activity in homozygous subjects, whereas those with 2 wild-type alleles have normal activity. The frequency of homozygosity for the mutant allele among Caucasians and African Americans is 4% to 5% but is higher in Hispanics and Asians. Using an unambiguous polymerase chain reaction (PCR) method, we assayed nonmalignant lymphoblastoid cell lines derived from 104 patients with myeloid leukemias; 56 had therapy-related acute myeloid leukemia (t-AML), 30 had a primary myelodysplastic syndrome (MDS), 9 had AML de novo, and 9 had chronic myelogenous leukemia (CML). All patients had their leukemia cells karyotyped. Eleven percent of the t-AML patients were homozygous and 41% were heterozygous for the NQO1 polymorphism; these proportions were significantly higher than those expected in a population of the same ethnic mix (P = .036). Of the 45 leukemia patients who had clonal abnormalities of chromosomes 5 and/or 7, 7 (16%) were homozygous for the inactivating polymorphism, 17 (38%) were heterozygous, and 21 (47%) had 2 wild-type alleles for NQO1. Thus, NQO1 mutations were significantly increased compared with the expected proportions: 5%, 34%, and 61%, respectively (P= .002). An abnormal chromosome no. 5 or 7 was observed in 7 of 8 (88%) homozygotes, 17 of 45 (38%) heterozygotes, and 21 of 51 (41%) patients with 2 wild-type alleles. Among 33 patients with balanced translocations [14 involving bands 11q23 or 21q22, 10 with inv(16) or t(15;17), and 9 with t(9;22)], there were no homozygotes, 15 (45%) heterozygotes, and 18 (55%) with 2 wild-type alleles. Whereas fewer than 3 homozygotes were expected among the 56 t-AML patients, 6 were observed; 19 heterozygotes were expected, but 23 were observed. The gene frequency for the inactivating polymorphism (0.31) was increased approximately 1.4-fold among the 56 t-AML patients. This increase was observed within each of the following overlapping cohorts of t-AML patients: the 43 who had received an alkylating agent, the 27 who had received a topoisomerase II inhibitor, and the 37 who had received any radiotherapy. Thus, the frequency of an inactivating polymorphism in NQO1 appears to be increased in this cohort of myeloid leukemias, especially among those with t-AML or an abnormality of chromosomes 5 and/or 7. Homozygotes and heterozygotes (who are at risk for treatment-induced mutation or loss of the remaining wild-type allele in their hematopoietic stem cells) may be particularly vulnerable to leukemogenic changes induced by carcinogens.

THE WIDESPREAD USE of intensive combination chemotherapy regimens and megavoltage radiation therapy has resulted in steadily improving long-term survival among patients in whom cancer had previously been fatal. This therapeutic success has led to the survival of large numbers of patients who formerly were destined to die within a few years. One of the most serious consequences of cancer therapy is the development of a second cancer, especially myeloid leukemia. Therapy-related acute myeloid leukemia (t-AML) is a neoplastic hematopoietic disorder arising in most cases from a multipotent stem cell and, in a few cases, from a lineage-committed progenitor.1 The term therapy-related leukemia is descriptive and is based on a patient’s history of exposure to cytotoxic agents. Although a causal relationship is implied, the mechanism of this remains to be proven. This term may ultimately be too restrictive, because the leukemias that develop after exposure to benzene or to atomic bomb irradiation are very similar or identical to the therapy-related leukemia syndrome.2 

It has been known for many years that benzene causes hematotoxicity and is also associated with AML.2-7 Many clinical reports suggest that individuals vary greatly in their susceptibility to adverse health outcomes from benzene exposure. One explanation for this diversity is interindividual variation in metabolic activation and detoxification of benzene in humans.8,9 

Benzene is metabolized by the hepatic enzyme cytochrome P4502E1 (CYP2E1) to benzene oxide, which spontaneously forms phenol and is itself further metabolized by CYP2E1 to hydroquinone.9Hydroquinone and related hydroxy metabolites are converted in the bone marrow by myeloperoxidase to benzoquinones.10,11 These latter compounds are potent hematotoxins and genotoxins that can be converted by the enzyme NAD(P)H:quinone oxidoreductase (NQO1) to less toxic hydroxy metabolites. It has recently been shown in a case-control study of benzene-poisoned workers in Shanghai, China that lack of NQO1 enzyme activity was associated with benzene poisoning, leading to hematotoxicity.9 

NQO1 encodes an enzyme also known as DT-diaphorase. This enzyme is a dimeric flavin adenine dinucleotide (FAD)-containing cytosolic protein that catalyzes the 2 electron reduction of a variety of quinone compounds.12 The reduction of the quinone moiety to a hydroquinone prevents the generation of free radicals and reactive oxygen species, thus protecting cells from oxidative damage. However, the NQO1 enzyme also functions as a mechanism for the reduction and ultimate activation of certain chemotherapeutic drugs and of environmental carcinogens such as nitroaromatic compounds, heterocyclic amines, and possibly cigarette smoke condensate.13-17 

The NQO1 gene locus maps to chromosome band 16q23. A polymorphism exists due to a C→T substitution at nucleotide 609 in the cDNA, giving rise to a missense mutation in codon 187 (proline-serine).16-19 Among Northern Europeans and Caucasian Americans, the gene frequency is 0.79 for the wild-type allele and 0.21 for the mutated allele.17,20-22 The frequency of the mutated allele is known to be slightly higher among African Americans and considerably higher among Hispanics and Asians.9,17,22 NQO1 enzyme activity is normal in individuals with 2 wild-type alleles. It is variably reduced in individuals who are heterozygotes for the polymorphism.19The NQO1 protein and activity are absent in those who are homozygous for the point mutation.20 

We have been interested in trying to understand whether the development of therapy-related leukemia is a stochastic process (occurring by chance) or whether it is idiosyncratic, ie, whether certain individuals are at greater risk.1,23-25 The majority of t-AML cases are associated with alkylating agents or radiotherapy and are characterized by a median latency of 5 to 7 years, trilineage hematopoietic dysplasia, and the loss or deletion of chromosomes 5 and/or 7.1,26 Similar features are thought to characterize benzene-associated AML.5,27 A smaller proportion of cases is associated with exposure to topoisomerase-II–inhibiting drugs, suggesting a different mechanism of leukemogenesis.1,28,29These cases are characterized by a shorter latency, a monocytic phenotype, and balanced translocations involving the MLL gene at chromosome band 11q23 or the AML1 gene at band 21q22.

Our hypothesis is that the frequency of the 609C→T base substitution that results in an inactivating polymorphism in the NQO1 gene differs between different subgroups of patients with AML and will be greatest in those patients who develop t-AML after chemotherapy and in those with abnormalities of chromosomes 5 or 7.

MATERIALS AND METHODS

Patients with various myeloid leukemias gave informed consent for collection of blood and bone marrow specimens for this research. To perform this study, karyotypes were prepared by cytogenetic analysis on pretreatment bone marrow cells from leukemia patients using previously described methods.30 Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines were established from peripheral blood B lymphocytes from the same leukemia patients and provided the DNA from nonmalignant cells.31 Polymerase chain reaction (PCR) primers were used to amplify DNA from exon 6 of the NQO1 gene. Restriction enzyme digestion with Hinf1 gave 3 possible patterns of bands: a 271-bp band in those patients who were wild-type homozygotes; 3 bands of 271, 151, and 120 bp in heterozygotes; and 2 bands of 151 and 120 bp in patients who were homozygous for the mutation.

DNA was isolated using conventional methods. The DNA was PCR-amplified by the method developed by Eickelmann et al,32 with the following modifications. The sense primer NQO1 F (5′-AAG CCC AGA CCA ACT TCT-3′) and antisense primer DT-2 (5′-TCT CCT CAT CCT GTA CCT CT-3′) amplified a 304-bp region, including the NQO1 polymorphism, using a hot start protocol. DNA (1.5 μL; 0.1 to 0.5 μg), 25 pmol of each primer, 50 mmol/L KCl, 10 mmol/L Tris-HCl (pH 8.3), 2.5 pmol of each dNTP, 5% dimethyl sulfoxide (DMSO), and 2.5 U Taq polymerase in a total volume of 50 μL were subjected to 40 cycles (94°C for 50 seconds, 52°C for 50 seconds, and 72°C for 30 seconds) followed by an extension at 72°C for 10 minutes. The PCR products were electrophoresed in 2% agarose.

A nested PCR method was used if regular PCR failed. The DNA was first PCR amplified with the sense primer NQO1 454A (5′-GAG ACG CTA GCT CTG AAC TGA T-3′) and antisense primer NQO1 454B (5′-GGA AAT CCA GGC TAA GGA AT-3′). DNA (0.1 μL; 10 ng/μL), 25 pmol of each primer, 50 mmol/L KCl, 10 mmol/L Tris-HCl (pH 8.3), 2.5 pmol of each dNTP, and 2.5 U Taq polymerase in a total volume of 50 μL were subjected to 35 cycles (94°C for 30 seconds and 58°C for 30 seconds). A second nested PCR using 1 μL of the first PCR product was performed with the same reagents and primers NQO1 F and DT-2 as described above.

PCR products were ethanol precipitated and digested with 10 UHinf1 enzyme at 37°C for 2 hours or overnight. The digestion was stopped by heating to 65°C for 5 minutes.

The polymorphism was detected on an 8% polyacrylamide gel. Undigested DNA was 304 bp. One Hinf I restriction site cuts a 33-bp fragment in all samples, acting as a digestion control. The restriction site polymorphism is a second HinfI site and results in three different combinations of bands: only one band of 271 bp corresponding to the genotype of homozygotes for the wild-type allele (C/C); three bands with 271, 151, and 120 bp in length corresponding to the genotype of heterozygotes (C/T); and two bands with 151 and 120 bp in length, corresponding to the genotype of homozygotes for the mutant allele (T/T).

Statistical considerations.

It should be kept in mind that this is a selected series of patients. That is, the 104 patients who were studied all had myeloid leukemia, were referred for evaluation to the University of Chicago, provided a sample of blood or bone marrow, were successfully karyotyped, and had an EBV-transformed lymphoblastoid cell line successfully generated. Cell lines were selected for analysis for the NQO1 polymorphism based on the knowledge of the clinical diagnosis and the karyotype. Prospective unselected studies will be needed to validate the observations described herein.

The following allele frequencies for the NQO1 polymorphism within different ethnic groups were used: Caucasian, 0.21; African American, 0.23; Hispanic, 0.39; and Asian, 0.45.9,17,20-22 The expected values for the control group that we used for calculating statistical significance were taken from the literature involving different (although ethnically similar) populations. Conclusions based on prevalence estimates drawn from such external populations are less reliable. The χ2 distribution was used to test for statistical significance between the observed frequencies of the NQO1 polymorphism and the frequencies expected in a population with the same ethnic mix.

RESULTS

We studied 104 patients with myeloid leukemias. Their characteristics are shown in Table 1. Fifty-six had developed t-AML after treatment with cytotoxic drugs or radiotherapy. The other 48 patients had primary myelodysplastic syndrome (MDS; 30 patients), AML de novo (9 patients), or chronic myelogenous leukemia (CML; 9 patients).

Table 1.

Characteristics of 104 Patients With Myeloid Leukemias

No. (%) of Patients
TotalPrimary Leukemia t-AML
Sex  
 Male  52 (50) 26 (54)  26 (46)  
 Female  52 (50)  22 (46) 30 (54)  
Race  
 Caucasian  82 (79)  36 (75) 46 (82)  
 African American  17 (16)  8 (17) 9 (16)  
 Hispanic  3 (3)  2 (4)  1 (2)  
 Asian 2 (2)  2 (4)  0   
Leukemia  
 t-AML  56  
 Primary MDS  30   
 AML de novo  9   
 CML 9  
No. (%) of Patients
TotalPrimary Leukemia t-AML
Sex  
 Male  52 (50) 26 (54)  26 (46)  
 Female  52 (50)  22 (46) 30 (54)  
Race  
 Caucasian  82 (79)  36 (75) 46 (82)  
 African American  17 (16)  8 (17) 9 (16)  
 Hispanic  3 (3)  2 (4)  1 (2)  
 Asian 2 (2)  2 (4)  0   
Leukemia  
 t-AML  56  
 Primary MDS  30   
 AML de novo  9   
 CML 9  

The frequencies with which the NQO1 polymorphism was detected in 48 patients with primary MDS, AML de novo, or CML are compared with that for the 56 patients with t-AML in Table 2. Also shown are the expected frequencies of NQO1 polymorphism for a population with the same racial and ethnic composition as these 104 patients. Thus, we would expect that approximately 61% of our entire cohort would have 2 wild-type alleles, 34% would be heterozygotes, and 5% would be homozygous for the mutation. We found that the frequency of homozygous mutants was 4% among the primary leukemia patients and 11% among those with t-AML. Heterozygotes were also more common among both types of leukemia patients than expected in the general population. The frequency of the NQO1 polymorphism was significantly increased among all 104 patients (P = .050) and among the 56 patients with t-AML (P = .036) compared with the frequency expected. The allele frequency for the polymorphism observed among the t-AML patients was increased approximately 1.4-fold over that expected.

Table 2.

Frequency of the NQO1 Polymorphism in Primary and Therapy-Related Myeloid Leukemia

Diagnosis No. of PatientsNo. (%) of Patients With P
Wild-type Alleles Heterozygous MutationHomozygous Mutation
Primary MDS, AML de novo,  or CML 
 Observed  48  24 (50)  22 (46) 2 (4) .27   
 Expected*  28.56 16.72  2.72  
t-AML  
 Observed  56  27 (48) 23 (41)  6 (11)  .036  
 Expected  34.42  18.93  2.66  
Total  
 Observed  104 51 (49)  45 (43)  8 (8) .050 
 Expected   62.98  35.65  5.38 
Diagnosis No. of PatientsNo. (%) of Patients With P
Wild-type Alleles Heterozygous MutationHomozygous Mutation
Primary MDS, AML de novo,  or CML 
 Observed  48  24 (50)  22 (46) 2 (4) .27   
 Expected*  28.56 16.72  2.72  
t-AML  
 Observed  56  27 (48) 23 (41)  6 (11)  .036  
 Expected  34.42  18.93  2.66  
Total  
 Observed  104 51 (49)  45 (43)  8 (8) .050 
 Expected   62.98  35.65  5.38 
*

Calculated from the frequency of the polymorphism reported within different ethnic groups and the racial composition of the observed group (see Materials and Methods).

The median age at the time of first exposure to cytotoxic therapy for the 27 t-AML patients with wild-type alleles was 48 years (range, 11 to 73 years). The median age for the 23 t-AML patients with heterozygosity was 51 years (range, 7 to 82 years) and for the 6 t-AML patients who were homozygous for the NQO1 polymorphism was 52 years (range, 32 to 69 years).

In Table 3 are shown the specific cytogenetic rearrangements detected in the leukemia cells from these patients and the observed frequency of NQO1 polymorphism within each subgroup. Of the 13 patients with an abnormality of chromosome 5, 23% were homozygous for the mutation. Of the 16 with an abnormality of chromosome 7, 19% were homozygous, 56% were heterozygous, and only 25% had 2 wild-type alleles. An additional 16 patients had abnormalities of both chromosomes 5 and 7, and 1 (6%) of these was homozygous and 6 (38%) were heterozygous. There were no homozygous mutants among the 33 patients with a balanced translocation involving bands 11q23, or 21q22, or an inv(16), t(15;17), or t(9;22). Fourteen patients had other clonal abnormalities, and 15 patients had a normal karyotype.

Table 3.

Specific Clonal Cytogenetic Rearrangements and the NQO1 Polymorphism

Cytogenetics No. of PatientsNo. (%) of Patients With
Wild-type AllelesHeterozygous Mutation Homozygous Mutation
Abnormal no. 5  13  8 (62)  2 (15)  3 (23)  
Abnormal no. 7 16  4 (25)  9 (56)  3 (19)  
Abnormal no. 5 & 7 16  9 (56)  6 (38)  1 (6)  
t(11q23) or t(21q22) 14  10 (71)  4 (29)  0   
inv(16) or t(15;17)  10 3 (30)  7 (70)  0   
t(9;22)  9  5 (56) 4 (44)  0   
Other abnormality  14  6 (43) 8 (57)  0   
Normal  15  8 (53)  6 (40) 1 (5)  
Total numbers  1073-150 53 (50)  46 (43) 8 (7) 
Cytogenetics No. of PatientsNo. (%) of Patients With
Wild-type AllelesHeterozygous Mutation Homozygous Mutation
Abnormal no. 5  13  8 (62)  2 (15)  3 (23)  
Abnormal no. 7 16  4 (25)  9 (56)  3 (19)  
Abnormal no. 5 & 7 16  9 (56)  6 (38)  1 (6)  
t(11q23) or t(21q22) 14  10 (71)  4 (29)  0   
inv(16) or t(15;17)  10 3 (30)  7 (70)  0   
t(9;22)  9  5 (56) 4 (44)  0   
Other abnormality  14  6 (43) 8 (57)  0   
Normal  15  8 (53)  6 (40) 1 (5)  
Total numbers  1073-150 53 (50)  46 (43) 8 (7) 
F3-150

Three of the 104 patients had complex karyotypes with 2 recurring abnormalities, and each is included twice in this table. Two had wild-type alleles for NQO1: an Hispanic man with t-AML had del(5q) and t(3;21), and a Caucasian woman with AML after MDS had abnormalities of no. 5 and 7 and t(11;16)(q23;p13). One patient was heterozygous for the NQO1 polymorphism: a Caucasian man with AML de novo had inv(16) and t(11;21)(q13;q22).

In Table 4, the 45 patients with clonal abnormalities of chromosomes 5 or 7 or both are examined more closely. Thirty-six (80%) were Caucasian, 8 (18%) African American, and 1 (2%) was Hispanic. Forty-seven percent were observed to have 2 wild-type alleles, whereas 61% were expected. Thirty-eight percent were heterozygotes, whereas 34% were expected. Sixteen percent had 2 mutant alleles and, therefore, likely had no enzyme activity; only 5% were expected (P = .002). The mutant allele frequency was calculated to be 0.34 among these 45 patients, and this was increased approximately 1.6-fold over what was expected. In contrast, among the 33 leukemia patients with balanced translocations, the mutant allele frequency was 0.23, or approximately what would be expected in the general population.

Table 4.

Frequency of the NQO1 Polymorphism in 45 Primary and Therapy-Related Myeloid Leukemia Patients With Clonal Abnormalities of Chromosomes 5 and/or 7

NQO1 Genes No. Observed (%) No. Expected (%)P
2 Wild-type alleles  21 (47)  27.58 (61) 
Heterozygous  17 (38)  15.25 (34)  .002  
Homozygous 7 (16)  2.16 (5) 
NQO1 Genes No. Observed (%) No. Expected (%)P
2 Wild-type alleles  21 (47)  27.58 (61) 
Heterozygous  17 (38)  15.25 (34)  .002  
Homozygous 7 (16)  2.16 (5) 

The observed frequency of the mutant allele (0.34) was increased approximately 1.6-fold within this group of 45 patients (P = .002). Among 33 patients with balanced translocations, the mutant allele frequency was 0.23, approximately what would be expected.

We also analyzed our data to see if the frequency of NQO1 polymorphism correlated with the primary treatment that had been received by these 56 t-AML patients. This was made difficult by the fact that most of our patients had received multiple chemotherapy agents in various combinations or together with radiation therapy. We grouped patients according to their exposures to alkylating agents, topoisomerase II inhibitors, antimetabolites, antitubulin drugs (principally vinca alkaloids), and radiotherapy (Table 5). In most categories, the frequency of the NQO1 polymorphism was higher than expected but not markedly so. For example, among the 43 patients who had received an alkylating agent, the frequencies of both heterozygous and homozygous mutations were increased over the number expected.

Table 5.

The Frequency of the NQO1 Polymorphism in 56 t-AML Patients According to Their Primary Cytotoxic Treatment

No. of Patients5-150No. of Patients With
Wild-Type AllelesHeterozygous Mutation Homozygous Mutation
Observed Expected Observed ExpectedObserved Expected
Alkylating agents  43  21  26.23 17  14.62  5  2.06  
Topo II inhibitors  27  13 16.47  11  9.18  3  1.30  
Anti-metabolites  17 7  10.37  9  5.78  1  0.82  
Anti-tubulin drugs 30  15  18.30  12  10.20  3  1.44 
Radiotherapy  37  18  22.57  16  12.58  1.78  
Totals  56  27  34.42  23  18.93  2.66 
No. of Patients5-150No. of Patients With
Wild-Type AllelesHeterozygous Mutation Homozygous Mutation
Observed Expected Observed ExpectedObserved Expected
Alkylating agents  43  21  26.23 17  14.62  5  2.06  
Topo II inhibitors  27  13 16.47  11  9.18  3  1.30  
Anti-metabolites  17 7  10.37  9  5.78  1  0.82  
Anti-tubulin drugs 30  15  18.30  12  10.20  3  1.44 
Radiotherapy  37  18  22.57  16  12.58  1.78  
Totals  56  27  34.42  23  18.93  2.66 
F5-150

Patients are listed more than once if they received more than one class of drugs or radiotherapy.

DISCUSSION

Our hypothesis postulated that heterozygosity and homozygosity for the base pair substitution in codon 187 of NQO1 were associated with a functional decrease in the amount of quinone reductase activity and that these individuals would have a markedly increased susceptibility to the genotoxic and leukemogenic effects of cytotoxic therapy. This hypothesis is supported by epidemiological data that have associated the 609C→T mutation of NQO1 with benzene-induced hematotoxicity.9 Occupational benzene poisoning is itself strongly associated with the subsequent development of AML and the related MDS.2-7 Because benzene-associated leukemia has clinical, morphologic, and cytogenetic features similar to the myeloid leukemias that follow exposure to alkylating agents, we focused on the frequency of NQO1 polymorphism in our patients who had AML with abnormalities of chromosomes 5 and/or 7 and compared them with other patients with myeloid leukemias characterized by balanced translocations or normal karyotypes. It is reasonable to assume that the mechanism of leukemogenesis between these two categories (ie, loss or deletion of no. 5 or 7 and balanced translocations) is considerably different.1,28,29 

Although typically thought of as a detoxification mechanism, NQO1 activity is also a well-documented component of pathways for mutagen and carcinogen activation.12-14 NQO1 is an inducible enzyme and is increased, for example, by cigarette smoking. Lung cancer in Mexican Americans and African Americans has been associated with the wild-type genotype of the NQO1 polymorphism.16,17 In this situation, functional NQO1 probably results in the activation of potential lung carcinogens.

In summary, the frequency of an inactivating polymorphism in NQO1 appears to be increased in a cohort of myeloid leukemia patients with abnormalities of chromosomes 5 and/or 7, but not in those with balanced translocations, other clonal abnormalities, or normal karyotypes. Most of the former group of patients had therapy-related AML. The mutant allele frequency was approximately 1.6-fold higher than expected among patients with abnormalities in chromosomes 5 and/or 7 and 1.4-fold higher than expected among all patients with t-AML. Thus, individuals who are homozygous for the inactivating allele of NQO1 and thereby completely lack enzyme activity may be particularly vulnerable to leukemogenic changes induced by carcinogens. Heterozygotes may share this increased leukemogenic risk through two mechanisms. NQO1 enzyme activity may be variably reduced in heterozygotes and then further depleted by the oxidative stress of cytotoxic drugs, or these individuals may experience a treatment-induced mutation or loss of the remaining wild-type allele in one of their hematopoietic stem cells. Further studies on a large population of patients are required to confirm these findings.

ACKNOWLEDGMENT

The authors thank the many physicians who referred patients to the University of Chicago for this study, Dr Theodore Karrison for his statistical assistance, Dr Janet D. Rowley for her careful review of the manuscript, and Melissa Ellifson and Marjorie Isaacson for their expert data management.

Supported in part by Grants No. PO1 CA40046 and CA14599 from the National Cancer Institute (Bethesda, MD; to R.A.L. and M.M.L.B.) and by the National Foundation for Cancer Research (to M.T.S.). J.W. was a Howard Hughes Predoctoral Fellow.

The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. section 1734 solely to indicate this fact.

REFERENCES

REFERENCES
1
Thirman
MJ
Larson
RA
Therapy-related myeloid leukemia.
Hematol Oncol Clinics North Am
10
1996
293
2
Vigliani
EC
Saita
G
Benzene and leukemia.
N Engl J Med
271
1964
872
3
Laskin
S
Goldstein
BD
Benzene toxicity: A critical evaluation.
J Toxicol Environ Health
2
1977
1
4
Rinsky
RA
Smith
AB
Hornung
RF
Filloon
TG
Young
RJ
Okun
AH
Landrigan
PJ
Benzene and leukemia. An epidemiologic risk assessment.
N Engl J Med
316
1987
1044
5
Aksoy
M
Benzene Carcinogenicity.
1988
113
CRC
Boca Raton, FL
6
Hayes
RB
Yin
SN
Dosemeci
M
Li
GL
Wacholder
S
Travis
LB
Li
CY
Rothman
N
Hoover
RN
Linet
MS
Benzene and the dose-related incidence of hematologic neoplasms in China. Chinese Academy of Preventive Medicine–National Cancer Institute Benzene Study Group.
J Natl Cancer Inst
89
1997
1065
7
Rothman
N
Li
GL
Dosemeci
M
Bechtold
WE
Marti
GE
Wang
YZ
Linet
M
Xi
LJ
Lu
W
Smith
MT
Titenko-Holland
N
Zhang
LP
Blot
W
Yin
SN
Hayes
RB
Hematotoxicity among Chinese workers heavily exposed to benzene.
Am J Ind Med
29
1996
236
8
Boddy
AV
Ratain
MJ
Pharmacogenetics in cancer etiology and chemotherapy.
Clin Cancer Res
3
1997
1025
9
Rothman
N
Smith
MT
Hayes
RB
Traver
RD
Hoener
BA
Campleman
S
Li
GL
Dosemeci
M
Linet
M
Zhang
L
Xi
L
Wacholder
S
Lu
W
Meyer
KB
Titenko-Holland
N
Stewart
JT
Yin
S
Ross
D
Benzene poisoning, a risk factor for hematological malignancy, is associated with the NQO1 609C→T mutation and rapid fractional excretion of chlorzoxazone.
Cancer Res
57
1997
2839
10
Eastmond
DA
Smith
MT
Irons
RD
An interaction of benzene metabolites reproduces the myelotoxicity observed with benzene exposure.
Toxicol Appl Pharmacol
91
1987
85
11
Smith
MT
Yager
JW
Steinmetz
KL
Eastmond
DA
Peroxidase-dependent metabolism of benzene’s phenolic metabolites and its potential role in benzene toxicity and carcinogenicity.
Environ Health Perspect
82
1989
23
12
Ross
D
Beall
H
Traver
RD
Siegel
D
Phillips
RM
Gibson
NW
Bioactivation of quinones by DT-diaphorase. Molecular, biochemical and chemical studies.
Oncol Res
6
1994
493
13
Beall
HD
Mulcahy
RT
Siegel
D
Traver
RD
Gibson
NW
Rodd
D
Metabolism of bioreductive antitumor compounds by purified rat and human DT-diaphorases.
Cancer Res
54
1996
3196
14
Mikami
K
Naito
M
Tomida
A
Yamada
M
Sirakusa
T
Tsuruo
T
DT-diaphorase as a critical determinant of sensitivity to mitomycin C in human colon and gastric carcinoma cell lines.
Cancer Res
56
1996
2823
15
Hu
LT
Stamberg
J
Pan
SS
The NAD(P)H:quinone oxidoreductase locus in human colon carcinoma HCT 116 cells resistant to mitomycin C.
Cancer Res
56
1996
5253
16
Rosvold
EA
McGlynn
KA
Lustbader
ED
Buetow
KH
Identification of an NAD(P)H:quinone oxidoreductase polymorphism and its association with lung cancer and smoking.
Pharmacogenetics
5
1995
199
17
Wiencke
JK
Spitz
MR
McMillan
A
Kelsey
KT
Lung cancer in Mexican-Americans and African-Americans is associated with the wild-type genotype of the NAD(P)H:quinone oxidoreductase polymorphism.
Ca Epidemiol Biol Prevent
6
1997
87
18
Traver
RD
Horikoshi
T
Danenberg
KD
Stadlbauer
THW
Danenberg
PV
Ross
D
Gibson
NW
NAD(P)H:quinone oxidoreductase gene expression in human colon carcinoma cells; characterization of a mutation which modulates DT-diaphorase activity and mitomycin sensitivity.
Cancer Res
52
1992
797
19
Ross
D
Traver
RD
Siegel
D
Kuehl
BL
Misra
V
Rauth
AM
A polymorphism in NAD(P)H:quinone oxidoreductase (NQO1): Relationship of a homozygous mutation at position 609 of the NQO1 cDNA to NQO1 activity.
Br J Cancer
74
1996
995
20
Traver
RD
Siegel
D
Beall
HD
Phillips
RM
Gibson
NW
Franklin
WA
Ross
D
Characterization of a polymorphism in NADP(H):quinone oxidoreductase (DT diaphorase).
Br J Cancer
75
1997
69
21
Traver
RD
Rothman
N
Smith
MT
Yin
SY
Hayes
RB
Li
GL
Franklin
WA
Ross
D
Incidence of a polymorphism in NAD(P)H:quinone oxidoreductase (NQO1).
Proc Am Assoc Cancer Res
37
1996
278
(abstr 1894)
22
Kelsey
KT
Ross
D
Traver
RD
Christiani
DC
Zuo
Z-F
Spitz
MR
Wang
M
Xu
X
Lee
B-K
Schwartz
BS
Wiencke
JK
Ethnic variation in the prevalence of a common NAD(P)H quinone oxidoreductase polymorphism and its implications for anti-cancer chemotherapy.
Br J Cancer
76
1997
852
23
Larson
RA
Le Beau
MM
Vardiman
JW
Rowley
JD
Myeloid leukemia after hematotoxins.
Environ Health Perspect
104
1996
1303
(suppl 6)
24
Joventino
LP
Stock
W
Lane
NJ
Daly
KM
Mick
R
Le Beau
MM
Larson
RA
Certain HLA antigens are associated with specific morphologic and cytogenetic subsets of acute myeloid leukemia.
Leukemia
9
1995
433
25
Fourth International Workshop on Chromosomes in Leukemia, 1982
The correlation of karyotype and occupational exposure to potential mutagenic/carcinogenic agents in acute nonlymphocytic leukemia.
Cancer Genet Cytogenet
11
1984
326
26
Le Beau
MM
Albain
KS
Larson
RA
Vardiman
JW
Davis
EM
Blough
RR
Golomb
HM
Rowley
JD
Clinical and cytogenetic correlations in 63 patients with therapy-related myelodysplastic syndromes and acute nonlymphocytic leukemia: Further evidence for characteristic abnormalities of chromosome no. 5 and 7.
J Clin Oncol
4
1986
325
27
Irons
RD
Stillman
WS
The process of leukemogenesis.
Environ Health Perspect
104
1996
1239
(suppl 6)
28
Pedersen-Bjergaard
J
Rowley
JD
The balanced and unbalanced chromosome aberrations of acute myeloid leukemia may develop in different ways and may contribute differently to malignant transformation.
Blood
83
1994
2780
29
Pedersen-Bjergaard
J
Pedersen
M
Roulston
D
Philip
P
Different genetic pathways in leukemogenesis for patients presenting with therapy-related myelodysplasia and therapy-related acute myeloid leukemia.
Blood
86
1995
3542
30
Le Beau
MM
Cytogenetic analysis of hematological malignancies
The ACT Cytogenetic Laboratory Manual
ed 2
Barch
MJ
1991
395
Raven
New York, NY
31
Tosato
G
Generation of Epstein-Barr virus (EBV)-immortalized B cell lines
Current Protocols in Immunology.
Coligan
JE
Kruisbeek
AM
Margulies
DH
Shevach
EM
Strober
W
1991
7.22.1
Wiley
New York, NY
32
Eickelmann
P
Schulz
WA
Rohde
D
Schmitz-Drager
B
Sies
H
Loss of heterozygosity at the NAD(P)H:quinone oxidoreductase locus associated with increased resistance against mitomycin C in a human bladder carcinoma cell line.
Biol Chem Hoppe Seyler
375
1994
439

Author notes

Address reprint requests to Richard A. Larson, MD, University of Chicago, MC-2115, 5841 S Maryland Ave, Chicago, IL 60637; e-mail:ralarson@mcis.bsd.uchicago.edu.