NAD(P)H: Quinone NAD(P)H: Quinone Oxidoreductase 1 (NQO1) Oxidoreductase 1 (NQO1) Pro187Ser Polymorphism Pro187Ser Polymorphism

and the Risk of Lung and the Risk of Lung Cancer:Cancer:

A Meta-AnalysisA Meta-AnalysisChun ChaoChun Chao, Zuo-Feng Zhang, Julien Berthiller, Paolo , Zuo-Feng Zhang, Julien Berthiller, Paolo

Buffetta, Mia HashibeBuffetta, Mia Hashibe

Department of Epidemiology, UCLADepartment of Epidemiology, UCLA

International Agency for Research on CancerInternational Agency for Research on Cancer

NQO1: an Antioxidant NQO1: an Antioxidant EnzymeEnzyme

NQO1 protects cells from oxidative damage by preventing the formation of free radical byproduct of quinone metabolism.

NQO1 activates the antioxidant forms of vitamin E and ubiquinone after free radical attack.

NQO1 stabilizes p53, especially in response to oxidative stress.

NQO1 is highly expressed in tissues requiring high level of antioxidant protection E.g., Epithelial cells of lung and colon, vascular

endothelium, corneal epithelium, etc.

NQO1 Catalyzes Two Electron NQO1 Catalyzes Two Electron ReductionReduction

Quinone

o

o

R

R

R

ROH

OH

R

R

R

R

NQO1

2e-

Hydroquinone

Toxicity ↓

Toxicity ↑

BenzeneBenzo(a)pyrene

Nitro compounds

Mitomycin CSemi-quinoneAlkylating

species Free radicals

Phase I Enzymes1e-

NQO1 PolymorphismsNQO1 Polymorphisms Over 80 SNPs in NQO1 identifiedOver 80 SNPs in NQO1 identified

2 nonsynonymous SNPs in exons have been described.2 nonsynonymous SNPs in exons have been described.

The 609 variant (Pro187Ser) results in reduced The 609 variant (Pro187Ser) results in reduced enzyme activity:enzyme activity: Heterozygous: 3-fold decrease Heterozygous: 3-fold decrease Homozygous variant allele: almost null activityHomozygous variant allele: almost null activity

Frequency of NQO1 609 Variant Frequency of NQO1 609 Variant GenotypeGenotype

AsianCT/TT:48.3%

TT: 20.3%

Non-Hispanic White CT/TT: 39.5%

TT: 4.4%

African-American CT/TT:

33.8% TT: 5.2%

Mexican-American CT/TT:

52.2% TT: 15.5%

Ref: Kelsey KT et al. Br J Cancer 1997; 76:852-4.

Defected NQO1 Activity has Defected NQO1 Activity has been Link to Several been Link to Several

DiseasesDiseases Benzene toxicityBenzene toxicity

Hematological toxicity (leukocytopenia, anemia, Hematological toxicity (leukocytopenia, anemia, thrombocytopenia)thrombocytopenia)

LeukemiaLeukemia Renal cell and urothelial cell carcinomaRenal cell and urothelial cell carcinoma Basal cell carcinomaBasal cell carcinoma Secondary myeloid leukemia among Secondary myeloid leukemia among

individuals receiving chemotherapy. individuals receiving chemotherapy. Lung cancer

risk?

Meta-analysis of NQO1 Pro187Ser Meta-analysis of NQO1 Pro187Ser polymorphism and lung cancer polymorphism and lung cancer

riskrisk

21 case-control studies identified

19 studies included (6,980 cases/8,080 controls)

Whites: 8 studies

Asians: 7 studies

Multiethnic: 4 studies

Inclusion CriteriaDisease histologically confirmed

Genotype distribution in controls in H-W equilibrium

Genotype frequency/precision estimate reported

Identification of Studies PubMed and ISI web of knowledge database

Reference search Unpublished data that we were aware of

Methods for Meta-Methods for Meta-AnalysisAnalysis

Estimates combined using inverse variance Estimates combined using inverse variance weightingweighting Random effects model used if heterogeneity was Random effects model used if heterogeneity was

detected. detected. Mantel-Haenszel test for heterogeneityMantel-Haenszel test for heterogeneity

Stratified analysis by gender and region to explore Stratified analysis by gender and region to explore source of heterogeneitysource of heterogeneity

Publication bias assessed using Egger’s test & Publication bias assessed using Egger’s test & Begg’s funnel plotBegg’s funnel plot

Influence analysisInfluence analysis 20% change in summary estimate as an indication for 20% change in summary estimate as an indication for

influential study.influential study.

ResultsResults

No. of studies

OR for variant genotype (95% CI)

Test for heterogeneity P-value

Egger’s test P-value

Lung cancer Overall CT 14 1.04 (0.92-1.19) 0.02 0.59 TT 14 1.07 (0.98-1.16) 0.03 0.69 CT/TT 19 0.97 (0.86-1.11) <0.01 0.75 White CT 8 1.07 (0.98-1.16) 0.87 0.07 TT 8 1.19 (0.94-1.50) 0.44 0.60 CT/TT 10 1.05 (0.97-1.14) 0.30 0.90 Asian CT 7 1.00 (0.70-1.43) 0.01 0.10 TT 7 0.95 (0.58-1.55) <0.01 0.81 CT/TT 9 0.97 (0.73-1.29) <0.01 0.18 Black CT/TT 3 0.95 (0.66-1.36) 0.63 0.57

*Reference group are persons with the C/C genotype

Summary OR for WhitesSummary OR for Whites

ORCT.5 1 1.5

Combined

Hung (2000)

Saldivar (2005)

Chen (1999)

Xu (2001)

Lewis (2001)

Alexandrie (2004)

Sorensen (2005)

Benhamou (2001)

ORTT.5 1 1.5

Combined

Hung (2000)

Saldivar (2005)

Chen (1999)

Xu (2001)

Lewis (2001)

Alexandrie (2004)

Sorensen (2005)

Benhamou (2001)

OR C/T vs. C/C: 1.07 (0.98-1.16)

OR T/T vs. C/C: 1.19 (0.94-1.50)

OR C/T+T/T vs. C/C: 1.04 (0.96-1.13)

P for heterogeneity: 0.87

P for heterogeneity: 0.44

P for heterogeneity: 0.30

Summary OR for AsiansSummary OR for Asians

ORCT.5 1 1.5

Combined

Lin (2000)

Liang (2004)

Hamajima (2002)

Chen (1999)

Yin (2001)

Lan (2004)

Sunaga (2002)

ORTT.5 1 1.5

Combined

Lin (2000)

Liang (2004)

Hamajima (2002)

Chen (1999)

Yin (2001)

Lan (2004)

Sunaga (2002)

OR C/T vs. C/C: 1.00 (0.70-1.43)

OR T/T vs. C/C: 0.95 (0.58-1.55)

OR C/T + T/T vs. C/C: 0.99 (0.72-1.34)

P for heterogeneity: 0.01

P for heterogeneity: < 0.01

P for heterogeneity: < 0.01

After excluding the outlier study:OR C/T vs. C/C: 0.85 (0.69-1.05)OR T/T vs. C/C: 0.81 (0.52-1.24)OR C/T+T/T vs. C/C: 0.87 (0.68-1.11)

Summary OR for BlacksSummary OR for Blacks

ORCTTT.5 1 1.5

Combined

Saldivar (2005)

Bock (2005)

Wiencke (1997)

OR C/T + T/T vs. C/C: 0.95 (0.66-1.36)

P for heterogeneity: 0.63

Adjusted vs. Unadjusted Adjusted vs. Unadjusted OROR

Summary adjusted OR are similar to the summary Summary adjusted OR are similar to the summary

unadjusted OR.unadjusted OR. No. of

studies Adjusted OR

(95% CI) Unadjusted OR

(95% CI)

Lung cancer Overall CT 6 0.97 (0.81-1.16) 0.94 (0.81-1.09) TT 7 0.84 (0.62-1.13) 0.83 (0.63-1.08) CT/TT 9 0.79 (0.70-0.90) 0.83 (0.72-0.96) White CT 4 1.13 (0.96-1.34) 1.16 (1.00-1.36) TT 4 1.39 (0.90-2.14) 1.40 (0.91-2.15) CT/TT 6 1.02 (0.87-1.21) 1.06 (0.91-1.24) Asian CT 3 0.74 (0.56-0.99) 0.74 (0.57-0.96) TT 4 0.67 (0.48-0.94) 0.71 (0.52-0.97) CT/TT 4 0.79 (0.67-0.92) 0.84 (0.68-1.05)

Analyses restricted to studies that reported adjusted OR. Most studies adjusted for age, sex, and cigarette smoking.

Summary OR by Smoking Summary OR by Smoking Status and Lung Cancer Status and Lung Cancer

Cell TypeCell Type No. of

studies OR for variant genotype*

(95% CI) Test for heterogeneity

P-value Egger’s test

P-value

Lung cancer White

Ever-smokers 5 1.11 (0.97-1.27) 0.95 0.18 Never-smokers 5 0.97 (0.73-1.30) 0.08 0.90

Adenocarcinoma 5 0.95 (0.79-1.14) 0.91 0.18 Squamous cell carcinoma 5 1.14 (0.93-1.41) 0.36 0.05 Small cell 3 0.99 (0.69-1.43) 0.15 0.12 Asian

Ever-smokers 5 0.79 (0.61-1.02) 0.85 0.30 Never-smokers 4 0.82 (0.60-1.12) 0.79 0.92

Adenocarcinoma 5 0.82 (0.64-1.05) 0.08 0.95 Squamous cell carcinoma 4 1.31 (0.92-1.85) 0.42 0.72

*ORs are (C/T+T/T) vs. C/C

0

DiscussionDiscussion A positive association between the variant alleles and A positive association between the variant alleles and

lung cancer risk was suggested in Whites.lung cancer risk was suggested in Whites. Low power to detect association for the T/T genotypeLow power to detect association for the T/T genotype

The variant alleles appeared to be inversely associated The variant alleles appeared to be inversely associated with lung cancer risk in Asians.with lung cancer risk in Asians.

No association was observed in Blacks. No association was observed in Blacks. Increased risk was observed among white ever Increased risk was observed among white ever

smokers.smokers. Increased risk was suggested for squamous cell Increased risk was suggested for squamous cell

carcinoma among both Whites and Asians. carcinoma among both Whites and Asians. Inverse association between the variant alleles and Inverse association between the variant alleles and

adenocarcinoma was observed in Asians.adenocarcinoma was observed in Asians.

Discussion (Cont.)Discussion (Cont.)

The difference seen in Whites and Asians was The difference seen in Whites and Asians was consistent with results from bladder cancer and consistent with results from bladder cancer and colorectal cancer meta-analysis results.colorectal cancer meta-analysis results.

Different results observed between ethnic Different results observed between ethnic groups may be due to:groups may be due to: Relevant environmental exposures in Asia may Relevant environmental exposures in Asia may

differ from Western countries. differ from Western countries. There may exist other genetic mechanisms that There may exist other genetic mechanisms that

compensate more effectively for the loss of the compensate more effectively for the loss of the detoxifying activity of NQO1 in Asians. detoxifying activity of NQO1 in Asians.

Copyright ©2001 American Association for Cancer Research

Xu, L. L. et al. Cancer Epidemiol Biomarkers Prev 2001;10:303-309

OR of C/T vs. C/C in former smokers,♦ light smoker, five cigarettes/day; ■, mild smoker, 20 cigarettes/day; ∆, heavy smoker, 40 cigarettes/day.

NQO1 and Cigarette Smoking: Gene-Environment Interaction

ConclusionsConclusions

The effect of NQO1 Pro187Ser polymorphism The effect of NQO1 Pro187Ser polymorphism may be different in each individual depending may be different in each individual depending on his/her other genetic make up and on his/her other genetic make up and environmental exposure. environmental exposure.

Multiple genes and smoking behaviors (or Multiple genes and smoking behaviors (or other exposures) should be considered if the other exposures) should be considered if the genotype information were to be used to assess genotype information were to be used to assess susceptibility.susceptibility.

Thank you!Thank you!

We thank the following individuals for We thank the following individuals for providing unpublished genotype data providing unpublished genotype data for our analysis: Dr. Cathryn Bock, Dr. for our analysis: Dr. Cathryn Bock, Dr.

Karin Broberg, Dr. Nobuyuki Karin Broberg, Dr. Nobuyuki Hamajima, Dr. Rayjean Hung, Dr. Hamajima, Dr. Rayjean Hung, Dr.

Pinpin Lin, and Dr. Mette Sorensen. Pinpin Lin, and Dr. Mette Sorensen.