Multiple analytical approaches reveal distinct gene-environment interactions in smokers and non smokers in lung cancer.
Complex disease such as cancer results from interactions of multiple genetic and environmental factors. Studying these factors singularly cannot explain the underlying pathogenetic mechanism of the disease. Multi-analytical approach, including logistic regression (LR), classification and regression tree (CART) and multifactor dimensionality reduction (MDR), was applied in 188 lung cancer cases and 290 controls to explore high order interactions among xenobiotic metabolizing genes and environmental risk factors. Smoking was identified as the predominant risk factor by all three analytical approaches. Individually, CYP1A1*2A polymorphism was significantly associated with increased lung cancer risk (OR = 1.69;95%CI = 1.11-2.59,p = 0.01), whereas EPHX1 Tyr113His and SULT1A1 Arg213His conferred reduced risk (OR = 0.40;95%CI = 0.25-0.65,p<0.001 and OR = 0.51;95%CI = 0.33-0.78,p = 0.002 respectively). In smokers, EPHX1 Tyr113His and SULT1A1 Arg213His polymorphisms reduced the risk of lung cancer, whereas CYP1A1*2A, CYP1A1*2C and GSTP1 Ile105Val imparted increased risk in non-smokers only. While exploring non-linear interactions through CART analysis, smokers carrying the combination of EPHX1 113TC (Tyr/His), SULT1A1 213GG (Arg/Arg) or AA (His/His) and GSTM1 null genotypes showed the highest risk for lung cancer (OR = 3.73;95%CI = 1.33-10.55,p = 0.006), whereas combined effect of CYP1A1*2A 6235CC or TC, SULT1A1 213GG (Arg/Arg) and betel quid chewing showed maximum risk in non-smokers (OR = 2.93;95%CI = 1.15-7.51,p = 0.01). MDR analysis identified two distinct predictor models for the risk of lung cancer in smokers (tobacco chewing, EPHX1 Tyr113His, and SULT1A1 Arg213His) and non-smokers (CYP1A1*2A, GSTP1 Ile105Val and SULT1A1 Arg213His) with testing balance accuracy (TBA) of 0.6436 and 0.6677 respectively. Interaction entropy interpretations of MDR results showed non-additive interactions of tobacco chewing with SULT1A1 Arg213His and EPHX1 Tyr113His in smokers and SULT1A1 Arg213His with GSTP1 Ile105Val and CYP1A1*2C in nonsmokers. These results identified distinct gene-gene and gene environment interactions in smokers and non-smokers, which confirms the importance of multifactorial interaction in risk assessment of lung cancer.
National Institute of Pathology (Indian Council of Medical Research) Safdarjung Hospital Campus, New Delhi, India.
Rakhshan
R
Ihsan
Pradeep Singh
PS
Chauhan
Ashwani Kumar
AK
Mishra
Dhirendra Singh
DS
Yadav
Mishi
M
Kaushal
Jagannath Dev
JD
Sharma
Eric
E
Zomawia
Yogesh
Y
Verma
Sujala
S
Kapur
Sunita
S
Saxena
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics; D057225:Data Mining / Q000379:methods*; D004851:Epoxide Hydrolases / Q000235:genetics; D005189:False Positive Reactions; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D058011:Multifactor Dimensionality Reduction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011336:Probability; D015203:Reproducibility of Results; D018401:Sample Size; D012907:Smoking / Q000009:adverse effects; D018709:Statistics, Nonparametric
D019363:Cytochrome P-450 CYP1A1; D004851:Epoxide Hydrolases; C522330:EPHX1 protein, human