CYP1A1 and CYP2D6 polymorphism and risk of lung cancer in a North Indian population

This case–control study was conducted to examine the association between the CYP1A1 and CYP2D6 genotypes and lung cancer risk among North Indians. The estimated relative risk for lung cancer associated with the CYP1A1 Val/Val allele was 2.68, and was four-fold when cases with small cell lung cancer (SCLC) were considered alone. With regard to the metabolism of debrisoquine, no poor metabolizers were found amongst the subjects. The odds ratio of risk with the heterozygous extensive metabolizer (HEM) genotype was 1.5. However, in the presence of at least a single copy of the variant CYP1A1 MspI allele and the CYP2D6 HEM genotype, the risk was two-fold for squamous cell carcinoma (SQCC). When the CYP1A1 Val/Val and CYP2D6 HEM genotypes were taken together, the risk for SCLC was four-fold. Stratified analysis indicated an interaction between bidi smoking and variant CYP1A1 genotypes on the risk for SQCC and SCLC. Heavy smokers (Brinkman index>400) with Val/Val genotypes were at a very high risk of developing lung cancer (odds ratio 29.30, 95% confidence interval 2.42–355, p=0.008). Heavy smokers with CYP1A1 MspI (CYP1A1*1/2A or CYP1A1*2A/*2A) genotype had a seven-fold risk for SCLC compared with non-smokers. This study is the first to be carried out on a North Indian population, and, although small, suggests that CYP1A1 and CYP2D6 polymorphisms might have a role in determining the risk for lung cancer and should be investigated further.     

CYP17, SRD5A2, CYP1B1, and CYP2D6 gene polymorphisms with prostate cancer risk in North Indian population

To investigate the involvement of the CYP17, SRD5A2, CYP1B1, and CYP2D6 variants with prostate cancer, a case-control study of 100 patients and an equal number of age-matched control men was conducted. There appears to be a nonsignificant increase with risk of prostate cancer for individuals carrying one copy of the CYP17 A2 allele (OR, 1.80; 95% CI, 0.99-3.29, P=0.05). The risk was increased in individuals having two A2 alleles (OR; 2.81, 95% CI, 1.06-7.40, P=0.03). Compared with men having the VV genotype of SRD5A2 gene, there was no significant association between the VL genotype and the risk of prostate cancer (OR; 0.54, 95% CI; 0.29-1.03, P=0.06). There was no difference in the occurrence of the genotype LL between controls and prostate cancer patients (OR; 0.90, 95% CI; 0.43-1.89, P=0.79). There was a nonsignificant increased risk of prostate cancer for individuals carrying the CYP1B1Leu/Val genotype (OR, 1.70, 95% CI, 0.91-3.17, P =0.09), which was increased in those having the Val/Val allele (OR, 3.38; 95% CI, 1.13-10.07, P=0.02). Relative to men homozygous for the wild-type allele in CYP2D6 gene, those heterozygous for the B allele had an odds ratio of 1.78 (95% CI, 0.76-4.17, P=0.18) for patients, and for homozygous individuals, it was 1.95 (0.55-6.93, P=0.30). These observations have suggested that the CYP17 A2/A2, CYP1B1 Val/Val, and CYP2D6 genotypes may be associated with an altered risk of prostate cancer, while the CYP2D6 and SRD5A2 V89L polymorphism have no association with its risk in the North Indian population.     

Genetic polymorphism of the CYP1A1, CYP2E1, GSTM1 and GSTT1 genes and lung cancer susceptibility in a north Indian population

The present study investigates in a experimental system in vitro the relationship between the non-enzymatic (ascorbate-Fe2+) and enzymatic (NADPH) lipid peroxidation in rat liver microsomes and nuclei. Chemiluminescence was measured as cpm/mg protein during 180 min at 37 degrees C. Approximately 50-55% of the fatty acids located in rat liver microsomes and nuclei are polyunsaturated with a prevalence of C18:2 n6 and C20:4 n6. The values of total light emission during the non-enzymatic and enzymatic lipid peroxidation were highest in microsomes than in nuclei. A significant decrease of C20:4 n6 and C22:6 n3 in rat liver microsomes and nuclei was observed during the lipid ascorbate-Fe2+-dependent peroxidation, whereas a significant decrease of C20:4 n6 in rat liver microsomes was observed during enzymatic lipid peroxidation. Over the time course studies, analysis of chemiluminescence in microsomes and nuclei demonstrated that the lipid peroxidation in the presence of ascorbate-Fe2+ reach a maximum at 50 and 30 min, respectively, whereas in the presence of NADPH it reachs a maximum at 20 min in both organelles. In liver microsomes and nuclei the peroxidizability index (pi) which indicates the degree of vulnerability to degradation of a selected membrane showed statistically significant differences between control versus ascorbate-Fe2+ when microsomes or nuclei were compared. Our results indicate that non-enzymatic (ascorbate-Fe2+) and enzymatic (NADPH) lipid peroxidation are operative in rat liver microsomes and nuclei but the sensitivities of both organelles to lipid peroxidation evidenced by chemiluminescence was greater in the presence of ascorbate-Fe2+ when compared with NADPH.     

CYP2D6 and CYP1A1 mutations in the Turkish population

Drugs and carcinogens are substrates of a group of metabolic enzymes including cytochrome p450 enzymes and gluthatione S-transferases. Many of the genes encoding these enzymes exhibit functional polymorphisms that contribute individual cancer susceptibility and drug response. Molecular studies based on these polymorphic enzymes also explain the aetiology of cancer and therapeutic management in clinics. We analysed the cytochrome p4501A1 (CYP1A1) and 2D6 (CYP2D6) variant genotype and allele frequencies by PCR-RFLP in Turkish individuals (n=140). The frequency of the CYP1A1*2A mutant allele was found to be 15.4%, and the CYP2D6*3 and *4 mutant allele (poor metabolizer) frequencies were 2.5% and 13.9%, respectively. This study presents the first results of CYP1A1 and CYP2D6 mutant allele distributions in the Turkish population and these data provide an understanding of epidemiological studies that correlate therapeutic approaches and aetiology of several types of malignancy in Turkish patients.     

CYP1A2 genetic polymorphisms and adenocarcinoma lung cancer risk in the Tunisian population

AimsIn this study, the effects of four single nucleotide polymorphisms (SNPs), ? 3860G > A, ? 2467delT, ? 739T > G and ? 163C > A, of CYP1A2 gene on lung cancer were evaluated in Tunisian population.Main methodsFour polymorphisms of CYP1A2 gene were analysed in 109 healthy smokers and in 101 lung cancer cases, including 63 with squamous cell carcinoma (SCC) and 41 with adenocarcinoma (AD). The genotyping for the SNPs ? 3860 G > A, ? 2467delT, ? 739T > G and ? 163C > A was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis.Key findingsThe results showed that smokers with CYP1A2 gene polymorphisms were associated with an increased risk for the development of lung AD. There was however no significant increased risk of developing lung SCC in smokers having CYP1A2 gene polymorphisms. An increased risk of developing AD was observed in smokers who are carriers of at least one copy of ? 3680A or ? 739G giving a significant odds ratio (OR) of 6.02 (CI = 2.91–12.9) and 3.01 (CI = 1.54–5.98), respectively.SignificanceThese genotyping data are consistent with the hypothesis that tobacco-specific-N-nitrosamines (TSN) such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are major contributors to the development of lung AD and that CYP1A2 gene product plays an important role in the metabolic activation of NNK. This study suggests that SNPs of CYP1A2 could be considered as promising biomarkers in the aetiology of lung AD in smokers.     

CYP2E1 gene polymorphism and ovarian cancer risk in the Yakut population

The CYP2E1 gene polymorphism has been studied in Yakut women with ovarian cancer and without cancer. The two groups have been found to substantially differ in the frequency of the CYP2E1* 1D allele (with a 96-bp insertion in the promoter region of the gene): it is more frequent in healthy women (16.3 versus 7.4%, P = 0.007).     

Association of CYP1A1, GSTM1, and GSTT1 gene polymorphism with risk of oral submucous fibrosis in a section of North Indian population

Genetic alterations in the genes expressing drug metabolizing enzymes can make an individual susceptible to various cancers. This study detects the polymorphisms at CYP1A1, GSTM1, and GSTT1 genes in a section of North Indian population and determines the susceptibility to oral submucous fibrosis (OSF). In this case-control study one hundred and two OSF patients were genotyped to detect the GSTM1, GSTT1, CYP1A1 polymorphism. Two hundred healthy controls were also included. Genotypes were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach. The frequency of GSTM1 and GSTT1 genotype was higher in OSF patients, as compared to controls. A trend risk analysis showed 7.6 fold increase in risk, when both the genes were absent. The frequency of CYP1A1 (m1) and CYP1A1 (m2) genotypes was higher in controls. No polymorphic alleles were detected in the m4 site. CYP1A1 (m1) wild genotype in the absence of GSTM1 null genotype, falls under the highest risk group (OR 3.74). Our findings suggest that CYP1A1 (m1) genotype and (m2) genotype singly acts as a protective factor but in the absence of GSTM1 and/or GSTT1 gene significantly alters risk towards OSF.     

CYP1A1 genetic polymorphisms,tobacco smoking and lung cancer risk in a French Caucasian population

The CYP1A1 gene encoding for an enzyme involved in the metabolic activation of important tobacco carcinogens could be implicated in smoking-induced lung cancer. Given the strong association between tobacco smoking and lung cancer, the effect of tobacco smoke exposure has to be taken into account when studying the potential association between lung cancer and CYP1A1 genotypes. The effect of two CYP1A1 genetic polymorphisms (Mspl and IIe-Val) on lung cancer risk were evaluated using peripheral blood DNA from 150 lung cancer patients and 171 controls. The Mspl sitepresent allele was found among 19.3% of both cases and controls and the variant allele Val among 6.7% of cases and 8.8% of controls. Lung cancer risks associated with the Mspl site-present allele (OR= 0.9; 95%Cl: 0.5-1.8) or with the Val allele (OR= 0.8; 95%Cl: 0.3-1.9) were not increased after adjustment for tobacco and asbestos exposures. These results persisted when analyses were stratified on smoking status, daily consumption of tobacco or duration of smoking. Similar findings were obtained when squamous cell or small cell carcinomas were studied separately. This study thus suggests a minor role for the known CYP1A1 gene polymorphisms in predisposition to lung cancer among Caucasian populations.     

CYP1A1 genetic polymorphisms, tobacco smoking and lung cancer risk in a French Caucasian population

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Genetic polymorphism of CYP2A6 in relation to cancer.

To clarify the roles of human cytochrome P450 (P450 or CYP) 2A6 and 2E1 on the metabolic activation of N-nitrosamines, we established genetically engineered Salmonella typhimurium strains harboring human CYP2A6 or CYP2E1 together with NADPH-P450 reductase (OR). The 5'-terminus of CYP cDNA was modified to achieve a high-level expression in S. typhimurium. Modified CYP2A6 or CYP2E1 cDNA and native OR cDNA were introduced into a pCW vector. S. typhimurium YG7108 cells were transformed with this vector. The mutagen producing ability of these enzymes for some N-nitrosamines were evaluated using the established S. typhimurium cells. We found that the substrate specificity of CYP2A6 and CYP2E1 was different among mutagens. CYP2A6 was responsible for the metabolic activation of N-nitrosamines possessing relatively long alkyl chains, whereas CYP2E1 was responsible for the metabolic activation of N-nitrosamines with relatively short alkyl chains. It is likely that CYP2A6 gene polymorphism is responsible for the interindividual variability on the cancer susceptibility. We found the whole deletion of CYP2A6 gene as a type of genetic polymorphism in Japanese. Thus, we developed a gene diagnosis method to detect the variant. We evaluated the relationship between the CYP2A6 gene whole deletion and the susceptibility to the lung cancer. The frequency of CYP2A6 gene whole deletion was significantly lower in the lung cancer patients than that of healthy volunteers.     

Cyclin D1 (G870A) polymorphism and risk of cervix cancer: a case control study in north Indian population

Cyclin D1 (CCND1) is a key regulatory protein, playing a critical role in the transition from G1 to S phase of the cell cycle. We have evaluated the association between CCND1 A870G polymorphism and risk of cervix cancer in north Indian women by using PCR-RFLP method. This association was estimated by computing odds ratio (ORs) and a 95% Confidence Intervals (95% CI) using a Multivariate Logistic Regression Analysis. No significant association was observed between CCND1 genotypes and overall risk of cervix cancer. But when stratified histologically, statistically significant (OR: 3.7, 95% CI: 1.56-8.87, P: 0.001) increased risk of squamous cell carcinoma (SCC) was observed for individuals with AA genotype. Thus our findings suggest that CCND1 (G870A) polymorphism may be associated with increased risk of SCC of the uterine cervix in north Indian women.     

Association between CYP1A1 polymorphism and colorectal cancer risk: a meta-analysis

Colorectal cancer is one of the most common forms of cancer and is the third leading cause of cancer-related death worldwide. Published data on the association between CYP1A1 (MspI and Ile ⁴⁶² Val) polymorphisms and colorectal cancer risk are inconclusive. To address these issues, we carried out a meta-analysis of available case–control study. Online electronic searches of PubMed were performed. We identified 17 studies (6,673 colorectal cancer patients and 8,102 control subjects) that examined the association between CYP1A1 (MspI and Ile ⁴⁶² Val) polymorphisms and risk of colorectal cancer. For CYP1A1 MspI polymorphism, we performed a meta-analysis from 13 studies including 5,468 cases and 6,492 controls. Overall, there was no statistically significant association between CYP1A1 MspI polymorphism and colorectal cancer susceptibility. In the subgroup analyses based on ethnicities, no statistically significant associations were observed in all genetic models. With respect to CYP1A1 Ile ⁴⁶² Val polymorphism, a total of 14 studies including 6,654 cases and 7,859 controls were involved in this meta-analysis. The CYP1A1 Ile ⁴⁶² Val polymorphism was associated with risk of colorectal cancer. Ethnic subgroup analyses revealed that significant associations were found in Asians and Caucasians. In summary, this meta-analysis suggests that CYP1A1 Ile ⁴⁶² Val polymorphism was a low-penetrance susceptibility gene in colorectal cancer development. On the contrary, CYP1A1 MspI polymorphism does not seem capable of modifying colorectal cancer risk.     

CYP1A1*2 and CYP1A1*3 polymorphisms cosegregate in the Indian population

Several ethnic groups have been genotyped for polymorphisms at the CYP1A1 gene locus that encodes the enzyme that catalyzes the initial step in the metabolism of polycyclic aromatic hydrocarbons. Two of the CYP1A1 polymorphisms, namely, CYP1A1*2 and CYP1A1*3 are reported to cosegregate among the Japanese and to a lesser extent in Caucasians, but not in people of African descent. In the absence of such information in the Indian population, the frequency of the CYP1A1*2 polymorphism was determined in this study, using DNA samples from 649 ethnic Indians who had been earlier genotyped for the CYP1A1*3 polymorphism. Analysis of the combined genotype data revealed that the two polymorphisms cosegregate in the Indian population.     

Association of inflammatory chemokine gene CCL2I/D with bladder cancer risk in North Indian population

Chemokine genes have been proposed as good candidate genes for conferring susceptibility to Bladder cancer (BC). We examined the combined effect of multiple alleles of pro inflammatory chemokine genes for determining the risk of BC. We tested association of three gene polymorphisms of CCL2I/D (rs3917887), CCL2A2518G (rs1024611) and CCR2V64I (rs1799864) with BC risk in North Indian population. Genotypes were assessed in hospital-based case-control study comprising of 200?BC patients and 200 healthy controls. Genomic DNA was isolated from blood and genotyping done using PCR-RFLP method. In CCL2I/D polymorphism, the heterozygous genotype (I/D) showed high risk of BC p?相似文献   

Cytochrome P450 2A6 deletion polymorphism and risk of lung cancer: a meta-analysis

Previous studies concerning the association between cytochrome P450 2A6 (CYP2A6) deletion polymorphism and lung cancer risk provided controversial results. To clarify the precise association, a meta-analysis was performed. The electronic databases PubMed, Chinese Biomedical Database and Chinese National Knowledge Infrastructure Database were searched for case–control studies last updated on June 3, 2012 that investigated CYP2A6 deletion polymorphism and lung cancer risk. The odds ratio (OR) and its respective 95 % confidence interval (95 % CI) were used to measure the strength of association by means of a genetic model free approach. A total of 8 studies including 2,607 cases and 2,595 controls met the inclusion criteria and were subjected to the final analysis. The most appropriate co-dominant model was adopted. Overall, we found that CYP2A6 *1/*1 genotype was associated with an increased risk of lung cancer relative to *4/*4 genotype (OR = 2.65, 95 % CI: 1.84–3.81, P < 0.001). Significant association was also detected among Asians. Publication bias was absent in this meta-analysis. Therefore, our data suggested that the presence of the CYP2A6 *1/*1 might be associated with an increased lung cancer risk, especially for Asians. Further studies well-designed among different ethnicity populations are required.     

Genetic polymorphism of the human cytochrome CYP2A13 in a French population: implication in lung cancer susceptibility

The human cytochrome CYP2A13, which is mainly expressed in the respiratory tract, has been shown to be highly efficient in vitro in the metabolism of tobacco-smoke carcinogens and procarcinogens such as 4-methylnitroso-1-(3-pyridyl)-1-butanone (NNK). In order to investigate the extent of CYP2A13 genetic polymorphism in a French Caucasian population of 102 individuals, a screening for sequence variations in the 5'-untranslated and protein encoding regions of its gene was performed using a polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) strategy. Six polymorphisms in the coding region were identified, including two rare missense mutations (C474G or Asp158Glu, G967T or Val323Leu) and one nonsense mutation (Arg101Stop). This deleterious mutation, the most frequent (5%) in our population, presumably encodes a severely truncated protein. The influence of the nonsense mutation in lung cancer susceptibility was examined by PCR-SSCP using peripheral blood DNA from 204 cases of lung cancer and 201 controls. The CYP2A13*7 allele, which harbours the C301T mutation, was present in 2.0% of controls and 3.4% of cases. However, multivariate analysis showed an elevated risk for small cell lung cancer in subjects heterozygous for the null allele (odds ratio OR=9.9; 95% confidence interval CI=1.9-52.2). This increased risk was not linked to other histological types of lung cancer.     

Polymorphisms of the GSTM1 and CYP2D6 genes associated with susceptibility to lung cancer in Chinese.

The case-control study was conducted to examine the association between GSTM1 null and CYP2D6Ch (T(188)/T) genotypes and lung cancer risk among Chinese of Han nationality living in Guangdong. All 191 subjects were investigated with unitary questionnaire and their DNAs were isolated from peripheral lymphocytes by standard procedures with proteinase K digestion and phenol/chloroform extraction. GSTM1(-) was detected with polymerase chain reaction (PCR) in all 191 subjects, involving 59 lung cancer cases, 59 hospital controls and 73 healthy controls. The frequencies of GSTM1(-) were not significantly different between the cases and the two controls overall. However, among adenocarcinoma of lung, the frequency of GSTM1(-) (76.9%) appeared to be higher than that in controls (49.2%), and the odd radios were 3.42-3.45. The results suggested an elevated risk for adenocarcinoma of lung would be shown by GSTM1(-). Using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) to detect CYP2D6 T(188)/T genotype in 59 lung cancer patients and 59 hospital controls, it showed no significant difference between the two groups. However, non-smokers with non-T(188)/T (C(188)/C or C(188)/T) genotype showed 3.78-folds increased risk of lung cancer compared with those with T(188)/T genotype (P=0.036). The data did not suggest a substantial interaction effect between GSTM1 and CYP2D6 polymorphisms and the risk of lung cancer. Additionally, among Chinese (Han) of Guangdong, the frequency of CYP2D6 T(188) allele appeared to be 57.2%, and GSTM1(-) to be 51.8%.     

CYP2A6 gene deletion reduces susceptibility to lung cancer.

CYP2A6 is an enzyme with a high ability to activate a nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), to its potent and ultimate carcinogen. In the present study, we investigated the relationship between genetic polymorphism of CYP2A6 and lung cancer risk in a case-control study of Japanese subjects. Genotyping of the CYP2A6 gene in both healthy volunteers and lung cancer patients was conducted. The frequency with which the subjects carried homozygotes of the CYP2A6 gene deletion-type mutation (deletion), which causes lack of the enzyme activity, was lower in the lung cancer patients than in the healthy control subjects. The odds ratio (OR) of the group homozygous for the deletion was significantly lower and calculated to be 0.25 (95% CI; 0.08-0.83) when the OR for the population with homozygotes of the CYP2A6 wild-type gene was defined as 1.00. In the allelic-base analysis, there was also a significant decrease in the OR for the deletion allele. These data suggest that deficient CYP2A6 activity due to genetic polymorphism reduces lung cancer risk.     

Association of Toll-like receptor (TLR) 2, 3 and 9 genes polymorphism with prostate cancer risk in North Indian population

Prostate cancer (PCa) is the most common cancer among men. It has been suggested that toll like receptors (TLRs) may contribute to PCa pathogenesis by stimulating prostate epithelial cell proliferation in response to infectious stimuli. We performed case control study to analyze the genetic variants of TLR2, 3 and 9 gene polymorphisms with PCa risk in a North Indian population. For this study we genotyped age matched, unrelated 195 PCa patients and 250 healthy controls of similar ethnicity in a case-control study. They were genotyped for TLR2 (-196 to -174 Del), TLR3 (c.1377C/T) [rs3775290] and TLR9 (G2848A) [rs352140] gene polymorphisms using polymerase chain reaction and restriction fragment length polymorphism method. Variant allele Del (D) carriers i.e. (ID + DD) of TLR2 (-196 to -174 Del) SNP, demonstrated 1.57 fold increased risk (p = 0.040; OR = 1.57, 95% CI = 1.02-2.24) as compared to Ins (I) allele, suggesting a dominant effect model involved in the risk of this polymorphism in PCa. However, variants of TLR3 and 9 gene polymorphisms were not associated with PCa risk. Our results suggested the low penetrance variant of TLR2 (-196 to -174 Del) to be at increased PCa risk in North Indian population. Functional studies in ethnically diverse populations may provide a more comprehensive involvement of innate immunity in identifying the disease-associated variants for PCa etiology.     

Association of CYP1A1 and CYP2D6 gene polymorphisms with head and neck cancer in Tunisian patients

The purpose of this study was to investigate the relationship between head and neck cancer (HNC) and environmental agents and polymorphisms in CYP1A1, CYP2D6, NAT1 and NAT2 metabolic enzymes genes. To the best of our knowledge, this is the first report on polymorphisms in CYP1A1 6310C>T, CYP2D6 Arg365His, NAT1 52936A>T and NAT2 Arg268Lys (NAT2*12A) genes and susceptibility to HNC in Tunisian population. We study the prevalence of these polymorphisms in 169 patients with HNC and 261 control subjects using polymerase chain reaction based methods in a Tunisian population. We detected an association between HNC and CYP1A1 6310C>T (TT) and CYP2D6 Arg365His (His/His) variant carriers (OR 1.75, P = 0.008 and OR 1.66, P = 0.016, respectively). No association was found between the polymorphisms genotypes of NAT1 52936T>A and NAT2 Arg268Lys and risk of HNC. An association between HNC and CYP1A1 (TT) genotype was found among patients with smoking (P = 0.011) and drinking habit (P = 0.009). The combinations of NAT1 (AT or AA) and NAT2 (AA) at-risk genotypes increased HNC risk (OR 4.23, P = 0.005 and OR 3.60, P = 0.048, respectively). However, the combinations of CYP1A1 (AA) and CYP2D6 (CC) genotypes decreased risk of HNC (OR 0.20; P = 0.006). Genetic polymorphisms in CYP1A1 and CYP2D6 may significantly associate with HNC in the Tunisian population. The results of this study suggest a possible gene–environment interaction for certain carcinogen metabolizing enzymes, but larger studies that fully evaluate the interaction are needed.