Parag P. Shah

Polymorphism in environment responsive genes and association with Parkinson disease

Attempts were made in the present case-control study to investigate the association of polymorphism in the genes encoding proteins involved in toxication–detoxication and dopaminergic pathways and susceptibility to Parkinson’s disease (PD). Seventy patients suffering from PD and one hundred healthy controls belonging to the same geographical location and same ethnicity were included in the study. PCR-RFLP and allele-specific PCR-based methodology were used to identify the genotypes. Multivariate logistic regression analysis revealed that heterozygous genotypes of cytochrome P4502D6*4(CYP2D6*4), CYP2E1*5B (RsaI) polymorphism and homozygous mutant genotypes of CYP2E1*6 (Dra1) were found to be overrepresented in PD cases when compared to the controls. Risk was also found to be increased in patients carrying glutathione S-transferase T1 (GSTT1) null or homozygous variant genotypes of GSTP1. Significant association was observed for monoamine oxidase-B(MAO-B) variant allele G and PD, whereas no difference in genotype and allele frequencies was observed for manganese-superoxide dismutase (MnSOD), dopamine receptor-D2(DRD2), and dopamine transporter (DAT) genes between controls and PD cases. Genotype combinations characterized by the presence of two variant genotypes on their corresponding loci revealed that four combinations of GSTT1 null and MnSOD(-9Val) or GST null and MAOB-G or CYP2E1*5B and MAO-B-AG or CYP2E1*5B and DRD2 (Taq1A-het) genotypes in the patients exhibited severalfold higher and significant association with risk to PD. Our data suggest that polymorphism in the genes involved in detoxification and dopamine regulation may modulate the susceptibility to PD and could be important risk factors in the pathogenesis of PD.

Evidence for increased cytochrome P450 1A1 expression in blood lymphocytes of lung cancer patients

To develop blood lymphocyte cytochrome P450 1A1 (CYP1A1) expression as a surrogate for monitoring tissue expression for polycyclic aromatic hydrocarbon (PAH) induced toxicity, the present study attempted to characterize CYP1A1 mRNA expression and its associated catalytic activity in freshly prepared blood lymphocytes isolated from healthy controls and patients suffering from tobacco induced lung cancer. Human blood lymphocytes were found to express CYP1A1 mRNA and significant activity of 7-ethoxyresorufin-O-deethylase (EROD). Significant increase in the activity of EROD and CYP1A1 mRNA was observed in blood lymphocytes isolated from patients suffering from lung cancer. Further, controls with variant genotypes of CYP1A1 (Msp1 or Ile/Val polymorphism) exhibited significant increase in the enzyme activity associated with an increase in CYP1A1 mRNA expression when compared to the controls with wild type genotype. Patients with variant genotypes of CYP1A1 also exhibited much greater increase in the blood lymphocyte CYP1A1 mRNA expression and EROD activity when compared to controls or patients with wild type genotype. Our data thus provides evidence of CYP1A1 expression in freshly isolated blood lymphocytes and differences in reactivity in individuals with variant genotypes of CYP1A1, suggesting that blood lymphocyte CYP1A1 expression profile could help in identifying individuals at risk to environment induced lung cancer.

Cytochrome P450 2E1 and head and neck cancer: interaction with genetic and environmental risk factors.

The present case‐control study investigates the association of polymorphisms in cytochrome P450 2E1 (CYP2E1), involved in the metabolism of tobacco carcinogens and alcohol, with Head and Neck Squamous Cell Carcinoma (HNSCC). In addition, the interaction of CYP2E1 (CYP2E1*5B and CYP2E1*6) with other genetic factors (null genotype of glutathione‐S‐Transferase M1, GSTM1, X‐Ray Repair Cross Complementing Group I, XRCC1 (Arg194Trp), and environmental risk factors such as alcohol and tobacco in modifying HNSCC risk were investigated. Genotypes were determined by the polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) assay in a total of 350 male cases of HNSCC and an equal number of healthy male controls. Statistical analysis showed a significant increase in HNSCC risk in cases with variant genotypes of CYP2E1*5B (RsaI) (O.R. 3.44; 95% C.I. 1.45–8.14) and CYP2E1*6 (DraI) (O.R. 1.76; 95% C.I. 1.28–2.41). Haplotype analysis revealed that haplotype T‐A was associated with a greater than 10‐fold increase in risk for HNSCC. Our data also revealed a several fold increase in HNSCC risk in cases carrying a combination of variant genotypes of CYP2E1 with the null genotype of GSTM1 or XRCC1 variant genotypes. Alcohol or tobacco use (both smoking and chewing) were also found to interact with variant genotypes of CYP2E1 in significantly enhancing HNSCC risk. This increase in risk associated with an interaction of CYP2E1 genotypes with GSTM1 or XRCC1 or with tobacco and alcohol use demonstrates the importance of gene–gene and gene–environment interactions in the development of HNSCC. Environ. Mol. Mutagen. 2009.

Association of functionally important polymorphisms in cytochrome P4501B1 with lung cancer.

In the present study, genotype and haplotype frequencies of four polymorphisms of cytochrome P450 1B1 (CYP1B1) that cause amino acid changes (Arg-Gly at codon 48, Ala-Ser at codon 119, Leu-Val at 432 and Asn-Ser at codon 453) were studied in 200 patients suffering from lung cancer and equal number of controls. A significant difference was observed for the distribution of variant genotypes of CYP1B1Arg48Gly and Ala119Ser polymorphisms (CYP1B1*2) in cases when compared to the controls. No significant difference was observed for the distribution of variant genotypes of CYP1B1Leu432Val (CYP1B1*3) and CYP1B1Asn453Ser (CYP1B1*4) polymorphism. When the four SNPs were analyzed using a haplotype approach, SNPs at codon 48 (Arg48Gly) and codon 119 (Ala119Ser) exhibited complete linkage disequilibrium (LD) in all the cases and controls. Significant differences in the distribution of the three haplotypes (G-T-C-A, G-T-G-A and G-T-C-G) were observed in the cases when compared to controls. Tobacco use in the form of smoking as well as chewing was found to significantly increase the risk of lung cancer in patients by interacting with CYP1B1Ala119Ser genotypes demonstrating the role of gene-environment interaction in lung cancer. Further, the risk of lung cancer increased several fold in the patients carrying the genotype combinations of CYP1B1Ala119Ser and CYP1B1Leu432Val with GSTM1, a phase II enzyme suggesting the importance of gene-gene interactions in enhancing the susceptibility to lung cancer.

Polymorphism in cytochrome P450 2A6 and glutathione S-transferase P1 modifies head and neck cancer risk and treatment outcome

A case control study was carried out to investigate the association of functionally important polymorphism in cytochrome P450 2A6 (CYP2A6) and glutathione S-transferase P1 (GSTP1) genes with head and neck squamous cell carcinoma (HNSCC) and treatment response in cases receiving a combination of chemo-radiotherapy. The study group consisted of 350 males suffering from HNSCC and an equal number of male controls. Multivariate logistic regression analysis revealed statistically significant decrease in risk to HNSCC in cases with variant genotypes (CYP2A6*1B and CYP2A6*4C) of CYP2A6 (OR: 0.78; 95% CI: 0.43-1.22; P=0.04) or GSTP1 (OR: 0.71; 95% CI: 0.51-1.00; P=0.05). The risk associated with these variant genotypes was found to be further decreased in cases carrying a combination of variant genotypes of CYP2A6 and GSTP1 (OR: 0.40; 95% CI: 0.25-0.65; P=0.00). A similar decrease in risk was observed in cases with variant genotypes of CYP2A6 (OR: 0.59; 95% CI: 0.40-0.86; P=0.00) or GSTP1 (OR: 0.62; 95% CI: 0.42-0.91; P=0.01) and who were regular tobacco users (cigarette smokers or tobacco chewers). Interestingly, only 27% of the cases carrying the variant forms of CYP2A6 (*1A/*4C+*1B/*4C+*4C/*4C) responded to the treatment for HNSCC when compared to those with wild-type genotype (69%). However with GSTP1, cases with homozygous mutant genotype (Val/Val) showed a superior treatment response (75%) when compared to cases with wild-type genotype (25%). Further, cases carrying a combination of variant genotype of CYP2A6 and wild-type genotype of GSTP1 exhibited a very poor treatment response demonstrating that polymorphisms in CYP2A6 and GSTP1 not only modified the risk to HNSCC but also played a major role in determining the chemotherapeutic response.

Polymorphism in cytochrome P4501A1 is significantly associated with head and neck cancer risk.

A case control study was undertaken to investigate the association of polymorphisms in cytochrome P4501A1 (CYP1A1) with squamous cell carcinoma of head and neck (HNSCC) in North Indian population. The variant genotypes of CYP1A1*2A and CYP1A1*2C were found to be overrepresented in cases when compared to controls. The HNSCC risk also increased several folds in cases with combination of variant genotypes of CYP1A1*2A or CYP1A1*2C with null genotype of glutathione-S-transferase M1 (GSTM1), a phase II enzyme, particularly in cases who were tobacco users (smokers and tobacco chewers), demonstrating the role of gene–gene and gene–environment interactions in the development of HNSCC.

Association of poor metabolizers of cytochrome P450 2C19 with head and neck cancer and poor treatment response

A case-control study consisting of 300 patients and an equal number of healthy controls was carried out to investigate the association of polymorphism in cytochrome P450 2C19 (CYP2C19), which results in poor and extensive metabolizers (PMs and EMs) genotypes, with squamous cell carcinoma of head and neck (HNSCC) and treatment response in patients receiving combination of chemo-radiotherapy. A higher frequency of CYP2C19 2 variants was observed in the cases resulting in significantly higher risk to HNSCC (Ad OR 3.36, 95% CI 1.94-5.82, p-value<0.05). The PM genotype of CYP2C19 3 was also found to be slightly increased in the cases, though the increase in risk was not significant when analyzed by multivariate logistic regression model. Tobacco chewing amongst the cases resulted in almost 13-fold increase in the risk with CYP2C19 2 (OR: 12.39) and 3-fold with CYP2C19 3 genotype (OR: 2.90) when compared to the tobacco chewers amongst the controls. Likewise, cigarette smoking in the cases increased the risk approximately 9-fold and 3-fold with CYP2C19 2 (OR: 8.93) and CYP2C19 3 (OR: 2.18) genotypes respectively when compared to smokers amongst the controls. Similar increase in risk was associated with alcohol use amongst the cases carrying variant genotypes of CYP2C19 2 (OR: 7.75) or CYP2C19 3 (OR: 2.60), demonstrating the importance of gene-environment interaction in modifying susceptibility to HNSCC. Interestingly, patients with PMs of CYP2C19 (CYP2C19 2 and CYP2C19 3) exhibited little response to the respective chemotherapy than the patients carrying wild-type genotype demonstrating that functional enzyme deficiencies due to polymorphism in CYPs may not only be important in modifying the susceptibility to HNSCC but also in determining chemotherapeutic response.

P2-024: Association of cytochrome P450 polymorphism and its combination genotypes with lung cancer risk

Promoter analysis of co-expressing genes after exposure to asbestos Ruosaari, Salla1,4 Nymark, Penny1,2 Hienonen-Kempas, Tuija1 Knuutila, Sakari2,3 Anttila, Sisko1 Hollmén, Jaakko4 1 Health and Work Ability, Biological Mechanisms and Prevention of Work-related Diseases, Finnish Institute of Occupational Health, Helsinki, Finland, 2 Department of Pathology, Haartman Institute and HUSLAB, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland, Helsinki, Finland 3 Helsinki University Central Hospital, Helsinki, Finland, Helsinki, Finland 4 Laboratory of Computer and Information Science, Helsinki University of Technology, Espoo, Finland Background: Occupational exposure to asbestos is associated with the development of asbestosis, malignant mesothelioma, and lung cancer. Research related to the mechanisms by which asbestos fibers cause damage in the cells and which are the mediator genes is important as exact mechanisms underlying asbestos-associated carcinogenesis are not known. Knowledge about the genome-wide alterations involved in asbestos-associated carcinogenesis can be obtained by characterizing changes in gene expression after exposure to the carcinogen or between asbestos-exposed and non-exposed patients using microarrays. Methods: We have previously analyzed the DNA copy number and gene expression profiles of 14 lung tumors from highly asbestos-exposed and 14 non-exposed patients using microarrays and revealed that a specific aberration profile could be characteristic of lung tumors associated with asbestos-exposure. Furthermore, by exposing human epithelial and metsothelial cells to crocidolite asbestos and performing time-series microarray experiments, we have recently reported asbestos-exposure related temporal changes in gene expression profiles. In this study, the gene expression microarray data from these experiments were combined. Promoter sequence analysis was first applied to clusters of co-expressed genes detected from the cell line data to identify genes that are likely co-regulated by the same mechanisms. Thereafter, common changes between the cell line and patient data were revealed. Results: 15 transcription factors were identified to be under-represented in the promoter regions of genes with similar temporal expression profiles in comparison to the remaining genes on the array (p<0.00001). Among the under-represented transcription factors were those that have been previously associated with regulation of mitochondria, oxidative stress, and carcinogenesis but not with exposure to asbestos. Conclusions: The study provides new information about putative transcription factors and mediator genes involved in asbestos-associated carcinogenesis. We show that the integration of gene expression data from cell line and human studies gives insight of the mechanisms underlying asbestos-related carcinogenesis. P2-024 BSTB: Cancer Genetics Posters, Tue, Sept 4