Sachin Gulati

CYP1A1 Gene Polymorphisms: Modulator of Genetic Damage in Coal-Tar Workers

AIM It is well known that polycyclic aromatic hydrocarbons (PAHs) such as benzo (a) pyrene have carcinogenic properties and may cause many types of cancers in human populations. Genetic susceptibility might be due to variation in genes encoding for carcinogen metabolizing enzymes, such as cytochrome P-450 (CYP450). Our study aimed to investigate the effect of genetic polymorphisms of CYP1A1 (m1 and m2) on genetic damage in 115 coal-tar workers exposed to PAHs in their work place. METHODS Genetic polymorphisms of CYP1A1 were determined by the PCR-RFLP method. Comet and buccal micronucleus assays were used to evaluate genetic damage among 115 coal tar workers and 105 control subjects. RESULTS Both CYP1A1 m1 and CYP1A1 m2 heterozygous and homozygous (wt/mt+mt/mt) variants individually as well as synergistically showed significant association (P<0.05) with genetic damage as measured by tail moment (TM) and buccal micronuclei (BMN) frequencies in control and exposed subjects. CONCLUSION In our study we found significant association of CYP1A1 m1 and m2 heterozygous (wt/mt) +homozygous (mt/mt) variants with genetic damage suggesting that these polymorphisms may modulate the effects of PAH exposure in occupational settings.

Frequency distribution of high risk alleles of CYP2C19, CYP2E1, CYP3A4 genes in Haryana population.

The genotype of an individual can significantly influence the disposition of a chemical, and determine their susceptibility to its toxicity. Many enzymes involved in either activation or detoxification of chemical carcinogen metabolism are polymorphically expressed, with the alleles presenting different enzymatic activities and some of them having been associated with susceptibility to cancer. Cytochrome P450 (P450 or CYP) constitutes the most important phase I enzyme group responsible for the metabolism of endogenous and exogenous (xenobiotics) substances. The present study was aimed to analyze the frequencies of commonly known polymorphisms of human xenobiotic metabolizing genes (XMG) in the Haryana State population of North India. The study was conducted in 308 healthy Haryana volunteers. DNA was extracted from leucocytes and the genetic polymorphisms in CYP2C19*2, CYP2C19*3, CYP2E1*5B and CYP3A4*1B were determined by digesting the PCR Product with restriction enzymes BamHI, SmaI, PstI and PstI respectively. The genotype frequencies of CYP2C19*2, CYP2C19*3, CYP2E1*5B, and CYP3A4*1B were found to be 22.0%, 0.0%, 2.11% and 2.0% respectively. The North Indian population which is known to be Caucasoid Aryans is ethnically different from South Indians known as Caucasoid Dravidians but no significant difference in genetic polymorphism was found.

Antigenotoxic Effect of Curcumin and Carvacrol against Parathion Induced DNA Damage in Cultured Human Peripheral Blood Lymphocytes and Its Relation to GSTM1 and GSTT1 Polymorphism

In recent years, the use of organophosphorus pesticides has been extensively increased and these compounds signify a major class of agricultural pesticides today. We studied antigenotoxic potential of curcumin and carvacrol against the parathion induced DNA damage in cultured peripheral blood lymphocytes using sister chromatid exchanges as a biomarker of genotoxicity. Heparinised fresh blood from healthy individuals was treated with 2.5 μg/mL concentration of parathion in presence of curcumin and carvacrol in order to observe the antigenotoxic potential of both curcumin and carvacrol. Significant reduction (P < 0.05) was observed in the frequencies of SCEs in presence of 10 μg/mL and 15 μg/mL concentrations of curcumin as compared to parathion exposed sample. Similarly carvacrol had significant (P < 0.05) antigenotoxic effect at the concentrations of 2.5 μg/mL and 5.0 μg/mL against the parathion. We also studied the effect of GSTT1 and GSTM1 on genotoxicity of parathion and antigenotoxic potential of curcumin and carvacrol. We did not observe any significant effect (P > 0.05) of GSTT1 and GSTM1 polymorphism on genotoxicity of parathion and antigenotoxic potential of curcumin and carvacrol.

Polymorphic Variation of CYP1A1 and CYP1B1 Genes in a Haryana Population

Cytochrome P450 (CYP) 1A1 and CYP1B1 are important phase I xenobiotic metabolizing enzymes involved in the metabolism of numbers of toxins, endogenous hormones, and pharmaceutical drugs. Polymorphisms in these phase I genes can alter enzyme activity and are known to be associated with cancer susceptibility related to environmental toxins and hormone exposure. Their genotypes may also display ethnicity-dependent population frequencies. The present study was aimed to determine the frequencies of commonly known functional polymorphisms of CYP1A1 and CYP1B1 genes in a Haryana state population of North India. The allelic frequency of CYP1A1 polymorphism m1 (MspI) was 29.65% and m2 (Ile462Val) was 24.85%. The frequency of CYP1B1 polymorphism m1 (Val432Leu) was 45.85% and m2 (Asn453Ser) was 16.2%. We observed inter- and intra-ethnic variation in the frequency distribution of these polymorphisms. Analysis of polymorphisms in these genes might help in predicting the risk of cancer. Our results emphasize the need for more such studies in high-risk populations.

Phenotypic and genotypic characterization of antioxidant enzyme system in human population exposed to radiation from mobile towers

In the present era, cellular phones have changed the life style of human beings completely and have become an essential part of their lives. The number of cell phones and cell towers are increasing in spite of their disadvantages. These cell towers transmit radiation continuously without any interruption, so people living within 100s of meters from the tower receive 10,000 to 10,000,000 times stronger signal than required for mobile communication. In the present study, we have examined superoxide dismutase (SOD) enzyme activity, catalase (CAT) enzyme activity, lipid peroxidation assay, and effect of functional polymorphism of SOD and CAT antioxidant genes against mobile tower-induced oxidative stress in human population. From our results, we have found a significantly lower mean value of manganese superoxide dismutase (MnSOD) enzyme activity, catalase (CAT) enzyme activity, and a high value of lipid peroxidation assay in exposed as compared to control subjects. Polymorphisms in antioxidant MnSOD and CAT genes significantly contributed to its phenotype. In the current study, a significant association of genetic polymorphism of antioxidant genes with genetic damage has been observed in human population exposed to radiations emitted from mobile towers.

Glutathione S-Transferase Gene Polymorphisms: Modulator of Genetic Damage in Gasoline Pump Workers.

This study investigated genetic damage in gasoline pump workers using the cytokinesis blocked micronucleus (CBMN) assay. Blood and urine samples were collected from 50 gasoline pump workers and 50 control participants matched with respect to age and other confounding factors except for exposure to benzene through gasoline vapors. To determine the benzene exposure, phenol was analyzed in urinary samples of exposed and control participants. Urinary mean phenol level was found to be significantly high (P < 0.05) in exposed workers. The CBMN frequency was found to be significantly higher in gasoline pump workers (6.70 ± 1.78) when compared to control individuals (2.20 ± 0.63; P < 0.05). We also investigated influence of polymorphisms of GSTM1, GSTT1, and GSTP1 genes on CBMN frequency. The individuals having GSTM1 and GSTT1 null genotypes had significantly higher frequency of CBMN (P < 0.05). Our study indicates that chronic and long-term exposure of gasoline vapors can increase genotoxic risk in gasoline pump workers.

Association of Polymorphisms of Phase I Metabolizing Genes with Sister Chromatid Exchanges in Occupational Workers Exposed to Toluene Used in Paint Thinners

This study investigated genetic damage in paint workers mainly exposed to toluene as it is a major solvent used in paint thinners. Sister chromatid exchange (SCE) assay was used as biomarker of genotoxicity. Blood samples were collected from 30 paint workers and 30 control subjects matched with respect to age and other confounding factors except for exposure to toluene. SCE frequency was found to be significantly higher in paint workers (4.81 ± 0.92) as compared to control individuals (1.73 ± 0.54) (p < 0.05). We also investigated influence of polymorphisms of CYP2E1 and CYP1A1m2 genes on SCE frequency. Our results showed that there was significant increase in frequencies of SCE among the mutant genotypes of CYP2E1 and CYP1A1m2 as compared to wild genotypes. Our study indicated that long term exposure of toluene can increase genotoxic risk in paint workers.