Role of NAD(P)H:quinone oxidoreductase polymorphism at codon 187 in susceptibility to lung, laryngeal and oral/pharyngeal cancers

NAD(P)H:quinone oxidoreductase (NQO1) has been proposed to play a protective role against the toxic effects of benzo[a]pyrene quinones. The C⁶⁰⁹T base change in the NQO1 gene, resulting in a Pro¹⁸⁷Ser amino acid change in the protein, has been associated with deficient enzyme activity. We examined whether this polymorphism modified the risks of smoking-related cancers in a case-control study involving patients with lung cancer (n = 150), laryngeal cancer (n = 129), oral/pharyngeal cancer (n = 121) and control individuals (n = 172), all Caucasian smokers. No statistically significant associations were observed between the NQO1 genotypes and smoking-related cancers, although the Ser/Ser genotype was associated with a tendency towards increased risk for lung cancer (odds ratio [OR] = 2.2, 95% confidence interval [CI] 0.7-6.7) and for oral/pharyngeal cancer (OR = 2.3, 95% CI 0.6-8.2). No significant interaction between the NQO1 genotype and either smoking exposure or GSTM1 genotype was found. Our results are consistent with the hypothesis that lack of NQO1 activity may be involved in some smoking-related cancers. However, they were based on small numbers of individuals with the putative atrisk genotype, and the associations did not reach statistical significance. Moreover, these results contrast with those observed in some other ethnic populations, where a protective effect of the NQO1 Ser allele was found. Further studies are therefore clearly needed for a better understanding of the potential role of NQO1 activity in tobacco-related cancers.     

DCPIP (2,6-dichlorophenolindophenol) as a genotype-directed redox chemotherapeutic targeting NQO1*2 breast carcinoma

Abstract

Accumulative experimental evidence suggests feasibility of chemotherapeutic intervention targeting human cancer cells by pharmacological modulation of cellular oxidative stress. Current efforts aim at personalization of redox chemotherapy through identification of predictive tumour genotypes and redox biomarkers. Based on earlier research demonstrating that anti-melanoma activity of the pro-oxidant 2,6-dichlorophenolindophenol (DCPIP) is antagonized by cellular NAD(P)H:quinone oxidoreductase (NQO1) expression, this study tested DCPIP as a genotype-directed redox chemotherapeutic targeting homozygous NQO1*2 breast carcinoma, a common missense genotype [rs1800566 polymorphism; NP_000894.1:p.Pro187Ser] encoding a functionally impaired NQO1 protein. In a panel of cultured breast carcinoma cell lines and NQO1-transfectants with differential NQO1 expression levels, homozygous NQO1*2 MDA-MB231 cells were hypersensitive to DCPIP-induced caspase-independent cell death that occurred after early onset of oxidative stress with glutathione depletion and loss of genomic integrity. Array analysis revealed upregulated expression of oxidative (GSTM3, HMOX1, EGR1), heat shock (HSPA6, HSPA1A, CRYAB) and genotoxic stress response (GADD45A, CDKN1A) genes confirmed by immunoblot detection of HO-1, Hsp70, Hsp70B’, p21 and phospho-p53 (Ser15). In a murine xenograft model of human homozygous NQO1*2-breast carcinoma, systemic administration of DCPIP displayed significant anti-tumour activity, suggesting feasibility of redox chemotherapeutic intervention targeting the NQO1*2 genotype.     

Association of Bladder Cancer Risk with an NAD(P)H:Quinone Oxidoreductase Polymorphism in an Ethnic Kashmiri Population

NQO1 gene polymorphism at nucleotide 609 (Pro187Ser) results in a lowering of NQO1 detoxifying activity and is associated with susceptibility to various cancers. The NQO1 genotypes were identified by RFLP in 104 bladder cancer cases and 120 control subjects in an ethnic Kashmiri population. The frequency of the variant NQO1 alleles (CT/TT) was 23.3% for controls and 32.2% for cases (P?相似文献   

The Association between NQO1 Pro187Ser Polymorphism and Bladder Cancer Susceptibility: A Meta-Analysis of 15 Studies

Background

NAD(P)H:quinone oxidoreductase 1 (NQO1), an obligate two-electron reductase, plays an important role in reducing reactive quinones to less reactive and less toxic hydroquinones. Genetic variations in NQO1 gene that impede its enzyme function may be considered as putative risk factor for cancer. Numerous studies have been performed to investigate the association between NQO1 Pro187Ser polymorphism and bladder cancer risk; nevertheless, the results remain controversial.

Methods

We indentified eligible publications from PubMed, Embase and CBM databases. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to access the strength of the associations. False-positive report probability (FPRP) analysis was also performed for all statistically significant findings.

Results

We collected a total of 15 studies including 4298 cases and 4275 controls in the final meta-analysis. Overall, the NQO1 187Ser carriers were associated with an increased bladder cancer risk (homozygous: OR = 1.43, 95% CI = 1.08-1.90; recessive: OR = 1.33, 95% CI = 1.03-1.72; dominant: OR = 1.19, 95% CI = 1.04-1.37, and allele comparing: OR = 1.18, 95% CI = 1.06-1.33). Stratification analyses showed a statistically significant association among Asians (homozygous: OR = 1.82, 95% CI = 1.39-2.38; recessive: OR = 1.52, 95% CI = 1.20-1.93, dominant: OR = 1.40, 95% CI = 1.05-1.88, and allele comparing: OR = 1.35, 95% CI = 1.15-1.58), never smokers (homozygous: OR = 2.30, 95% CI = 1.14-4.65; heterozygous: OR = 2.26, 95% CI = 1.43-3.56; dominant model: OR = 1.59, 95% CI = 1.14-2.21, and allele comparing: OR = 1.72, 95% CI = 1.27-2.33), hospital-based studies (homozygous: OR = 1.46, 95% CI = 1.09-1.94; recessive: OR = 1.32, 95% CI = 1.02-1.69; dominant: OR = 1.28, 95% CI = 1.05-1.56, and allele comparing: OR = 1.24, 95% CI = 1.07-1.43), studies with genotyping performed by PCR-RFLP under all genetic models, and studies with minor allele frequency >0.30 (homozygous: OR = 1.69, 95% CI = 1.25-2.27; recessive: OR = 1.46, 95% CI = 1.10-1.95, and allele comparing: OR = 1.25, 95% CI = 1.04-1.51), respectively.

Conclusions

Despite some limitations, our meta-analysis provides sufficient evidence that NQO1 Pro187Ser polymorphism may contribute to bladder cancer risk. These findings need further validation in well-designed prospective studies with larger sample size and different ethnicities, especially for Asians.     

NAD(P)H: Quinone oxidoreductase 1, glutathione S-transferase M1, environmental tobacco smoke exposure, and childhood asthma

Environmental tobacco smoke (ETS) exposure might increase the risk for childhood asthma, and we hypothesized the effect may be modified by the phase II genes NAD(P)H: quinone oxidoreductase 1 (NQO1) and glutathione S-transferase (GST) M1. To investigate the genetic and environmental associations with asthma, GSTM1 and NQO1 functional polymorphisms and ETS were analyzed in a two-staged cross-sectional study among elementary schoolchildren in Taiwan. Multiple logistic regression analysis revealed a significant association between the Ser allele of the NQO1 Pro187Ser polymorphism and asthma (OR = 1.6, 95% CI 1.3–1.8). Although GSTM1 genotype itself was not significantly associated with asthma (OR = 1.0, 95% CI 0.8–1.1), the GSTM1 genotype modified the association between the NQO1 polymorphism and asthma in children exposed to ETS (p = 0.0002). The NQO1 gene might be involved in the development of asthma, especially in children carrying the GSTM1 null genotype who are exposed to ETS.     

Role of NQO1 609C>T and NQO2 ?3423G>A gene polymorphisms in esophageal cancer risk in Kashmir valley and meta analysis

Esophageal cancer (EC) is a complex multifactorial disorder, where environmental and genetic factors play major role. NADPH:quinone oxidoreductase 1 (NQO1) and NRH:quinone oxidoreductase 2 (NQO2) are phase II cytosolic enzymes that catalyze metabolism of quinones, important in the detoxification of environmental carcinogens. A case-control study was performed to investigated the associations of NQO1 609C>T and NQO2 -3423G>A polymorphisms with susceptibility to EC in a high-risk Kashmiri population of India in 135 EC patients and 195 unrelated healthy controls using PCR-RFLP. We also performed a meta analysis of nine published studies (1,224 cases and 1,740 controls) on NQO1 609C>T and evaluated the association between the NQO1 609C>T polymorphisms and esophageal cancer risk. A significant difference in NQO1 609C>T and NQO2 -3423G>A genotype distribution between EC cases and corresponding controls groups was observed (OR = 2.65; 95 % CI = 1.29-5.42 and OR = 1.88; 95 % CI = 1.02-3.49 respectively). Further, gene-gene interaction showed significantly increased risk for esophageal adenocarcinoma with variant genotypes of NQO1 609C>T and NQO2 -3423G>A polymorphisms and interaction with environmental risk factors revealed pronounced risk of EC with NQO1 609C>T TT genotype in high salted tea users of Kashmir valley (OR = 3.72, 95 % CI = 0.98-14.19). Meta analysis of NQO 609C>T polymorphism also suggested association of the polymorphism with EC in Asians as well as Europeans. In conclusion, NQO1 609C>T and NQO2 -3423G>A genetic variations modulate risk of EC in high-risk Kashmir population.     

Polymorphisms in base-excision repair and nucleotide-excision repair genes in relation to lung cancer risk

Polymorphisms in DNA repair genes may be associated with differences in DNA repair capacity, thereby influencing the individual susceptibility to smoking-related cancer. We investigated the association of 10 base-excision and nucleotide-excision repair gene polymorphisms (XRCC1 -77 T/C, Arg194Trp, Arg280His and Arg399Gln; APE1 Asp148Glu; OGG1 Ser326Cys; XPA -4 G/A; XPC PAT; XPD Asp312Asn and Lys751Gln) with lung cancer risk in Caucasians. Genotypes were determined by PCR-RFLP and PCR-single base extension assays in 110 lung cancer patients and 110 age- and sex-matched controls, and the results were analyzed using logistic regression adjusted for relevant covariates. A significant association between the APE1 Asp148Glu polymorphism and lung cancer risk was found, with adjusted odds ratios (OR) of 3.38 (p=0.001) for the Asp/Glu genotype and 2.39 (p=0.038) for the Glu/Glu genotype. Gene-smoking interaction analyses revealed a statistically significant interaction between cumulative cigarette smoking and the XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms: these polymorphisms were significantly associated with lung cancer in nonsmokers and light smokers (<25 PY; OR=4.92, p=0.021 for XRCC1 399 Gln/Gln; OR=3.62, p=0.049 for XPD 751 Gln/Gln), but not in heavy smokers (> or =25 PY; OR=0.68, p=0.566 for XRCC1 399 Gln/Gln; OR=0.46, p=0.295 for XPD 751 Gln/Gln). Both the XRCC1 Arg194Trp and Arg280His as well as the OGG1 Ser326Cys heterozygous genotypes were associated with a significantly reduced risk for lung cancer (OR=0.32, p=0.024; OR=0.25, p=0.028; OR=0.51, p=0.033, respectively). No associations with lung cancer risk were found for the XRCC1 -77 T/C, the XPA -4 G/A and the XPC PAT polymorphisms. In conclusion, the APE1 Asp148Glu polymorphism is highly predictive for lung cancer, and cumulative cigarette smoking modifies the associations between the XRCC1 Arg399Gln and the XPD Lys751Gln polymorphisms and lung cancer risk.     

Increased levels of NAD(P)H: quinone oxidoreductase 1 (NQO1) in pancreatic tissues from smokers and pancreatic adenocarcinomas: A potential biomarker of early damage in the pancreas

NAD(P)H:quinone oxidoreductase 1 (NQO1) is elevated in several human tumors. This study was conducted to determine whether increased levels of NQO1 expression also occur in human pancreatic tumor tissue, and to compare expression levels in nontumorous tissue from smokers with those in nonsmokers. The expression of NQO1 was examined in pancreatic tissue samples from 82 human donors. These samples included normal (n = 20), smokers (n = 25), pancreatitis (n = 7), and adenocarcinomas of the pancreas (n = 30). Genotyping for the C609T polymorphism in NQO1 by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis was also performed. Polymorphic variants were confirmed by automatic sequencing. Higher levels of NQO1 expression were demonstrated in pancreatic adenocarcinomas (0.831 ± 0.021) compared to those in nontumorous tissues from nonsmokers (0.139 ± 0.024). These high levels were also found in smokers (0.729 ± 0.167) and in pancreatitis tissues (0.923 ± 0.184). NQO1 activity was also higher in smokers (2.43 ± 0.61 nmol/min per mg protein) compared to nonsmokers (0.44 ± 0.05 nmol/min per mg protein; p < 0.05). No differences were found in genotype distribution and frequencies of the variant alleles between normal and cancer tissues in this relatively small sample pool. Seventy-five percent of the normal pancreatic tissues showed 609(C/C) and 25% 609(C/T). In pancreatic adenocarcinomas the frequency distribution was 65% C/C, 30% C/T and 5% T/T. The increased expression in noncancer pancreatic tissue from smokers and the fact that smoking is a moderate risk factor for pancreatic cancer suggest that NQO1 expression may be a good candidate as a biomarker for pancreatic cancer, especially in risk groups such as smokers.     

Interactions between the OGG1 Ser326Cys polymorphism and intake of fruit and vegetables in relation to lung cancer

The enzyme 8-oxoguanine glycosylase 1 (OGG1) repairs oxidatively damaged DNA and a polymorphism in the OGG1 gene (Ser³²⁶Cys) has been associated with lung cancer. We examined associations between the polymorphism and intake of fruits and vegetables and smoking in the development of lung cancer, by genotyping blood samples from 431 lung cancer cases and 796 comparison persons, which were identified within a prospective cohort on 57,000 cohort members. We found no overall association between the OGG1 polymorphism and lung cancer. There was a statistically significant interaction between the polymorphism and dietary intake of vegetables, with a 54% decrease in lung cancer risk per 50% increase in vegetable intake among homozygous Cys³²⁶Cys carriers and no decrease in risk among carriers of Ser³²⁶Ser or Ser³²⁶Cys. The same tendency was seen in relation to intake of fruit. There were no statistically significant interactions between the OGG1 polymorphism and smoking.     

Binding to serine 65‐phosphorylated ubiquitin primes Parkin for optimal PINK1‐dependent phosphorylation and activation

Mutations in the mitochondrial protein kinase PINK1 are associated with autosomal recessive Parkinson disease (PD). We and other groups have reported that PINK1 activates Parkin E3 ligase activity both directly via phosphorylation of Parkin serine 65 (Ser⁶⁵)—which lies within its ubiquitin‐like domain (Ubl)—and indirectly through phosphorylation of ubiquitin at Ser⁶⁵. How Ser⁶⁵‐phosphorylated ubiquitin (ubiquitin^{Phospho‐Ser65}) contributes to Parkin activation is currently unknown. Here, we demonstrate that ubiquitin^{Phospho‐Ser65} binding to Parkin dramatically increases the rate and stoichiometry of Parkin phosphorylation at Ser⁶⁵ by PINK1 in vitro. Analysis of the Parkin structure, corroborated by site‐directed mutagenesis, shows that the conserved His302 and Lys151 residues play a critical role in binding of ubiquitin^{Phospho‐Ser65}, thereby promoting Parkin Ser⁶⁵ phosphorylation and activation of its E3 ligase activity in vitro. Mutation of His302 markedly inhibits Parkin Ser⁶⁵ phosphorylation at the mitochondria, which is associated with a marked reduction in its E3 ligase activity following mitochondrial depolarisation. We show that the binding of ubiquitin^{Phospho‐Ser65} to Parkin disrupts the interaction between the Ubl domain and C‐terminal region, thereby increasing the accessibility of Parkin Ser⁶⁵. Finally, purified Parkin maximally phosphorylated at Ser⁶⁵ in vitro cannot be further activated by the addition of ubiquitin^{Phospho‐Ser65}. Our results thus suggest that a major role of ubiquitin^{Phospho‐Ser65} is to promote PINK1‐mediated phosphorylation of Parkin at Ser⁶⁵, leading to maximal activation of Parkin E3 ligase activity. His302 and Lys151 are likely to line a phospho‐Ser⁶⁵‐binding pocket on the surface of Parkin that is critical for the ubiquitin^{Phospho‐Ser65} interaction. This study provides new mechanistic insights into Parkin activation by ubiquitin^{Phospho‐Ser65}, which could aid in the development of Parkin activators that mimic the effect of ubiquitin^{Phospho‐Ser65}.     

The relationship between aryl hydrocarbon hydroxylase activity and DNA adducts measured by 32P-postlabelling assay in lymphocytes of lung cancer patients

We have investigated the correlation between DNA adduct levels and aryl hydrocarbon hydroxylase (AHH) activity in peripheral lymphocyte samples obtained from 42 lung cancer patients. DNA adducts and AHH activity were determined by the ³²P-postlabelling technique and the fluorometric method, respectively. The mean +/- SD of DNA adduct level was 0.88 +/- 0.37 (ranged from 0.22 to 1.90) per 10⁸ nucleotides. The geometric means of non-induced and 3-methylcholanthrene (MC)-induced AHH activity, as well as AHH inducibility (MC-induced AHH activity/non-induced AHH activity) were 0.029, 0.228 pmol min^-1 10^-6 cells, and 7.776, respectively. There was no statistically significant correlation between DNA adduct levels and non-induced or MC-induced AHH activity. A tendency of positive correlation was found between DNA adduct levels and AHH inducibility for the all subjects (n = 42, r = 0.25, p = 0.11). Such a positive correlation reached statistical significance in the subjects with squamous cell carcinoma (n = 13, r = 0.70, p &lt; 0.01). In addition, similar correlation of DNA adducts with AHH inducibility was also observed in the GSTM1 present genotype (n = 17, r = 0.44, p = 0.07) and GSTP1-AA genotype (n = 29, r = 0.37, p = 0.05) individuals. These findings suggest that DNA adduct levels are mediated by CYP1A1 enzyme, and AHH inducibility may be a more relevant indicator than specific AHH activity for explaining the variation of DNA adduct levels in lymphocytes.     

An association between a NQO1 genetic polymorphism and risk of lung cancer

NAD(P)H:quinone oxidoreductase (NQO1) is a detoxification enzyme that protects against the regeneration of reactive oxygen species chemically induced by oxidative stress, cytotoxicity, mutagenicity, and carcinogenicity. The protection conferred by NQO1 protein reduces certain environmental carcinogens, such as nitroaromatic compounds, heterocyclic amines, and possible cigarette smoke condensate. The gene coding for NQO1 has a genetic polymorphism (C-->T) at nucleotide position 609 (i.e. amino acid codon 187) of the NQO1 cDNA. This polymorphism was shown to reduce NQO1 enzyme activity, thereby diminishing the protection provided by NQO1. Therefore, we hypothesized that individuals with the variant NQO1 genotype are at higher risk for lung cancer. Using a case-control study, we genotyped the NQO1 variants successfully by PCR-RFLP in 826 lung cancer patients and 826 healthy control subjects matched for age, sex, ethnicity, and smoking status. The frequency of the NQO1 T-allele was statistically significantly different among three ethnic groups (p<0.001). In further analysis of Caucasians, the variant NQO1 genotypes (CT and TT) were associated with a marginally increased lung cancer risk (OR=1.19; 95% CI: 0.95-1.50). The elevated lung cancer risk was only evident in younger individuals (age <62 years old) (OR=1.46; 95% CI: 1.04-2.05), women (OR=1.89; 95% CI: 1.33-2.68), and never smokers (OR=1.80; 95% CI: 1.03-3.13). Furthermore, we found a statistically significant trend in the development of lung cancer at an early age in women with increasing copies of the variant allele (p=0.03). These results suggest that the NQO1 variant genotype may modulate lung cancer risk, especially in younger individuals (age<62), women, and never smokers.     

Contribution of HOGG1 Ser³²⁶Cys polymorphism to the development of prostate cancer in smokers: meta-analysis of 2779 cases and 3484 controls

The HOGG1 gene catalyzes the excision of modified bases and removal of DNA damage adducts. It may play an important role in the prevention of carcinogenesis. Ser³²⁶Cys polymorphism localizes in exon 7 of the hOGG1 gene. It takes the form of an amino acid substitution, from serine to cysteine, in codon 326. Several epidemiological association studies have been conducted on this polymorphism and its relationship with the risk of prostate cancer. However, results have been conflicting. To resolve this conflict, we conducted a meta-analysis on the association between this polymorphism and prostate cancer, taking into account race, country, sources of controls, and smoking status. A total of nine studies covering 2779 cases and 3484 controls were included in the current meta-analysis. Although no significant association was found between hOGG1 Ser³²⁶Cys polymorphism and prostate cancer susceptibility in the pooled analysis, individuals with Ser/Cys+Cys/Cys genotypes were found to have greater risk of prostate cancer if they were also smokers (OR = 2.66, 95% CI = 1.58−4.47) rather than non-smokers (OR = 2.18, 95% CI = 1.13−4.19), compared with those with Ser/Ser genotype. In conclusion, our meta-analysis demonstrates that hOGG1 Ser³²⁶Cys polymorphism is a risk factor for prostate cancer in smokers. Further studies are needed to confirm this relationship.     

Association of metabolic gene polymorphisms with alcohol consumption in controls

The objectives were to study the association between metabolic genes involved in alcohol metabolism (CYP2E1 RsaI, CYP2E1 DraI, ADH1C, NQO1) and alcohol consumption in a large sample of healthy controls. Healthy subjects were selected from the International Collaborative Study on Genetic Susceptibility to Environmental Carcinogens (GSEC). Subjects with information on both alcohol consumption and at least one of the studied polymorphisms were included in the analysis (n=2224). Information on the amount of alcohol consumption was available for a subset of subjects (n=844). None of the studied genes was significantly associated with drinking habits. A significant heterogeneity with age was observed when studying the association between CYP2E1 RsaI and alcohol drinking. CYP2E1 RsaI polymorphism was significantly associated with being a never drinker at older ages (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.2–4.8; at ages above 68 years), while the association was reversed at ages below 47 years (OR 0.5, 95% CI 0.2–1.4). For subjects with detailed information on alcohol intake, no association between alcohol quantity and polymorphisms in metabolic genes was observed; subjects carrying the NQO1 polymorphism tended to drink more than subjects carrying the wild-type alleles. Therefore, no significant association between CYP2E1 RsaI, CYP2E1 DraI, ADH1C, NQO1 polymorphisms and alcohol consumption was observed in healthy controls.     

The association of polymorphisms in DNA base excision repair genes <Emphasis Type="Italic">XRCC1</Emphasis>, <Emphasis Type="Italic">OGG1</Emphasis> and <Emphasis Type="Italic">MUTYH</Emphasis> with the risk of childhood acute lymphoblastic leukemia

The aim of this study was to evaluate the association of polymorphisms in genes encoding three key proteins of DNA base excision repair (BER): the OGG1 Ser326Cys, the MUTYH Tyr165Cys and the XRCC1 Arg399Gln with the risk of childhood acute lymphoblastic leukemia (ALL). Our study included 97 children patients with ALL (mean age 5.4 ± 2.5) and 131 healthy children (mean age 6.2 ± 2.8) used as controls. Genetic polymorphisms in BER pathway genes were examined using PCR and restriction fragment length polymorphism (RFLP). We have demonstrated that the OGG1 Cys/Cys genotype increases the risk of ALL (OR 5.36) whereas the Ser/Ser genotype variant strongly reduces the risk of this cancer among Polish children (OR 0.45). Although we did not observe the differences in single nucleotide polymorphisms (SNPs) in MUTYH and XRCC1 genes between control group and children with ALL, we have shown that the combined genotypes of examined genes can modulate the risk of childhood ALL in Polish population. We found that the combined genotype Arg/Gln–Cys/Cys of XRCC1/OGG1 (OR 3.83) as well as the Cys/Cys–Tyr/Tyr of OGG1/MUTYH (OR 6.75) increases the risk of ALL. In contrast, the combined genotype Arg/Arg–Ser/Ser of XRCC1/OGG1 (OR 0.40) as well as the Ser/Ser–Tyr/Tyr of OGG1/MUTYH (OR 0.43) played a protective role against this malignant disease. In conclusion, we suggest that polymorphisms of BER genes may be used as an important predictive factor for acute lymphoblastic leukemia in children.     

Expression of cytochrome P4502E1 in human liver: Relationship between genotype and phenotype in Chinese

Polymorphic cytochrome P4502E1 (CYP2E1) plays an important role in the metabolic activation of many carcinogens. We have previously shown that the c1/c1 genotype recognized by Rsa I in the 5'-regulatory region of the CYP2E1 may be a susceptibility factor for developing eso-phageal cancer and lung cancer in Chinese. The present study was to investigate the relationship between the Rsa I genotype and the expression of CYP2E1 in human livers. A total of 50 liver specimens were genotyped for CYP2E1 and assayed for CYP2E1 protein contents and functional activity by using specific antibody in immunoblot and a probe substrate, p-nitrophenol. A considerable interindividual variation in CYP2E1 protein (20-fold) and functional activity (56-fold) was observed among these liver samples. However, when they were categorized according to genotype, the mean content of CYP2E1 protein was significantly higher among individuals with the c1/c1 genotype than that among those having c1/c2 or c2/c2 genotype [124.0 ±83.9 pmol/     

Expression of cytochrome P4502E1 in human liver: Relationship between genotype and phenotype in Chinese

Polymorphic cytochrome P4502E1 (CYP2E1) plays an important role in the metabolic activation of many carcinogens. We have previously shown that the c1/c1 genotype recognized byRsa I in the 5′-regulatory region of theCYP2E1 may be a susceptibility factor for developing esophageal cancer and lung cancer in Chinese. The present study was to investigate the relationship between theRsa I genotype and the expression of CYP2E1 in human livers. A total of 50 liver specimens were genotyped forCYP2E1 and assayed for CYP2E1 protein contents and functional activity by using specific antibody in immunoblot and a probe substrate,p-nitrophenol. A considerable interindividual variation in CYP2E1 protein (20-fold) and functional activity (56-fold) was observed among these liver samples. However, when they were categorized according to genotype, the mean content of CYP2E1 protein was significantly higher among individuals with the c1/c1 genotype than that among those having c1/c2 or c2/c2 genotype [124.0±83.9 pmol/mg (n = 28) versus 65.5 ±38.9 pmol/mg (n = 22),P<0.01]. The mean activity of CYP2E1 towardsp-nitrophenol for the c1/c1 genotype was also higher than that for the variant genotypes (198.4±27.8 pmol/min/mg versus 101.2 ±18.1 pmol^-1 · min^-1 · mg^-1,P<0.01). Also, the protein levels and functional activity showed a significant correlation (r = 0.68,P<0.01). These results demonstrate an association between theRsa I genotype and the phenotype of CYP2E1 in our samples, and the data are compatible with the assumption thatCYP2E1 c1/c1 genotype is a susceptibility factor for certain cancers in Chinese.     

Synthesis and biological characterization of a series of analogues of ω-conotoxin gvia

The 27-residue polypeptide ω-conotoxin GVIA (ω-CgTx), from the venom of the cone shell Conus geographus, blocks N-type neuronal calcium channels. It contains three disulphide bridges. We reporte here the synthesis and biological characterization of a seires of analogues in which one disulphide has been replaced by substitution of appropriate Cys residues with Ser, viz. [Ser^1,16]-ω-CgTx, [Ser^8,19]-ω-CgTx, [Ser^15,26]-ω-CgTx, [Ser¹⁶]-ω-CgTx_8-27 and [Ser¹⁵]-ω-CgTx_1-19. All syntheses were conducted manually using either Boc or Fmoc methodology. Deprotected peptides were oxidized to their bridged forms using either aerial oxidation or aqueous dimethyl sulphoxide. Peptides were purified using RP-HPLC, and their purity and identity were checked by RP-HPLC, capillary electrophoresis and mass spectrometry. Inhibition of neuronal N-type calcium channels was assessed as the inhibition of the twitch responses of rat vas deferens stimualted with single electrical pulses at 20 second intervals. None of these analogues was biologically active, suggesting that the disulphides play an important role in maintaining biological activity.     

Polymorphisms of CYP1B1 and COMT in Breast and Endometrial Cancer

CYP1B1 and COMT code for the key enzymes of catecholestrogen biosynthesis and metabolism, and their polymorphisms determine the variation of enzyme activities. RFLP analysis was used to study the allele and genotype frequency distributions of CYP1B1 polymorphisms Arg48Gly, Ala119Ser, and Val432Leu, and COMT polymorphism Val158Met among 210 breast cancer patients, 138 endometrial cancer patients, and 152 healthy women. The COMT polymorphism showed no significant association with breast or endometrial cancer. For the first time, such association was observed for the CYP1B1 polymorphisms. CYP1B1 allele C (Arg48), which codes for the enzyme more active in estradiol 4-hydroxylation, was associated with higher risk of breast (OR = 3.22, CI 2.34–4.43, P = 0.000) and endometrial (OR = 2.43, CI 1.72–3.44, P = 0.000) cancer. Similar data were obtained for CYP1B1 allele G (Ala119): OR = 2.18, CI 1.58–3.01, P = 0.000 in breast cancer and OR = 2.52, CI 1.78–3.56, P = 0.000 in endometrial cancer. Risk of endometrial but not breast cancer was significantly higher in carriers of CYP1B1 genotype Val432/Val. This was explained by stronger estrogen dependence and, consequently, higher estrogen responsiveness of the endometrium as compared with the mammary gland.     

南京汉族群体肺癌易感性相关基因的研究

为了探讨南京汉族群体肺癌易感性相关基因,我们采用1:1病例对照研究方法,以PCR—RFLP技术检测了152对肺癌和健康对照的CYP1A1、CYP2E1、GSTM1、GSTT1、GSTP1、mEH和NQO1基因的基因型并分析其与肺癌的相关性。结果发现携带CYP1A1突变基因型（wt/mt和mt/mt）的个体明显增加患肺鳞癌的风险(OR=2.31,95%CI=1.23-4.36);GSTT1（-）基因型可使肺癌发生的风险增加2.06倍（95%CI=1.30-3.24）;具有NQO1wt/mt与mt/mt基因型者发生肺癌的风险也有所增高（OR=1.66,95CI%=1.01-2.74）; CYP1A1突变基因型与GSTT1缺失基因型、CYP1A1突变基因型与NQO1突变基因型对肺癌的发生存在协同作用,同时具有两种易感基因型的个体更容易发生肺癌。研究结果表明,CYP1A1、GSTT1、NQO1基因可能与南京汉族群体肺癌遗传易感性有关,基因型之间的联合检测更有助于高危人群的筛选。Abstract: To investigate the genes related to lung cancer susceptibility in Nanjing Han population, China, a 1:1 matched case-control study was performed in which 152 hospital controls were matched to the 152 original lung cancer cases. The polymorphisms of CYP1A1, CYP2E1, GSTM1, GSTT1, GSTP1, mEH and NQO1 genes were analyzed by PCR—RFLP assay. The results showed that the heterozygote and mutation homozygote genotypes of CYP1A1 were related to the risk of squamous cell carcinoma (OR=2.31, 95%CI=1.23-4.36). The risk of suffering from lung cancer was increased 2.06-fold in the individuals with GSTT1（-） genotype (95%CI= 1.30-3.24). The genotype of NQO1 wt/mt and mt/mt was found also to be associated with the risk of lung cancer (OR=1.66,95%CI=1.01-2.74). It was shown that there was no difference in the genotype distribution of CYP2E1, GSTM1, GSTP1 or mEH between cases and controls. Furthermore, stratified analysis suggested that the combination of genotypes of both CYP1A1 and GSTT1 enzymes had a synergistic action in risk of lung cancer (OR=3.41, 95%CI =1.77-6.55). Similarly, there was a cooperation between CYP1A1 mutation genotype and NQO1 mutation genotype (OR=2.45, 95%CI=1.13-5.31). This study suggested that CYP1A1, GSTT1 and gene NQO1 polymorphisms might be associated with the susceptibility to lung cancer in Nanjing Han population. Analysis of gene-gene interactions was helpful to identification of susceptible individuals and screening high-risk population to lung cancer.