Allelotype influence at glutathione S-transferase M1 locus on breast cancer susceptibility

The influence of polymorphisms of the glutathione S-transferase gene GSTM1 in breast cancer susceptibility has been assessed in this study. Previous studies correlated the absence of the GSTM1 protein with an increased risk of developing some cancers, especially lung or bladder cancers, in heavy smokers. In this study, we determined GSTM1 polymorphisms in a population of 437 female controls from the west of France and 361 community breast cancer patients. Three distinct alleles of this gene exist: GSTM1* A, GSTM1*B and GSTM1*0 (deleted allele). Null subjects (GSTM1 null) are homozygous for this deletion. The comparative analysis of GSTM1 allelotypes in our two populations did not demonstrate a statistically significant difference in distribution (P = 0.22), although the null genotype was more frequent in cancer patients. However, breast cancer risk was increased in null subjects ≥ 50 years of age compared with non-null subjects [odds ratio = 1.99 (1.19–3.32), P = 0.009], but not in null subjects < 50 years of age compared with non-null subjects (P = 0.86). Our results suggest that the GSTM1 null genotype may play a role in post-menopausal breast cancer development. They also point to a putative protective role of the A allele in the older female control group, especially in hemizygous subjects [odds ratio = 0.42 (0.23–0.77), P = 0.03]. © 1999 Cancer Research Campaig

A cross-sectional study of self-reported chemical-related sensitivity is associated with gene variants of drug-metabolizing enzymes

BACKGROUND: N-acetyltransferases (NAT) and glutathione S-transferases (GST) are involved in the metabolism of several ubiquitous chemical substances leading to the activation and detoxification of carcinogenic heterocyclic and aromatic amines. Since polymorphisms within these genes are described to influence the metabolism of ubiquitous chemicals, we conducted the present study to determine if individuals with self-reported chemical-related sensitivity differed from controls without self-reported chemical-related sensitivity with regard to the distribution of genotype frequencies of NAT2, GSTM1, GSTT1, and GSTP1 polymorphisms. METHODS: Out of 800 subjects who answered a questionnaire of ten items with regard to their severity of chemical sensitivity 521 unrelated individuals agreed to participate in the study. Subsequently, genetic variants of the NAT2, GSTM1, GSTT1, and GSTP1 genes were analyzed. RESULTS: The results show significant differences between individuals with and without self-reported chemical-related sensitivity with regard to the distribution of NAT2, GSTM1, and GSTT1 gene variants. Cases with self-reported chemical-related sensitivity were significantly more frequently NAT2 slow acetylators (controlled OR = 1.81, 95% CI = 1.27–2.59, P = 0.001). GSTM1 and GSTT1 genes were significantly more often homozygously deleted in those individuals reporting sensitivity to chemicals compared to controls (GSTM1: controlled OR 2.08, 95% CI = 1.46–2.96, P = 0.0001; GSTT1: controlled OR = 2.80, 95% CI = 1.65–4.75, P = 0.0001). Effects for GSTP1 gene variants were observed in conjunction with GSTM1, GSTT1 and NAT2 gene. CONCLUSION: The results from our study population show that individuals being slow acetylators and/or harbouring a homozygous GSTM1 and/or GSTT1 deletion reported chemical-related hypersensitivity more frequently

Pharmacogenetics: data, concepts and tools to improve drug discovery and drug treatment

Variation in the human genome is a most important cause of variable response to drugs and other xenobiotics. Susceptibility to almost all diseases is determined to some extent by genetic variation. Driven by the advances in molecular biology, pharmacogenetics has evolved within the past 40 years from a niche discipline to a major driving force of clinical pharmacology, and it is currently one of the most actively pursued disciplines in applied biomedical research in general. Nowadays we can assess more than 1,000,000 polymorphisms or the expression of more than 25,000 genes in each participant of a clinical study – at affordable costs. This has not yet significantly changed common therapeutic practices, but a number of physicians are starting to consider polymorphisms, such as those in CYP2C9, CYP2C19, CYP2D6, TPMT and VKORC1, in daily medical practice. More obviously, pharmacogenetics has changed the practices and requirements in preclinical and clinical drug research; large clinical trials without a pharmacogenomic add-on appear to have become the minority. This review is about how the discipline of pharmacogenetics has evolved from the analysis of single proteins to current approaches involving the broad analyses of the entire genome and of all mRNA species or all metabolites and other approaches aimed at trying to understand the entire biological system. Pharmacogenetics and genomics are becoming substantially integrated fields of the profession of clinical pharmacology, and education in the relevant methods, knowledge and concepts form an indispensable part of the clinical pharmacology curriculum and the professional life of pharmacologists from early drug discovery to pharmacovigilance

Meat, vegetables and genetic polymorphisms and the risk of colorectal carcinomas and adenomas

<p>Abstract</p> <p>Background</p> <p>The risk of sporadic colorectal cancer (CRC) is mainly associated with lifestyle factors, particularly dietary factors. Diets high in red meat and fat and low in fruit and vegetables are associated with an increased risk of CRC. The dietary effects may be modulated by genetic polymorphisms in biotransformation genes. In this study we aimed to evaluate the role of dietary factors in combination with genetic factors in the different stages of colorectal carcinogenesis in a Norwegian population.</p> <p>Methods</p> <p>We used a case-control study design (234 carcinomas, 229 high-risk adenomas, 762 low-risk adenomas and 400 controls) to test the association between dietary factors (meat versus fruit, berries and vegetables) genetic polymorphisms in biotransformation genes (<it>GSTM1</it>, <it>GSTT1</it>, <it>GSTP1 </it>Ile¹⁰⁵Val, <it>EPHX1 </it>Tyr¹¹³His and <it>EPHX1 </it>His¹³⁹Arg), and risk of colorectal carcinomas and adenomas. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by binary logistic regression.</p> <p>Results</p> <p>A higher ratio of total meat to total fruit, berry and vegetable intake was positively associated with both high and low-risk adenomas, with approximately twice the higher risk in the 2^ndquartile compared to the lowest quartile. For the high-risk adenomas this positive association was more obvious for the common allele (Tyr allele) of the <it>EPHX1 </it>codon 113 polymorphism. An association was also observed for the <it>EPHX1 </it>codon 113 polymorphism in the low-risk adenomas, although not as obvious.</p> <p>Conclusion</p> <p>Although, the majority of the comparison groups are not significant, our results suggest an increased risk of colorectal adenomas in individuals for some of the higher ratios of total meat to total fruit, berry and vegetable intake. In addition the study supports the notion that the biotransformation enzymes GSTM1, GSTP1 and EPHX1 may modify the effect of dietary factors on the risk of developing colorectal carcinoma and adenoma.</p

Lack of glutathione transferase activity in intermittent claudication

Glutathione transferase activity towards trans-stilbene oxide (GT-tSBO), an enzyme involved in the detoxification of many substances such as polycyclic aromatic hydrocarbons, was studied in 77 consecutive patients operated with coronary bypass, 73 patients with intermittent claudication, 78 healthy smokers and in 38 healthy non-smokers. The mean ages of these groups were similar. Lack of GT-tSBO was recorded in 45% of coronary bypass patients, in 39% of smoking coronary bypass patients, in 61% of patients with intermittent claudication, in 41% of healthy smokers and in 31% of healthy non-smokers. The lack of GT-tSBO was significantly more frequent among patients with intermittent claudication compared to healthy non-smokers (p less than 0.01) and healthy smokers (p less than 0.025) and to smoking coronary bypass. It is concluded that the lack of GT-tSBO is found more frequently among patients with intermittent claudication and this might contribute to explain the sensitivity to smoking among these subjects

In vitro metabolism and in vivo pharmacokinetics of quinoline 3-carboxamide derivatives in various species

The metabolism of a group of quinoline 3-carboxamide derivatives was evaluated in liver microsomes from various species. In addition, metabolism data were compared with in vivo pharmacokinetics in the mouse. The studied compounds were metabolized by cytochrome P450 enzymes. Microsomal clearance was low and seemed independent of a substituent in the quinoline moiety, whereas clearance was enhanced when an ethyl group replaced the methyl group at the carboxamide position. A similar metabolism with hydroxylated and dealkylated metabolites was found in the various species, with quantitative differences due to substituent. As predicted from the in vitro studies, in vivo pharmacokinetics showed low clearance and thus high exposure of the parent compounds in the mouse. The therapeutic effect seen in the acute EAE mouse model for these related compounds seems dependent on the high exposure of parent compound rather than formation of any potentially active metabolites