Minor contribution of SMAD7 and KLF10 variants to genetic susceptibility of type 2 diabetes

BACKGROUND

Transgenic mice over-expressing SMAD7 in pancreatic beta-cells develop type 2 diabetes (T2D). The expression of SMAD7 is affected by KLF11, which contains gene variants that have previously been shown to be involved in genetic susceptibility to T2D, and by the highly homologous KLF10. This study aims to assess the genetic contribution of SMAD7 and KLF10 gene variants to T2D susceptibility in the French population.

METHODS

We screened both genes to identify rare and frequent variants by direct sequencing and then genotyped these variants. Six frequent variants of SMAD7 and six of KLF10 were analyzed in 349 T2D patients and 349 normoglycaemic adult subjects. Variants with statistically significant differences in allele and/or genotype distribution were further analyzed in a population sample of 1.712 T2D patients and 1.072 normoglycaemic subjects.

RESULTS

Two variants showed a significant association under a recessive model: The intronic SMAD7 IVS2 -21 had an odds ratio of 0.62 (P=0.007, 95% CI=0.44-0.88; P=0.034 when adjusting for age, sex and BMI by logistic regression), and the KLF10 3'UTR +1002 variant had an Odds Ratio of 0.81 (P=0.009, 95% CI=0.69-0.95; P=0.042 when adjusting for age, sex and BMI).

CONCLUSION

Although the observed association of SMAD7 and KLF10 gene variants with T2D is modest, they may weakly contribute to a particular genetic background that increases the susceptibility to development of T2D.

Hypoadiponectinaemia and high risk of type 2 diabetes are associated with adiponectin-encoding (ACDC) gene promoter variants in morbid obesity: evidence for a role of ACDC in diabesity

AIMS/HYPOTHESIS

Morbid obesity (BMI>40 kg/m(2)) affecting 0.5-5% of the adult population worldwide is a major risk factor for type 2 diabetes. We aimed to elucidate the genetic bases of diabetes associated with obesity (diabesity), and to analyse the impact of corpulence on the effects of diabetes susceptibility genes.

METHODS

We genotyped known single nucleotide polymorphisms (SNPs) in the adiponectin-encoding adipocyte C1q and collagen-domain-containing (ACDC) gene (-11,391G>A, -11,377C>G, +45T>G and +276G>T), the peroxisome proliferator-activated receptor gamma (PPARG) Pro12Ala SNP and ACDC exon 3 variants in 703 French morbidly obese subjects (BMI 47.6+/-7.4 kg/m(2)), 808 non-obese subjects (BMI<30 kg/m(2)) and 493 obese subjects (30< or =BMI<40 kg/m(2)).

RESULTS

Two 5'-ACDC SNPs -11,391G>A, -11,377C>G were associated with adiponectin levels (p=0.0003, p=0.008) and defined a "low-level" haplotype associated with decreased adiponectin levels (p=0.0002) and insulin sensitivity (p=0.01) and with a risk of type 2 diabetes that was twice as high (p=0.002). In contrast, the prevalence of the PPARG Pro12Ala was identical in diabetic and normoglycaemic morbidly obese subjects. The PPARG Pro12 allele only displayed a trend of association with type 2 diabetes in the non-obese group. ACDC exon 3 variants were associated with type 2 diabetes in the non-obese group only (odds ratio 7.85, p<0.0001). In contrast, the 5'-ACDC "low-level" haplotype was associated with type 2 diabetes in obese and morbidly obese subjects (odds ratio 1.73 and 1.92) but not in non-obese individuals.

CONCLUSIONS/INTERPRETATION

These data clarify the contribution of the 5'-ACDC SNPs to the risk of diabesity. Their interaction with corpulence suggests for the first time a different genetic profile of type 2 diabetes in morbidly obese patients compared with in less obese individuals.

Effect of common polymorphisms in the HNF4alpha promoter on susceptibility to type 2 diabetes in the French Caucasian population

AIMS/HYPOTHESIS

The gene encoding HNF-4alpha, an orphan nuclear receptor playing critical roles in embryogenesis and metabolism by regulating gene expression in pancreatic beta cells, liver, and other tissues, is localised to chromosome 20q13, where linkage to type 2 diabetes has been shown in multiple studies. As two reports have independently demonstrated a convincing association with variants adjacent to the HNF-4alpha P2 promoter in Finnish and Ashkenazi Jewish populations, we evaluated their contribution to diabetes risk in the French Caucasian population.

METHODS

Genotypes for four haplotype tag SNPs were analysed for association with diabetes in a case-control study of 744 unrelated type 2 diabetic patients and 686 normoglycaemic subjects, and for linkage in 148 diabetic families in whom significant linkage to the HNF4alpha region had been shown.

RESULTS

The association seen in the Finnish and Ashkenazi studies for SNPs rs2144908 and rs1884614 located within a haplotype block encompassing the beta cell promoter P2 of HNF-4alpha was not replicated in our study; in French Caucasians the minor allele prevalence was increased in control subjects [odds ratio (OR) 0.80, uncorrected p=0.022 for rs2144908; OR 0.82 uncorrected p=0.058 for rs1884614]. Furthermore, none of the SNPs tested in the French familial sample was associated with diabetes, nor do they appear to contribute to the linkage.

CONCLUSIONS/INTERPRETATION

None of the previously associated SNPs confer an increased risk for diabetes in French Caucasians. A large meta-analysis of association studies will determine whether there is a consistent association between particular SNPs upstream of HNF-4alpha and type 2 diabetes in several ethnic groups.

Endothelin-converting enzyme-1 is expressed in human cerebral cortex and protects against Alzheimer's disease

Cerebral accumulation of beta-amyloid peptide (A beta) is a central event in the pathogenesis of Alzheimer's disease (AD). Endothelin-converting enzyme-1 (ECE-1) is a candidate A beta-degrading enzyme in brain, but its involvement in AD pathogenesis was never assessed. We first performed brain immunocytochemistry, using a monoclonal anti-ECE-1 antibody, and observed neuronal ECE-1 expression in various cortical regions of nondemented subjects. In the hippocampus, ECE-1 immunoreactivity showed a stereotypical pattern inversely correlated with susceptibility to A beta deposition, further suggesting a physiological role in A beta clearance. In order to undertake a genetic association study, we identified a functional genetic variant (ECE1B C-338A) located in a regulatory region of the ECE1 gene. We showed that the A allele is associated with increased transcriptional activity in promoter-reporter gene assays and with increased ECE-1 mRNA expression in human neocortex. In a case-control study involving 401 patients with late-onset AD and 461 aged controls, we found that homozygous carriers of the A allele had a reduced risk of AD (OR=0.47, 95% CI 0.25-0.88). This finding was strengthened by the analysis of two other genetic variants of the ECE1 gene, which showed that the genetic association is extended over at least 13 kilobases of the gene sequence. Our results suggest that ECE-1 expression in brain may be critical for cortical A beta clearance and offer new potential targets for therapeutic interventions in AD.

Overall alcohol intake, beer, wine, and systemic markers of inflammation in western Europe: results from three MONICA samples (Augsburg, Glasgow, Lille)

AIM

Anti-inflammatory effects of moderate alcohol consumption have been proposed to explain why moderate alcohol intake lowers coronary heart disease risk. We investigated the relationship between overall alcohol, beer or wine consumption and markers of systemic inflammation in three different geographical areas in Europe.

METHODS AND RESULTS

Cross-sectional samples, each representative of the general population from Germany, Scotland, and France (MONICA Augsburg 1994/95, 2275 men and 2186 women, 25-74 years; Glasgow MONICA 1994/95, 561/616, 25-74 years, and MONICA Lille 1994/95, 581/574, 35-64 years) were studied. Alcohol intake was assessed by standardized interview. Adjusted means of C-reactive protein (CRP), fibrinogen, white blood cell (WBC) count, plasma viscosity (PV), and albumin were calculated among categories of alcohol intake, and separately for beer or wine consumption, by multiple linear regression. Self-reported moderate daily alcohol intake up to 40 g was associated with lower concentrations of CRP, fibrinogen, PV and WBC count, compared to non-drinking and heavy drinking, even after adjustment for various potential confounders.

CONCLUSIONS

Moderate consumption of either wine or beer is associated with lower levels of systemic inflammatory markers in three different European areas, suggesting that ethanol itself might be largely responsible for the potential anti-inflammatory effects of these beverages.

Islet-brain1/C-Jun N-terminal kinase interacting protein-1 (IB1/JIP-1) promoter variant is associated with Alzheimer's disease

Islet-brain1 (IB1) or c-Jun NH2 terminal kinase interacting protein-1 (JIP-1), the product of the MAPK8IP1 gene, functions as a neuronal scaffold protein to allow signalling specificity. IB1/JIP-1 interacts with many cellular components including the reelin receptor ApoER2, the low-density lipoprotein receptor-related protein (LRP), kinesin and the Alzheimer's amyloid precursor protein. Coexpression of IB1/JIP-1 with other components of the c-Jun NH2 terminal-kinase (JNK) pathway activates the JNK activity; conversely, selective disruption of IB1/JIP-1 in mice reduces the stress-induced apoptosis of neuronal cells. We therefore hypothesized that IB1/JIP-1 is a risk factor for Alzheimer's disease (AD). By immunocytochemistry, we first colocalized the presence of IB1/JIP-1 with JNK and phosphorylated tau in neurofibrillary tangles. We next identified a -499A>G polymorphism in the 5' regulatory region of the MAPK8IP1 gene. In two separate French populations the -499A>G polymorphism of MAPK8IP1 was not associated with an increased risk to AD. However, when stratified on the +766C>T polymorphism of exon 3 of the LRP gene, the IB1/JIP-1 polymorphism was strongly associated with AD in subjects bearing the CC genotype in the LRP gene. The functional consequences of the -499A>G polymorphism of MAPK8IP1 was investigated in vitro. In neuronal cells, the G allele increased transcriptional activity and was associated with an enhanced binding activity. Taken together, these data indicate that the increased transcriptional activity in the presence of the G allele of MAPK8IP1 is a risk factor to the onset of in patients bearing the CC genotype of the LRP gene.

Polymorphisms in the insulin response element of APOC-III gene promoter influence the correlation between insulin and triglycerides or triglyceride-rich lipoproteins in humans

OBJECTIVE

To assess whether the -455 and -482 mutations in APOC-III gene insulin response element affect the relationships between plasma insulin and triglyceride-rich lipoprotein levels.

DESIGN

Population-based studies.

SUBJECTS

The population sample was composed of 983 subjects (485 men and 498 women), aged between 35 and 65 y, randomly sampled from the electoral rolls in Northern France and stratified on gender and 10 y age groups.

MEASUREMENTS

Plasma triglyceride, apolipoprotein C-III, apoB, LpC-III:B and LpE:B lipoprotein particles and insulin levels were measured. Two polymorphisms in APOC-III gene insulin response element (T-->C at -455 and/or C-->T at -482) were determined.

RESULTS

Plasma insulin was positively correlated to triglyceride levels (P<0.0001), apo C-III (P<0.003), LpC-III:B (P<0.0001), apoB (P<0.0001) and LpE:B (P<0.0001). This association differed significantly according to APOC-III insulin response element polymorphisms. The relationship between insulin and LpC-III:B (P<0.02) or apoB (P<0.02) was greater in women bearing the C allele of -455 than the T allele. Similarly, the relationship between insulin and LpC-III:B (P<0.02) or LpE:B (P<0.05) was greater in women bearing the T allele of -482 than the C allele. There was no evidence for any effect in men.

CONCLUSION

These results suggest that the relationship between plasma insulin and triglyceride-rich lipoprotein levels is partly influenced by polymorphisms in APOC-III insulin response element.

The angiotensin I converting enzyme gene as a susceptibility factor for dementia

The frequency of a genetic susceptibility vascular factor, the deletion (D) allele of the angiotensin I converting enzyme gene (ACE), coding for a key enzyme of the renin angiotensin system, was characterized in two independent case--control studies. The results of the current study suggest that bearing at least one ACE D allele is a risk factor to develop dementia for subjects older than 74 years. This observation reinforces the hypothesis of a major implication of vascular risk factors in the occurrence of all types of dementia.

Impact of sulfonylurea receptor 1 genetic variability on non-insulin-dependent diabetes mellitus prevalence and treatment: a population study

The high affinity sulfonylurea receptor 1 (SUR1) is involved in the metabolism of glucose in pancreatic beta-cells. We investigated the impact of the SUR1 intron 16-3t-->c polymorphism on non-insulin-dependent diabetes mellitus (NIDDM) prevalence in a large representative sample of French men and women, 35-64 years old, and explored potential relationships between the SUR1 intron 16 -t-->c polymorphism and sulfonylurea therapy efficiency. This study took place in Lille (northern), Strasbourg (eastern), and Toulouse (southern France). One hundred and twenty-two subjects with NIDDM were registered. We stratified NIDDM subjects according to their medical treatment: sulfonylureas (n = 70) versus other treatments (n = 50). From the three populations, a control group was selected (n = 1,250). Subjects carrying the cc intron 16 genotype had an increased risk of NIDDM [odds ratio (OR) = 1.76, 95% confidence interval (CI) 1.10-2.80; P = 0.017]. Subjects bearing at least one -3c allele and treated with sulfonylurea agents had fasting plasma triglyceride concentrations 35% lower than subjects that were tt homozygous (P = 0.026), whereas no difference could be detected between genotypes in NIDDM subjects treated with other treatments. The SUR1 intron 16 -3t-->c polymorphism was associated with an increased susceptibility to NIDDM in this population study, and seems to modulate the sulfonylurea therapy efficiency on hypertriglyceridemia reduction. This observation may help to better target the various therapies available for treatment of NIDDM.

The human G-protein β3 subunit C825T polymorphism is associated with coronary artery vasoconstriction

AIMS

Abnormal coronary vasomotion plays a role in the clinical expression of coronary artery disease. We hypothesized that the functional C825T polymorphism located in the ubiquitous G-protein beta3 subunit, implicated in the cellular signal transduction of many receptors, could modify artery coronary vasomotion. We assessed the potential association of the pertussis toxin-sensitive G protein beta3 subunit (GNB3) gene C825T polymorphism on coronary vasomotion in humans.

METHODS AND RESULTS

We examined the response of angiographically normal human coronary arteries (n=131) after intravenous injection of methylergonovine maleate, a vasoconstrictor, followed by injection of isosorbide dinitrate, a vasodilator, according to GNB3 genotypes. Coronary vasomotion was assessed with quantitative coronary angiography. Subjects bearing at least one T allele had greater susceptibility to vasoconstriction in response to methylergonovine maleate than CC subjects, whereas vasodilation in response to isosorbide dinitrate did not differ among the different genotypes.

CONCLUSION

The C825T polymorphism of the G-protein beta3 subunit may be a genetic determinant of coronary artery vasomotion in humans.

VLDL receptor polymorphism, cognitive impairment, and dementia

OBJECTIVE

Clinical, epidemiologic, and pathologic observations suggest that vascular risk factors are associated with impaired cognition. Previous studies supported an association between cognitive decline and APOE. Although the underlying mechanism is not clear, it might involve apoE receptors, such as the very low density lipoprotein receptor.

METHODS

The impact of a polymorphic triplet repeat in the very low density lipoprotein receptor gene (VLDLR) on cognitive function was examined in two independent studies: a population study involving 221 demented subjects compared with 249 control subjects and a clinical study involving 124 demented subjects compared with 179 control subjects.

RESULTS

In the population study, the presence of the VLDLR-5-repeat allele was associated with a relative risk of dementia (OR, 1.9; 95% CI, 1.2 to 3.0). This result was confirmed in the clinical study (OR, 8.1; 95% CI, 4.4 to 15.1) and was more pronounced in subjects with mixed or vascular dementia than in patients with AD.

CONCLUSION

The VLDLR-5-repeat allele may constitute a genetic susceptibility factor for dementia, particularly in the presence of vascular risk factors. This observation suggests the influence of vascular risk factors in the occurrence of dementia.

An uncoupling protein 3 gene polymorphism associated with a lower risk of developing Type II diabetes and with atherogenic lipid profile in a French cohort

AIMS/HYPOTHESIS

The UCP2-UCP3 gene region has been previously associated with obesity and diabetes. In a large representative cohort of Northern France (MONICA project), we studied the effect of a recently reported C/T polymorphism located in the 5' sequences of the UCP3 gene on anthropometric measurements and lipid profile. We also examined the association of this polymorphism with obesity and Type II (non-insulin-dependent) diabetes mellitus.

METHODS

The -55 C/T polymorphism of the UCP3 gene has been genotyped in 1155 subjects from the MONICA project. Association studies were done with diabetes, obesity and related phenotypes. Results were ascertained in a second cohort of well-characterized Type II diabetic and control subjects.

RESULTS

The variant T allele was associated with a decreased risk of developing Type II diabetes. Frequencies of the T allele were 13.3% compared with 22%, p = 0.04, in the diabetic and control groups, respectively. This observation was confirmed in the second cohort of French Type II diabetic (n = 171) and control (n = 124) subjects: 17.8% compared with 25%, p = 0.03. Moreover, subjects bearing the TT genotype had higher plasma total cholesterol and LDL-cholesterol concentrations (p = 0.0006 and p = 0.001, respectively) than subjects bearing wild or heterozygous genotypes.

CONCLUSION/INTERPRETATION

The UCP3 -55 C/T polymorphism was associated with a higher atherogenic profile and modified the risk for the development of Type II diabetes.

Very low density lipoprotein receptor in Alzheimer disease

The apolipoprotein (APO) E4 isoform is associated with an accelerated rate of Alzheimer disease (AD) expression in sporadic as well as late-onset familial forms of the disease but the precise mechanism is unknown. In an attempt to approach the possible mechanisms involved, APOE receptors have been studied. They all belong to the low density lipoprotein (LDL) receptor family and share the same structural motifs. Some of them are preferentially expressed in the brain such as the LDL receptor related protein, the apolipoprotein E receptor 2, and the very low density lipoprotein (VLDL) receptor. These receptors have been suspected to be involved in Alzheimer disease at various levels. Among them, the VLDL receptor was extensively explored. Although genetic studies conducted on a polymorphism in the promoter of the VLDL receptor in Japanese and Caucasian populations gave divergent results, this does not exclude a possible involvement of the VLDL receptor in AD.

Gender related association between genetic variations of APOC-III gene and lipid and lipoprotein variables in northern France

The goal of the present study was to assess the impact of variability at the APOC-III insulin response element (APOC-III IRE) genetic locus on lipid, lipoprotein and complex lipoprotein particle levels as well as on the risk of dyslipidemia, in the population of northern France. To this end, 590 men and 579 women were randomly selected in the urban community of Lille in the framework of the MONICA project. Three polymorphisms, -482, -455 in the APOC-III insulin response element (IRE) and SstI in the 3'-noncoding region of the APOC-III gene locus were assessed. Compared to the most common alleles, the rare alleles of -482 and -455 were associated with increased levels of apoB-containing particles (LDL-cholesterol, apoB) and of triglyceride-related markers (apoC-III and LpC-III:B) in women, but not in men, suggesting a gender-related impact of APOC-III polymorphisms on these variables. Similarly, triglycerides, LpC-III:B and apoB were higher in women bearing the rare allele of SstI than in those with the most common allele. There was no evidence for any significant association between any of the -482, -455, and SstI alleles and lipid disorders (mixed hyperlipidemia, hypertriglyceridemia and hypercholesterolemia) in this sample of randomly selected men and women from northern France. In contrast, the prevalence of the haplotype that combined the rare alleles of the -482 and -455 sites was increased only in women with hypertriglyceridemia. Therefore, although the individual risk of hypertriglyceridemia is increased in women with the haplotype T, C at -482, -455, it appears that the -482, -455 and SstI APOC-III gene polymorphisms are not major contributors to the risk of dyslipidemia in the population of northern France.

Intronic polymorphism in the fatty acid transport protein 1 gene is associated with increased plasma triglyceride levels in a French population

Fatty acids play important biological roles in cells. The precise mechanism whereby fatty acids cross the plasma membrane is still poorly understood. They can cross membranes because of their hydrophobic properties and/or be transported by specific proteins. Recently, a gene coding for fatty acid transport protein 1 (FATP1), an integral plasma membrane protein implicated in this process, was cloned in humans. We screened the gene by single-strand conformation polymorphism analysis and detected an A/G polymorphism in intron 8. We analyzed the potential relations of this genetic polymorphism with various obesity markers and with plasma lipid profiles in a random sample of 1144 French subjects aged 35 to 64 years. We detected statistically significant associations between this FATP1 A/G polymorphism and an increase in plasma triglyceride levels, mainly in women. These results suggest that genetic variability in the FATP1 gene may affect lipid metabolism, especially in women, and reinforce the potential implication of FATP1 in lipid homeostasis.

Interactions between apolipoprotein E and apolipoprotein(a) in patients with late-onset Alzheimer disease

BACKGROUND

Apolipoprotein(a) [apo(a)], the distinctive, highly polymorphic glycoprotein of lipoprotein(a), shares a series of common features with apolipoprotein E (apoE), which is implicated in the development of Alzheimer disease.

OBJECTIVE

To determine whether apo(a) is associated with Alzheimer disease.

DESIGN

Case-control study.

SETTING

University hospitals in Europe.

PARTICIPANTS

285 patients with Alzheimer disease and 296 controls.

MEASUREMENTS

Plasma lipoprotein(a) levels, size of the apo(a) isoforms, and apoE and apo(a) genotyping.

RESULTS

Among carriers of the apoE epsilon4 allele, lipoprotein(a) was associated with a progressive, age-dependent increased risk for late-onset Alzheimer disease (odds ratio for patients >80 years of age, 6.0 [95% CI, 1.2 to 30.8]; P<0.01). Among noncarriers older than 80 years of age, lipoprotein(a) was associated with a reduced risk for Alzheimer disease (odds ratio, 0.4 [CI, 0.2 to 0.91; P<0.05).

CONCLUSIONS

In this convenience sample, lipoprotein(a) was an additional risk factor for late-onset Alzheimer disease in carriers of the apoE epsilon4 allele. However, lipoprotein(a) may protect against late-onset Alzheimer disease in noncarriers.

The renin angiotensin system and Alzheimer's disease

Recent reports sustain the hypothesis of tight links between vascular and neurodegenerative diseases: associations between atherosclerosis lesions and Alzheimer's disease (AD), increased risk of AD for hypertensive subjects, decreased risk of dementia for elderly treated with hypotensive drugs, and a major impact of apolipoprotein E polymorphism, a protein of the lipid metabolism, on the occurrence of AD. All these results suggest that vascular determinants, both environmental and genetic, may predispose to or speed up dementia. As a major player of vascular homeostasis, the renin angiotensin system (RAS) proteins constitute an interesting source of candidate genes. Among these, the angiotensin I-converting enzyme gene (ACE), a central enzyme of the RAS, presents in its sequence a deletion (D)/insertion (I) polymorphism associated with variations of plasma ACE levels and with the risk of myocardial infarction. We explored the impact of this genetic polymorphism on the risk of cognitive impairment and of dementia in several epidemiological studies. Physiopathological hypotheses suggest a possible involvement of the RAS proteins in the occurrence and evolution of AD. Moreover, although inconsistent, several results of case-control studies tend to suggest that the ACE I/D genetic polymorphism may constitute a genetic susceptibility factor for dementia, reinforcing the hypothesis of a major implication of vascular risk factors in the occurrence of dementia.

Impact of polymorphisms of the human beta2-adrenoceptor gene on obesity in a French population

OBJECTIVE

To investigate the impact of two common polymorphisms in the human beta2-adrenoceptor gene (Gly16Arg and Gln27Glu substitutions) on obesity and anthropometric measurements as well as blood variables in a large sample of a French population.

DESIGN AND SUBJECTS

Within the framework of the WHO-MONICA project, a population study composed of 1195 subjects aged 35-64 y was randomly sampled from the electoral rolls of the Urban Community of Lille, in northern France. Subjects without any medical treatment (for hypercholesterolaemia, hypertension or diabetes mellitus) susceptible to interfere with body weight and biological variables were selected (n = 836, 419 men/417 women, age = 49.5+/-8.1 y, body mass index (BMI) = 25.7+/-4.4 kg/m2). Subjects with a body mass index > or = 30 kg/m2 were considered as obese (n = 119, age = 49.5+/-8.2 y, BMI = 33.9+/-3.3 kg/m2 range 30-44).

MEASUREMENTS

Genotyping was carried out with allele-specific oligonucleotides hybridization. Association between genotypes and various obesity markers (body weight, body mass index, waist and waist-to-hip ratio), lipid, glucose and insulin variables were studied.

RESULTS

The Gly16Arg and Gln27Glu polymorphisms were in complete linkage disequilibrium. Gln27Gln subjects had an increased risk of obesity (odds ratio (OR) = 1.77, 95% CI 1.19-2.62, P = 0.005). This effect was mainly detected in men (OR = 2.40, 95% CI 1.34-4.27, P = 0.003). Men bearing the Gln27Gln genotype had higher body weight, BMI, waist and hip circumferences and waist-to-hip ratio than others. Moreover, if Gln27Gln men carried in addition the Arg16 allele, the increase in body weight, BMI and waist-to-hip ratio was more important.

CONCLUSION

Our results suggest that genetic variability of the beta2-adrenoceptor gene is implicated in body weight regulation and in the onset of obesity in French men.

Impact of the Peroxisome Proliferator Activated Receptor gamma2 Pro12Ala polymorphism on adiposity, lipids and non-insulin-dependent diabetes mellitus

OBJECTIVE

The Pro12Ala polymorphism of the Peroxisome Proliferator Activated Receptor gamma2 (PPARgamma2) gene has been inconsistently associated with body mass index variations and non-insulin-dependent diabetes mellitus (NIDDM). We investigated the impact of this polymorphism on obesity markers, lipid and glucose variables in a sample of French subjects and evaluated its possible role in the onset of NIDDM.

DESIGN AND SUBJECTS

Within the framework of the WHO-MONICA project, a population study composed of 1195 subjects aged 35-64 y was randomly sampled from the electoral rolls of the urban community of Lille, in northern France. Subjects receiving medical treatment for hypercholesterolemia, hypertension or diabetes mellitus were excluded for the analyses, to avoid any interferences between medical treatment and biological variables. This resulted in a sample size of 839 subjects (421 men/418 women, age=49.4+/-8.1 y, body mass index (BMI)=25.7+/-4.4 kg/m2). To evaluate the role of the Pro12Ala polymorphism in the onset of NIDDM, we evaluated its distribution in 170 Caucasian NIDDM subjects from a clinical series (117 men/53 women, age=62.3+/-9.0 y, BMI=30.1+/-3.6 kg/m2).

MEASUREMENTS

The PPARgamma2 Pro12Ala polymorphism genotyping was carried out with allele specific oligonucleotides hybridisation. Data were statistically analysed for association with various obesity markers (body weight (BW), BMI, waist-to-hip ratio (WHR), plasma leptin concentrations, lipid and glucose variables.

RESULTS

In the WHO-MONICA population, the Ala allele frequency was 0.11. The presence of the Ala allele was significantly associated with higher body weight (P=0.002), BMI (P=0.02), height (P=0.02) and waist circumference (P=0.04). Increased plasma concentrations of total cholesterol (P=0.01), LDL-cholesterol (P=0.004) and apolipoprotein B (P=0.01) were also detected in Ala allele bearers. The distribution of the Pro12Ala polymorphism was similar in NIDDM subjects (Ala allele frequency: 0.10) and in the WHO-MONICA population subjects.

CONCLUSION

Our results suggest that genetic variability of PPARgamma2 affects body weight control and lipid homeostasis in humans and do not support a significant role for the PPARgamma2 Pro12Ala polymorphism in the aetiology of NIDDM. International Journal of Obesity (2000) 24, 195-199

Effect of the angiotensin I-converting enzyme I/D polymorphism on cognitive decline. The EVA Study Group

Several clinical, epidemiological, and pathological observations suggest that vascular risk factors are associated with cognitive performances. The renin-angiotensin system components, major determinants of the cardiovascular system, are expressed in the brain. To estimate their potential impact on cognitive performances, we studied the association between cognitive functioning and an insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene. In a sample of 1168 highly performing subjects (59-71 years), DD homozygotes had the lowest cognitive scores as evaluated by the Mini-Mental State Examination. Cognitive decline at 4-year follow-up (defined as the loss of at least 3 points in Mini-Mental State Examination score) was more prevalent in these subjects, the odds ratio being equal to 1.53 (95% CI: 1.04-2.24) with subjects ID as reference class. Moreover, the combined effect of the presence of at least one APOE epsilon4 allele and ACE DD homozygosity was a risk factor for cognitive decline. This report reinforces the hypothesis of an influence of cardiovascular risk factors on cognitive performances.

Is the LDL receptor-related protein involved in Alzheimer's disease?

LDL-related protein receptor (LRP) is the main receptor in the brain for apolipoprotein E. Moreover, the LRP gene is located on chromosome 12, the site of a potential Alzheimer's disease (AD) locus. We explored the association between the LRP gene and AD in 600 French Caucasian patients (37.8% men, mean age 72.0+/-8.0 years, mean age at onset 68.7+/-8.1 years) and age-matched controls (n=646, 37.0% men, mean age 72.5+/-8.2 years) and observed an association between a (TTTC) repeat at the 3' end of an Alu sequence in the LRP gene and the risk of developing AD. Three alleles were detected in this population [corresponding to 83, 87, and 91 base pairs (bp)], the 91-bp allele being associated with an increased risk of developing AD [all patients: odds ratio (OR) 1.6, P<0.01; late-onset AD: OR 1.8, P<0.01]. This suggests an association between the LRP locus and AD. However, in the light of studies related to the exon 3 LRP polymorphism and given the low strength of the association reported here, a biologically active variant may exist on chromosome 12, either in the LRP gene itself or in another gene in the vicinity.

The very low density lipoprotein (VLDL) receptor is a genetic susceptibility factor for Alzheimer disease in a European Caucasian population

The epsilon4 allele of the apolipoprotein E gene (APOE) constitutes a major genetic susceptibility factor for Alzheimer disease (AD). Recently, a polymorphic triplet (CGG) in the very low density lipoprotein receptor (VLDL-R) gene, coding for a receptor binding only apoE-containing lipoproteins, was associated with AD in a Japanese population but not in Caucasian American populations. We explored this association and the potential interaction with the APOE polymorphism in a Caucasian sample of sporadic AD and control subjects of similar ages of European origin. The allelic distribution of the VLDL-R polymorphism differed significantly between Japanese and Caucasian populations (p < 0.0001). However, in our population, the presence of at least one VLDL-R 5 repeat allele increased significantly (p < 0.0003) the probability to develop AD after 65 years of age in APOE epsilon4 allele bearers.

A genetic polymorphism of the peroxisome proliferator-activated receptor gamma gene influences plasma leptin levels in obese humans

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a transcription factor implicated in adipocyte differentiation, lipid and glucose metabolism. A polymorphism corresponding to a silent C-->T substitution was detected in exon 6 of the PPAR gamma gene. We analysed the relationships between this genetic polymorphism and various markers of the obesity phenotype (body weight, body mass index, waist:hip ratio and plasma leptin levels) in a representative sample of 820 men and women living in northern France. The frequencies of the C and T alleles were 0.860 and 0.140 respectively. In the whole sample no association of the polymorphism with the markers tested was observed but a statistically significant interaction ( P < 0.03) existed between this polymorphism and body mass index for plasma leptin levels. This result suggested that the impact of the PPAR gamma gene polymorphism on plasma leptin levels differed according to the BMI of the subjects. Indeed, obese subjects (BMI >30 kg/m2) bearing at least one T allele ( CT + TT ) had higher plasma leptin levels than subjects who did not (35.0 +/- 17.4 ng/ml versus 28.3 +/- 14.8 ng/ml respectively; P < 0.001). This effect existed in both genders, despite the higher plasma leptin levels observed in women. The plasma leptin level increase was not associated with elevation of body mass index, even though these two variables were highly correlated. Thus for a given leptin level the BMI was relatively lower in obese subjects carrying at least one T allele than in obese CC homozygotes. Our results show that in obese subjects variability within the PPAR gamma gene locus is associated with circulating leptin levels and may modify the relationship between leptin levels and adipose tissue mass.

Dual determination of angiotensin-converting enzyme and angiotensin-II type 1 receptor genotypes as predictors of restenosis after coronary angioplasty

This study sought to assess the potential influence of the angiotensin-converting enzyme (ACE) and angiotensin II type 1 (AT1) receptor gene polymorphisms on restenosis after coronary balloon angioplasty. The authors conclude that screening for genetic suspectibility to restenosis based on genotyping of ACE and AT1 receptor polymorphisms before conventional balloon angioplasty is not clinically useful.

The role of a triplet repeat sequence of the very low density lipoprotein receptor gene in plasma lipid and lipoprotein level variability in humans

The biological role of the very low density lipoprotein receptor (VLDL-R) in humans is not yet elucidated. This cellular receptor binds apolipoprotein E (apoE)-containing lipoparticles and is mainly expressed in peripheral tissues. The VLDL-R gene contains a polymorphic triplet (CGG) repeat located 19 bp upstream of the initiation codon. We explored the allelic distribution of this repeat in 1384 subjects of European Caucasian origin, 609 of them surviving a myocardial infarction. Six alleles corresponding to 5, 6, 7, 8, 9, and 11 repeats were detected in this population. The alleles 5, 8, and 9 were the most frequent, with frequencies of 0.413, 0.275, and 0.292, respectively. No association was found between the VLDL-R polymorphism and myocardial infarction. In controls without lipid lowering treatment, a statistically significant interaction between VLDL-R genotype and apoE phenotype was found for plasma triglycerides (P < .04), suggesting a gene-gene interaction. There was also a main effect of the VLDL-R polymorphism on LpE:B and LpA-I. The VLDL-R 9 allele was associated with lower levels of plasma LpE:B (P < .05) and higher concentrations of plasma LpA-I (P < .01) than the other alleles. These results suggest that VLDL-R has a modest influence on circulating lipoproteins in humans.

D allele of the angiotensin I-converting enzyme is a major risk factor for restenosis after coronary stenting

BACKGROUND

Although intracoronary stent implantation significantly reduces restenosis compared with balloon angioplasty, a minority of patients still develop restenosis predominantly due to neointimal hyperplasia. Experimental studies suggest that the renin-angiotensin system is involved in neointimal hyperplasia after arterial injury. In humans, the plasma and cellular levels of ACE are associated with an I/D genetic polymorphism in the ACE gene, DD patients having higher levels.

METHODS AND RESULTS

We investigated a possible relation between the ACE I/D polymorphism and restenosis in 146 patients who underwent successful implantation of a Palmaz-Schatz stent and had 6-month follow-up angiography. The minimal lumen diameter (MLD) before and after the procedure did not differ significantly among the three groups of genotypes (DD, ID, and II). At follow-up, MLD had a significant inverse relationship to the number of D alleles present (DD, 1.65 +/- 0.71 mm; ID, 1.84 +/- 0.60 mm; II, 2.05 +/- 0.61 mm; P < .007). Late luminal loss during the follow-up period was significantly related to the number of D alleles (DD, 0.89 +/- 0.61 mm; ID, 0.60 +/- 0.52 mm; II, 0.40 +/- 0.53 mm; P < .0001). The relative risk of restenosis (defined as a > 50% diameter stenosis at follow-up) approximated by the adjusted odds ratio was 2.00 per number of D alleles (95% confidence interval, 1.03 to 3.88, P < .04).

CONCLUSIONS

The ACE I/D polymorphism influences the level of late luminal loss after coronary stent implantation. These results suggest that the renin-angiotensin system may be implicated in the pathogenesis of restenosis after coronary stenting.

Association of angiotensin converting enzyme and angiotensin II type 1 receptor genotypes with left ventricular function and mass in patients with angiographically normal coronary arteries

OBJECTIVE

To analyse the potential association of the angiotensin converting enzyme (ACE) and angiotensin II type 1 receptor (AT1R) gene polymorphisms on left ventricular function and mass in patients with normal coronary arteries.

DESIGN

Consecutive sample.

SETTING

University hospital.

SUBJECTS

141 consecutive white patients referred for coronary angiography and with angiographically normal coronary arteries. Patients with valvar diseases, cardiomyopathies, or a history of myocardial infarction were excluded.

MAIN OUTCOME MEASURES

Left ventricular variables were measured for all patients. The ACE and AT1R genotypes were determined with a polymerase chain reaction based protocol using DNA prepared from white blood cells. A general linear model was used to compare data according to the ACE and to the AT1R genotypes.

RESULTS

A strong association was observed between left ventricular mass and systemic hypertension (mean (SD) hypertension: 114 (31) g/m2; no hypertension 98 (23) g/m2; P < 0.003). However, no influence of ACE and AT1R polymorphisms on left ventricular mass was found, regardless of systemic hypertension. The subjects homozygous for the AT1R CC mutation had a significantly lower ejection fraction than those with allele A (AC+AA) (mean (SD) 62(12)% and 68(10)%, respectively, P < 0.05). No synergistic interaction of ACE and AT1R gene polymorphisms on left ventricular function and mass was found.

CONCLUSIONS

These data do not support an association of the ACE and AT1R genotypes on left ventricular hypertrophy in white patients with normal coronary arteries.

The angiotensin II type 1 receptor gene polymorphism is associated with coronary artery vasoconstriction

OBJECTIVES

This study sought to assess the potential association of the angiotensin-converting enzyme (ACE) and angiotensin II type 1 (AT1) receptor gene polymorphisms on coronary vasomotion in humans.

BACKGROUND

Abnormal coronary vasomotion plays a role in the clinical expression of coronary atherosclerosis. The components of the renin-angiotensin system are important determinants of vasomotor tone. Furthermore, epidemiologic evidence suggests that these components are involved in the pathogenesis of coronary artery disease. Indeed, two genetic polymorphisms of the ACE and AT1 receptor genes were synergistically associated with the occurrence of myocardial infarction. The influence of these genetic polymorphisms on the risk of myocardial infarction may be related, at least in part, to a deleterious effect on coronary vasomotion.

METHODS

We studied the response of angiographically normal human coronary arteries after intravenous injection of methylergonovine maleate, a potent vasoconstrictor whose effects have been previously explored in various aspects of coronary artery disease. We characterized the ACE and AT1 receptor genotypes in a consecutive series of 140 patients with normal coronary arteries. Coronary vasomotion was assessed with quantitative coronary angiography.

RESULTS

No effect of the ACE gene polymorphism was detected. Conversely, the patients carrying the AT1 receptor CC genotype (n = 13) had significantly greater vasoconstriction in distal coronary vessels (p < 0.009).

CONCLUSIONS

The AT1 receptor gene polymorphism is associated with coronary vasomotion in humans.

The deletion allele of the angiotensin I converting enzyme gene as a genetic susceptibility factor for cognitive impairment

Experimental evidences suggest an implication of the renin angiotensin system (RAS) as a potential determinant of cognitive functions. To explore this hypothesis, we compared the distribution of an insertion (I)/deletion (D) polymorphism of the gene coding for the angiotensin I converting enzyme (ACE), a key enzyme of the RAS, in 228 elderly with cognitive impairment to that of 255 controls. The ACE D allele frequency was higher in the group with cognitive impairment (0.594) than in controls (0.514) (P < 0.02). The ACE DD genotype carriers had an increased risk of cognitive impairment (OR = 1.60, 95% CI (1.04-2.36), P < 0.03), independent of other risk factors of cognitive impairment: age, gender and presence of the apolipoprotein E epsilon 4 allele. This association was stronger in men (OR = 3.25, 95% CI (1.40-7.58), P < 0.006). This result suggests a possible implication of the RAS in human brain and cognitive functions.

Interaction with DNA of oligopeptides related to the Arc repressor

Three different peptides, A13, A14x2 and A20, related to the Arc repressor from Salmonella phage P22, were synthesized. They all contained the 13 N-terminal residues of Arc known to form a beta-sheet interacting with the operator OArc. In the case of A20, the tripeptide Lys-Trp-Lys was added in the C-terminal position because of its propensity to increase affinity to DNA. The interaction of the three peptides with OArc and with other related (OMnt from the same phage) and unrelated oligonucleotides was followed using circular dichroism, filter binding assays and DNaseI protection experiments. While Kd = 10(-9) M for the protein, 8.7 x 10(-5) M and 7.7 x 10(-6) M Kd values were obtained for A14x2 and A20 interacting with OArc.

Relation between the deletion polymorphism of the angiotensin-converting enzyme gene and late luminal narrowing after coronary angioplasty

BACKGROUND

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been implicated in the pathogenesis of coronary artery disease. The deletion allele is strongly associated with the level of circulating ACE and is a potent risk factor for myocardial infarction. Recently, the deletion allele was also associated with the occurrence of visually diagnosed restenosis after percutaneous transluminal coronary angioplasty (PTCA) in a selected population of patients with acute myocardial infarction.

METHODS AND RESULTS

We investigated the influence of the ACE I/D polymorphism on the occurrence of restenosis after PTCA with the use of quantitative coronary angiography. ACE I/D genotypes were characterized in 118 consecutive patients who had one-vessel disease and were undergoing systematic angiographic follow-up. Coronary angiograms were analyzed before and after PTCA and at follow-up (7.4 +/- 3.0 months). Before PTCA, there were no clinical or angiographic differences among the three groups of genotypes (DD, n = 39; ID, n = 62; II, n = 17). After PTCA, the mean differences in minimal luminal diameter between post-PTCA and pre-PTCA angiograms (acute gain) were identical in the three groups, as was the mean percent residual stenosis. At follow-up angiography, the mean difference in minimal coronary luminal diameter between post-PTCA and follow-up angiograms (late loss) was not significantly different in the three groups of genotypes. The percentage of patients with restenosis defined as a > 50% stenosis was identical in the three groups.

CONCLUSIONS

In this quantitative study, the I/D polymorphism of the ACE gene had no influence on the occurrence of restenosis after coronary angioplasty.

Influence of the methyl substituents of a thiazole-containing lexitropsin on the mode of binding to DNA

We have studied the DNA-binding properties of two thiazole-containing analogues of netropsin which differ by the absence (Thia-Nt) or presence (Methia-Nt) of methyl groups on the thiazole rings. The mode of binding to DNA of the two lexitropsins was investigated by circular dichroism, electric linear dichroism and viscosity measurements. The spectroscopic and hydrodynamic results indicate that the non-methylated lexitropsin binds to the minor groove of DNA, whereas the methylated analogue behaves as an intercalator. Our findings led to the notion that the methyl substituents on the thiazole rings might play a significant part in the intercalation process.

Synthesis and antitumor properties of an anthraquinone bisubstituted by the copper chelating peptide Gly-Gly-L-His

A new molecule 4 [(GGH-DAE)2DHQ] associating the 1,4,5,8-tetrahydroxyanthraquinone ring (DHQ) of the antitumor drug mitoxantrone (2), two diaminoethylene chains (DAE), and the metal-chelating peptide Gly-Gly-His (GGH) has been synthesized. Such a molecule presents characteristics able to induce antitumor activity: compound 4 intercalates into DNA as measured by delta Tm, fluorescence quenching, and viscometry; ESR studies demonstrate that several types of Cu complexes are formed depending on pH; and the production of free radicals, as evidenced by spin-trapping, is enhanced by 4. In vitro, in leukemia cells L1210 and mammary cells MCF7, 4 is slightly less cytostatic than mitoxantrone, but substantially less toxic. In vivo, in leukemia P388 on mice, a T/C value of 230 is obtained at 25 mg/kg, higher than the one of mitoxantrone, which is toxic at the same dose.

Cyclomaltodextrin glucanotransferase from Bacillus circulans E 192: nitration with tetranitromethane

Nitration of tyrosine residues was performed on Bacillus circulans E 192 cyclomaltodextrin glucanotransferase (CGTase) using tetranitromethane (TNM). A maximum of 15 out of 28 tyrosine residues is modified with 8 mM TNM, entailing a concomitant loss of enzymic activity and tryptophan fluorescence. Spectroscopic studies suggest that these two phenomena are related to an impairment of the enzyme conformation as a consequence of the tyrosine nitration. The presence of 5 mM acarbose during the CGTase nitration results in the protection of one tyrosine residue and the rate of inactivation is reduced 9.4-fold. These results support a contribution of a tyrosine residue in the CGTase catalytic site. The nitration of CGTase also entails a decrease in the enzyme's affinity for a beta-cyclodextrin (beta-CD) co-polymer. Kinetic and analytical investigations on isolated modified enzymes support the concept that this phenomenon is unrelated to the modification of tyrosine residues, but rather concerns a side reaction of the reagent occurring at the raw-starch-binding site of the CGTase.

The coordination of copper(II) to 1-hydroxy-4-(glycyl-histidyl-lysine)-anthraquinone; a synthetic model of anthraquinone anti-cancer drugs

Results are reported of a pH-metric and spectroscopic (CD and ESR) study of the complexes formed between the pseudo-peptide 1-hydroxy-4-(Gly-His-Lys)-anthraquinone (Q-GHK) since, when complexed to copper ions, Q-GHK has been shown to be very effective in promoting the formation of free radicals and inducing DNA cleavage. Q-GHK forms very stable complexes with copper, the major species being bonded to three nitrogen donors in the coordination plane: an imidazole-N of the His residue and the peptide nitrogens of the Gly and His residues. This species is probably stabilized through bonding of the fourth planar coordination site of Cu(II) to the 9-anthraquinone oxygen. At high Q-GHK:copper ratios a second Q-GHK molecule is coordinated through its imidazole-N donor.

Relationship between DNA-binding and biological activity of anilinoacridine derivatives containing the nucleic acid-binding unit SPKK

The synthesis of two peptidic derivatives, including an anilinoacridine chromophore (related to the antileukemic drug amsacrine) and either the tetrapeptide SPKK (a nucleic acid-binding unit) (1) or the octapeptide SPKKSPKK (2), has been carried out. The interaction of both drugs with DNA has been studied. Binding data are consistent with a model in which the acridine nucleus occupies an intercalation site and the tetrapeptidic or octapeptidic portion is located in the DNA minor groove. Compound 1 fully intercalates into DNA. In contrast, minor groove binding of the octapeptide SPKKSPKK seems to partially modify the intercalative properties of the acridine moiety of 2. In vitro cytostatic and cytotoxic activities against a murine leukemia cell line (L1210), as well as inhibition of [3H]thymidine incorporation, are reported. Compound 1, which is a better inhibitor of DNA synthesis than 2, is also 2.8-fold more potent in terms of growth inhibition. Both drugs are efficient cytostatic agents, but are weakly cytotoxic. The DNA-binding abilities of the two molecules are well correlated to their biological properties. Thus, DNA can be considered as the primary target for these new ligands.

Comparison between synthetic nuclear localization signal peptides from the steroid/thyroid hormone receptors superfamily

The main objective of the study is to demonstrate that short basic peptides from the steroid/thyroid hormone receptors superfamily act as Nuclear Localization Signals out of receptors context. Such synthesized peptides, chemically coupled to Bovine Serum Albumin, were shown to enable the corresponding BSA-conjugate to be transported to the nucleus. A second objective is to demonstrate the utility of viral cointernalization as a good method for rapid quantitation, comparison and competition in nuclear entry.

Antagonistic effect of a vasoactive intestinal peptide fragment, vasoactive intestinal peptide(1-11), on guinea pig trachea smooth muscle relaxation

The conformation of various regions of vasoactive intestinal peptide (VIP) has been analyzed by semiempirical methods, CD, and NMR spectroscopy, indicating that residues 11-21 are most likely to be helical, whereas the amino-terminal portion VIP(1-11) could exhibit two beta-turn structures. VIP(1-11) inhibits 125I-VIP binding to intact guinea pig tracheal epithelial cells and the VIP-induced smooth muscle response. However, the endecapeptide exhibits no effect on the muscle tone. All these data suggest that VIP(1-11) may be a useful tool in studying VIP receptor recognition, its regulation, and cellular functions.

Nuclear targeting of a viral-cointernalized protein by a short signal sequence from human retinoic acid receptors

The synthesis of a putative nuclear localization signal from the human retinoic acid receptor is described. Its ability to target a carrier protein to the nucleus is demonstrated following microinjection or a new technique of cell internalization in the presence of adenovirus 3.

Conformational study of the chromosomal protein MC1 from the archaebacterium Methanosarcina barkeri

Methanogen chromosomal protein MC1 is a polypeptide of 93 amino acid residues (Mr 10,757) which represents the major protein associated with the DNA of the archaebacterium Methanosarcina barkeri and can protect DNA against thermal denaturation. The conformation of protein MC1 has been investigated by means of predictive methods, infrared spectroscopy, circular dichroism and tryptophan fluorescence studies. Protein MC1 has a low amount of alpha-helix but contains antiparallel beta-sheet strands. The larger hydrophobic cluster which contains tryptophan at position 61 appears buried in the protein. Addition of salts induces the unfolding of the protein and makes the tryptophan indole ring more rigid. With respect to its primary structure and its conformation, protein MC1 appears radically different from the chromosomal DNA-binding protein II (also called HU-type protein) in eubacteria.

Molecular recognition between oligopeptides and nucleic acids. DNA sequence specificity and binding properties of an acridine-linked netropsin hybrid ligand

The binding to DNA of a mixed function ligand (NETGA) is described, in which a potential intercalating group, an acridine moiety, is incorporated at the carboxyl terminus of the minor groove binding oligopeptide netropsin skeleton. Scatchard analysis of absorption data provided evidence of two modes of binding to DNA with K1 = 9.1 x 10(5) M-1 at low r values (0.003-0.1), and a binding site size n = 10, indicative of binding of both moeities. At high binding ratios (greater than 0.1), K2 = 0.9 x 10(5) M-1 and n = 5 corresponding to external binding. Complementary strand MPE footprinting on a pBR322 restriction fragment showed NETGA binds to 5'-AAAT like netropsin. It causes enhanced cleavage by MPE, particularly at G-C rich sequences and remote from the preferred binding sites. Viscometry measurements provided evidence for biphasic modes of the two binding portions of NETGA. Fluorescence polarization and linear dichroism measurements were in accord with distinct modes of interaction of the acridine (intercalation) and oligopeptide (minor groove binding) portions of NETGA. LD measurements on NETGA indicate that the oligopeptide moiety (netropsin-like) has an orientation typical of minor groove binders, whereas the degree of intercalation of the acridine group is decreased by association of the oligopeptide moiety.

Synthesis, biological activity and DNA interaction of anilinoacridine and bithiazole peptide derivatives related to the anti-tumor drugs m-AMSA and bleomycin

The synthesis of two depsipeptides including a peptide metal-chelating moiety (Gly-His-Lys) and a moiety with DNA affinity, namely either glycyl-anilino-9-aminoacridine 1 or 2'-(2-aminoethyl)-4-methoxycarbonyl-2",4'-bithiazole 2, has been carried out. The goal was to introduce separately on the same molecule the two factors contributing to the biological activity of many anti-tumor drugs. The interaction of both drugs with DNA has been studied and the acridine ring of 1 was found to intercalate in the double helix. The production of free radicals has been evidenced by spin-trapping for 1 although both compounds were revealed to be good copper-chelating agents. In vitro cytostatic activity and inhibition of [3H]-thymidine incorporation were obtained for 1 while 2 exhibited no activity in both tests. In view of these results, it can be pointed out that the anti-tumor properties of such drugs rely (1) on their ability to reach and to bind DNA and (2) on redox mechanisms involving interactions between the drugs, metals and molecular oxygen. The latter phenomenon leads to the formation of active radical species, able to degrade the DNA.

Effect of combination of m-AMSA and doxorubicin on their redox properties and on DNA cleavage

In vitro studies with the drug combination m-AMSA and doxorubicin were carried out in order to point out whether they can form a redox-system. Indeed, while doxorubicin is known to be bioactivated by NADPH cytochrome P-450 reductase, m-AMSA is readily and reversibly oxidized either chemically or microsomally, to give a quinone diimine with electrophile properties. This redox chemistry has been shown to play a major role in the antineoplastic properties of both drugs. The oxidation of m-AMSA was followed by absorption spectroscopy and the reduction of doxorubicin was observed by circular dichroism. It has been found that both drugs may form a redox-couple and that their association enhances their ability to cut DNA in the absence of cupric ions. Indeed, doxorubicin catalyses the oxidation of m-AMSA in sodium borate buffer (pH 9.25) and conversely the chemical reduction of doxorubicin by m-AMSA induces single and double strand breaks in pBR 322 DNA. This chemical activation may be of importance in vivo, and perhaps the combination of both drugs may lead to a therapeutic advantage.