Apoptosis-related gene expression in glioblastoma (LN-18) and medulloblastoma (Daoy) cell lines

The expression of apoptosis genes in a commercial pre-designed low-density array from Applied Biosystems was evaluated in two human brain cancer cell models, LN-18 and Daoy (HTB-186™) in comparison to the reference human primary endothelial cells under basic conditions. Analysis of the gene expression in the cancer cell lines compared to the normal control revealed features reflecting anti-apoptotic and inflammatory characteristics of the former. There was an overall downregulation of apoptosis-stimulating genes in both cancer cell lines, along with an upregulation of certain apoptosis inhibitors. A number of genes demonstrated statistically significant changes in their expressions, including BAX (BCL2-associated X protein); the CARD4/NLR family, CARD domain containing 4; CASP10 (caspase 10, apoptosis-related cysteine peptidase); DAP1 (death-associated protein kinase 1), and BIRC5 (baculoviral IAP repeat-containing 5). Anti-apoptotic potential in both cell lines was demonstrated by changes in the Bax:Bcl-2 ratio and downregulation of the APAF1 gene in LN18 cells. There was also significant downregulation of extrinsic signals and the TNF/FADD/inflammatory cascade, and upregulation of caspase inhibitors (IAPs). These results provided a novel molecular characterization of important human cancer cell lines, which might provide a useful research tool for investigating the experimental model of the CNS cell.

Pleiotropic effects of TCF7L2 gene variants and its modulation in the metabolic syndrome: from the LIPGENE study

AIMS/HYPOTHESIS

Variants of the TCF7L2 gene predict the development of type 2 diabetes mellitus (T2DM). We investigated the associations between gene variants of TCF7L2 and clinical features of the metabolic syndrome (MetS) (an entity often preceding T2DM), and their interaction with non-genetic factors, including plasma saturated fatty acids (SFA) concentration and insulin resistance (IR).

METHODS

Fasting lipid profiles, insulin sensitivity, insulin secretion, anthropometrics, blood pressure and 10 gene variations of the TCF7L2 gene were determined in 450 subjects with MetS.

RESULTS

Several single nucleotide polymorphisms (SNP) showed phenotypic associations independent of SFA or IR. Carriers of the rare T allele of rs7903146, and of three other SNPs in linkage disequilibrium with rs7903146, had lower blood pressure and insulin secretion. High IR and the presence of the T-allele of rs7903146 acted synergistically to define those with reduced insulin secretion. Carriers of the minor allele of rs290481 exhibited an altered lipid profile, with increased plasma levels of apolipoprotein B, non-esterified fatty acids, cholesterol and apolipoprotein B in triglyceride rich lipoproteins, and LDL cholesterol. Carriers of the minor allele of rs11196224 that had higher plasma SFA levels showed elevated procoagulant/proinflammatory biomarkers, impaired insulin secretion and increased IR, whereas carriers of the minor allele of rs17685538 with high plasma SFA levels exhibited higher blood pressure.

CONCLUSIONS/INTERPRETATION

SNP in the TCF7L2 gene are associated with differences in insulin secretion, blood pressure, blood lipids and coagulation in MetS patients, and may be modulated by SFA in plasma or IR.

The adipose tissue gene expression in mice with different nitric oxide availability

Mice with the knockout of endothelial nitric oxide synthase (eNOS ko) demonstrate symptoms resembling the human metabolic syndrome. NO has been recently demonstrated to be deeply involved in regulation of not only blood flow and angiogenesis, but also in modulation of mammalian basal energy substrate metabolism. Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of NOS. The enzyme dimethylarginine dimethylaminohydrolase (DDAH) catabolizes ADMA, what leads to increase of endogenous NO bioavailability. This study was aimed to compare the brown (BAT) and white (WAT) adipose tissue gene expression of age matched mice with decreased (eNOS ko) and increased (overexpressing DDAH) endogenous NO generation. The 19 week old eNOS ko mice demonstrated significantly lower weight, higher circulating glucose, insulin, leptin and cholesterol concentrations. The adiponectin as well as fasting triglyceride concentrations were not significantly altered. Animals with DDAH knock in, presented significantly increased angiogenic activity than eNOS ko mice. The microarray analysis pointed to activation of adipogenesis-related genes in eNOS ko mice in WAT, what was in contrast with the inhibition observed in the DDAH overexpressing mice. The angiogenesis related gene expression was down-regulated in both models in comparison to WT animals. This study support the multipotential role of endogenous NO in maintaining homeostasis of energy substrate catabolism.

Evaluation of genetic predisposition to insulin resistance by nutrient-induced insulin output ratio (NIOR)

BACKGROUND

New tools to identify genotype-phenotype interactions need to be described and implemented. The aim of this study was to identify correlation between the risk originating from gene variation and diet-dependent development of insulin resistance.

METHODS

Insulin output in terms of area under the curve after an oral glucose tolerance test (AUC Ins OGTT) and lipid tolerance tests (AUC Ins OLTT) were measured in 167 overweight/obese patients. Estimation of the 18 common gene polymorphisms for obesity risk and standard phenotyping were performed.

RESULTS

Insulin output (AUC Ins OGTT) correlated strongly between both insulin treatments across the whole group. However, within the genotype sub-groups, correlation was lower or did not exist. Using a nutrient-induced insulin output ratio (NIOR), calculated as AUC Ins OLTT/AUC Ins OGTT, values ranged from 0.42 to 5.83 and correlated significantly with body mass index (BMI) and leptin, but not with age, gender, waist-to-hip ratio (WHR) and homeostasis model assessment of insulin resistance (HOMA-IR) or plasma adiponectin. High NIOR was found in a subgroup of carriers of rare allelic variants of genes characteristic for poorer tolerance to lipids in the diet. Low NIOR values were found within a sub-group with rare genetic variants regulating carbohydrate metabolism. Thus, the new insulin index NIOR may distinguish gene variant carriers into groups of glucose- or lipid-sensitive phenotypes.

CONCLUSIONS

We suggest that the OLTT/OGTT insulin output ratio (NIOR) may be predictive for identifying individuals who are phenotypically susceptible to insulin resistance in response to high fat or carbohydrate in their habitual diet.

Nutrigenomic approaches for benefit-risk analysis of foods and food components: defining markers of health

To be able to perform a comprehensive and rigorous benefit-risk analysis of individual food components, and of foods, a number of fundamental questions need to be addressed first. These include whether it is feasible to detect all relevant biological effects of foods and individual food components, how such effects can confidently be categorised into benefits and risks in relation to health and, for that matter, how health can be quantified. This article examines the last of these issues, focusing upon concepts for the development of new biomarkers of health. Clearly, there is scope for refinement of classical biomarkers so that they may be used to detect even earlier signs of disease, but this approach defines health solely as the absence of detectable disease or disease risk. We suggest that the health of a biological system may better be reflected by its ability to withstand and manage relevant physiological challenges so that homeostasis is maintained. We discuss the potential for expanding the range of current challenge tests for use in conjunction with functional genomic technologies to develop new types of biomarkers of health.

Nutrient–gene interactions in benefit–risk analysis

Individuals respond differently to nutrients and foods. This is reflected in different levels of benefits and risks at the same intake of a nutrient and, consequently, different ‘windows of benefit’ in terms of nutrient intake. This has led recently to the concept of ‘personalised nutrition’. Genetic factors such as single nucleotide polymorphisms may be one source of this inter-individual variation in benefit–risk response to nutrients. In 2004 a European Union-funded network of excellence in the area of nutrigenomics (European Nutrigenomics Organisation; NuGO) organised a workshop on the role of nutrient–gene interactions in determining benefit–risk of nutrients and diet. The major issues discussed at theworkshop are presented in the present paper and highlighted with examples from the presentations. The overall consensus was that although genetics provides a new vision where genetic information could in the future be used to provide knowledge on disease predisposition and nutritionalrequirements, such a goal is still far off and much more research is required before we can reliably include genetic factors in the risk–benefit assessment of nutrients and diets.

The microarray expression analysis identifies BAX as a mediator of beta-carotene effects on apoptosis

Beta-carotene is a ubiquitous compound rich in foods. However, there are conflicting reports regarding its role in carcinogenesis. We performed a microarray expression analysis in normal [human umbilical vein endothelial cells (HUVECs)] and neoplastic (melanoma A375 and myelomonocytic leukemia U937) actively proliferating cells and found evidence that beta-carotene stimulated vital cellular functions in the former and suppressed them in the latter. These differential effects correlated with the expression of the proapoptotic BCL2-associated X protein (BAX), which was downregulated in HUVECs and upregulated in the two neoplastic cell lines. The quantitative expression analysis using real-time polymerase chain reaction largely confirmed the inhibition of B-cell CLL/lymphoma 2 (BCL2) pathway-mediated apoptosis in HUVECs and its activation in melanoma and leukemic cells. The assays for apoptosis, detecting DNA breaks and caspase activation, showed consistent proapoptotic and antiapoptotic effects in U937 and HUVEC lines, respectively. However, beta-carotene-induced expression changes of BAX and other BCL2 pathway genes did not lead to the predicted induction of apoptosis in the A375 cells.

Analysis of candidate genes in Polish families with obesity

This study analyzes the relationship between risk factors related to overweight/obesity, insulin resistance, lipid tolerance, hypertension, endothelial function and genetic polymorphisms associated with: i) appetite regulation (leptin, melanocortin-3-receptor (MCR-3), dopamine receptor 2 (D2R)); ii) adipocyte differentiation and insulin sensitivity (peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2), tumor necrosis factor-alpha (TNF-alpha)); iii) thermogenesis and free fatty acid (FFA) transport/catabolism (uncoupling protein-1 (UCP1), lipoprotein lipase (LPL), beta2- and beta3-adrenergic receptor (beta2AR, beta3AR), fatty acid transport protein-1 (FATP-1) and iv) lipoproteins (apoliprotein E (apoE), apo CIII). The 122 members of 40 obese Caucasian families from southern Poland participated in the study. The genotypes were analyzed by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) or by direct sequencing. Phenotypes related to obesity (body mass index (BMI), fat/lean body mass composition, waist-to-hip ratio (WHR)), fasting lipids, glucose, leptin and insulin, as well as insulin during oral glucose tolerance test (OGTT) (4 points within 2 hours) and during oral lipid tolerance test (OLTT) (5 points within 8 hours) were assessed. The insulin sensitivity indexes: homeostasis model assessment of insulin resistance, whole body insulin sensitivity index, hepatic insulin sensitivity and early secretory response to an oral glucose load (HOMA-IR, ISI-COMP, ISI-HOMA and DELTA) were calculated. The single gene mutations such as C105 T OB and Pro115 Gln PPAR-gamma2 linked to morbid obesity were not detected in our group. A weak correlation between obesity and certain gene polymorphisms was observed. Being overweight (25 < BMI > or = 30 kg/m2) significantly correlated with worse FFA tolerance in male PPAR-gamma2 12Pro, LPL-H (G) allele carriers. Insulin resistance was found in female PPAR-gamma2 Pro12, TNF-alpha (-308A) and LPL-H (G) allele carriers. Hypertension linked to the PPAR-gamma2 Pro allele carriers was characterized by high leptin output during OLTT. We conclude that the polymorphisms we investigated were weakly correlated with obesity but significantly modified the risk factors of the metabolic syndrome.

Dexamethasone inhibits TNF-alpha synthesis more effectively in Alzheimer's disease patients than in healthy individuals

Inflammatory mechanisms are involved in the pathogenesis of Alzheimer's disease (AD). It is postulated that cytokine synthesis is altered in AD patients compared with nondemented subjects. Glucocorticoids play an important role in cytokine synthesis. We assessed the release of tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10) and interleukin-12 (IL-12) and its regulation by dexamethasone in AD patients in vitro. Cytokine levels were measured using the ELISA method in unstimulated, LPS-stimulated or whole-blood samples incubated with LPS and dexamethasone from 18 AD patients and 12 controls. The cytokine levels spontaneously produced by blood cells after incubation with LPS or LPS and dexamethasone did not differ significantly between groups. Dexamathasone inhibited TNF-alpha synthesis by LPS-stimulated blood cells more effectively in AD patients than in controls. These results suggest that cytokine synthesis in AD patients could be regulated by glucocorticoids in a different way than in nondemented subjects.

Interaction of reconstituted high density lipoprotein discs containing human apolipoprotein A-I (ApoA-I) variants with murine adipocytes and macrophages. Evidence for reduced cholesterol efflux promotion by apoA-I(Pro165-->Arg)

Interaction of cells with both native and reconstituted high density lipoproteins (rHDL) containing apolipoprotein (apo) A-I mediates efflux of cellular cholesterol. To characterize structural requirements for this activity in apoA-I, six different genetic apoA-I variants and the corresponding normal allele products were isolated from heterozygous carriers, reconstituted with dimyristoylphosphatidylcholine (DMPC) into discoidal HDL and compared with regard to their ability to release intracellular cholesterol from murine adipocytes and peritoneal macrophages. In previous studies we determined the amino acid changes of these variants: Pro3-->Arg, Pro4-->Arg, Lys107-->0, Lys107-->Met, Pro165-->Arg, and Glu198-->Lys (von Eckardstein, A., Funke, H., Walter, M., Altland, K., Benninghoven, A., and Assmann, G. (1990) J. Biol. Chem. 265, 8610-8617) and demonstrated that all apoA-I variants except apoA-I(Lys107-->0) form discoidal HDL particles with phosphatidylcholine analogues indistinguishable from normal apoA-I (Jonas, A., von Eckardstein, A., Kezdy, K. E., Steinmetz, A., and Assmann, G. (1991) J. Lipid Res. 32, 95-106). In the present study, all apoA-I.DMPC complexes except those containing apoA-I(Pro165-->Arg) promoted cholesterol efflux as effectively as those containing normal apoA-I. Cholesterol efflux from adipocytes obtained after 180 min of incubation with apoA-I(Pro165-->Arg).DMPC complexes was decreased by 30% although this variant was bound to adipocytes with normal affinity. By contrast, apoA-I(Lys107-->Met).DMPC complexes were decreased in their binding affinity compared to normal apoA-I.DMPC complexes but normally promoted cholesterol efflux. Incubation of mouse peritoneal macrophages with apoA-I(Pro165-->Arg).DMPC complexes did also result in a 30% decreased efflux of radiolabeled cholesterol if compared to rHDL with the normal allele product from the same donor. Together the observations suggest that the substitution of proline at residue 165 interferes with the formation of a structural domain in apoA-I that is crucial for cellular cholesterol efflux stimulation. Furthermore, our results suggest that binding of HDL to adipocytes and cholesterol efflux promotion by HDL requires different structural domains.