Activation of lipid metabolism is an early event in carcinogenesis and a central hallmark of many cancers. However, the precise molecular composition of lipids in tumors remains generally poorly characterized. The aim of the present study was to analyze the global lipid profiles of breast cancer, integrate the results to protein expression, and validate the findings by functional experiments. Comprehensive lipidomics was conducted in 267 human breast tissues using ultraperformance liquid chromatography/ mass spectrometry. The products of de novo fatty acid synthesis incorporated into membrane phospholipids, such as palmitatecontaining phosphatidylcholines, were increased in tumors as compared with normal breast tissues. These lipids were associated with cancer progression and patient survival, as their concentration was highest in estrogen receptor-negative and grade 3 tumors. In silico transcriptomics database was utilized in investigating the expression of lipid metabolism related genes in breast cancer, and on the basis of these results, the expression of specific proteins was studied by immunohistochemistry. Immunohistochemical analyses showed that several genes regulating lipid metabolism were highly expressed in clinical breast cancer samples and supported also the lipidomics results. Gene silencing experiments with seven genes [ACACA (acetyl-CoA carboxylase a), ELOVL1 (elongation of very long chain fatty acid-like 1), FASN (fatty acid synthase), INSIG1 (insulin-induced gene 1), SCAP (sterol regulatory element-binding protein cleavageactivating protein), SCD (stearoyl-CoA desaturase), and THRSP (thyroid hormone-responsive protein)] indicated that silencing of multiple lipid metabolism-regulating genes reduced the lipidomic profiles and viability of the breast cancer cells. Taken together, our results imply that phospholipids may have diagnostic potential as well as that modulation of their metabolism may provide therapeutic opportunities in breast cancer treatment. Cancer Res; 71(9); 3236-45. Ó2011 AACR.

The risk determinants of type 1 diabetes, initiators of autoimmune response, mechanisms regulating progress toward ␤ cell failure, and factors determining time of presentation of clinical diabetes are poorly understood. We investigated changes in the serum metabolome prospectively in children who later progressed to type 1 diabetes. Serum metabolite profi les were compared between sample series drawn from 56 children who progressed to type 1 diabetes and 73 controls who remained nondiabetic and permanently autoantibody negative. Individuals who developed diabetes had reduced serum levels of succinic acid and phosphatidylcholine (PC) at birth, reduced levels of triglycerides and antioxidant ether phospholipids throughout the follow up, and increased levels of proinfl ammatory lysoPCs several months before seroconversion to autoantibody positivity. The lipid changes were not attributable to HLA-associated genetic risk. The appearance of insulin and glutamic acid decarboxylase autoantibodies was preceded by diminished ketoleucine and elevated glutamic acid. The metabolic profi le was partially normalized after the seroconversion. Autoimmunity may thus be a relatively late response to the early metabolic disturbances. Recognition of these preautoimmune alterations may aid in studies of disease pathogenesis and may open a time window for novel type 1 diabetes prevention strategies.

Both genetic and environmental factors are involved in the etiology of obesity and the associated lipid disturbances. We determined whether acquired obesity is associated with changes in global serum lipid profiles independent of genetic factors in young adult monozygotic (MZ) twins. 14 healthy MZ pairs discordant for obesity (10 to 25 kg weight difference) and ten weight concordant control pairs aged 24–27 years were identified from a large population-based study. Insulin sensitivity was assessed by the euglycemic clamp technique, and body composition by DEXA (% body fat) and by MRI (subcutaneous and intra-abdominal fat). Global characterization of lipid molecular species in serum was performed by a lipidomics strategy using liquid chromatography coupled to mass spectrometry. Obesity, independent of genetic influences, was primarily related to increases in lysophosphatidylcholines, lipids found in proinflammatory and proatherogenic conditions and to decreases in ether phospholipids, which are known to have antioxidant properties. These lipid changes were associated with insulin resistance, a pathogonomic characteristic of acquired obesity in these young adult twins. Our results show that obesity, already in its early stages and independent of genetic influences, is associated with deleterious alterations in the lipid metabolism known to facilitate atherogenesis, inflammation and insulin resistance.

Peroxisome proliferator activated receptor gamma 2 (PPARg2) is the nutritionally regulated isoform of PPARg. Ablation of PPARg2 in the ob/ob background, PPARg2−/− Lepob/Lepob (POKO mouse), resulted in decreased fat mass, severe insulin resistance, β-cell failure, and dyslipidaemia. Our results indicate that the PPARg2 isoform plays an important role, mediating adipose tissue expansion in response to positive energy balance. Lipidomic analyses suggest that PPARg2 plays an important antilipotoxic role when induced ectopically in liver and muscle by facilitating deposition of fat as relatively harmless triacylglycerol species and thus preventing accumulation of reactive lipid species. Our data also indicate that PPARg2 may be required for the β-cell hypertrophic adaptive response to insulin resistance. In summary, the PPARg2 isoform prevents lipotoxicity by (a) promoting adipose tissue expansion, (b) increasing the lipid-buffering capacity of peripheral organs, and (c) facilitating the adaptive proliferative response of β-cells to insulin resistance.

Despite the tremendous importance of secondary metabolites for humans as for the plant itself, plant secondary metabolism remains poorly characterized. Here, we present an experimental approach, based on functional genomics, to facilitate gene discovery in plant secondary metabolism. Targeted metabolite analysis was combined with cDNA-amplified fragment length polymorphism-based transcript profiling of jasmonate-elicited tobacco Bright yellow 2 cells. Transcriptome analysis suggested an extensive jasmonatemediated genetic reprogramming of metabolism, which correlated well with the observed shifts in the biosynthesis of the metabolites investigated. This method, which in addition to transcriptome data also generates gene tags, in the future might lead to the creation of novel tools for metabolic engineering of medicinal plant systems in general. P lants are capable of synthesizing an overwhelming variety of low-molecular-weight organic compounds called secondary metabolites, usually with unique and complex structures. Presently, Ϸ100,000 such compounds have been isolated from higher plants (1). Numerous plant secondary metabolites possess interesting biological activities and find applications, such as pharmaceuticals, insecticides, dyes, flavors, and fragrances. Although secondary metabolism offers attractive targets for plant breeding, the enormous biosynthetic potential of plant cells is still not being exploited. In sharp contrast, metabolism of microorganisms has been successfully engineered for increased production of pharmaceuticals or novel compounds (2, 3). Despite a few decades of research, plant secondary metabolism remains poorly characterized (4). Genetic maps of biosynthetic pathways are still far from complete, whereas knowledge on the regulation of these pathways is practically nonexistent. However, such knowledge is of crucial importance to bypass the low product yield of various secondary metabolites in plants or plant cell cultures.Functional genomics approaches are powerful tools to accelerate comprehensive investigations of cellular metabolism in specialized tissues or whole organisms (5). Yet, related to plant secondary metabolism, only a few reports have been published on such studies, which include the use of comparative quantitative trait loci mapping (6), 2D gel electrophoresis-based proteomics (7), or transcript analysis tools, such as differential display (8, 9), EST databases (10-12), and microarrays (13,14). Nevertheless, still little is known about the genetics that control quantitatively and qualitatively natural variation in secondary metabolism.Because of the lack of extensive genomic data for the vast majority of medicinal plants, it is difficult to use the commonly used microarray-based approach for transcriptome analysis in these plant systems. Such an approach requires prior development of large EST or cDNA clone collections (13,14). As such, the cDNA-amplified fragment length polymorphism (AFLP) technology (15-17) offers an attractive alternative to identify genes involved i...

The authors describe a new approach to studying cellular lipid profiles and propose a compensatory mechanism that may help maintain the normal membrane function of adipocytes in the context of obesity.

cell culture ͉ periwinkle ͉ profiling ͉ secondary metabolism ͉ jasmonate

Plants make specialized bioactive metabolites to defend themselves against attackers. The conserved control mechanisms are based on transcriptional activation of the respective plant speciesspecific biosynthetic pathways by the phytohormone jasmonate. Knowledge of the transcription factors involved, particularly in terpenoid biosynthesis, remains fragmentary. By transcriptome analysis and functional screens in the medicinal plant Catharanthus roseus (Madagascar periwinkle), the unique source of the monoterpenoid indole alkaloid (MIA)-type anticancer drugs vincristine and vinblastine, we identified a jasmonate-regulated basic helix-loop-helix (bHLH) transcription factor from clade IVa inducing the monoterpenoid branch of the MIA pathway. The bHLH iridoid synthesis 1 (BIS1) transcription factor transactivated the expression of all of the genes encoding the enzymes that catalyze the sequential conversion of the ubiquitous terpenoid precursor geranyl diphosphate to the iridoid loganic acid. BIS1 acted in a complementary manner to the previously characterized ethylene response factor Octadecanoid derivative-Responsive Catharanthus APETALA2-domain 3 (ORCA3) that transactivates the expression of several genes encoding the enzymes catalyzing the conversion of loganic acid to the downstream MIAs. In contrast to ORCA3, overexpression of BIS1 was sufficient to boost production of highvalue iridoids and MIAs in C. roseus suspension cell cultures. Hence, BIS1 might be a metabolic engineering tool to produce sustainably high-value MIAs in C. roseus plants or cultures.basic helix loop helix | Catharanthus roseus | jasmonate | Madagascar periwinkle | iridoids