Magic Angle Spinning Magnetic Resonance Spectroscopy Research Articles

Metabolic clusters of breast cancer in relation to gene- and protein expression subtypes.

BackgroundThe heterogeneous biology of breast cancer leads to high diversity in prognosis and response to treatment, even for patients with similar clinical diagnosis, histology, and stage of disease. Identifying mechanisms contributing to this heterogeneity may reveal new cancer targets or clinically relevant subgroups for treatment stratification. In this study, we have merged metabolite, protein, and gene expression data from breast cancer patients to examine the heterogeneity at a molecular level.MethodsThe study included primary tumor samples from 228 non-treated breast cancer patients. High-resolution magic-angle spinning magnetic resonance spectroscopy (HR MAS MRS) was performed to extract the tumors metabolic profiles further used for hierarchical cluster analysis resulting in three significantly different metabolic clusters (Mc1, Mc2, and Mc3). The clusters were further combined with gene and protein expression data.ResultsOur result revealed distinct differences in the metabolic profile of the three metabolic clusters. Among the most interesting differences, Mc1 had the highest levels of glycerophosphocholine (GPC) and phosphocholine (PCho), Mc2 had the highest levels of glucose, and Mc3 had the highest levels of lactate and alanine. Integrated pathway analysis of metabolite and gene expression data uncovered differences in glycolysis/gluconeogenesis and glycerophospholipid metabolism between the clusters. All three clusters had significant differences in the distribution of protein subtypes classified by the expression of breast cancer-related proteins. Genes related to collagens and extracellular matrix were downregulated in Mc1 and consequently upregulated in Mc2 and Mc3, underpinning the differences in protein subtypes within the metabolic clusters. Genetic subtypes were evenly distributed among the three metabolic clusters and could therefore contribute to additional explanation of breast cancer heterogeneity.ConclusionsThree naturally occurring metabolic clusters of breast cancer were detected among primary tumors from non-treated breast cancer patients. The clusters expressed differences in breast cancer-related protein as well as genes related to extracellular matrix and metabolic pathways known to be aberrant in cancer. Analyses of metabolic activity combined with gene and protein expression provide new information about the heterogeneity of breast tumors and, importantly, the metabolic differences infer that the clusters may be susceptible to different metabolically targeted drugs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40170-016-0152-x) contains supplementary material, which is available to authorized users.

Metabolite profiling in retinoblastoma identifies novel clinicopathological subgroups.

Background:Tumour classification, based on histopathology or molecular pathology, is of value to predict tumour behaviour and to select appropriate treatment. In retinoblastoma, pathology information is not available at diagnosis and only exists for enucleated tumours. Alternative methods of tumour classification, using noninvasive techniques such as magnetic resonance spectroscopy, are urgently required to guide treatment decisions at the time of diagnosis.Methods:High-resolution magic-angle spinning magnetic resonance spectroscopy (HR-MAS MRS) was undertaken on enucleated retinoblastomas. Principal component analysis and cluster analysis of the HR-MAS MRS data was used to identify tumour subgroups. Individual metabolite concentrations were determined and were correlated with histopathological risk factors for each group.Results:Multivariate analysis identified three metabolic subgroups of retinoblastoma, with the most discriminatory metabolites being taurine, hypotaurine, total-choline and creatine. Metabolite concentrations correlated with specific histopathological features: taurine was correlated with differentiation, total-choline and phosphocholine with retrolaminar optic nerve invasion, and total lipids with necrosis.Conclusions:We have demonstrated that a metabolite-based classification of retinoblastoma can be obtained using ex vivo magnetic resonance spectroscopy, and that the subgroups identified correlate with histopathological features. This result justifies future studies to validate the clinical relevance of these subgroups and highlights the potential of in vivo MRS as a noninvasive diagnostic tool for retinoblastoma patient stratification.

Metyrapone effects on systemic and cerebral energy metabolism

Metyrapone is a cytochrome P450 inhibitor that protects against ischemia- and excitotoxicity-induced brain damages in rodents. This study examines whether metyrapone would act on energy metabolism in a manner congruent with its neuroprotective effect. In a first investigation, the rats instrumented with telemetric devices measuring abdominal temperature, received i.p. injection of either metyrapone or saline. One hour after injection, their blood and hippocampus were sampled. Hippocampus metabolite concentrations were measured using 1H high-resolution magic angle spinning-magnetic resonance spectroscopy (1H HRMAS-MRS). The hippocampus levels in phosphorylated mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) were measured by Western Blot analysis and those of c-fos and HSP70-2 mRNA were quantified by RT-PCR. In a second investigation, the rats received the same treatment and were sacrificed 1h after. The functioning of mitochondria was immediately studied on their whole brain. Metyrapone provoked a slight hypothermia which was correlated to the increase in blood glucose concentration. Metyrapone also increased blood lactate concentrations without modifying hippocampus lactate content. In the hippocampus, metyrapone decreased γ-aminobutyric acid (GABA) and glutamate levels but increased glutamine and N-acetyl-aspartate contents (NAA). Phosphorylated mTOR and AMPK and the c-fos and HSP70-2 mRNA levels were similar between treatment groups. Metyrapone did not modify blood corticosterone levels. Mitochondrial oxygen consumption was similar in both groups whatever the substrate used. These metabolic modifications, which take place without modifying blood glucocorticoid levels, are consistent with the neuroprotective properties of metyrapone as demonstrated in animal models.

389: Development and Evaluation of an In-Vitro Reperfusion Circuit for Reconditioning of Predamaged Donor-Lungs

Purpose: Perfusion preservation may extend the storage interval and permit utilization of marginal donor hearts. A limitation of this technique is predicting reperfusion cardiac function prior to implantation. We hypothesized that H magic angle spinning magnetic resonance spectroscopy (MASMRS) could be used to rapidly determine the metabolic state of preserved myocardium. We applied MASMRS to a large animal model of cardiac transplantation to compare metabolism after standard static storage and perfusion storage. Methods and Materials: Dog hearts were harvested after cardioplegic arrest. Animals were randomized to either static storage in Celsior (n 5) or perfusion preservation (n 6) in a device (Lifecradle® ,Organ Transport Systems) that delivers Celsior to the coronaries at 10 mL/100g/min. After 4 hours storage at 5°C, small left ventricular biopsies (10 mg) were taken and H MASMRS was carried out with a gHx nanoprobe on a Varian 14.1T spectrometer. Spectral data were analyzed with a peak-picking, partial least squares algorithm to identify biomarkers that were indicative of the storage method. Results: Analysis time for each sample was less than ten minutes. The peak-picking algorithm identified 5 resonances at .89 (triglyceride methyl), 2.02 (alpha to a triglyceride double bond), 3.92 (creatine), 4.63 (unassigned), and 5.22ppm (glycerol) that were sufficient to categorize spectra as either static storage or perfusion preservation with 100% efficiency. The algorithm selects the minimum number of resonances needed to classify the spectrum. Other compounds that were significantly different between the two preparations included lactate and myo-inositol, for example. Conclusions: H MASMRS can identify metabolic differences between cardiac preservation methods. The ability to use minute tissue samples and obtain metabolic data make this technique an attractive option for cardiac transplantation, and may provide clinicians with important information on the status of a donor heart without deleterious extension of the ischemic interval.

Evaluation of Tissue Metabolites with High Resolution Magic Angle Spinning MR Spectroscopy Human Prostate Samples after Three-Year Storage at –80 °C

Accurate interpretation and correlation of tissue spectroscopy with pathological conditions requires disease-specific tissue metabolite databases; however, specimens for research are often kept in frozen storage for various lengths of time. Whether such frozen storage results in alterations to the measured metabolites is a critical but largely unknown issue. In this study, human prostate tissues from specimens that had been stored at –80 °C for 32 months were analyzed with high resolution magic angle spinning (HRMAS) magnetic resonance (MR) spectroscopy, and compared with the initial measurements of the adjacent specimens from the same cases when snap frozen in the operation room and kept frozen for less than 24 hours. Results of the current study indicate that that the storage-induced metabolite alterations are below the limits that tissue MR spectroscopy can discriminate. Furthermore, quantitative pathology evaluations suggest the observed alterations in metabolite profiles measured from the adjacent specimens of the same prostates may be accounted for by tissue pathological heterogeneities and are not a result of storage conditions. Hence, these results indicate that long-term frozen storage of prostate specimens can be quantitatively analyzed by HRMAS MR spectroscopy without concerns regarding significant metabolic degradation or alteration.