Analysis of a Broad Range of Carbonyl Metabolites in Exhaled Breath by UHPLC-MS.

Analysis of volatile organic compounds (VOCs) in exhaled breath (EB) has shown great potential for disease detection including lung cancer, infectious respiratory diseases, and chronic obstructive pulmonary disease. Although many breath sample collection and analytical methods have been developed for breath analysis, analysis of metabolic VOCs in exhaled breath is still a challenge for clinical application. Many carbonyl compounds in exhaled breath are related to the metabolic processes of diseases. This work reports a method of ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-MS) for the analysis of a broad range of carbonyl metabolites in exhaled breath. Carbonyl compounds in the exhaled breath were captured by a fabricated silicon microreactor with a micropillar array coated with 2-(aminooxy)ethyl-N,N,N-trimethylammonium (ATM) triflate. A total of six subgroups consisting of saturated aldehydes and ketones, hydroxy-aldehydes, and hydroxy-ketones, unsaturated 2-alkenals, and 4-hydroxy-2-alkenals were identified in the exhaled breath. The combination of a silicon microreactor for the selective capture of carbonyl compounds with UHPLC-MS analysis may provide a quantitative method for the analysis of carbonyls to identify disease markers in exhaled breath.

Synthesis and Analysis of 64Cu-Labeled GE11-Modified Polymeric Micellar Nanoparticles for EGFR-Targeted Molecular Imaging in a Colorectal Cancer Model.

Polymeric micellar nanoparticles represent versatile and biocompatible platforms for targeted drug delivery. However, tracking their biodistribution, stability, and clearance profile in vivo is challenging. The goal of this study was to prepare surface-modified micelles with peptide GE11 for targeting the epidermal growth factor receptor (EGFR). In vitro fluorescence studies demonstrated significantly higher internalization of GE11 micelles into EGFR-expressing HCT116 colon cancer cells versus EGFR-negative SW620 cells. Azo coupling chemistry of tyrosine residues in the peptide backbone with aryl diazonium salts was used to label the micelles with radionuclide 64Cu for positron emission tomography (PET) imaging. In vivo analysis of 64Cu-labeled micelles showed prolonged blood circulation and predominant hepatobiliary clearance. The biodistribution profile of EGFR-targeting GE11 micelles was compared with nontargeting HW12 micelles in HCT116 tumor-bearing mice. PET revealed increasing tumor-to-muscle ratios for both micelles over 48 h. Accumulation of GE11-containing micelles in HCT116 tumors was higher compared to HW12-decorated micelles. Our data suggest that the efficacy of image-guided therapies with micellar nanoparticles could be enhanced by active targeting, as demonstrated with cancer biomarker EGFR.

Magnetic nanoparticle-supported lipid bilayers for drug delivery.

Magnetic nanoparticle-supported lipid bilayers (SLBs) constructed around core-shell Fe3O4-SiO2 nanoparticles (SNPs) were prepared and evaluated as potential drug carriers. We describe how an oxime ether lipid can be mixed with SNPs to produce lipid-particle assemblies with highly positive ζ potential. To demonstrate the potential of the resultant cationic SLBs, the particles were loaded with either the anticancer drug doxorubicin or an amphiphilic analogue, prepared to facilitate integration into the supported lipid bilayer, and then examined in studies against MCF-7 breast cancer cells. The assemblies were rapidly internalized and exhibited higher toxicity than treatments with doxorubicin alone. The magnetic SLBs were also shown to increase the efficacy of unmodified doxorubicin.

PET Imaging of L-Type Amino Acid Transporter (LAT1) and Cystine-Glutamate Antiporter (xc-) with [18F]FDOPA and [18F]FSPG in Breast Cancer Models.

PURPOSE: The present study describes the analysis of amino acid transporters ASCT1, ASCT2, LAT1, and xc- in breast cancer under normoxic and hypoxic conditions. [18F]FDOPA-PET and [18F]FSPG-PET were used as imaging biomarkers to probe L-type amino acid transporter (LAT1) and cystine-glutamate antiporter (xc-) in breast cancer models. PROCEDURES: LAT1 and xc- transporters were studied under normoxic and hypoxic conditions with radiotracers [18F]FDOPA and [18F]FSPG in estrogen receptor-positive (ER+) MCF7 and triple-negative MDA-MB231 cells and in human mammary epithelial MCF10A control cells. Protein expression was analyzed using Western blot and immunohistochemistry. RESULTS: ASCT1 protein expression levels were comparable in all three cell lines, while noticeable ASCT2 expression levels were only found in MCF10A control cells. Higher LAT1 protein expression was detected in ER+ MCF7 cells. High xc- protein expression levels were detected in MDA-MB231 cells. Uptake of [18F]FDOPA through LAT1 was significantly higher in MCF7 versus MDA-MB231 cells, while the uptake of [18F]FSPG through xc- resulted in the opposite confirming expression and functional differences for both amino acid transporters in different breast cancer models. Hypoxia significantly increased [18F]FDOPA uptake in MCF7 cells and [18F]FSPG uptake in MDA-MB231 cells. In vivo PET imaging revealed substantially higher tumor uptake of [18F]FDOPA in MCF7 tumors as well as [18F]FSPG uptake in MDA-MB231 tumors confirming differences detected in vitro. CONCLUSIONS: ER+ breast cancer cells express higher levels of amino acid transporter LAT1, whereas triple-negative breast cancer cells express more xc-. Cellular uptake and PET imaging experiments with [18F]FDOPA and [18F]FSPG confirmed functional LAT1 and xc- expression profiles. There was initial evidence that hypoxia regulates the function of both amino acid transporters in breast cancer. The results further indicated that [18F]FDOPA and [18F]FSPG are suitable radiotracer to distinguish between ER+ and triple-negative breast cancer types.

Synthesis and in vivo evaluation of a radiofluorinated ketone body derivative.

The ketone bodies d-beta-hydroxybutyric acid and acetoacetic acid represent the principal oxidative energy sources of most tissues when dietary glucose is scarce. An 18F-labeled ketone body could be a useful tool for studying ketone body metabolism using positron emission tomography (PET). Here, we report the first radiofluorinated ketone body derivative (3S)-4-[18F]fluoro-3-hydroxybutyric acid ([18F]FBHB) as well as its enantiomer and l-beta-hydroxybutyric acid derivative, (3R)-4-[18F]fluoro-3-hydroxybutyric acid ((R)-[18F]F3HB). PET imaging in mice showed biodistribution profiles of the radiotracers that were consistent with the biodistribution of the respective endogenous compounds. Moreover, both enantiomers visualized breast cancer xenografts in vivo. Fasting over 24 h showed significantly enhanced brain and heart uptake of [18F]FBHB and tumor uptake of (R)-[18F]F3HB. Disorders exhibiting altered energy substrate utilization, such as Alzheimer's disease, epilepsy, diabetes, and cancer may be of interest for PET imaging studies using [18F]FBHB.

A Nutritional Perspective of Ketogenic Diet in Cancer: A Narrative Review.

The predominant use of glucose anaerobically by cancer cells (Warburg effect) may be the most important characteristic the majority of these cells have in common and, therefore, a potential metabolic pathway to be targeted during cancer treatment. Because this effect relates to fuel oxidation, dietary manipulation has been hypothesized as an important strategy during cancer treatment. As such, the concept of a ketogenic diet (KD) in cancer emerged as a metabolic therapy (ie, targeting cancer cell metabolism) rather than a dietary approach. The therapeutic mechanisms of action of this high-fat, moderate-to-low protein, and very-low-carbohydrate diet may potentially influence cancer treatment and prognosis. Considering the lack of a dietetics-focused narrative review on this topic, we compiled the evidence related to the use of this diet in humans with diverse cancer types and stages, also focusing on the nutrition and health perspective. The use of KD in cancer shows potentially promising, but inconsistent, results. The limited number of studies and differences in study design and characteristics contribute to overall poor quality evidence, limiting the ability to draw evidence-based conclusions. However, the potential positive influences a KD may have on cancer treatment justify the need for well-designed clinical trials to better elucidate the mechanisms by which this dietary approach affects nutritional status, cancer prognosis, and overall health. The role of registered dietitian nutritionists is demonstrated to be crucial in planning and implementing KD protocols in oncology research settings, while also ensuring patients' adherence and optimal nutritional status.

Oxime ether lipids containing hydroxylated head groups are more superior siRNA delivery agents than their nonhydroxylated counterparts.

AIM: To evaluate the structure-activity relationship of oxime ether lipids (OELs) containing modifications in the hydrophobic domains (chain length, degree of unsaturation) and hydrophilic head groups (polar domain hydroxyl groups) toward complex formation with siRNA molecules and siRNA delivery efficiency of resulting complexes to a human breast cancer cell line (MDA-MB-231). MATERIALS & METHODS: Ability of lipoplex formation between oxime ether lipids with nucleic acids were examined using biophysical techniques. The potential of OELs to deliver nucleic acids and silence green fluorescent protein (GFP) gene was analyzed using MDA-MB-231 and MDA-MB-231/GFP cells, respectively. RESULTS & CONCLUSION: Introduction of hydroxyl groups to the polar domain of the OELs and unsaturation into the hydrophobic domain favor higher transfection and gene silencing in a cell culture system.

A Carbonyl Capture Approach for Profiling Oxidized Metabolites in Cell Extracts.

Fourier-transform ion-cyclotron resonance mass spectrometry (FT-ICR-MS) detection of oxidized cellular metabolites is described using isotopologic, carbonyl-selective derivatizing agents that integrate aminooxy functionality for carbonyl capture, quaternary nitrogen for electrospray enhancement, and a hydrophobic domain for sample cleanup. These modular structural features enable rapid, sensitive analysis of complex mixtures of metabolite-derivatives by FT-ICR-MS via continuous nanoelectrospray infusion. Specifically, this approach can be used to globally assess levels of low abundance and labile aldehyde and ketone metabolites quantitatively and in high throughput manner. These metabolites are often key and unique indicators of various biochemical pathways and their perturbations. Analysis of lung adenocarcinoma A549 cells established a profile of carbonyl metabolites spanning multiple structural classes. We also demonstrate a procedure for metabolite quantification using pyruvate as a model analyte.