Noninvasive imaging of the transcriptional activities of human telomerase promoter fragments in mice

We have assessed the feasibility of positron emission tomography (PET) and ex vivo gamma-counting to measure the pattern of expression of telomerase promoter fragments in vivo. Promoter fragments from either the RNA [human telomerase RNA (hTR)] or the catalytic components [human telomerase reverse transcriptase (hTERT)] of the telomerase genes were used to drive the expression of the sodium iodide symporter PET reporter gene in recombinant adenoviruses. Both promoter fragments provided cancer-selective expression that could be visualized and quantitated by PET. The transcriptional activity of the hTR promoter was found to be consistently stronger than that of the hTERT promoter. Both promoters appear therefore to be good candidates for safe use in gene therapy, and PET imaging can be used to assess the selectivity of promoters in vivo. Given that this methodology is directly scalable to humans, imaging gene expression using the sodium iodide symporter PET reporter gene could be applied to measure telomerase promoter activity in humans

The lancet series nutritional interventions in Ghana: a determinants analysis approach to inform nutrition strategic planning

BACKGROUND: Malnutrition is a leading cause of mortality and morbidity among children in low- and middle-income countries. Ghana is one of 36 countries with the highest burden of stunting, globally. The aim of this work is to use data driven planning methods to conduct in-depth analysis on the Lancet series nutrition interventions in Ghana to inform nutritional strategic planning. METHODS: A mixed methods approach was employed for this national nutritional assessment conducted in May 2016. Quantitative data on nutritional interventions were generated by application of the Determinants Analysis Tool and phenomenological approach was employed to explain the causes of barriers identified. Outputs from the tool were analyzed by simple descriptive statistics and data from group discussions were assessed by thematic content analysis. The base line years for this assessment were 2014 and 2015. RESULTS: Overall in Ghana, 21.0% of frontline health workers are trained on lactation management and breastfeeding counselling and support, 56.6% of mothers of children 0–2 years initiated breastfeeding within one hour of birth, and 59.4% of mothers with children 0–5 months took iron folate supplementation for 90 or more days during pregnancy. In addition, only 19.9% of children 12–59 months received two doses of vitamin A supplementation in a calendar year, and 32.5% of children 6–59 months with severe acute malnutrition were admitted for treatment at health facilities. In all, among infants 6–8 months old, 6.9% were fed with minimum dietary diversity, 50.6% received age appropriate meal frequency and 21.6% received iron rich diet. Inadequate pre-service and in-service training for staff, low prioritization and coordination (at higher levels) and weak integration of services (at lower levels) were key barriers to nutrition coverage in Ghana. CONCLUSION: Data driven analysis and planning based on proven nutritional interventions in Ghana demonstrated gaps and barriers and garnered workable strategies to improve nutrition services

3'-Deoxy-3'-[F-18]Fluorothymidine Uptake Is Related to Thymidine Phosphorylase Expression in Various Experimental Tumor Models

Contains fulltext : 190106.pdf (publisher's version ) (Closed access

Reactivating HIF prolyl hydroxylases under hypoxia results in metabolic catastrophe and cell death

Cells exposed to low-oxygen conditions (hypoxia) alter their metabolism to survive. This response, although vital during development and high-altitude survival, is now known to be a major factor in the selection of cells with a transformed metabolic phenotype during tumorigenesis. It is thought that hypoxia-selected cells have increased invasive capacity and resistance to both chemo-and radiotherapies, and therefore represent an attractive target for antitumor therapy. Hypoxia inducible factors (HIFs) are responsible for the majority of gene expression changes under hypoxia, and are themselves controlled by the oxygen-sensing HIF prolyl hydroxylases (PHDs). It was previously shown that mutations in succinate dehydrogenase lead to the inactivation PHDs under normoxic conditions, which can be overcome by treatment with alpha-ketoglutarate derivatives. Given that solid tumors contain large regions of hypoxia, the reactivation of PHDs in these conditions could induce metabolic catastrophe and therefore prove an effective antitumor therapy. In this report we demonstrate that derivatized alpha-ketoglutarate can be used as a strategy for maintaining PHD activity under hypoxia. By increasing intracellular alpha-ketoglutarate and activating PHDs we trigger PHD-dependent reversal of HIF1 activation, and PHD-dependent hypoxic cell death. We also show that derivatized alpha-ketoglutarate can permeate multiple layers of cells, reducing HIF1 alpha levels and its target genes in vivo

A novel radiotracer to image glycogen metabolism in tumors by positron emission tomography

The high rate of glucose uptake to fuel the bioenergetic and anabolic demands of proliferating cancer cells is well recognized, and exploited with (18)F-2-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG-PET) to image tumors clinically. In contrast, enhanced glucose storage as glycogen (glycogenesis) in cancer is less well understood and the availability of a non-invasive method to image glycogen in vivo could provide important biologic insights. Here, we demonstrate that (18)F-N-(methyl-(2-fluoroethyl)-1H-[1,2,3]triazole-4-yl)glucosamine ((18)F-NFTG) annotates glycogenesis in cancer cells and tumors in vivo, measured by PET. Specificity of glycogen labeling was demonstrated by isolating (18)F-NFTG-associated glycogen and with stable knockdown of glycogen synthase 1, which inhibited (18)F-NFTG uptake, while oncogene (Rab25) activation-associated glycogen synthesis led to increased uptake. We further show that the rate of glycogenesis is cell cycle-regulated, enhanced during the non-proliferative state of cancer cells. We demonstrate that glycogen levels, (18)F-NFTG, but not (18)F-FDG uptake, increase proportionally with cell density and G(1)/G(0) arrest with potential application in the assessment of activation of oncogenic pathways related to glycogenesis and the detection of post treatment tumor quiescence

Preclinical evaluation of 3-¹⁸F-fluoro-2,2-dimethylpropionic acid as an imaging agent for tumor detection

Deregulated cellular metabolism is a hallmark of many cancers. In addition to increased glycolytic flux, exploited for cancer imaging with 18F-FDG, tumor cells display aberrant lipid metabolism. Pivalic acid is a short-chain, branched carboxylic acid used to increase oral bioavailability of prodrugs. After prodrug hydrolysis, pivalic acid undergoes intracellular metabolism via the fatty acid oxidation pathway. We have designed a new probe, 3-18F-fluoro-2,2-dimethylpropionic acid, also called 18F-fluoro-pivalic acid (18F-FPIA), for the imaging of aberrant lipid metabolism and cancer detection. Methods: Cell intrinsic uptake of 18F-FPIA was measured in murine EMT6 breast adenocarcinoma cells. In vivo dynamic imaging, time course biodistribution, and radiotracer stability testing were performed. 18F-FPIA tumor retention was further compared in vivo to 18F-FDG uptake in several xenograft models and inflammatory tissue. Results: 18F-FPIA rapidly accumulated in EMT6 breast cancer cells, with retention of intracellular radioactivity predicted to occur via a putative 18F-FPIA carnitine-ester. The radiotracer was metabolically stable to degradation in mice. In vivo imaging of implanted EMT6 murine and BT474 human breast adenocarcinoma cells by 18F-FPIA PET showed rapid and extensive tumor localization, reaching 9.1% ± 0.5% and 7.6% ± 1.2% injected dose/g, respectively, at 60 min after injection. Substantial uptake in the cortex of the kidney was seen, with clearance primarily via urinary excretion. Regarding diagnostic utility, uptake of 18F-FPIA was comparable to that of 18F-FDG in EMT6 tumors but superior in the DU145 human prostate cancer model (54% higher uptake; P = 0.002). Furthermore, compared with 18F-FDG, 18F-FPIA had lower normal-brain uptake resulting in a superior tumor-to-brain ratio (2.5 vs. 1.3 in subcutaneously implanted U87 human glioma tumors; P = 0.001), predicting higher contrast for brain cancer imaging. Both radiotracers showed increased localization in inflammatory tissue. Conclusion: 18F-FPIA shows promise as an imaging agent for cancer detection and warrants further investigation