[1-(13)C]pyruvate is the most widely used hyperpolarized metabolic magnetic resonance imaging agent. Using a custom-built 7.0 T polarizer operating at 1.0 K and trityl radical-doped [1-(13)C]pyruvic acid, unextrapolated solution-state (13)C polarization greater than 60% was measured after dissolution and rapid transfer to a spectrometer magnet, demonstrating the signal enhancement attainable using optimized hardware. Slower rates of polarization under these conditions can be largely overcome with higher radical concentrations.

Various tumors develop addiction to glutamine to support uncontrolled cell proliferation. Here we identify the nuclear receptor liver receptor homolog 1 (LRH-1) as a key regulator in the process of hepatic tumorigenesis through the coordination of a noncanonical glutamine pathway that is reliant on the mitochondrial and cytosolic transaminases glutamate pyruvate transaminase 2 (GPT2) and glutamate oxaloacetate transaminase 1 (GOT1), which fuel anabolic metabolism. In particular, we show that gain and loss of function of hepatic LRH-1 modulate the expression and activity of mitochondrial glutaminase 2 (GLS2), the first and rate-limiting step of this pathway. Acute and chronic deletion of hepatic LRH-1 blunts the deamination of glutamine and reduces glutamine-dependent anaplerosis. The robust reduction in glutaminolysis and the limiting availability of α-ketoglutarate in turn inhibit mTORC1 signaling to eventually block cell growth and proliferation. Collectively, these studies highlight the importance of LRH-1 in coordinating glutamineinduced metabolism and signaling to promote hepatocellular carcinogenesis.Supplemental material is available for this article.Received January 7, 2016; revised version accepted May 12, 2016.During tumorigenesis, cancer cells usually switch from oxidative metabolism to a highly glycolytic metabolic status (Vander Heiden et al. 2009). While glucose is predominantly metabolized into lactate rather than entering the tricarboxylic acid (TCA) cycle, cancer cells particularly rely on glutamine to replenish TCA cycle intermediates. This process, termed anaplerosis, is accomplished through the conversion of glutamine to α-ketoglutarate (α-KG) via a two-step deamination reaction catalyzed by glutaminases and then by glutamate dehydrogenase 1 (GLUD1) or transaminases Wise et al. 2008;Csibi et al. 2013;Son et al. 2013). Cancer cells therefore critically depend on glutamine as a fuel for proliferation, and abrogation of glutamine metabolism blocks tumorigenesis, indicating an accessible therapeutic window for cancer treatment (Hensley et al. 2013).Liver receptor homolog 1 (LRH-1; also called NR5A2) is a nuclear receptor that is enriched in enterohepatic tissues, where it has diverse molecular and physiological functions (Stein and Schoonjans 2015). LRH-1 has been linked to cell proliferation and cancer development in the intestine (Botrugno et al. 2004;Schoonjans et al. 2005) and pancreas (Petersen et al. 2010;Benod et al. 2011). In the liver, LRH-1 regulates various metabolic processes, including bile acid synthesis (Mataki et al. 2007;Lee et al. 2008;Out et al. 2011), glucose sensing and processing (Oosterveer et al. 2012), and reverse cholesterol transport (Stein et al. 2014). Although the function of LRH-1 in the liver has been extensively studied, its commanding role in intermediary metabolism has never been connected to tumorigenesis.In this study, we report that LRH-1 promotes diethylnitrosamine (DEN)-induced hepatocellular carcinoma (HCC) by coordinating glutamine-induced anabolic metabo...

The γ-glutamyl transpeptidase (GGT) enzyme plays a central role in glutathione homeostasis. Direct detection of GGT activity could provide critical information for the diagnosis of several pathologies. We propose a new molecular probe, γ-Glu-[1-(13) C]Gly, for monitoring GGT activity in vivo by hyperpolarized (HP) (13) C magnetic resonance (MR). The properties of γ-Glu-[1-(13) C]Gly are suitable for in vivo HP (13) C metabolic analysis since the chemical shift between γ-Glu-[1-(13) C]Gly and its metabolic product, [1-(13) C]Gly, is large (4.3 ppm) and the T1 of both compounds is relatively long (30 s and 45 s, respectively, in H2 O at 9.4 T). We also demonstrate that γ-Glu-[1-(13) C]Gly is highly sensitive to in vivo modulation of GGT activity induced by the inhibitor acivicin.

The metabolic shift induced in human CD4 + t lymphocytes by stimulation is characterized by an upregulation of glycolysis, leading to an augmentation in lactate production. this adaptation has already been highlighted with various techniques and reported in several previous studies. We herein propose a method to rapidly and noninvasively detect the associated increase in flux from pyruvate to lactate catalyzed by lactate dehydrogenase using hyperpolarized 13 c magnetic resonance, a technique which can be used for in vivo imaging. it was shown that the conversion of hyperpolarized 13 c-pyruvate to 13 C-lactate during the one-minute measurement increased by a mean factor of 3.6 in T cells stimulated for 5 days as compared to resting T cells. This method can be extended to other metabolic substrates and is therefore a powerful tool to noninvasively analyze t cell metabolism, possibly in vivo.Our dual parallel measurements (activated vs. resting T cells) could be extended to a larger number of parallel measurements using an integrated microfluidic system 46 , for instance to compare T cells that have been stimulated for a number of different time periods in a single measurement. HP 13 C MR can also be used to directly and noninvasively analyze the behavior of T cells in presence of antigens, possibly in vivo. Since it is well known that cancer cells will also compete for pyruvate 21 , HP [1-13 C]pyruvate might however not be the ideal substrate to detect T cell activation in the tumor microenvironment and alternative HP 13 C tracers shall be tested. We therefore plan on extending the proposed method to other metabolic substrates such as fatty acid and glutamine, the uptake and metabolism of which is also known to be altered in T lymphocytes upon activation 11 .

The prevalence of cardiovascular disease increases exponentially with age, highlighting the contribution of aging mechanisms to cardiac diseases. Although model organisms which share human disease pathologies can elucidate mechanisms driving disease, they do not provide us with innate examples how cardiac aging might be slowed or attenuated. The identification of animal models that preserve cardiac function throughout most of life offers an alternative approach to study mechanisms which might slow cardiac aging. One such species may be the naked mole-rat (NMR), a mouse-sized (40 g) rodent with extraordinary longevity (> 37 years), and constant mortality hazard over its four decades of life. We used a cross-sectional study design to measure a range of physiological parameters in NMRs between 2 and 34 years of age and compared these findings with those of mice aged between 3 months and 2.5 years. We observed a rapid decline in body fat content and bone mineral density in old mice, but no changes in NMRs. Similarly, rhythm disorders (premature atrial and ventricular complexes) occurred in aged mice but not in NMRs. Magnetic resonance and ultrasound imaging showed age-dependent increases in cardiac hypertrophy and diastolic dysfunction in mice which were absent in NMRs. Finally, cardiac stress tests showed an age-dependent decline in normalized cardiac output in mice, which was absent in NMRs. Unlike mice, that manifest several aspects of human cardiac aging, NMRs maintain cardiac function and reserve capacity throughout their long lives and may offer insights on how to delay or prevent cardiac aging.