Anthony Mancuso^1,2, Kathryn E Wellen¹, Chao Lu¹, Weixia Liu³, Stephen Pickup³, and Craig B Thompson^1,4
1Cancer Biology, University of Pennsylvania, Philadelphia, PA, United States, ²Radiology, University of Pennsylvania, Philadelphia, PA, United States Minor Outlying Islands,³Radiology, University of Pennsylvania, Philadelphia, PA, United States, ⁴Memorial Sloan Kettering Cancer Center, New York, NY, United States

We have been studying lipogenesis because of its importance in mammalian cell growth and proliferation. Glucose is normally the primary precursor for this process; however, we have observed that human glioblastoma cells derive much lipogenic carbon from glutamine. In this work, we report that immortalized hematopoietic cells produce lipid from glutamine via both the glutaminolytic and reverse isocitrate dehydrogenase (IDH) pathways in the presence of glucose. In the absence of glucose, the more energy efficient glutaminolytic pathway was predominant. These results are fundamentally different from those observed for glioblastoma cells, which predominantly use the more energy inefficient reverse IDH pathway, perhaps compromising efficiency for the sake of rapid biosynthesis.

Ellen Ackerstaff¹, Brijesh B. Patel², Yanique I. Rattigan², George Sukenick³, Natalia Kruchevsky¹, John W. Glod², Jason A. Koutcher¹, and Debabrata Banerjee^2
1Memorial Sloan-Kettering Cancer Center, New York, NY, United States, ²The Cancer Institute of New Jersey, RWJMS, UMDNJ, New Brunswick, NJ, United States, ³Sloan-Kettering Institute, New York, NY, United States

We hypothesize that tumor cells recruit stromal cells and that stromal cells metabolize lactate expelled by tumor cells into the microenvironment. Human mesenchymal stem cells (hMSCs) are bone marrow-derived stromal cells which migrate toward hypoxic tumor cells and overexpress functional monocarboxylate transporter 1 in response to lactate exposure. Naive hMSCs and carcinoma-associated fibroblasts (CAFs) exposed to ¹³C-3-lactate, produced detectable levels of ¹³C-α-ketoglutarate. Additional ¹⁴C-lactate studies showed that lactate uptake in CAFs was higher than in hMSCs. Also, lactate stimulated hMSC migration. Our results suggests the metabolic cooperation between stromal and tumor cells.

Balaji Krishnamachary¹, Noriko Mori¹, Mayur Gadiya¹, Yelena Mironchik¹, Flonne Wildes¹, Kristine Glunde¹, and Zaver M Bhujwalla^1
1Radiology, Johns Hopkins University, Baltimore, Maryland, United States

Synopsis: Increased phosphocholine (PC) and total choline are consistently observed in cancers, especially breast cancer. Only now are we beginning to uncover the complexity of factors that regulate choline metabolism in cancer, and the compensatory mechanisms that exist in this pathway. Here we have shown the interdependence between two enzymes in choline metabolism, choline kinase (Chk) the enzyme that forms phosphocholine from free choline, and phosphatidylcholine-specific phospholipase D1 (PLD1), the enzyme that forms choline from phosphatidylcholine. We have also identified increased free choline as an inhibitor of the increase of PLD1 observed following Chk downregulation.

Maria Dung Cao^1,2, Lu Jiang¹, Balaji Krishnamachary¹, Mailin Doepkens^1,3, Zaver M Bhjuwalla¹, Ingrid Gribbestad², and Kristine Glunde^1
1Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States, ²Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway, ³Department of Chemistry and Biology, University of Bremen, Bremen, Germany

In our study we investigated the effects of silencing the glycerophosphocholine phosphodiesterase GDPD5 in MCF7 breast cancer cells and tumor xenograft models using both ex vivo high-resolution MRS and in vivo MRSI. Here we demonstrated for the first time that silencing the specific GPC-PDE enzyme GDPD5 increased the tCho levels in breast cancer cells and tumor models. Interestingly, the tumor growth rate of the GDPD5-silenced breast tumor xenografts was significantly reduced. These findings emphasize that GDPD5 may have a potential role as an anticancer target in regulating choline phospholipid metabolism in breast cancer.

Lauren C.J Baker¹, Yuen-Li Chung¹, Jessica K Boult¹, Margaret A Ashcroft², and Simon P Robinson^1
1CRUK and EPSRC Cancer Imaging Centre, The Institute of Cancer Research and Royal Marsden NHS Trust, Sutton, Surrey, United Kingdom, ²University College London, United Kingdom

Hypoxia-inducible factor (HIF) pathway inhibitors are an emerging class of therapeutics, whose precise mechanism of action is unclear. In this study, we examined the metabolic effects of NSC-134754, a small molecule inhibitor of the HIF pathway. Firstly, we show that NSC-134754 downregulates both the expression and distribution of glucose transporter 1, a downstream target of HIF-1. Secondly, magnetic resonance spectroscopy reveals a unique metabolic profile of the actions of NSC-134754 on cellular metabolism. Finally, we demonstrate that effects on glucose transport in vitro with NSC-134754 are reproduced in vivo in an orthotopic model of prostate cancer.

Alessia Lodi¹, and Sabrina M Ronen^1
1University of California San Francisco, San Francisco, California, United States

Carcinogenesis often involves signaling pathway deregulation and targeted inhibitors are under investigation as anticancer therapeutics. Here we used a completely untargeted, MRS-based metabolomics approach to investigate the metabolic consequences of treatment with PI3K or combined PI3K/MAPK inhibitors in human prostate cancer cells. The modulation of phosphocholine and lactate concentrations following treatment with either PI3K or combined PI3K/MAPK inhibitors was similar in different prostate cell lines and recapitulated similar findings in breast cancer cells. Interestingly treatment of prostate cells with 17AAG increased the accumulation of citrate, a key metabolite dramatically decreased upon prostate malignant transformation.

Daniel-Joseph Leung^1,2, and E. James Delikatny^2
1Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, United States, ²Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

Observations of intracellular lipid (particularly triglyceride) accumulation in the form of MR-visible mobile lipids and lipid droplets have been associated with apoptosis and necrosis in a variety of cancer models. Here we use MRS in combination with fluorescent fatty acids to assess the process of mobile lipid formation in DU145 prostate cancer cells. This assay is then used to screen DU145 cells against a range of anticancer drugs, resulting in measured fluorescence indicative of a range of lipid response. This approach, used as a screening tool in conjunction with MRS, will aid in the functional dissection of the contributing pathways involved in lipid formation in cancer cells undergoing chemotherapy.

Kayvan R. Keshari¹, Bertram Koelsch², Rahwa Iman², Mark Van Criekinge², Daniel B. Vigneron², John Kurhanewicz², and Zhen J Wang^2
1UCSF, San Francisco, CA, United States, ²UCSF

The widespread use of cross-sectional imaging has led to the incidental discovery of many renal tumors. However, triage of therapies is currently difficult due to our inability to reliably differentiate benign from malignant, or indolent from aggressive renal tumors noninvasively by conventional imaging techniques. In this study we use a combination steady-state [3-13C]pyruvate cell labeling and HP [1-13C]pyruvate cell culture bioreactor studies to show that HP13C MR has the potential to noninvasively characterize renal tumor aggressiveness. Specifically, increasing HP [1-13C]lactate may be a useful biomarker for discriminating benign from malignant, and indolent from aggressive renal tumors.

Deborah Katherine Hill¹, Yann Jamin¹, Nicolas Tardif¹, Anne-Christine Wong Te Fong¹, Simon P Robinson¹, Harold G Parkes¹, Matthew R Orton¹, Martin O Leach¹, Yuen-Li Chung¹, and Thomas R Eykyn^1,2
1Clinical Magnetic Resonance, CRUK and EPSRC Cancer Imaging Centre, Royal Marsden NHS Trust and The Institute of Cancer Research, Sutton, Surrey, United Kingdom,²Division of Imaging Sciences, The Rayne Institute, Lambeth Wing, St Thomas Hospital, London, United Kingdom

Signal enhancements by DNP have facilitated the interrogation of metabolic processes using ¹³C MRS in real-time. We demonstrate that it is possible to measure in vitropyruvate-lactate exchange kinetics by utilising scalar couplings of methyl ¹H resonances to adjacent [3-¹³C] labelled nuclei, without the need of hyperpolarisation. The ¹H MRS-based assay measured the forward reaction rate with comparable reproducibility to the hyperpolarised ¹³C assay. The ¹H assay has the advantage of also reliably probing the backward reaction, which has large errors in the ¹³C assay. Both assays detected a comparable response to treatment with Paclitaxel, a widely used chemotherapy drug.

Talia Harris¹, Lucio Frydman¹, and Hadassa Degani^2
1Chemical Physics, Weizmann Institute of Science, Rehovot, Israel, ²Biological Regulation, Weizmann Institute of Science, Rehovot, Israel

Elevated glycolytic rates are a known feature of many cancers. The recent development of a method to hyperpolarize nuclear spins more than 10,000x in the liquid states opens up new opportunities to follow metabolic processes non-invasively with high temporal resolution using 13C NMR. In this study we utilize a perfusion-injection system to study the metabolism of hyperpolarized U-13C-d7-D-Glucose in living T47D breast cancer cells. The conversion of Glucose Lactate as well as labeling of other metabolites is seen. Further, the conversion of GlucoseLactate by T47D cells is shown to have the same concentration dependence as the uptake of radioactively labeled 2-deoxy-D-Glucose.