title: Facile synthesis [5-(13)C-4-(2)H(2)]-L-glutamine for hyperpolarized MRS imaging of cancer cell metabolism.
abstract: OBJECTIVE
  Recent reports suggest that cancer cells may use glutamine, instead of glucose, as an alternative source of metabolic energy. This suggests that hyperpolarized (13)C glutamine may be useful as a magnetic resonance spectroscopy (MRS) imaging agent for detecting changes in glutamine metabolism in cancerous cells or tissues.
  
  
  METHODS
  Synthesis of [5-(13)C-4-(2)H(2)]-L-glutamine was accomplished through a seven-step synthetic pathway with a 44% overall yield. The introduction of two stable isotopes was performed by a NaB(2)H(4)-mixed anhydride reduction and K(13)CN-nuclophilic substitution, respectively. The desired [5-(13)C-4-(2)H(2)]-L-glutamine was successfully obtained by a one-pot reaction of deprotection and controlled cyanide hydrolysis. Hyperpolarized [5-(13)C-4-(2)H(2)]-L-glutamine samples were tested in human glioma cells (myc upregulated glia cells, SF188-Bcl-x(L)). MRS signals were obtained with a 9.4 Tesla 89-mm bore nuclear magnetic resonance spectrometer and a direct-detection multi-nuclear probe.
  
  
  RESULTS
  The initial degree of polarization for [5-(13)C-4-(2)H(2)]-L-glutamine was ~5% and the initial (13)C signal to noise ratio was ~100:1. Glutamate was detected within seconds after the injection of hyperpolarized glutamine into the cells. The ratio of glutamate to glutamine was very high, indicating rapid conversion to glutamate. Similar cell uptake studies using [(3)H]-L-glutamine also demonstrated cell uptakes higher than that of [(18)F]fluorodeoxyglucose.
  
  
  CONCLUSIONS
  We are reporting the first example of using specifically deuterated [5-(13)C-4-(2)H(2)]-L-glutamine in conjunction with hyperpolarized MRS for studying "glutaminolysis" in proliferating tumor cells.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Wenchao
authors.initials: W
authors.lastname: Qu
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Zha
authors.forename: Brian P
authors.initials: BP
authors.lastname: Lieberman
authors.forename: Anthony
authors.initials: A
authors.lastname: Mancuso
authors.forename: Mathew
authors.initials: M
authors.lastname: Stetz
authors.forename: Rahim
authors.initials: R
authors.lastname: Rizzi
authors.forename: Karl
authors.initials: K
authors.lastname: Ploessl
authors.forename: David
authors.initials: D
authors.lastname: Wise
authors.forename: Craig
authors.initials: C
authors.lastname: Thompson
authors.forename: Hank F
authors.initials: HF
authors.lastname: Kung
mesh_terms: D002247:Carbon Isotopes / Q000138:chemical synthesis*; D045744:Cell Line, Tumor; D004734:Energy Metabolism / Q000502:physiology; D005910:Glioma / Q000378:metabolism*; D005973:Glutamine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D016271:Proto-Oncogene Proteins c-myc; D005973:Glutamine