text: Production of hyperpolarized [1,4-13C2]malate from [1,4-13C2]fumarate is a marker of cell necrosis and treatment response in tumors. - PubMed - NCBI
  1 selected item: 19903889
  Proc Natl Acad Sci U S A. 2009 Nov 24;106(47):19801-6. doi: 10.1073/pnas.0911447106. Epub 2009 Nov 10.
  Gallagher FA1, Kettunen MI, Hu DE, Jensen PR, Zandt RI, Karlsson M, Gisselsson A, Nelson SK, Witney TH, Bohndiek SE, Hansson G, Peitersen T, Lerche MH, Brindle KM.
  Cancer Research United Kingdom, Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge CB2 0RE, United Kingdom.
  PMC2785247
  10.1073/pnas.0911447106
  13C spectra acquired over a period of 1 min after injection of hyperpolarized [1,4-13C2]fumarate into suspensions of intact murine lymphoma cells (≈5 × 107 cells) or lysed cells; these are representative spectra from the data shown in . For clarity, only every third spectrum is shown and each series has been scaled to the maximum fumarate signal. (A) Untreated cells. (B) Cells 16 h after etoposide treatment. (C) Lysed cells. The truncated signal from the hyperpolarized [1,4-13C2]fumarate is at 175.4 ppm, the signal from [1-13C]malate at ≈181.8 ppm, and the signal from [4-13C]malate at ≈180.6 ppm.
  Effect of drug treatment and induction of cellular necrosis on 13C label flux between [1,4-13C2]fumarate and [1,4-13C2]malate in EL-4 lymphoma cell suspensions. (A) Ratio of the average [1-13C] and [4-13C]malate peak intensity/total hyperpolarized 13C signal intensity (± SD, n = 3). It has been corrected for total cell number, which includes viable, apoptotic, and necrotic cell populations. Untreated cells (circles), cells 16 h after etoposide treatment (triangles), and lysed cells (squares). The open symbols refer to experiments performed with 10 mM hyperpolarized [1,4-13C2]fumarate only, and the filled symbols show experiments performed with the coadministration of 50 mM nonhyperpolarized and unlabeled succinate; for clarity, the open symbols have been offset by −0.5 s and the filled symbols have been offset by +0.5 s. (B) Rate of malate production (calculated from the initial slope of malate amplitude/total 13C signal over time) plotted against the percentage of cell necrosis in each experiment. The conditions used to vary the levels of necrosis are described in Materials and Methods.
  13C spectra acquired from slices through subcutaneous murine lymphoma tumors. (A and B) Untreated (A) and etopside-treated (B) tumors 30 s after the i.v. injection of hyperpolarized [1,4-13C2]fumarate; these are representative spectra from the experiments shown in C and D. The signal from hyperpolarized fumarate is seen at 175.4 ppm, the signal from [1-13C]malate is seen at ≈181.8 ppm, and the signal from [4-13C]malate is seen at ≈180.6 ppm. An unidentified contaminant is seen at ≈177 ppm. (C) Total hyperpolarized 13C malate signal over time (i.e., the summed intensities of [1-13C] and [4-13C]malate) normalized to the maximum [1,4-13C2]fumarate signal for untreated (○) and etoposide-treated (■) animals (± SD, n = 5). (D) Hyperpolarized [1,4-13C2]fumarate signal in the same animals as in C. The superimposed curves represent the average fits for both the fumarate and the malate resonances using the kinetic modeling described in the text (assuming TM = TF). The solid line represents treated animals, and the dashed line represents untreated animals.
  Representative transverse images from untreated (A) and etoposide-treated (B) mice with s.c.-implanted lymphoma tumors. The 1H image shows the anatomical location of the tumor, outlined in white. Adjacent to this are false-color CSIs superimposed on the 1H image, which demonstrate the spatial distribution of the total hyperpolarized 13C malate and 13C fumarate signals. The color scale indicates the relative signal intensity compared with the maximum intensity in each image. To reduce the effects of noise, voxels with signal intensities ≤20% of the maximum signal intensity were removed from the image. Although the images have been scaled to their respective maxima, the maximum malate signal intensity in each experiment is ≈10–25% of the maximum fumarate signal.