title: Noninvasive magnetic resonance spectroscopic pharmacodynamic markers of a novel histone deacetylase inhibitor, LAQ824, in human colon carcinoma cells and xenografts.
abstract: The aim of this work was to use phosphorus magnetic resonance spectroscopy ((31)P MRS) to investigate the pharmacodynamic effects of LAQ824, a histone deacetylase (HDAC) inhibitor. Human HT29 colon carcinoma cells were examined by (31)P MRS after treatment with LAQ824 and another HDAC inhibitor, suberoylanilide hydroxamic acid. HT29 xenografts and tumor extracts were also examined using (31)P MRS, pre- and post-LAQ824 treatment. Histone H3 acetylation was determined using Western blot analysis, and tumor microvessel density by immunohistochemical staining of CD31. Phosphocholine showed a significant increase in HT29 cells after treatment with LAQ824 and suberoylanilide hydroxamic acid. In vivo, the ratio of phosphomonoester/total phosphorus (TotP) signal was significantly increased in LAQ824-treated HT29 xenografts, and this ratio was inversely correlated with changes in tumor volume. Statistically significant decreases in intracellular pH, beta-nucleoside triphosphate (beta-NTP)/TotP, and beta-NTP/inorganic phosphate (Pi) and an increase in Pi/TotP were also seen in LAQ824-treated tumors. Tumor extracts showed many significant metabolic changes after LAQ824 treatment, in parallel with increased histone acetylation and decreased microvessel density. Treatment with LAQ824 resulted in altered phospholipid metabolism and compromised tumor bioenergetics. The phosphocholine and phosphomonoester increases may have the potential to act as pharmacodynamic markers for noninvasively monitoring tumor response after treatment with LAQ824 or other HDAC inhibitors.
authors.affiliation: Cancer Research UK, Biomedical Magnetic Resonance Research Group, Department of Basic Medical Sciences, St. George's University of London, London, UK. ylichung@icr.ac.uk
authors.forename: Yuen-Li
authors.initials: YL
authors.lastname: Chung
authors.forename: Helen
authors.initials: H
authors.lastname: Troy
authors.forename: Rebecca
authors.initials: R
authors.lastname: Kristeleit
authors.forename: Wynne
authors.initials: W
authors.lastname: Aherne
authors.forename: L Elizabeth
authors.initials: LE
authors.lastname: Jackson
authors.forename: Peter
authors.initials: P
authors.lastname: Atadja
authors.forename: John R
authors.initials: JR
authors.lastname: Griffiths
authors.forename: Ian R
authors.initials: IR
authors.lastname: Judson
authors.forename: Paul
authors.initials: P
authors.lastname: Workman
authors.forename: Martin O
authors.initials: MO
authors.lastname: Leach
authors.forename: Mounia
authors.initials: M
authors.lastname: Beloueche-Babari
mesh_terms: D000107:Acetylation; D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019073:HT29 Cells; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000627:therapeutic use*; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D008819:Mice, Nude; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010759:Phosphorus Isotopes; D010767:Phosphorylcholine / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000077337:Vorinostat; D023041:Xenograft Model Antitumor Assays
chemical_list: D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; C477361:LAQ824; D010759:Phosphorus Isotopes; D010767:Phosphorylcholine; D000077337:Vorinostat