title: Detection of histone deacetylase inhibition by noninvasive magnetic resonance spectroscopy.
abstract: Histone deacetylase (HDAC) inhibitors are new and promising antineoplastic agents. Current methods for monitoring early response rely on invasive biopsies or indirect blood-derived markers. Our goal was to develop a magnetic resonance spectroscopy (MRS)-based method to detect HDAC inhibition. The fluorinated lysine derivative Boc-Lys-(Tfa)-OH (BLT) was investigated as a (19)F MRS molecular marker of HDAC activity together with (31)P MRS of endogenous metabolites. In silico modeling of the BLT-HDAC interaction and in vitro MRS studies of BLT cleavage by HDAC confirmed BLT as a HDAC substrate. BLT did not affect cell viability or HDAC activity in PC3 prostate cancer cells. PC3 cells were treated, in the presence of BLT, with the HDAC inhibitor p-fluoro-suberoylanilide hydroxamic acid (FSAHA) over the range of 0 to 10 micromol/L, and HDAC activity and MRS spectra were monitored. Following FSAHA treatment, HDAC activity dropped, reaching 53% of control at 10 micromol/L FSAHA. In parallel, a steady increase in intracellular BLT from 14 to 32 fmol/cell was observed. BLT levels negatively correlated with HDAC activity consistent with higher levels of uncleaved BLT in cells with inhibited HDAC. Phosphocholine, detected by (31)P MRS, increased from 7 to 16 fmol/cell following treatment with FSAHA and also negatively correlated with HDAC activity. Increased phosphocholine is probably due to heat shock protein 90 inhibition as indicated by depletion of client proteins. In summary, (19)F MRS of BLT, combined with (31)P MRS, can be used to monitor HDAC activity in cells. In principle, this could be applied in vivo to noninvasively monitor HDAC activity.
authors.affiliation: Experimental Diagnostic Imaging, The University of Texas M.D. Anderson Cancer Center, 57-3D, 1515 Holcombe Blvd., Houston, TX 77030-4009, USA.
authors.forename: Madhuri
authors.initials: M
authors.lastname: Sankaranarayanapillai
authors.forename: William P
authors.initials: WP
authors.lastname: Tong
authors.forename: David S
authors.initials: DS
authors.lastname: Maxwell
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Pal
authors.forename: Jihai
authors.initials: J
authors.lastname: Pang
authors.forename: William G
authors.initials: WG
authors.lastname: Bornmann
authors.forename: Juri G
authors.initials: JG
authors.lastname: Gelovani
authors.forename: Sabrina M
authors.initials: SM
authors.lastname: Ronen
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D018360:Crystallography, X-Ray; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010759:Phosphorus Isotopes; D010767:Phosphorylcholine / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D056572:Histone Deacetylase Inhibitors; D010759:Phosphorus Isotopes; D010767:Phosphorylcholine; D019908:Proto-Oncogene Proteins c-raf; D051358:Cyclin-Dependent Kinase 4; D006655:Histone Deacetylases; D008239:Lysine