title: Identification of potential protein targets of isothiocyanates by proteomics.
abstract: Isothiocyanates (ITCs), such as phenethyl isothiocyanate (PEITC) and sulforaphane (SFN), are effective cancer chemopreventive compounds. It is believed that the major mechanism for the cancer preventive activity of ITCs is through the induction of cell cycle arrest and apoptosis. However, the upstream molecular targets of ITCs have been underexplored until recently. To identify proteins that are covalently modified by ITCs, human non-small cell lung cancer A549 cells were treated with (14)C-PEITC and (14)C-SFN, and the cell lysates were extracted for analysis by 2-D gel electrophoresis and mass spectrometry. After superimposing the colloidal Coomassie blue protein staining pattern with the pattern of radioactivity obtained from X-ray films, it was clear that only a small fraction of cellular proteins contained radioactivity, presumably resulting from selective binding with PEITC or SFN via thiocarbamation. More than 30 proteins with a variety of biological functions were identified with high confidence. Here, we report the identities of these potential ITC target proteins and discuss their biological relevance. The discovery of the protein targets may facilitate studies of the mechanisms by which ITCs exert their cancer preventive activity and provide the molecular basis for designing more efficacious ITC compounds.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, 3800 Reservoir Road, Washington, D.C. 20057, United States.
authors.forename: Lixin
authors.initials: L
authors.lastname: Mi
authors.forename: Brian L
authors.initials: BL
authors.lastname: Hood
authors.forename: Nicolas A
authors.initials: NA
authors.lastname: Stewart
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xiao
authors.forename: Sudha
authors.initials: S
authors.lastname: Govind
authors.forename: Xiantao
authors.initials: X
authors.lastname: Wang
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Conrads
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Veenstra
authors.forename: Fung-Lung
authors.initials: FL
authors.lastname: Chung
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis; D059447:Cell Cycle Checkpoints; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D014404:Tubulin / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; D017879:Isothiocyanates; D014404:Tubulin; C058305:phenethyl isothiocyanate; D046988:Proteasome Endopeptidase Complex; C473643:sulphoraphene