title: Multiplex target protein imaging in tissue sections by mass spectrometry--TAMSIM.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS) is becoming a popular tool for imaging histological sections. Currently, this technology is used to image naturally occurring molecules. Here we report a novel development for multiplex imaging of candidate proteins. Rather than detecting whatever molecules happen to be present and above the detection threshold in the desorption pixel, we attach photocleavable mass tags to antibodies to target proteins. 'Staining' of histological sections is carried out similarly to common immunohistochemical procedures with chemiluminescent or fluorescent detection using all antibodies of a multiplex simultaneously. Mass tags with discrete masses are released from their respective antibodies by a laser pulse at 355 nm without added matrix. After scanning, mass spectrometry images are created for the mass of each tag. In contrast to fluorescent tags, mass tags do not exhibit mutual quenching. Sections of healthy human pancreatic tissue were imaged to visualize synaptophysin in neuroendocrine cells, and sections from human lymph node and liver invaded by metastatic melanoma to localize the cancer markers PS100 and HMB45 simultaneously. All these proteins are below the detection threshold of direct MALDI-MS imaging. This method is termed TAMSIM for TArgeted multiplex Mass Spectrometry IMaging.
authors.affiliation: Centre National de Génotypage, Bâtiment G2, 2 rue Gaston Crémieux, 91057 Evry Cedex, France.
authors.forename: Gwendoline
authors.initials: G
authors.lastname: Thiery
authors.forename: Mikhail S
authors.initials: MS
authors.lastname: Shchepinov
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Southern
authors.forename: Anne
authors.initials: A
authors.lastname: Audebourg
authors.forename: Virginie
authors.initials: V
authors.lastname: Audard
authors.forename: Benoît
authors.initials: B
authors.lastname: Terris
authors.forename: Ivo G
authors.initials: IG
authors.lastname: Gut
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D016503:Drug Delivery Systems / Q000379:methods; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008113:Liver Neoplasms / Q000378:metabolism / Q000556:secondary; D008207:Lymphatic Metastasis; D008545:Melanoma / Q000378:metabolism* / Q000556:secondary*; D008856:Microscopy, Fluorescence / Q000379:methods; D009363:Neoplasm Proteins / Q000032:analysis*; D040081:Protein Array Analysis / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D046888:Tissue Array Analysis / Q000379:methods
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins