Novel in situ pretreatment method for significantly enhancing the signal in MALDI-TOF MS of formalin-fixed paraffin-embedded tissue sections.
The application of matrix-assisted laser desorption/ionization (MALDI)-based mass spectrometry (MS) to the proteomic analysis of formalin-fixed paraffin-embedded (FFPE) tissue presents significant technical challenges. In situ enzymatic digestion is frequently used to unlock formalin-fixed tissues for analysis, but the results are often unsatisfactory. Here, we report a new, simplified in situ pretreatment method for preparing tissue sections for MS that involves heating with vapor containing acetonitrile in a small airtight pressurized space. The utility of the novel method is shown using FFPE tissue of human colon carcinoma. The number and intensity of MALDI peaks obtained from analysis of pretreated tissue was significantly higher than control tissue not subjected to pretreatment. A prominent peak (m/z 850) apparently specific to cancerous tissue was identified as a fragment of histone H2A in FFPE tissue pretreated using our method. This highly sensitive treatment may enable MALDI-MS analysis of archived pathological FFPE samples, thus leading to the identification of new biomarkers.
Department of Forensic Medicine and Molecular Pathology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Yu
Y
Kakimoto
Tatsuaki
T
Tsuruyama
Takushi
T
Yamamoto
Masaru
M
Furuta
Hirokazu
H
Kotani
Munetaka
M
Ozeki
Akihiko
A
Yoshizawa
Hironori
H
Haga
Keiji
K
Tamaki
D015415:Biomarkers / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016612:Paraffin Embedding / Q000379:methods*; D040901:Proteomics / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D016707:Tissue Fixation / Q000379:methods*
D015415:Biomarkers