64 ARTICLE Submitted 3 August 2020, Resubmitted 14 October 2020, Accepted 15 October 2020, Available online 20 October 2020. Cite: Menegasso, A. R. S.; Pratavieira, M.; dos Santos, L. D.; Lima, F. O.; Moraes, M. P. T.; Zanini, M. A.; Palma, M. S. In Situ Proteomic Analysis of Glioblastoma Multiforme: A Translational Approach to Improve Prognostic/Diagnostic Routines. Braz. J. Anal. Chem., 2020, 7 (29), pp 64–83. doi: http://dx.doi.org/10.30744/brjac.2179-3425.AR-41-2020 In Situ Proteomic Analysis of Glioblastoma Multiforme: A Translational Approach to Improve Prognostic/Diagnostic Routines Anally Ribeiro da Silva Menegasso 1 , Marcel Pratavieira 1 , Lucilene Delazari dos Santos 2 , Flávio de Oliveira Lima 2 , Marcelo Padovani T. Moraes 3 , Marco Antonio Zanini 3 , Mario Sergio Palma 1 * 1 Institute of Biosciences, Department of Basic and Applied Biology, Center of the Study of Social Insects, Sao Paulo State University (UNESP), Rio Claro, SP, Brazil 2 Center for the Study of Venoms and Venomous Animals (CEVAP), Sao Paulo State University (UNESP), Botucatu, SP, Brazil 3 Botucatu Medical School (FMB) – Sao Paulo State University (UNESP), Botucatu, SP, Brazil *Correspondence: Prof. Dr. Mario Sergio Palma. CEIS-IBRC- UNESP, Av. 24A nº 1515, Bela Vista - 13506-900, Rio Claro, SP, Brazil Brazilian Journal of Analytical Chemistry 2020, Volume 7, Issue 29, pp 64-83 doi: 10.30744/brjac.2179-3425.AR-41-2020 In order to evaluate the use of matrix-assisted laser desorption ionization (MALDI) Mass Spectral Imaging (MSI) to Glioblastoma (GBM) studies, some sections of formalin fxed parafn embedded samples of GBM tumors were submitted to classical immunoassays, to defne the profle of distribution of some classical and well recognized molecular markers of GBM grade IV (Ki-67, S100, Glial GFAP, CD31 and CD34), while other sections of the same samples were submitted to in- tissue proteomic analysis by MALDI MSI, and both results compared to each other. The overlapping of the MALDI spectra obtained for the tryptic peptides with the immunohistochemical reactions of each marker protein were used to build a distribution map of the marker proteins all over the GBM tissue section. The results revealed a high correlation between both methods, indicating that MALDI MSI has enough sensitivity to be compared to the immunohistochemical methods, as well is sufciently reliable to be used in biomarkers identifcation. Keywords: MALDI-TOF MS, MALDI Imaging, Tumor biomarkers, Glioblastoma multiforme, In situ proteomics. 1 of 20