title: Fourier transform infrared microspectroscopy reveals biochemical changes associated with glioma stem cell differentiation.
abstract: According to the cancer stem cell theory malignant glioma is incurable because of the presence of the cancer stem cells - a subpopulation of cells that are resistant to therapy and cause the recurrence of a tumor after surgical resection. Several protein markers of cancer stem cell were reported but none of those is fully reliable to grade the content of stem cells in a tumor. Hereby we propose Fourier transform infrared (FTIR) microspectroscopy as an alternative, labelfree, non-damaging and fast method to identify glioma stem cells based on their own spectral characteristics. The analysis of FTIR data revealed that in NCH421k cells, a model of glioma stem cells, the relative content of lipids is higher than in their all-trans retinoic acid-differentiated counterparts. Moreover, it has been assessed that stem cells have more rigid cellular membranes and more phosphorylated proteins, whereas after differentiation glycogen level increases. The ability of FTIR to estimate the content of stem cells in a heterogeneous sample, on the base of the identified spectral markers, and to classify stem and non-stem cells into two separate populations was probed. Although it was not possible to calculate the exact percentage of each subpopulation, we could clearly see that with the increasing amount of differentiated cells in a sample, more hits occupy the PC space previously identified as a space of differentiated cells. The present study is therefore an initial step towards the development of a FTIR based protocol in clinical practice to estimate the content of stem cells in a tumor sample.
authors.affiliation: Structural Biology Laboratory, Elettra-Sincrotrone Trieste, Italy. Electronic address: sasa.kenig@elettra.eu.
authors.forename: Saša
authors.initials: S
authors.lastname: Kenig
authors.affiliation: SISSI beamline, Elettra-Sincrotrone Trieste, Italy.
authors.forename: Diana E
authors.initials: DE
authors.lastname: Bedolla
authors.affiliation: SISSI beamline, Elettra-Sincrotrone Trieste, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Birarda
authors.affiliation: Structural Biology Laboratory, Elettra-Sincrotrone Trieste, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Faoro
authors.affiliation: SISSI beamline, Elettra-Sincrotrone Trieste, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Mitri
authors.affiliation: Structural Biology Laboratory, Elettra-Sincrotrone Trieste, Italy; Edward Doisy Department of Biochemistry and Molecular Biology, St. Louis University, MO, USA.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vindigni
authors.affiliation: Structural Biology Laboratory, Elettra-Sincrotrone Trieste, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Storici
authors.affiliation: SISSI beamline, Elettra-Sincrotrone Trieste, Italy.
authors.forename: Lisa
authors.initials: L
authors.lastname: Vaccari
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D005910:Glioma / Q000378:metabolism / Q000473:pathology; D006003:Glycogen / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence; D014411:Neoplastic Stem Cells / Q000166:cytology* / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D025341:Principal Component Analysis; D017550:Spectroscopy, Fourier Transform Infrared; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; D010455:Peptides; D014212:Tretinoin; D006003:Glycogen
keywords: Cancer stem cells; Differentiation; Glioma; Glycogen; Infrared microspectroscopy; Lipids