title: Extended ultrastructural characterization of chordoma cells: the link to new therapeutic options.
abstract: Chordomas are rare bone tumors, developed from the notochord and largely resistant to chemotherapy. A special feature of this tumor is the heterogeneity of its cells. By combining high pressure freezing (HPF) with electron tomography we were able to illustrate the connections within the cells, the cell-cell interface, and the mitochondria-associated endoplasmic reticulum membrane complex that appears to play a special role among the characteristics of chordoma. These lipid raft-like regions are responsible for lipid syntheses and for calcium signaling. Compared to other tumor cells, chordoma cells show a close connection of rough endoplasmic reticulum and mitochondria, which may influence the sphingolipid metabolism and calcium release. We quantified levels of ceramide and glycosylceramide species by the methyl tert-butyl ether extraction method and we assessed the intracellular calcium concentration with the ratiometric fluorescent dye Fura-2AM. Measurements of the changes in the intracellular calcium concentration revealed an increase in calcium due to the application of acetylcholine. With regard to lipid synthesis, glucosylceramide levels in the chordoma cell line were significantly higher than those in normal healthy cells. The accumulation of glycosylceramide in drug resistant cancer cells has been confirmed in many types of cancer and may also account for drug resistance in chordoma. This study aimed to provide a deep morphological description of chordoma cells, it demonstrated that HPF analysis is useful in elucidating detailed structural information. Furthermore we demonstrate how an accumulation of glycosylceramide in chordoma provides links to drug resistance and opens up the field for new research options.
authors.affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria; Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Kolb
authors.affiliation: Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Pritz
authors.affiliation: Ludwig Boltzmann Institute for Rehabilitation of Internal Diseases, Ludwig Boltzmann Cluster for Rheumatology, Balneology and Rehabilitation, Saalfelden, Austria.
authors.forename: Bibiane
authors.initials: B
authors.lastname: Steinecker-Frohnwieser
authors.affiliation: Department of Orthopaedic Surgery, Medical University of Graz, Graz, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Lohberger
authors.affiliation: Division of Hematology, Department of Internal Medicine, Medical University of Graz, Graz, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Deutsch
authors.affiliation: Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kroneis
authors.affiliation: Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.
authors.forename: Amin
authors.initials: A
authors.lastname: El-Heliebi
authors.affiliation: Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Dohr
authors.affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Meditz
authors.affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Wagner
authors.affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria.
authors.forename: Harald
authors.initials: H
authors.lastname: Koefeler
authors.affiliation: Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.
authors.forename: Gerd
authors.initials: G
authors.lastname: Leitinger
authors.affiliation: Department of Orthopaedic Surgery, Medical University of Graz, Graz, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Leithner
authors.affiliation: Institute of Pathology, Medical University of Graz, Graz, Austria.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Liegl-Atzwanger
authors.affiliation: Biophysics Division, Institute of Molecular Biosciences, University of Graz, Graz, Austria.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Zweytick
authors.affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria.
authors.forename: Beate
authors.initials: B
authors.lastname: Rinner
mesh_terms: D001859:Bone Neoplasms / Q000473:pathology / Q000648:ultrastructure*; D045744:Cell Line, Tumor; D002817:Chordoma / Q000473:pathology / Q000648:ultrastructure*; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure*; D009672:Notochord / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D013107:Sphingolipids / Q000378:metabolism
chemical_list: D013107:Sphingolipids