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Extended ultrastructural characterization of chordoma cells: the link to new therapeutic options.

Kolb D, Pritz E, Steinecker-Frohnwieser B, Lohberger B, Deutsch A, Kroneis T, El-Heliebi A, Dohr G, Meditz K, Wagner K, Koefeler H, Leitinger G, Leithner A, Liegl-Atzwanger B, Zweytick D, Rinner B - PLoS ONE (2014)

Bottom Line: A special feature of this tumor is the heterogeneity of its cells.These lipid raft-like regions are responsible for lipid syntheses and for calcium signaling.Measurements of the changes in the intracellular calcium concentration revealed an increase in calcium due to the application of acetylcholine.

View Article: PubMed Central - PubMed

Affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria; Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.

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.

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Related in: MedlinePlus

Electron tomogram showing ultrastructural details of mitochondria (M) embedded in several layers of endoplasmic reticulum (ER) (bar  =  0.5 µm).A) virtual image made from an electron tomogram showing how the mitochondria (M) are covered by ER. B) Virtual image with 3D contours of objects that were segmented (yellow: ER, red: M). C) 3D surface model of mitochondria covered by ER.
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pone-0114251-g006: Electron tomogram showing ultrastructural details of mitochondria (M) embedded in several layers of endoplasmic reticulum (ER) (bar  =  0.5 µm).A) virtual image made from an electron tomogram showing how the mitochondria (M) are covered by ER. B) Virtual image with 3D contours of objects that were segmented (yellow: ER, red: M). C) 3D surface model of mitochondria covered by ER.

Mentions: To directly visualize the interaction between mitochondria and ER we used electron tomography, as it can reveal high resolution ultrastructural details. This showed how the mitochondria are embedded in several layers of ER. Only parts of the surface remained free (Figure 6). Sequences of virtual images were used to generate a 3D model of mitochondria, ER, ribosomes and the so called “tethers” that link the mitochondrial membranes to the MAM complex using Amira software. The tethers appeared to occur in a row of connections (Figure 7).


Extended ultrastructural characterization of chordoma cells: the link to new therapeutic options.

Kolb D, Pritz E, Steinecker-Frohnwieser B, Lohberger B, Deutsch A, Kroneis T, El-Heliebi A, Dohr G, Meditz K, Wagner K, Koefeler H, Leitinger G, Leithner A, Liegl-Atzwanger B, Zweytick D, Rinner B - PLoS ONE (2014)

Electron tomogram showing ultrastructural details of mitochondria (M) embedded in several layers of endoplasmic reticulum (ER) (bar  =  0.5 µm).A) virtual image made from an electron tomogram showing how the mitochondria (M) are covered by ER. B) Virtual image with 3D contours of objects that were segmented (yellow: ER, red: M). C) 3D surface model of mitochondria covered by ER.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4257693&req=5

pone-0114251-g006: Electron tomogram showing ultrastructural details of mitochondria (M) embedded in several layers of endoplasmic reticulum (ER) (bar  =  0.5 µm).A) virtual image made from an electron tomogram showing how the mitochondria (M) are covered by ER. B) Virtual image with 3D contours of objects that were segmented (yellow: ER, red: M). C) 3D surface model of mitochondria covered by ER.
Mentions: To directly visualize the interaction between mitochondria and ER we used electron tomography, as it can reveal high resolution ultrastructural details. This showed how the mitochondria are embedded in several layers of ER. Only parts of the surface remained free (Figure 6). Sequences of virtual images were used to generate a 3D model of mitochondria, ER, ribosomes and the so called “tethers” that link the mitochondrial membranes to the MAM complex using Amira software. The tethers appeared to occur in a row of connections (Figure 7).

Bottom Line: A special feature of this tumor is the heterogeneity of its cells.These lipid raft-like regions are responsible for lipid syntheses and for calcium signaling.Measurements of the changes in the intracellular calcium concentration revealed an increase in calcium due to the application of acetylcholine.

View Article: PubMed Central - PubMed

Affiliation: Center for Medical Research, Medical University of Graz, Graz, Austria; Institute of Cell Biology, Histology & Embryology, Medical University of Graz, Graz, Austria.

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.

Show MeSH
Related in: MedlinePlus