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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: These lipid raft-like regions are responsible for lipid syntheses and for calcium signaling.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.

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

Structural association of mitochondrial membrane with the ER called MAM, represented by HPF.A) Abundant mitochondria within the cell, small connected vacuoles, and the connection of two chordoma cells with contact zones as well as excrescences (asterisk). B) Very close continuous contact zones of mitochondria (M) and ER. C) Connection of two chordoma cells with contact zones, excrescences (asterisk) and MAM complex.
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pone-0114251-g005: Structural association of mitochondrial membrane with the ER called MAM, represented by HPF.A) Abundant mitochondria within the cell, small connected vacuoles, and the connection of two chordoma cells with contact zones as well as excrescences (asterisk). B) Very close continuous contact zones of mitochondria (M) and ER. C) Connection of two chordoma cells with contact zones, excrescences (asterisk) and MAM complex.

Mentions: On many 2D sections the whole circumference of mitochondria was covered with ER (Figure 5 A–C). Measurements on mitochondrial profiles of MUG-Chor1 in a total area of 1,550.1 µm2 showed that 64.8% of the mitochondrial profiles appeared to be completely surrounded with ER, whereas in U-CH2 in an area of 1,588.4 µm2 68.98% of mitochondrial profiles were fully encircled. In contrast, in the U2OS cells in an area of 1,571.4 µm2 none of the profiles were fully covered by ER (Table 1).


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)

Structural association of mitochondrial membrane with the ER called MAM, represented by HPF.A) Abundant mitochondria within the cell, small connected vacuoles, and the connection of two chordoma cells with contact zones as well as excrescences (asterisk). B) Very close continuous contact zones of mitochondria (M) and ER. C) Connection of two chordoma cells with contact zones, excrescences (asterisk) and MAM complex.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0114251-g005: Structural association of mitochondrial membrane with the ER called MAM, represented by HPF.A) Abundant mitochondria within the cell, small connected vacuoles, and the connection of two chordoma cells with contact zones as well as excrescences (asterisk). B) Very close continuous contact zones of mitochondria (M) and ER. C) Connection of two chordoma cells with contact zones, excrescences (asterisk) and MAM complex.
Mentions: On many 2D sections the whole circumference of mitochondria was covered with ER (Figure 5 A–C). Measurements on mitochondrial profiles of MUG-Chor1 in a total area of 1,550.1 µm2 showed that 64.8% of the mitochondrial profiles appeared to be completely surrounded with ER, whereas in U-CH2 in an area of 1,588.4 µm2 68.98% of mitochondrial profiles were fully encircled. In contrast, in the U2OS cells in an area of 1,571.4 µm2 none of the profiles were fully covered by ER (Table 1).

Bottom Line: These lipid raft-like regions are responsible for lipid syntheses and for calcium signaling.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.

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