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CD133 Expression Is Not Synonymous to Immunoreactivity for AC133 and Fluctuates throughout the Cell Cycle in Glioma Stem-Like Cells.

Barrantes-Freer A, Renovanz M, Eich M, Braukmann A, Sprang B, Spirin P, Pardo LA, Giese A, Kim EL - PLoS ONE (2015)

Bottom Line: CD133 expression is commonly evaluated by using antibodies specific for the AC133 epitope located in one of the extracellular domains of membrane-bound CD133.A possible source for controversies about CD133/AC133 is the widespread assumption that expression patterns of the AC133 epitope reflect linearly those of the CD133 protein.Consequently, the readouts from AC133 assessments are often interpreted in terms of the CD133 protein.

View Article: PubMed Central - PubMed

Affiliation: Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany; Institute of Neuropathology, University Medical Centre, Göttingen, Germany.

ABSTRACT
A transmembrane protein CD133 has been implicated as a marker of stem-like glioma cells and predictor for therapeutic response in malignant brain tumours. CD133 expression is commonly evaluated by using antibodies specific for the AC133 epitope located in one of the extracellular domains of membrane-bound CD133. There is conflicting evidence regarding the significance of the AC133 epitope as a marker for identifying stem-like glioma cells and predicting the degree of malignancy in glioma cells. The reasons for discrepant results between different studies addressing the role of CD133/AC133 in gliomas are unclear. A possible source for controversies about CD133/AC133 is the widespread assumption that expression patterns of the AC133 epitope reflect linearly those of the CD133 protein. Consequently, the readouts from AC133 assessments are often interpreted in terms of the CD133 protein. The purpose of this study is to determine whether and to what extent do the readouts obtained with anti-AC133 antibody correspond to the level of CD133 protein expressed in stem-like glioma cells. Our study reveals for the first time that CD133 expressed on the surface of glioma cells is poorly immunoreactive for AC133. Furthermore, we provide evidence that the level of CD133 occupancy on the surface of glioma cells fluctuates during the cell cycle. Our results offer a new explanation for numerous inconsistencies regarding the biological and clinical significance of CD133/AC133 in human gliomas and call for caution in interpreting the lack or presence of AC133 epitope in glioma cells.

No MeSH data available.


Related in: MedlinePlus

Comparative assessment of the AC133 epitope and CD133 protein in human GCSs.A. Representative histograms showing CD133 surface expression detected by anti-AC133 Ab (left panels) or anti-CD133CT Ab (right panels) in primary GSCs cultures and stem-like glioma clone G112SP. B. Mean percentage of cells positively labelled with anti-AC133 Ab (blue) or anti-CD133CT Ab (black) in a panel of GSC lines and CaCo-2 cells used as a positive control. C. Comparative assessment of the total (“input”) and membrane-associated (“PM”) CD133 protein in human GSC lines No. 1063, No. 1080 and No. 1051. 20 μg of proteins were loaded per lane. D. Representative histograms showing surface expression of CD133/2 detected by anti-AC141 Ab in primary cultures of GSCs, stem-like glioma clone G112SP and reference cell line CaCo-2 used as a positive control.
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pone.0130519.g003: Comparative assessment of the AC133 epitope and CD133 protein in human GCSs.A. Representative histograms showing CD133 surface expression detected by anti-AC133 Ab (left panels) or anti-CD133CT Ab (right panels) in primary GSCs cultures and stem-like glioma clone G112SP. B. Mean percentage of cells positively labelled with anti-AC133 Ab (blue) or anti-CD133CT Ab (black) in a panel of GSC lines and CaCo-2 cells used as a positive control. C. Comparative assessment of the total (“input”) and membrane-associated (“PM”) CD133 protein in human GSC lines No. 1063, No. 1080 and No. 1051. 20 μg of proteins were loaded per lane. D. Representative histograms showing surface expression of CD133/2 detected by anti-AC141 Ab in primary cultures of GSCs, stem-like glioma clone G112SP and reference cell line CaCo-2 used as a positive control.

Mentions: Comparative flow cytometric assessments revealed gross variations between numerical estimates obtained with anti-AC133 or anti-CD133CT antibodies in different GSC lines. In contrast to the abundant expression of the AC133 epitope in CaCo-2 cells (72.75 ± 4.91%, Fig 1B), AC133 estimates in GSCs were found generally low spanning between 1 and 13 percent (Fig 3A, left panels in and Fig 3B, blue bars).


CD133 Expression Is Not Synonymous to Immunoreactivity for AC133 and Fluctuates throughout the Cell Cycle in Glioma Stem-Like Cells.

Barrantes-Freer A, Renovanz M, Eich M, Braukmann A, Sprang B, Spirin P, Pardo LA, Giese A, Kim EL - PLoS ONE (2015)

Comparative assessment of the AC133 epitope and CD133 protein in human GCSs.A. Representative histograms showing CD133 surface expression detected by anti-AC133 Ab (left panels) or anti-CD133CT Ab (right panels) in primary GSCs cultures and stem-like glioma clone G112SP. B. Mean percentage of cells positively labelled with anti-AC133 Ab (blue) or anti-CD133CT Ab (black) in a panel of GSC lines and CaCo-2 cells used as a positive control. C. Comparative assessment of the total (“input”) and membrane-associated (“PM”) CD133 protein in human GSC lines No. 1063, No. 1080 and No. 1051. 20 μg of proteins were loaded per lane. D. Representative histograms showing surface expression of CD133/2 detected by anti-AC141 Ab in primary cultures of GSCs, stem-like glioma clone G112SP and reference cell line CaCo-2 used as a positive control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4472699&req=5

pone.0130519.g003: Comparative assessment of the AC133 epitope and CD133 protein in human GCSs.A. Representative histograms showing CD133 surface expression detected by anti-AC133 Ab (left panels) or anti-CD133CT Ab (right panels) in primary GSCs cultures and stem-like glioma clone G112SP. B. Mean percentage of cells positively labelled with anti-AC133 Ab (blue) or anti-CD133CT Ab (black) in a panel of GSC lines and CaCo-2 cells used as a positive control. C. Comparative assessment of the total (“input”) and membrane-associated (“PM”) CD133 protein in human GSC lines No. 1063, No. 1080 and No. 1051. 20 μg of proteins were loaded per lane. D. Representative histograms showing surface expression of CD133/2 detected by anti-AC141 Ab in primary cultures of GSCs, stem-like glioma clone G112SP and reference cell line CaCo-2 used as a positive control.
Mentions: Comparative flow cytometric assessments revealed gross variations between numerical estimates obtained with anti-AC133 or anti-CD133CT antibodies in different GSC lines. In contrast to the abundant expression of the AC133 epitope in CaCo-2 cells (72.75 ± 4.91%, Fig 1B), AC133 estimates in GSCs were found generally low spanning between 1 and 13 percent (Fig 3A, left panels in and Fig 3B, blue bars).

Bottom Line: CD133 expression is commonly evaluated by using antibodies specific for the AC133 epitope located in one of the extracellular domains of membrane-bound CD133.A possible source for controversies about CD133/AC133 is the widespread assumption that expression patterns of the AC133 epitope reflect linearly those of the CD133 protein.Consequently, the readouts from AC133 assessments are often interpreted in terms of the CD133 protein.

View Article: PubMed Central - PubMed

Affiliation: Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany; Institute of Neuropathology, University Medical Centre, Göttingen, Germany.

ABSTRACT
A transmembrane protein CD133 has been implicated as a marker of stem-like glioma cells and predictor for therapeutic response in malignant brain tumours. CD133 expression is commonly evaluated by using antibodies specific for the AC133 epitope located in one of the extracellular domains of membrane-bound CD133. There is conflicting evidence regarding the significance of the AC133 epitope as a marker for identifying stem-like glioma cells and predicting the degree of malignancy in glioma cells. The reasons for discrepant results between different studies addressing the role of CD133/AC133 in gliomas are unclear. A possible source for controversies about CD133/AC133 is the widespread assumption that expression patterns of the AC133 epitope reflect linearly those of the CD133 protein. Consequently, the readouts from AC133 assessments are often interpreted in terms of the CD133 protein. The purpose of this study is to determine whether and to what extent do the readouts obtained with anti-AC133 antibody correspond to the level of CD133 protein expressed in stem-like glioma cells. Our study reveals for the first time that CD133 expressed on the surface of glioma cells is poorly immunoreactive for AC133. Furthermore, we provide evidence that the level of CD133 occupancy on the surface of glioma cells fluctuates during the cell cycle. Our results offer a new explanation for numerous inconsistencies regarding the biological and clinical significance of CD133/AC133 in human gliomas and call for caution in interpreting the lack or presence of AC133 epitope in glioma cells.

No MeSH data available.


Related in: MedlinePlus