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Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors.

Noell S, Fallier-Becker P, Mack AF, Hoffmeister M, Beschorner R, Ritz R - PLoS ONE (2015)

Bottom Line: In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples.On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found.This was similar to our previous findings in malignant glioblastomas.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.

ABSTRACT

Background: We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.

Methods and results: Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.

Conclusions: Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

No MeSH data available.


Related in: MedlinePlus

Highly schematic diagram indicating the location of subependymomys (SEs) in the human brain.The main findings on AQP distributions are also indicated.
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pone.0131367.g001: Highly schematic diagram indicating the location of subependymomys (SEs) in the human brain.The main findings on AQP distributions are also indicated.

Mentions: Besides alteration in AQP4 expression, the water channel AQP1 is upregulated under pathological conditions, e.g. in glioma cells and reactive astrocytes as well as in reactive brain endothelial cells [23]. AQP1 is expressed in the epithelial cells of the choroid plexus but not in other healthy ependymal cells nor in healthy astrocytes[24]. AQP1 is capable of transporting oxygen as well as water across cell membranes which is an important function of being mostly expressed in red blood cells and in the choroid plexus In brain tumors like ependymomas AQP4 as well as AQP1 are found but AQP4 was only expressed in ependymomas when tumors grow in the fossa inferior of the brain, but not in supratentorial regions [25]. Ependymomas (E) belong to glial tumors and are graded in WHO grade II and III. They are more aggressive than SEs and tend to develop recurrent tumors. SEs are graded WHO grade I. They are benign and grow very slowly. Transformations from WHO grade I to WHO grade II are extremely rare [26]. Two thirds of these tumors are found infratentorial and grow from the bottom of the fourth ventricle. One third grows supratentorial and has mostly contact to the ventricle system (Fig 1).


Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors.

Noell S, Fallier-Becker P, Mack AF, Hoffmeister M, Beschorner R, Ritz R - PLoS ONE (2015)

Highly schematic diagram indicating the location of subependymomys (SEs) in the human brain.The main findings on AQP distributions are also indicated.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482577&req=5

pone.0131367.g001: Highly schematic diagram indicating the location of subependymomys (SEs) in the human brain.The main findings on AQP distributions are also indicated.
Mentions: Besides alteration in AQP4 expression, the water channel AQP1 is upregulated under pathological conditions, e.g. in glioma cells and reactive astrocytes as well as in reactive brain endothelial cells [23]. AQP1 is expressed in the epithelial cells of the choroid plexus but not in other healthy ependymal cells nor in healthy astrocytes[24]. AQP1 is capable of transporting oxygen as well as water across cell membranes which is an important function of being mostly expressed in red blood cells and in the choroid plexus In brain tumors like ependymomas AQP4 as well as AQP1 are found but AQP4 was only expressed in ependymomas when tumors grow in the fossa inferior of the brain, but not in supratentorial regions [25]. Ependymomas (E) belong to glial tumors and are graded in WHO grade II and III. They are more aggressive than SEs and tend to develop recurrent tumors. SEs are graded WHO grade I. They are benign and grow very slowly. Transformations from WHO grade I to WHO grade II are extremely rare [26]. Two thirds of these tumors are found infratentorial and grow from the bottom of the fourth ventricle. One third grows supratentorial and has mostly contact to the ventricle system (Fig 1).

Bottom Line: In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples.On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found.This was similar to our previous findings in malignant glioblastomas.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.

ABSTRACT

Background: We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.

Methods and results: Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.

Conclusions: Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

No MeSH data available.


Related in: MedlinePlus