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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

Immunofluorescent double staining for aquaporins in SEs.Double staining of GFAP- (green) and AQP4 (red) in infratentorial (A, patient 5) and supratentorial (B patient 6) SE. Dapi stained nuclei in blue. Double staining of AQP4 (red) and AQP1 (green) in infratentorial (C patient 4) and supratentorial (D patient 6) SE. AQP 1 and AQP4 positive cells are more or less evenly distributed in infratentorial tumors, in contrast they were found only in the border region of supratentorial tissue. Bar: 50μm (A, B, C); 100μm (D).
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pone.0131367.g002: Immunofluorescent double staining for aquaporins in SEs.Double staining of GFAP- (green) and AQP4 (red) in infratentorial (A, patient 5) and supratentorial (B patient 6) SE. Dapi stained nuclei in blue. Double staining of AQP4 (red) and AQP1 (green) in infratentorial (C patient 4) and supratentorial (D patient 6) SE. AQP 1 and AQP4 positive cells are more or less evenly distributed in infratentorial tumors, in contrast they were found only in the border region of supratentorial tissue. Bar: 50μm (A, B, C); 100μm (D).

Mentions: First we tested the expression of typical glial markers in SE tissues by immunochemistry. Like in other glial derived tumors GFAP expression was positive in all SEs. Double staining with antibodies against GFAP and AQP4 revealed evenly distributed immunofluorescence for GFAP, throughout all tumors (Fig 2A and 2B), whereas AQP4 immunofluorescence appeared evenly in infratentorial tumors only (Fig 2A). In supratentorial SEs, AQP4 staining was restricted to the peripheral region (Fig 2B). AQP4- and AQP1—immunostaining revealed a more or less even distribution in infratentorial SE tumors of the fourth ventricle of the fossa inferior as shown in Fig 2A, 2C, Fig 3A, 3C and S1 Fig. In contrast, in SEs growing supratentorial in other parts of the ventricle system AQP4 and -1 mostly appeared in the margin of some tissue samples in accordance with the tumor margin (Fig 2B and 2D, Fig 3B and 3D and S2 Fig).


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)

Immunofluorescent double staining for aquaporins in SEs.Double staining of GFAP- (green) and AQP4 (red) in infratentorial (A, patient 5) and supratentorial (B patient 6) SE. Dapi stained nuclei in blue. Double staining of AQP4 (red) and AQP1 (green) in infratentorial (C patient 4) and supratentorial (D patient 6) SE. AQP 1 and AQP4 positive cells are more or less evenly distributed in infratentorial tumors, in contrast they were found only in the border region of supratentorial tissue. Bar: 50μm (A, B, C); 100μm (D).
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Related In: Results  -  Collection

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pone.0131367.g002: Immunofluorescent double staining for aquaporins in SEs.Double staining of GFAP- (green) and AQP4 (red) in infratentorial (A, patient 5) and supratentorial (B patient 6) SE. Dapi stained nuclei in blue. Double staining of AQP4 (red) and AQP1 (green) in infratentorial (C patient 4) and supratentorial (D patient 6) SE. AQP 1 and AQP4 positive cells are more or less evenly distributed in infratentorial tumors, in contrast they were found only in the border region of supratentorial tissue. Bar: 50μm (A, B, C); 100μm (D).
Mentions: First we tested the expression of typical glial markers in SE tissues by immunochemistry. Like in other glial derived tumors GFAP expression was positive in all SEs. Double staining with antibodies against GFAP and AQP4 revealed evenly distributed immunofluorescence for GFAP, throughout all tumors (Fig 2A and 2B), whereas AQP4 immunofluorescence appeared evenly in infratentorial tumors only (Fig 2A). In supratentorial SEs, AQP4 staining was restricted to the peripheral region (Fig 2B). AQP4- and AQP1—immunostaining revealed a more or less even distribution in infratentorial SE tumors of the fourth ventricle of the fossa inferior as shown in Fig 2A, 2C, Fig 3A, 3C and S1 Fig. In contrast, in SEs growing supratentorial in other parts of the ventricle system AQP4 and -1 mostly appeared in the margin of some tissue samples in accordance with the tumor margin (Fig 2B and 2D, Fig 3B and 3D and S2 Fig).

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