Article
A1 adenosine receptor deficiency in the host brain promotes the growth of inoculated glioblastoma cells
Verlust des A1-Adenosin-Rezeptors im ZNS fördert das Wachstum induzierter Glioblastome
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Published: | May 8, 2006 |
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Objective: In the present study, we have addressed the question whether deletion of A1 adenosine receptors affect glioblastoma – host interaction observed in A1AR deficient mice.
Methods: G261 glioblastoma cells stably expressing were inoculated into A1AR-/- mice and A1AR+/+ littermate controls. With this approach, we deleted the A1AR in the host cells, but not in the inoculated GL261 glioblastoma cells. Animals were sacrificed 14 days after GL261 inoculation and the tumor area was determined double-blinded in axial section at the maximal diameter. Immunofluorescent triple labeling was carried out on 40-µm-free-floating sections using a spectral confocal microscope.
Results: The tumor size in A1AR-/- mice was significantly larger as compared to A1AR+/+ mice (mean±SE, 0.96±0.09 mm for control (n=73); 1.69±0.03 mm for A1AR-/- mice (n=99)). There were no differences in neurological symptoms between the groups within the 14 days after GL261 inoculation. To analyze the cell populations from the host in the vicinity of the tumor cells, we studied the distribution of microglial cells and astrocytes in A1AR-/- and A1AR+/+ mice. Immunoreactivity for the macrophage / microglia marker Iba-1 revealed an accumulation of Iba-1 positive cells at the tumor border. In A1AR-/- mice the density and number of Iba-1 positive cells was significantly higher as compared to wild-type littermates. No differences in the GFAP-positive cell population was observed comparing A1AR-/- and A1AR+/+.
Conclusions: These results imply that A1AR modulate tumor growth and that microglial cells are the cellular candidates to mediate this effect.