Expression of β-adrenergic receptors in pediatric malignant brain tumors

Abstract

β-adrenergic receptors (β-ARs) are G protein-coupled receptors that activate signal transduction pathways involved in angiogenesis, resulting in enhanced tumor vascularization and more aggressive growth. In this study, we evaluated the expression of β-ARs in a population of 12 children affected by malignant primary brain tumors. We found a significant expression of β1- and β2-ARs in all 12 samples as well as the 3 cell lines tested (U87MG, T98G and DAOY). The mean absolute β1-AR mRNA level standardized to GAPDH was 5.81 (range, -7.91 to 11.29) for brain tumors and 8.59 (range, 6.046 to 12.59) for cell lines (U87MG, DAOY and T98G), respectively. The mean absolute β2-AR mRNA level was 4.74 (range, -9.30 to 8.45) for tumor specimens and 7.64 (range, 5.85 to 8.88) for cell lines. These real-time quantitative (qRT)-PCR expression data were confirmed by immunohistochemical analysis. Our study evaluated the presence of β1- and β2-ARs in malignant pediatric brain tumors and brain tumor cell lines.

Figure 1

(A) β1-AR and (B) β2-AR relative expression (mean values from three replicates) calculated as 2^−ΔΔCt. MB, medulloblastoma; EP, ependymoma; GBM, glioblastoma multiforme. Ref, universal human reference RNA (Stratagene); U87MG, glioblastoma-astrocytoma; DAOY, medulloblastoma; T98G, glioblastoma multiforme.

Figure 2

Immunohistochemical stain for (A) β1-AR in anaplastic ependymoma samples and (B) β2-AR in glioblastoma samples. A mainly cytoplasmic immunostaining was observed in almost the entirety of the tumor and endothelial cells; original magnification (A) ×200, (B) ×400.