β2-adrenergic receptor stimulation upregulate Cx43 expression in Glioblastoma multiforme

Background and Aim : Glioblastoma multiforme (GBM) is an invasive astrocytic tumor in adults that despite the best available treatment approaches remains mainly incurable. One of the molecular transformations in GBM cells is the downregulation of Connexin43 (Cx43) expression and subsequently gap junction intercellular communication (GJIC). Since β2-adrenergic receptor stimulation could regulate Cx43 protein levels, we illuminate whether β2-adrenergic agonist may increase Cx43 expression in primary human GBM-derived astrocyte cells.Methods : We first purified the astrocyte cells from human GBM tumor and then we investigated the effect of Clenbuterol hydrochloride as a selective β2-adrenergic agonist on the Cx43 expression in human GBM-derived astrocyte cells. The astrocyte cells exposed to ICI 118,551, as a selective β2-adrenergic antagonist, at concentrations of 0.1, 0.3 and 1 μg/ml as well as Clenbuterol hydrochloride at concentration of 10 μg/ml with or without the various concentrations of ICI 118,551 (0.1, 0.3 and 1 μg/ml) for 24 hours. The characterization of astrocytes were assessed by Immunocytochemistry. The cytotoxicity were evaluated by MTT assays and the Cx43 levels were measured with western blot analysisResults : the immunocytochemistry results showed that approximately 93 % of cells expressed S100-β antigen.The MTT results showed cell viability of more than 95%. When the cells treated with Clenbuterol hydrochloride (10 μg/ml), the Cx43 protein level dramatically increased. Pretreatment of cells with ICI 118,551 at concentrations of 0.3 and 1 μg/ml for 45 min prevented the Clenbuterol hydrochloride effect on Cx43 upregulation. However, the concentrations of 0.1 μg/ml did not reverse this effect.Conclusion : Our results suggest that Clenbuterol hydrochloride could upregulates the Cx43 level on primary human GBM derived astrocyte cells and this effect mediated with β2-adrenergic receptor.

Keywords:

Glioblastoma multiforme , Connexin 43 , β2-adrenergic receptor