Some considerations for the study of TGFbeta in medium of irradiated T98G cells: activation, release and consumption.
Transforming growth factor β1 (TGFβ1) has been proposed as a candidate for the transmission of radiation-induced bystander signals. To assess the influence that the presence of latent TGFβ in the medium may have on the modulation of TGFβ1 release and on its receptor (TGFβR2) expression after irradiation of glioblastoma cells or after treatment with medium collected from γ-irradiated cells. T98G cells cultured with a complete medium or a serum-free medium were irradiated with 0.25 and 1 Gy and the concentration of total TGFβ1 was measured. Irradiation of cells growing with a complete medium (i.e. a medium containing latent TGFβ1, LTGFβ1) caused a consistent dose-dependent decrease of the TGFβ1 available in the medium. When LTGFβ1 was not available in the medium (i.e. a medium without serum supplement), the levels of TGFβ1 increased significantly. Changes in the pattern of expression of TGFβR2 were evident only when a serum-free medium was used.