EFFECT OF IRRADIATION ON TRANSFORMING GROWTH-FACTOR-BETA SECRETION BYMALIGNANT GLIOMA-CELLS

Glioblastoma cells secrete transforming growth factor-beta (TGF-beta), which has a variety of immunosuppressive properties. We investigated the effect of irradiation TGF-beta secretion by malignant glioma cells . Three malignant glioma cell lines (T98G, A172, KG-1-C) were cultured and irradiated using 10 and 50 Gy Linac radiation. After further cult ure for 36 hours in serum-free culture medium, the supernatants were c ollected. The TGF-beta activity in the culture supernatants was determ ined using a specific bioassay. The levels of the active form and tota l TGF-beta in the supernatants from irradiated malignant glioma cells decreased compared to those from un-irradiated cells. However, since i rradiation inhibited the growth of tumor cells, the amount of TGF-beta secretion per cell in irradiated cells tended to increase after irrad iation. These results suggest that malignant glioma cells can still se crete TGF-beta and activate latent TGF-beta even after large dose irra diation, despite the inhibition of tumor growth.