[Effects of TGF beta 1 on the cell cycle of irradiated human lung fibroblasts and its signal transduction mechanism].

Aim: To investigate the effects of TGF beta 1 on the proliferative activity and cell cycle of normal and gamma ray-irradiated human lung fibroblasts (HLFs).

Methods: HLFs were cultured and irradiated with 3Gy gamma rays and then stimulated by TGF beta 1 at 0.01, 0.1, 1 and 10 microg/L. The proliferative activity and cell cycle were detected by MTT colorimetry and FACS. Furthermore, the expressions of signal proteins Smad3/4 in HLFs were observed by immunohistochemical staining and FACS.

Results: TGF beta 1 of 10 microg/L could promote the proliferation of HLFs, with the number of cells in S phase increased. It also could enhance the expression of Smad3 protein and promote the nuclear translocation of Smad4 protein.

Conclusion: A given dose of TGF beta 1 can promote the proliferation of gamma rays-irradiated HLFs by regulating their cell cycle in which the activation of Smad pathway may play a role.