Effect and significance of TGF-β1 in the process of radiation fibrosis

Radiation fibrosis of human normal tissues is very common in radiotherapy. One of the main fundamental problems yet unsolved in fibrotic tissues is the origin of the chronic activation of myofibroblasts within these tissues. It has been postulated by some researchers that this chronic activation results from a continuous production of activating factors. So fibrosis could be defined as a wound where continuous signals for repair are emitted. Cytokines and growth factors probably play a vital role in this process. Among them transforming growth factor β1(TGF β1) is considered as a master switch for the fibrotic program. This review discusses recent evidence on the critical role played by TGF β1 in the initiation, development, and persistence of radiation fibrosis. It summarized the results concerning this factor after irradiation of various tissues and cells. All these researches show that the TGF β1 pathway may be a specific target for anti fibrotic agents. [