Indoleamine 2, 3-
dioxygenase (IDO) is one of the rate-limiting
enzymes that degrade
tryptophan (Trp) into
kynurenine (Kyn). Inflammatory factor IFN-γ mediates
tumor′s immune escape by activating the IDO signaling pathway, upregulating theKyn/Trp (K/T ratio) and suppressing the activity of both CD 8+T and
regulatory T cells.
Radiotherapy plays a major
role in treating
non-small cell lung cancer. It not only bi-directionally regulates
immune response of the host, but also collaborates with
immunosuppressive agents to kill
tumors. Meanwhile, immune status of the host can
affect the
therapeutic effect of
radiotherapy. In recent years, studies have shown that IDO activity levels change before and after
radiotherapy and is related to clinical
prognosis. Nevertheless, relevant mechanism remains unclear. This article aims to elucidate the application of IDO signaling pathway in
radiotherapy for
non-small cell lung cancer.