Conclusions
By enhancing tumor immunogenicity and increasing CD8+T infiltration in TME through a threshold dosage, X-ray or carbon ion radiation and PD-1 inhibitors improve anti-tumor activity and cause abscopal effect in Lewis lung adenocarcinoma-bearing mice. TREX1 is a possible therapeutic target and prognostic marker.
Results
Bilateral tumors were significantly inhibited by the use of carbon ion or X-ray in combination with PD-1, particularly to non-irradiated tumor(p<0.05). The percentage of infiltrating CD8+ T cells and the level of IFN-β expression were both raised by 10Gy carbon ion irradiation in the irradiated side tumor, although PD-L1 and TREX1 expression levels were also elevated. Lewis cell in vitro experiment further demonstrated that both X-ray and carbon ion irradiation can up-regulate the expression levels of PD-L1 and TREX1 with dose-dependent in tumors, particularly the trend of up-regulation TREX1 is more apparent at a higher dose in carbon ion, i.e. 8 or 10Gy, while the level of IFN-β is decreased. IFN-β levels were considerably raised under hypofractionated doses of carbon ion radiation by gene silencing TREX1. Conclusions: By enhancing tumor immunogenicity and increasing CD8+T infiltration in TME through a threshold dosage, X-ray or carbon ion radiation and PD-1 inhibitors improve anti-tumor activity and cause abscopal effect in Lewis lung adenocarcinoma-bearing mice. TREX1 is a possible therapeutic target and prognostic marker.