ABSTRACT
Programmed cell death-1/programmed cell death-ligand 1(PD-1/PD-L1) inhibitors have been approved for a variety of tumors, whereas the efficacy as monotherapy is low. How to sensitize the efficacy of PD-1/PD-L1 inhibitors through combined radiotherapy is the current research focus. Multiple studies have demonstrated that the combination of radiotherapy and anti-PD-1/PD-L1 therapy has yielded survival benefits. Nevertheless, ionizing radiation is a double-edged sword for anti-PD-1/PD-L1 therapy. For patients with metastatic cancers, radiotherapy should be fully exerted as a sensitizer to systemic anti-PD-1/PD-L1 therapy and the immunosuppressive effects should be avoided as much as possible. It is closely correlated with the selection of radiation dose, fraction size, treatment timing and irradiated numbers and sites. Therefore, this article reviews how to optimize radiotherapy combined with anti-PD-1/PD-L1 treatment scheduled for advanced stage metastatic cancers.
ABSTRACT
Objective To investigate the effect of ionizing radiation on the expression of NKG2D ligand on the surface of oral squamous cell carcinoma cell line SCC25 and its cytotoxicity to tumor cells.Methods When SCC25 cells were cultured into logarithmic growth phase,they were randomly designed as control (without treatment) and experimental group (2 Gy ionizing radiation treatment) by drawing lots.Flow cytometry was used to detect the expressions of NKG2D ligands major histocompatibility complex class Ⅰ chainrelated molecule (MIC)A,MICB,UL16 binding protein (ULBP)1 on the surface of SCC25 in the control group and the experimental group cultured for 24 h.Real-time fluorescence quantification polymerase chain reaction (RT-PCR) was used to detect the changes of NKG2D ligand mRNA expression on SCC25 cell surface after 24 h culture in the experimental group and the control group.The cells were prepared and divided into blank control group (NC),2 Gy ionizing radiation group (R),NK1 group (target ratio was 5 ∶ 1),NK2 group (target ratio was 20 ∶ 1),NK1 + R group (target ratio was 5 ∶ 1,2 Gy ionizing radiation),NK2 + R group (target ratio was 20 ∶ 1,2 Gy ionizing radiation).After each group was cultured for 24 h,the killing abilities of ionizing radiation and natural killer (NK) cells to oral squamous cell carcinoma SCC25 cells were detected by CCK8.Results Flow cytometry experiment showed that,among the NKG2D ligands,the MICA fluorescence values of experimental group and control group were respectively 21.04 ± 0.39,22.90 ± 0.40 (t =2.465,P =0.069),MICB fluorescence values were 27.58 ± 0.50,29.83 ± 1.05 (t =1.936,P =0.125),and ULBP1 fluorescence values were 21.04 ± 0.40,21.78 ± 0.50 (t =1.154,P =0.313).This indicated that after ionizing radiation on SCC25,the NKG2D ligand MICA,MICB,ULBP1 expression increased slightly,but the differences were not statistically significant.RT-PCR indicated that mRNA expressions of MICB,ULBP1 were significantly different between the control group and the experimental group (t =18.334,P =0.000;t =6.381,P =0.008).The expressions of the experimental group were respectively 6.49,1.64 times as those of the control group.The results of CCK8 showed that,there was a significant difference in cell killing ability among NK1 group,NK2 group and NC group (F =344.600,P =0.000),suggesting that NK cells could kill tumor cells,and the higher ratio of NK cells and SCC25,the stronger killing effect.The comparison between R group and NC group showed that the difference in cell killing ability was not statistically significant (P =0.567).NK1 + R group and NK1 group were compared and the difference was not statistically significant (P =0.915).There was no significant difference between NK2 + R group and NK2 group (P =0.678).This showed that the killing effect of ionizing radiation was weak.Conclusion Ionizing radiation can increase the mRNA expression of NKG2D ligands MICB and ULBP1.This may provide a new way for tumor immunotherapy.The killing effect of ionizing radiation on cells is not obvious.It may be related to low radiation dose and only 24 h for cell culture.
ABSTRACT
Objective To investigate the effect of ionizing radiation on the expression of NKG2D ligand on the surface of oral squamous cell carcinoma cell line SCC25 and its cytotoxicity to tumor cells.Methods When SCC25 cells were cultured into logarithmic growth phase,they were randomly designed as control (without treatment) and experimental group (2 Gy ionizing radiation treatment) by drawing lots.Flow cytometry was used to detect the expressions of NKG2D ligands major histocompatibility complex class Ⅰ chainrelated molecule (MIC)A,MICB,UL16 binding protein (ULBP)1 on the surface of SCC25 in the control group and the experimental group cultured for 24 h.Real-time fluorescence quantification polymerase chain reaction (RT-PCR) was used to detect the changes of NKG2D ligand mRNA expression on SCC25 cell surface after 24 h culture in the experimental group and the control group.The cells were prepared and divided into blank control group (NC),2 Gy ionizing radiation group (R),NK1 group (target ratio was 5 ∶ 1),NK2 group (target ratio was 20 ∶ 1),NK1 + R group (target ratio was 5 ∶ 1,2 Gy ionizing radiation),NK2 + R group (target ratio was 20 ∶ 1,2 Gy ionizing radiation).After each group was cultured for 24 h,the killing abilities of ionizing radiation and natural killer (NK) cells to oral squamous cell carcinoma SCC25 cells were detected by CCK8.Results Flow cytometry experiment showed that,among the NKG2D ligands,the MICA fluorescence values of experimental group and control group were respectively 21.04 ± 0.39,22.90 ± 0.40 (t =2.465,P =0.069),MICB fluorescence values were 27.58 ± 0.50,29.83 ± 1.05 (t =1.936,P =0.125),and ULBP1 fluorescence values were 21.04 ± 0.40,21.78 ± 0.50 (t =1.154,P =0.313).This indicated that after ionizing radiation on SCC25,the NKG2D ligand MICA,MICB,ULBP1 expression increased slightly,but the differences were not statistically significant.RT-PCR indicated that mRNA expressions of MICB,ULBP1 were significantly different between the control group and the experimental group (t =18.334,P =0.000;t =6.381,P =0.008).The expressions of the experimental group were respectively 6.49,1.64 times as those of the control group.The results of CCK8 showed that,there was a significant difference in cell killing ability among NK1 group,NK2 group and NC group (F =344.600,P =0.000),suggesting that NK cells could kill tumor cells,and the higher ratio of NK cells and SCC25,the stronger killing effect.The comparison between R group and NC group showed that the difference in cell killing ability was not statistically significant (P =0.567).NK1 + R group and NK1 group were compared and the difference was not statistically significant (P =0.915).There was no significant difference between NK2 + R group and NK2 group (P =0.678).This showed that the killing effect of ionizing radiation was weak.Conclusion Ionizing radiation can increase the mRNA expression of NKG2D ligands MICB and ULBP1.This may provide a new way for tumor immunotherapy.The killing effect of ionizing radiation on cells is not obvious.It may be related to low radiation dose and only 24 h for cell culture.
ABSTRACT
Tumor radiation therapy (RT)can affect the immune system.Latest studies show that appropriate RT can activate the immune system through regulating tumor microenvironment,activating immune cells and releasing danger signals,and can produce bystander or abscopal effect.With the development of clini-cal biomarkers research and clinical trials about RT combined with immunotherapy,it is expected to change the traditional pattern of tumor treatment.