Effect of EBI3 on radiation-induced immunosuppression of cervical cancer HeLa cells by regulating Treg cells through PD-1/PD-L1 pathway

Abstract

This study aimed to investigate the effect of EBI3 on radiation-induced immunosuppression of cervical cancer HeLa cells by regulating Treg cells through PD-1/PD-L1 signaling pathway. A total of 43 adult female Wistar rats were selected and injected with HeLa cells in the caudal vein to construct a rat model of cervical cancer. All model rats were randomly divided into the radiotherapy group ( n = 31) and the control group ( n = 12). The immunophenotype of Treg cells was detected by the flow cytometry. The protein expressions of EBI3, PD-1, and PD-L1 in cervical cancer tissues were tested by the streptavidin-peroxidase method. HeLa cells in the logarithmic growth phase were divided into four groups: the blank, the negative control group, the EBI3 mimics group, and the EBI3 inhibitors group. Western blotting was used to detect PD-1 and PD-L1 protein expressions. MTT assay was performed to measure the proliferation of Treg cells. Flow cytometry was used to detect cell cycle and apoptosis, and CD4/CD8 T cell ratio in each group. Compared with before and 1 week after radiotherapy, the percentages of CD4T cells and CD8T cells were significantly decreased in the radiotherapy group at 1 month after radiotherapy. Furthermore, down-regulation of EBI3 and up-regulation of PD-1 and PD-L1 were observed in cervical cancer tissues at 1 month after radiotherapy. In comparison to the blank and negative control groups, increased expression of EBI3 and decreased expressions of PD-1 and PD-L1 were found in the EBI3 mimics group. However, the EBI3 inhibitors group had a lower expression of EBI3 and higher expressions of PD-1 and PD-L1 than those in the blank and negative control groups. The EBI3 mimics group showed an increase in the optical density value (0.43 ± 0.05), while a decrease in the optical density value (0.31 ± 0.02) was found in the EBI3 inhibitors group. Moreover, compared with the blank and negative control groups, the apoptosis rates of Treg/CD4T/CD8T cells were decreased in the EBI3 mimics group, but the EBI3 inhibitors group exhibited an increase in apoptosis rate. In conclusion, over-expression of EBI3 could reduce the apoptosis of Treg/CD4T/CD8T cells and prevent radiation-induced immunosuppression of cervical cancer HeLa cells by inhibiting the activation of PD-1/PD-L1 signaling pathway.

Hypofractionated stereotactic radiation therapy activates the peripheral immune response in operable stage I non-small-cell lung cancer

“…In the rat model of cervical cancer, the up-regulation of programmed cell death-1(PD-1) and programmed cell death-Ligand 1(PD-L1) was observed in cervical cancer tissues at 1 month after RT. In addition, the percentages of CD4 + T cells and CD8 + T cells were significantly decreased in the RT group 35 . H. van Meir reported that external beam radiation therapy (EBRT) treatment decreased the frequency of both CD4 + and CD8 + T cells and enhances the PD-1 expression in CD4 + T cells displayed in the patients with cervical cancer 36 .…”

A Novel Model of Cancer Drug Resistance: Oncosomal Release of Cytotoxic and Antibody-Based Drugs

“…The interaction of PD-L1, with its receptor programmed death 1 (PD-1), inhibits T cell-mediated cellular immune responses, including priming, growth, proliferation, and apoptosis, and functional maturation [18] (Figure 4a). Recent studies have shown that the activation of the PD-1/PD-L1 signaling pathway inhibits T cell responses through inducible Tregs (iTregs) [152], as well as mediating the arrest of the T cell cycle at the G1 phase [153]. Disrupting the interaction of the PD-L1 ligand with the PD-1 receptor on T cells restores T cell-mediated immune responses and potentiates anti-tumor immunity ( Figure 4b).…”

The role of exosomal PD-L1 in tumor progression and immunotherapy

“…Recently, research studies have found that the activation of the PD-1/PD-L1 signaling pathway can arrest the T cell cycle at the G1 phase rather than directly causing apoptosis [5]. In addition to mediating T cell–intrinsic inhibitory effects, the PD-1/PD-L1 signaling pathway could also induce the inhibition of T cell responses by inducible Tregs (iTregs) [6].…”