Abstract
Background: Radiotherapy has a promising anti-tumor effect in hepatocellular carcinoma (HCC), depending on the its regulatory effects on both cancer cells and tumor immune microenvironment (TME). Wnt/β-catenin signaling pathway activation, which is one of the most common alterations in HCC patients, has been reported to induce radioresistance, and also create immunosuppressive TME. However, it is unclear whether inhibition of wnt/β-catenin pathway could enhance the treatment efficacy of radiotherapy. In this study, we aim to explore the effect of wnt/β-catenin inhibitor ICG-001 in combination with radiotherapy and the underlying mechanism in HCC.Methods: C57BL/6 and nude mouse subcutaneous tumor models were used to evaluate the efficacy of different treatment regimens in tumor growth control, tumor recurrence inhibition and survival improvement. Flow cytometry was performed to assess the alterations of tumor infiltrating lymphocytes (TILs). Radioresistance was investigated by clone formation assay and γ-H2AX measurements. Wnt/β-catenin and cGAS/STING pathway activation was detected by immunoblotting. Results: The addition of ICG-001 to radiotherapy exhibited better anti-tumor control efficacy in tumor-bearing C57BL/6 mice than nude mice, which suggested that ICG-001 had a critical role in activating TME. The comprehensive analysis of TILs revealed that compared with radiotherapy alone, the combination of ICG-001 with radiotherapy boosted the infiltration and IFN-γ production ability of TIL CD8+ T cells, meanwhile reduced the number of TIL Tregs. Moreover, mechanism study demonstrated that ICG-001 exerted a radiosensitizing effect on HCC cells, thus leading to stronger activation of cGAS/STING signaling pathway upon radiotherapy in vitro and in vivo. Utilization of STING inhibitor, C-176, significantly impaired the synergetic effect of ICG-001 with radiotherapy on tumor control and TME activation. Furthermore, combination therapy led to a stronger immunologic memory and lasting anti-tumor immunity than radiotherapy, thus preventing tumor relapse in HCC tumor-bearing mice.Conclusion: Our findings showed that ICG-001 increased radioresistance and improved TME upon radiotherapy in HCC. Compared with radiotherapy alone, the combination of ICG-001 with radiotherapy displayed better therapeutic efficacy in inhibiting tumor growth, prolonging survival, and preventing recurrence in tumor-bearing mice. These data indicated that ICG-001 might be a potential synergetic treatment for radiotherapy and radioimmunotherapy in HCC.
The Synergistic Anti-tumor Effect of Iodine-125 Low-dose-rate Brachytherapy and Anti-PD-1 Therapy on Lung Cancer in Mice
