Exosomal circGSE1 promotes immune escape of hepatocellular carcinoma by inducing the expansion of regulatory T cells.

Studies have shown exosomal circRNAs can regulate the immune escape of tumors by carrying cancer-derived molecules. Regulatory T cells (Tregs) participate in the process of tumor immune escape. However, the mechanism by which exosomal circRNAs regulate Tregs to create a microenvironment for tumor immune escape is unclear. The effect of exosomes on the proliferation, migration, and invasion of tumor cells was evaluated by CCK-8, transwell, and wound-healing assays. The expression of circGSE1 was evaluated by real-time quantitative PCR, and the function of exosomal circGSE1 was explored by Western blot and RNA pull-down assays. In vivo animal metastasis models and bioluminescence imaging were used to verify the effect of exosomal circGSE1 on tumor progression. Collectively, we revealed that exosomal circGSE1 derived from hepatocellular carcinoma (HCC) cells promotes the progression of HCC by inducing Tregs expansion via regulating the miR-324-5p/TGFBR1/Smad3 axis. Therefore, in the future, exosomal circGSE1 can be used as a promising biomarker for immunotherapy of HCC.