Abstract
The aim of the present study was to investigate the effect of Forkhead family transcription factor P3 (Foxp3) knockdown on the function of cluster of differentiation (CD)4+CD25+ regulatory T cell (Tregs) and the tumor growth of a hepatocellular carcinoma (HCC) mouse model. CD4+CD25+ Tregs and CD4+CD25- T cells were sorted from peripheral blood mononuclear cells (PBMCs) of patients with HCC. Then, ultrasound-targeted microbubble destruction (UTMD)-mediated Foxp3-microRNA (miRNA) was transfected into Tregs. Subsequently, CD4+CD25- T cells were co-cultured with PBMC and Tregs without Foxp3-miRNA (Foxp3+Tregs) or Tregs with Foxp3-miRNA (Foxp3-Tregs) and the proliferation-inhibition ratio of CD4+CD25- T cells was detected using a Cell Counting Kit-8. Additionally, HCC mice were treated with UTMD-mediated Foxp3-shRNA, the tumor volume was calculated and the content of CD4+ and CD25+ T cells in the blood were detected using flow cytometry. The content of interferon-γ (IFN-γ), interleukin (IL)-2, IL-10, transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) in cultural supernatant and serum were detected by ELISA analysis. Foxp3-Tregs significantly reduced the inhibition effect of Foxp3+Tregs on the proliferation of CD4+CD25- T cells (P<0.01). The content of IFN-γ and IL-2 significantly increased, while IL-10 and TGF-β significantly decreased in the co-cultured system of Foxp3-Tregs compared with the co-cultured system of Foxp3+Tregs (P<0.01). Following treatment with Foxp3-shRNA, the average tumor volume, ratio of Tregs/CD4+ T cells and level of IL-10, TGF-β and VEGF significantly decreased, however, the level of IFN-γ and IL-2 significantly increased compared with un-treated HCC mice (P<0.05). Foxp3 knockdown may suppress the tumor growth of HCC mice through relieving the immunosuppressive function of Tregs.