[Formononetin enhances the antitumor effect of H22 hepatoma transplanted mice]

Objective To explore the effect of formononetin on immunity of mice with transplanted H22 hepatocarcinoma. Methods Male C57BL/6 mice were subcutaneously inoculated with H22 cells (4×10⁵) to establish a tumor-bearing mouse model. The mice were treated with formononetin [10 mg/(kg.d)] or [50 mg/(kg.d)] for 28 days, and then the tumor inhibition rate was calculated. Carrilizumab was used as a positive control drug. The expressions of CD8, granzyme B and forkbox transcription factor 3 (FOXP3) in HCC tissues were analyzed by immunohistochemical staining. The mRNA and protein expression of programmed cell death protein 1 (PD-1) and its ligand 1 (PD-L1) in HCC tissues were detected by real-time PCR or Western blot analysis, respectively. The serum levels of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) were detected by ELISA. Results Formononetin increased the tumor inhibition rate and the positive rate of CD8 and granzyme B staining in tumor-bearing mice. There was no significant difference in the positive rate of FOXP3 staining in tumor tissues of mice in each group. Formononetin decreased the levels of IL-10 and TGF-β in serum of tumor-bearing mice, and decreased the relative expression of mRNA and protein of PD-1 and PD-L1 in tumor tissue of tumor-bearing mice. Conclusion Formononetin can activate CD8⁺ T cells and reduce the release of immunosuppressive factors in regulatory T cells by blocking PD-1/PD-L1 pathway and play an antitumor role.