Cinnamaldehyde Treatment of Prostate Cancer-Associated Fibroblasts Prevents Their Inhibitory Effect on T Cells Through Toll-Like Receptor 4.

Introduction: Cancer-associated fibroblasts (CAFs) promote tumor progression; thus, drugs that can modify CAFs need to be identified. Methods: To test the effect of cinnamaldehyde on prostate CAFs, the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-2H-tetrazolium bromide assay was used to determine their survival. When spleen cells were treated with CAF supernatant, the proliferation of T cells was inhibited as determined by flow cytometry. After cinnamaldehyde treatment, this immunosuppressive function of CAFs was partially reversed. To explore the molecular mechanism, Western blotting and the quantitative real-time polymerase chain reaction were applied, and TLR4-dependent signaling pathway-related protein and mRNA levels were quantified. Results: Cinnamaldehyde acted on the TLR4-dependent signaling pathway, altering the function of CAFs such that its supernatant no longer inhibited the proliferation of T cells. Conclusion: These data indicate that cinnamaldehyde can modify the functions of CAFs, which may be helpful for treating tumors. Cinnamaldehyde can suppress CAF T-cell inhibition.