Background: Royal jelly, a natural product from bees' hypopharyngeal glands, is commonly used in biomedicine due to its antioxidant and anti-tumor activities. The aim of this study was to compare royal jelly in free form and loaded in layered double hydroxide (LDH) nanoparticle for the treatment of breast cancer with a focus on Th1 and T regulatory parameters in an animal model.
Methods: Nanoparticles were produced using the coprecipitation method and characterized using DLS, FTIR, and SEM techniques. Forty female BALB/c mice were inoculated with 7.5 x 105 4T1 cells and treated with royal jelly in free and nanoparticle form. Clinical signs and tumor volume were assessed weekly. The effect of royal jelly products on the serum level of IFN-γ and TGF-β was measured by ELISA. In addition, the mRNA expression of these cytokines and Th1 and regulatory T cells' transcription factors (T-bet and FoxP3) was assessed by real-time PCR in the splenocytes of tumor-bearing mice.
Results: The physicochemical analysis of nanoparticles confirmed the synthesis of LDH nanoparticles and loading of royal jelly into the LDH structures (RJ-LDH). Animal studies showed that royal jelly and RJ-LDH significantly reduced the size of tumor in BALB/c mice. Additionally, treatment with RJ-LDH significantly inhibited TGF-β and increased IFN-γ production. The data also revealed that RJ-LDH inhibited the differentiation of regulatory T cells, while promoting Th1 cell differentiation via regulating their master transcription factors.
Conclusions: These results indicated that royal jelly and RJ-LDH could inhibit breast cancer progression by in-hibiting regulatory T cells and expansion of Th1 cell. Furthermore, the current study demonstrated the therapeutic efficacy of royal jelly is enhanced by LDH nanoparticles; hence, RJ-LDH is significantly more efficient than Free-RJ in the treatment of breast cancer.