(F-224) A peptide derived from IL-10 exhibits potential anticancer activity and can facilitate cell targeting of gold nanoparticles loaded with anticancer therapeutics

Introduction
Human interleukin-10 (IL-10) is an immunosuppressive and anti-inflammatory cytokine, produced by various cells, including T cells, B cells, keratinocytes, mast cells, eosinophils, dendritic cells, monocytes, and macrophages. Its expression is upregulated in tumor tissues and serum samples of patients with various cancers. Because of its immunosuppressive nature, IL-10 has also been suggested to be a factor leading to tumor cells’ evasion of immune surveillance and clearance by the host immune system. In patients with breast cancer, elevated levels of IL-10 were observed in serum, which is closely related to tumor progression. Moreover, the expression of IL-10 and its receptor is regulated by autocrine IL-10 signaling pathways. Therefore, IL-10 antagonists may be a critical factor that influences the success of cancer treatments.

Materials and Methods
In this study, we refined a peptide with 20 amino acids, named NK20a, derived from the binding region of IL-10 on the basis of in silico analysis of the complex structure of IL-10 with IL-10Ra, the ligand binding subunit of the IL-10 receptor. The binding ability of the peptide was confirmed through in vitro biophysical biolayer interferometry (BLI) and cellular experiments. Cell morphology was evaluated through atomic force microscopy (AFM) to observe the effects of the peptide on the cells. We next conjugated the peptides to streptavidin-conjugated gold nanoparticles. We also loaded the anticancer drug 5-fluorouracil (5-FU) onto the gold nanoparticles. The functionalized nanoparticles of NK20a@Au were characterized using attenuated total reflection FTIR spectroscopy (ATR-FTIR).

Results and Discussions
In this study, using in silico approaches, we designed a peptide with superior binding affinity to IL-10Ra that can be used to inhibit the effects of IL-10. The IL-10 inhibitory peptide exerted anticancer effects on lymphoma B cells and could abolish the suppression effect of IL-10 on macrophages. NK20a was also conjugated with gold nanoparticles to target the chemotherapeutic 5-FU-loaded nanoparticles to explore the possibility of using the peptide to navigate the anticancer drug-loaded nanoparticles to breast cancer cell line BT-474 and enhance the anticancer therapeutic efficacy of the drug. The animal model also validated the cellular experiments. Our study demonstrated that NK20a designed in silico with improved binding affinity to the IL-10 receptor can be used as a tool in developing anticancer strategies.