Dually regulating the proliferation and the immune microenvironment of melanoma via nanoparticle-delivered siRNA targeting onco-immunologic CD155.

Studies have shown that the simultaneous regulation of tumor cell proliferation and the suppressive tumor immune microenvironment (TIME) could achieve better therapeutic effects. However, the targets of the proliferation and the TIME are different, which greatly limits the development of cancer therapy. A recent study found CD155, a highly expressed poliovirus receptor in melanoma cells and melanoma-infiltrating macrophages, functions as both an oncogene and immune checkpoint. Thus, it is supposed that targeting CD155 could bring dual therapeutic effects. Herein, we propose silencing the CD155 of melanoma cells and melanoma-infiltrating macrophages by a nanoparticle-delivered small interference RNA (siRNA) targeting CD155 (siCD155). We encapsulated siCD155 into cationic lipid-assisted nanoparticles (CLAN) and demonstrated that the intravenous injection of CLAN could efficiently deliver siCD155 into melanoma cells and melanoma-infiltrating macrophages. The downregulation of CD155 in melanoma cells directly inhibited their proliferation, and meanwhile, the downregulation of CD155 in melanoma-infiltrating macrophages increased the activation of NK cells and T cells. Owing to this dual effect, CLAN significantly inhibited the growth of B16-F10 melanoma. Our study suggests that nanoparticle-delivered siCD155 may be a simple but effective strategy for inhibiting tumor proliferation and reprogramming TIME.