Enhancing the Anti-Tumor Activity and Reprogramming M2 Macrophages by Delivering Sirnas Against Sirpα and Stat6 Via M1 Exosomes and Combining With Anti-Pd-L1 Publisher Pubmed



Taghavifarahabadi M¹ ; Mahmoudi M^{2, 3} ; Mojtabavi N^{2, 3} ; Noorbakhsh F¹ ; Ghanbarian H⁴ ; Koochaki A⁵ ; Hashemi SM⁵ ; Rezaei N^{1, 6, 7} Show Affiliations
Source: Life Sciences Published:2025

Abstract

Background: The invasive property of breast cancer and the complex composition of the tumor microenvironment (TME) antibodies like anti-PD-L1, can inhibit tumor growth by promoting macrophage phagocytosis. In this research, we used anti-PD-L1 antibody and siRNAs targeting SIRPα (siSIRPα) and STAT6 (siSTAT6). The siRNAs were transported to macrophages using M1-derived exosomes. Methods: For this purpose, exosomes were isolated from the supernatant of lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Next, siSIRPα and siSTAT6 were electroporated into the M1-exosomes. M1-exosomes without siRNA or loaded with different siRNAs were used to treat M2 macrophages. Then, the polarization of macrophages was evaluated. By co-culturing of treated macrophages with 4T1 cells, anti-tumor functions of macrophages were assessed. Results: It was demonstrated that siRNA-loaded M1-exosomes induced macrophage polarization into an M1 phenotype and promoted the anti-tumor effects of macrophages as shown by a reduction in migration, invasion and proliferation of 4T1 cells, as well as an enhancement of phagocytosis of 4T1 cells by macrophages. Conclusion: This study demonstrated the potential of a multifaceted therapeutic approach targeting TAMs to enhance anti-tumor immune responses in breast cancer. © 2024 Elsevier Inc.