Holothurian triterpene glycoside cucumarioside A₂-2 induces macrophages activation and polarization in cancer immunotherapy

Background: Despite intensive developments of adoptive T cell and NK cell therapies, the efficacy against solid tumors remains elusive. Our study demonstrates that macrophage-based cell therapy could be a potent therapeutic option against solid tumors. Methods: To this end, we determine the effect of a natural triterpene glycoside, cucumarioside A₂-2 (CA₂-2), on the polarization of mouse macrophages into the M1 phenotype, and explore the antitumor activity of the polarized macrophage. The polarization of CA₂-2-pretreated macrophages was analyzed by flow cytometry and confocal imaging. The anti-cancer activity of CA₂-2 macrophages was evaluated against 4T1 breast cancer cells and EAC cells in vitro and syngeneic mouse model in vivo. Results: Incubation of murine macrophages with CA₂-2 led to polarization into the M1 phenotype, and the CA₂-2-pretreated macrophages could selectively target and kill various types of cancer in vitro. Notably, loading near-infrared (NIR) fluorochrome-labeled nanoparticles, MnMEIO-mPEG-CyTE777, into macrophages substantiated that M1 macrophages can target and penetrate tumor tissues in vivo efficiently. Conclusion: In this study, CA₂-2-polarized M1 macrophages significantly attenuated tumor growth and prolonged mice survival in the syngeneic mouse models. Therefore, ex vivo CA₂-2 activation of mouse macrophages can serve as a useful model for subsequent antitumor cellular immunotherapy developments.