A Lung-Targeted Lipid Nanoparticle System Delivers miRNA to Suppress Colorectal Cancer Pulmonary Metastases

Background: Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide, with more than 90% patients dying from metastasis due to limited treatment options. Although miRNA-based therapeutics represent a promising strategy, their clinical application has been hindered by poor stability in vivo and the lack of efficient organ-specific delivery systems. Methods: In this study, we developed a lung-targeted lipid nanoparticle (LuT-LNP) platform for the delivery of a chemically modified miRNA, AM22, which demonstrated enhanced tumor-suppressive activity. By replacing cholesterol and helper lipids with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), the most abundant lipid in pulmonary surfactant, and systematically optimizing the ratios of ionizable and cationic lipids, we obtained a LuT-LNP formulation with superior lung tropism. Results: The resulting LuT-LNPs exhibited excellent stability, biocompatibility, and efficient encapsulation and protection of AM22. Both in vitro and in vivo, AM22-loaded LuT-LNP (AM22@LuT-LNP) significantly inhibited the proliferation and migration of CRC cells and markedly suppressed lung metastasis in a mouse model. Mechanistic studies revealed that AM22 acts by targeting Poly (ADP-ribose) polymerase 1 (PARP1), inducing DNA damage, and inhibiting the epithelial-mesenchymal transition (EMT) process. Conclusions: These findings established a lung-targeted delivery platform for miRNA-based therapy, offering a promising strategy for the treatment of colorectal cancer pulmonary metastasis (CRPM).