ABSTRACT
The lung is one of the most common sites for cancer metastasis. Collagens in the lung provide a permissive microenvironment that supports the colonization and outgrowth of disseminated tumor cells. Therefore, down-regulating the production of collagens may contribute to the inhibition of lung metastasis. It has been suggested that miR-29 exhibits effective anti-fibrotic activity by negatively regulating the expression of collagens. Indeed, our clinical lung tumor data shows that miR-29a-3p expression negatively correlates with collagen I expression in lung tumors and positively correlates with patients' outcomes. However, suitable carriers need to be selected to deliver this therapeutic miRNA to the lungs. In this study, we found that the chemotherapy drug cisplatin facilitated miR-29a-3p accumulation in the exosomes of lung tumor cells, and this type of exosomes exhibited a specific lung-targeting effect and promising collagen down-regulation. To scale up the preparation and simplify the delivery system, we designed a lung-targeting liposomal nanovesicle (by adjusting the molar ratio of DOTAP/cholesterol-miRNAs to 4:1) to carry miR-29a-3p and mimic the exosomes. This liposomal nanovesicle delivery system significantly down-regulated collagen I secretion by lung fibroblasts in vivo, thus alleviating the establishment of a pro-metastatic environment for circulating lung tumor cells.
ABSTRACT
Metastasis is the leading cause of mortality for cancer patients, and lymphatic metastasis is one of the main ways of tumor metastasis. The role of CCL21 and its receptor CCR7 in lymphatic metastasis has been increasingly concerned in recent years. CCR7 is mainly expressed by both dendritic cells and T cells for immune responses. CCL21, the chemokine ligand for CCR7, secreted from lymphatic endothelial cells binds CCR7 and recruits immune cells toward lymphatic vessels and lymphatic nodes. CCR7 expressed tumor cells can also metastasize to lymphatic system by the similar way as immune cells. Targeting CCL21/CCR7 axis to inhibit lymphatic metastasis but remain potent anti-tumor immune response has increasingly become a spot light of tumor immunotherapy. In this review, we summarize the role of CCL21/CCR7 axis in lymphatic metastasis, as well as preclinical trials and clinical trials in targeting CCL21/CCR7 axis for tumor metastasis therapy, hoping to accelerate the progress on tumor metastasis therapy by targeting CCL21/CCR7 axis.