Nano-drug delivery strategies affecting cancer-associated fibroblasts to reduce tumor metastasis

Tumor metastasis is the leading cause of high mortality in most cancers, and numerous studies have demonstrated that the malignant crosstalk of multiple components in the tumor microenvironment (TME) together promotes tumor metastasis. Cancer-associated fibroblasts (CAFs) are the major stromal cells and crosstalk centers in the TME of various kinds of tumors, such as breast cancer, pancreatic cancer, and prostate cancer. Recently, the CAF-induced pro-tumor metastatic TME has gained wide attention, being considered as one of the effective targets for tumor therapy. With in-depth research, CAFs have been found to promote tumor metastasis through multiple mechanisms, such as inducing epithelial–mesenchymal transition in tumor cells, remodeling the extracellular matrix, protecting circulating tumor cells, and facilitating the formation of a pre-metastatic niche. To enhance the anti-tumor metastasis effect, therapeutic strategies designed by combining nano-drug delivery systems with CAF modulation are undoubtedly a desirable choice, as evidenced by the research over the past decades. Herein, we introduce the physiological properties of CAFs, detail the possible mechanisms whereby CAFs promote tumor metastasis, categorize CAFs-based nano-drug delivery strategies according to their anti-metastasis functions and discuss the current challenges, possible solutions, as well as the future directions in order to provide a theoretical basis and reference for the utilization of CAFs-based nano-drug delivery strategies to promote tumor metastasis therapy.