Bone-marrow-derived cell-released extracellular vesicle miR-92a regulates hepatic pre-metastatic niche in lung cancer

Metastatic tumors have been shown to establish a supportive pre-metastatic niche (PMN) in distant organs, which in turn determines disseminated tumor cells' targeting of such organs. PMN is formed through the recruitment of bone-marrow-derived cells (BMDCs); however, the role of BMDCs in PMN formation is not fully understood. On the basis of RNA-seq data and bioinformatic analysis, secretion of extracellular vesicle (EV) miR-92a by BMDCs of lung cancer-bearing mice contributes to the establishment of liver PMN. Both BMDC-derived EVs and miR-92a mimics potentiate the activation of hepatic stellate cells (HSCs), subsequently increasing extracellular matrix (ECM) deposition in mice. Consequently, remodeling of the liver microenvironment enhanced immunosuppressive cell accumulation and cancer cell attachment. EVs miR-92a directly suppressed its target SMAD7, leading to the enhancement of transforming growth factor-beta signaling in HSC. Elevated levels of circulating miR-92a are found in the sera of lung cancer patients, and EVs isolated from these patients have a similar ability to increase HSCs activation and ECM protein expression. Our study reveals the sequential steps of liver PMN formation in lung cancer, providing critical mediators that prepare PMN in the liver, and identifies new targets that offer valuable options for diagnosis and therapeutic intervention.