From steatosis to metastasis: microenvironmental reprogramming of the liver in metabolic dysfunction-associated steatotic liver disease.

Metabolic dysfunction-associated steatotic liver disease (MASLD) has recently gained attention as a risk factor for primary liver cancer and extrahepatic cancers. Increasing evidence shows that MASLD creates a fibrotic, immunosuppressive tumor microenvironment that supports metastatic growth, making it a risk factor for liver metastasis from extrahepatic tumors, such as colorectal cancer. In steatotic liver, tumor-stromal interactions promote colorectal liver metastasis through several mechanisms, including extracellular vesicles enriched with oncogenic microRNAs, hyaluronan synthase 2-mediated hyaluronic acid production by activated hepatic stellate cells and cancer-associated fibroblasts, M2-polarized tumor-associated macrophage infiltration, and Yes-associated protein-dependent tumor signaling. In this review, we summarize key pathways involved in a pre- and pro-metastatic niche in the liver, such as extracellular vesicle-mediated intercellular communication, feed-forward loops between tumor cells and stromal fibroblasts, and hyaluronic acid-induced extracellular matrix remodeling and immune cell modulation, all of which impair antitumor immunity and promote immune escape. We also discuss how targeting hyaluronic acid synthesis, interleukin-1 signaling, or CXCR2 can restore antitumor immunity and improve responses to programmed cell death protein-1 blockade. These therapeutic approaches may offer promising benefits for patients with colorectal cancer liver metastasis.