Fig. 8

Graphic summary of the role of IL-1β/SAA3 axis in the pre-metastatic niche formation of HCC metastasis. Briefly, hepatoma cells-derived factors upregulate IL-1β expression in alveolar macrophages. On the one hand, IL-1β stimulates MMP9 expression in alveolar macrophages in an autocrine manner. On the other hand, IL-1β enhances SAA3 expression in alveolar epithelial cells. Subsequently, SAA3 recruits MMP9⁺ myeloid cells to the lung. Then, the permissive pre-metastatic niche is formed and promotes pulmonary metastasis of HCC