S100 calcium-binding protein A9 from tumor-associated macrophage enhances cancer stem cell-like properties of hepatocellular carcinoma

Tumor-associated macrophages (TAMs) are crucial components of the tumor microenvironment. They play vital roles in hepatocellular carcinoma (HCC) progression. However, the interactions between TAMs and HCC cells have not been fully characterized. In this study, TAMs were induced using human monocytic cell line THP-1 cells in vitro to investigate their functions in HCC progression. S100 calcium-binding protein A9 (S100A9), an inflammatory microenvironment-related secreted protein, was identified to be significantly upregulated in TAMs. S100A9 expression in tumor tissues was associated with poor survival of HCC patients. It could enhance the stem cell-like properties of HepG2 and MHCC-97H cells by activating nuclear factor-kappa B signaling pathway through advanced glycosylation end product-specific receptor in a Ca2+-dependent manner. Furthermore, we found that, after treatment with S100A9, HepG2 and MHCC-97H cells recruited more macrophages via chemokine (C-C motif) ligand 2, which suggests a positive feedback between TAMs and HCC cells. Taken together, our findings reveal that TAMs could upregulate secreted protein S100A9 and enhance the stem cell-like properties of HCC cells and provide a potential therapeutic target for combating HCC.

Automated summary

The study revealed that TAMs can enhance the stem cell-like properties of HCC cells by upregulating the secreted protein S100A9, which in turn activates the NF-kB signaling pathway. Additionally, S100A9 can promote the recruitment of macrophages to HCC cells, suggesting a positive feedback loop between TAMs and HCC cells.