IL-1β promotes the nuclear translocaiton of S100A4 protein in gastric cancer cells MGC803 and the cell's stem-like properties through PI3K pathway

It has been shown that nuclear expression of S100A4 is significantly correlated with increased metastasis and reduced survival in patients with gastric cancer and many other cancers. However, the factors which could influence the nuclear contents of S100A4 in cancer cells are not clear. It has also been reported that Interleukin-1 beta (IL-1 beta) promotes the nuclear translocation of S100A4 in chondrocytes. Previous studies have shown that IL-1 beta promotes the stemness of colon cancer cells, and S100A4 is also involved in maintaining cancer-initiating cells in head and neck cancers. We speculate that IL-1 beta might promote the nuclear translocation of S100A4 protein in MGC803 gastric cancer cells and therefore enhance their stem-like properties. The results from Western-blot and qRT-PCR analysis showed that IL-1 beta increased the nuclear and total cellular content of S100A4 protein and S100A4 mRNA level in MGC803 cells. LY294002, a pharmacological inhibitor of Phosphoinositide 3-kinase (PI3K) reversed the above effects. Functional studies indicated that IL-1 beta promoted the colony-forming and spheroid-forming capabilities of the cells and the expression of SOX2 and NANOG gene. PI3K or S100A4 inhibition reversed the IL-1 beta-mediated increase in colony and spheroid-forming capabilities of the cells. LY294002 also reversed the elevated SOX2 and NANOG expression induced by IL-1 beta. Our study demonstrated that IL-1 beta promote the nuclear translocation of S100A4 protein in gastric cancer cells MGC803, which are PI3K dependent, suggesting the existence of IL-1 beta-PI3K-S100A4 pathway for the first time. The study also showed that IL-1 beta promoted stem-like properties of the cells through the new pathway.