Celastrol acts as a new histone deacetylase inhibitor to inhibit colorectal cancer cell growth via regulating macrophage polarity.

The tumorigenesis and progression of colorectal cancer are closely related to the tumor microenvironment, especially inflammatory response. Inhibitors of histone deacetylase (HDAC) have been reported as epigenetic regulators of the immune system to treat cancer and inflammatory diseases and our results demonstrated that Celastrol could act as a new HDAC inhibitor. Considering macrophages as important members of the tumor microenvironment, we further found that Celastrol could influence the polarization of macrophages to inhibit colorectal cancer cell growth. Specially, we used the supernatant of HCT116 and SW480 cells to induce Ana-1 cells in vitro and chose the spontaneous colorectal cancer model APC min/+ mice as an animal model to validate in vivo. The results indicated that Celastrol could reverse the polarization of macrophages from M2 to M1 through impacting the colorectal tumor microenvironment both in vitro and in vivo. Furthermore, using bioinformatics analysis, we found that Celastrol might mechanistically polarize the macrophages through MAPK signaling pathway. In conclusion, our findings identified that Celastrol as a new HDAC inhibitor and suggested that Celastrol could modulate macrophage polarization, thus inhibiting colorectal cancer growth, which may provide some novel therapeutic strategies for colorectal cancer.