Altogether, these results indicated that the interaction between CRC cells and M2 macrophages induced by MC-LR was achieved by increasing the expression of TGF-β1 in M2 macrophages to downregulate the expression of CST3 in CRC cells; at the same time, overexpressing CST3 could also downregulate the expression of TGF-β1 to inhibit migration. This evidence concerns the gene CST3 and colorectal carcinoma.