Collectively, our study demonstrated that BMDMs play a pivotal role during liver cancer metastasis, and loss of Ndrg2 inhibits this process by modulating macrophage polarization toward a tumor-suppressor phenotype by enhancing NF-κB pathway activation, indicating that macrophage NDRG2 may be a new therapeutic target for the treatment of liver metastasis. The gene discussed is NDRG2; the disease is liver cancer.