TREM2 and hepatocellular carcinoma: Compared with THLE-3, TREM2 protein levels were markedly reduced in HCC cell lines (Hep3B, Huh7, and PLC/PRF/5) with low metastatic and especially lower in the three HCC cell lines (MHCC97L, MHCC97H, and HCCLM3) with high metastatic potential (Fig. 1a).